Stars of Shareware: Raytrace & Morphing/SOS-RAYTRACE.ISO/programm/texte/gamma.txt

Text File | 1993-11-19 | 105.8 KB | 2,960 lines

#: 62186 S3/Autodesk 3D Studio
    18-Oct-93  13:48:36
Sb: #Setting r3 gamma
Fm: David Rhoten 71450,2654
To: ALL

I've got a question about setting the Framebuffer gamma with r3.

I've get a Targa+64 with an NTSC type monitor (a TV with composite video
input), and the TConfig batch files I use have been set with gamma at 1.0.

I run the little "Set" framebuffer gamma calibration in 3DS, but the two areas
look NOTHING like one another, no matter where I put the slider.  Am I just
not standing back and squinting far enough, or does it have something to do
with the picture/color/black_level/contrast/tint settings on the monitor?  I
have tried displaying a little test pattern image with red, blue, green,
greyscale, etc) and setting the monitor to make those colors look acceptable
first, but I have no other resource as to what they should look like than my
eyes.

Do I just set it at 2.0 and leave it?

Dave



There are 2 Replies.

#: 62210 S3/Autodesk 3D Studio
    18-Oct-93  16:28:09
Sb: #62186-Setting r3 gamma
Fm: Martin Foster[Animatrix] 70303,456
To: David Rhoten 71450,2654

David,

gamma certainly adds a knew level of confusion. I just faithfully use 2.2 for
all my NTSC work, regardless of the matching thing on my TV.

#: 62227 S3/Autodesk 3D Studio
    18-Oct-93  19:49:30
Sb: #62186-Setting r3 gamma
Fm: Yost Group 76702,413
To: David Rhoten 71450,2654

Martin's right on two counts: gamma adds confusion and, when in doubt, set it
for 2 or 2.2 for NTSC. (1.8 usually works for most other applications.)

        - Jack

#: 62311 S3/Autodesk 3D Studio
    19-Oct-93  09:37:57
Sb: #62227-Setting r3 gamma
Fm: David Rhoten 71450,2654
To: Yost Group 76702,413 (X)

OH!  I see, Jack & Martin!!!!!!  This whole gamma thing is just something that
old-timers (video-wise) use to confuse us neophytes (kinda like a high-tech
snipe hunt!).<g>  You sit back and laugh while we squat out there in the
bushes all night, waiting to catch the elusive Gamma Correction!

Dave



#: 62319 S3/Autodesk 3D Studio
    19-Oct-93  10:15:10
Sb: #62227-#Setting r3 gamma
Fm: Steve Ormonde 72647,2577
To: Yost Group 76702,413 (X)

Jack,

Is it uncommon to see a gamma level of 1.35?  Our final renderings will be
displayed on computer monitors only, so using the pattern setup, that's the
number it came up with.

I imagine the number will vary from monitor to monitor and likewise for
graphics cards...

Steve Ormonde

There is 1 Reply.

#: 62345 S3/Autodesk 3D Studio
    19-Oct-93  11:16:13
Sb: #62319-Setting r3 gamma
Fm: Yost Group 76702,413
To: Steve Ormonde 72647,2577

A gamma of 1.35 isn't that unusual for certain computer monitors.  If that's
the number that the pattern came up with, use it!

                - G

#: 62334 S3/Autodesk 3D Studio
    19-Oct-93  10:55:41
Sb: #62186-Setting r3 gamma
Fm: David J. Marks 72172,1036
To: David Rhoten 71450,2654

I also have a Targa 64+.  When I adjusting Gamma, I got results similar to
yours.  I discovered that contrast and brightness controls make a difference,
the Tconfig program for the Targa allows gamma correction, and some VTR's have
built in Gamma.  So...

Try to run from the framebuffer directly to the NTSC monitor, thus eliminating
any VTR gamma correction.  Then check TCONFIG to make certain it is NOT gamma
correcting.  Then try to adjust 3DS gamma to get the grey squares to match up.
Play with brightness and contrast on the monitor and you may detect a little
difference too.

Let the forum know how you make out.  I'm not completely satisfied that I've
got gamma working, and I'm sure more people will run into the same problems.



#: 62343 S3/Autodesk 3D Studio
    19-Oct-93  11:12:59
Sb: #62186-#Setting r3 gamma
Fm: Yost Group 76702,413
To: David Rhoten 71450,2654

It sounds like your Targa board might be trying to do some gamma correction on
its own.  Are you setting tconfig to make the gamma 1.0 (which would be
gamma-correcting to make it linear on a video device) or are you making sure
that the gamma board is booting up in 1.0 mode (with no gamma correction at
all)?  It's critical, if you want to use 3DS gamma correction that absolutely
nothing else in the video chain attempts to do gamma correction. DavidM's note
re playing with the brightness/contrast on your monitor is important... plus,
some monitors actually do their own built-in form of gamma correction.  First,
absolutely make sure that the targa is not gamma correcting at all, and then
plug a plain vanilla NTSC monitor (preferably composite) into the targa.

I'm assuming that you're going out to video.  Is that right?

                - G

There is 1 Reply.

#: 62460 S3/Autodesk 3D Studio
    19-Oct-93  23:08:58
Sb: #62343-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Yost Group 76702,413

Gary,
        I seem to be having the same problem setting the gamma on my Targa+.
I'm running through a T+ 16/32 straight to an NTSC monitor via S-video. The
Targa Gamma is set to 1.0 via "tconfig". I couldn't get the color swatches to
come even close. The outer box was much darker than the inside, and it also
gives off an annoying moire pattern. After reading the notes here, I tried
adjusting the brightness and contrast controls to get the grays to match,
(they still don't, but they're closer) with the gamma set to 2.1. I did this
in the Mat editor and left the display at 1.8 (a perfect gray match!) and
rendered some materials on both the display and the Targa. The samples appear
dark and kind of muddy on both displays, but they do match, however... I
loaded several JPEGs off the CD (view image) and they ALL apear much to dark.

        I've reverted to what I was doing, which is seting the Targa gamma to
2.1 in 3ds and then setting the monitor's bright/contrast so that the cd
sample images look their best.
        My display gamma is still set to 1.8, which seems to be the best by
matching the gray squares, but sample materials rendered on the display still
seem much to dark.

        Any thoughts...

                                                David

#: 62389 S3/Autodesk 3D Studio
    19-Oct-93  15:49:25
Sb: #62186-Setting r3 gamma
Fm: David J. Marks 72172,1036
To: David Rhoten 71450,2654

I also have a Targa 64+.  When I adjusting Gamma, I got results similar to
yours.  I discovered that contrast and brightness controls make a difference,
the Tconfig program for the Targa allows gamma correction, and some VTR's have
built in Gamma.  So...

Try to run from the framebuffer directly to the NTSC monitor, thus eliminating
any VTR gamma correction.  Then check TCONFIG to make certain it is NOT gamma
correcting.  Then try to adjust 3DS gamma to get the grey squares to match up.
Play with brightness and contrast on the monitor and you may detect a little
difference too.

Let the forum know how you make out.  I'm not completely satisfied that I've
got gamma working, and I'm sure more people will run into the same problems.



#: 62354 S3/Autodesk 3D Studio
    19-Oct-93  12:39:47
Sb: #Setting r3 gamma
Fm: Phillip L. Miller 74710,3061
To: Yost Group 76702,413 (X)

The gamma control dialogue box also seems to operate best (only?) when one is
using a 24-bit color display at the time. With lower color resolutions it
appears to "jump" in shade intensities across the slider. Is this observation
correct?

Just for better understanding, does 3DS' "gray" gamma control work as well as
PhotoShop's sepeperate RG&B gamma correction?

- Phil


There is 1 Reply.

#: 62452 S3/Autodesk 3D Studio
    19-Oct-93  21:40:15
Sb: #62354-Setting r3 gamma
Fm: Mark Bessette 71572,3251
To: Phillip L. Miller 74710,3061 (X)

Phillip -

I installed R3 tonight and seem to be having some of the same problems.

When I try to adjust Gamma the small box is dark or light. It changes from
dark to light at 2.00. I can't adjust it anywhere near what it should be to
match the grays of the two boxes.

I also rendered a couple of sample images and they seem to be very dark. Do
you know if this is caused by an improper Gamma setting?

mark

#: 62512 S3/Autodesk 3D Studio
    20-Oct-93  10:39:26
Sb: #62311-#Setting r3 gamma
Fm: Yost Group 76702,413
To: David Rhoten 71450,2654

"Elusive" is definitely the word to describe gamma. But once you get it
adjusted, you don't have to bother with it again (unless you change monitors),
and the results are fantastic.

        - J

There is 1 Reply.

#: 62581 S3/Autodesk 3D Studio
    20-Oct-93  17:43:40
Sb: #62512-#Setting r3 gamma
Fm: David J. Marks 72172,1036
To: Yost Group 76702,413 (X)

YG: "Elusive" is definitely the word to describe gamma. But once you get it
adjusted, you don't have to bother with it again (unless you change monitors),
and the results are fantastic.

I'd like to change the subject line to read "Trouble in Paradise!"

I just spent a marathon 1.5 hours on the phone with Truevision to find out why
Gamma correction in 3DSr3 isn't helping me at all.  The gamma adjustment
slider in 3DS always winds up darn close to 1.0 for my composite NTSC signal.

According to Truevision, here's why:  The Targa + boards are "optimized" for
NTSC video, utilizing look-up tables to put the correct information on the
screen.  To me, this translates to "pre-corrected" gamma.  The techies there
(I had 3 of them on speaker phone) asked that the Yost Group contact them
regarding my question.  They were able to reproduce my results exactly.  I
will Email you the phone number.

Please check into this as many of us would like to take advantage of your
gamma correction instead.  Thanks.

- David J. Marks



There is 1 Reply.

#: 62594 S3/Autodesk 3D Studio
    20-Oct-93  18:51:22
Sb: #62581-#Setting r3 gamma
Fm: Yost Group 76702,413
To: David J. Marks 72172,1036 (X)

There are definitely ways to inhibit the Targa+ boards from doing any gamma
correction.  I'll call the guy at Truevision you mentioned in your email and
see what he says.

                - G

There is 1 Reply.

#: 62646 S3/Autodesk 3D Studio
    20-Oct-93  23:03:57
Sb: #62594-Setting r3 gamma
Fm: David J. Marks 72172,1036
To: Yost Group 76702,413 (X)

Re: Disabling Targa Gamma correction

Thanks for looking into it.  I had three of their guys on the phone trying to
figure this one out.  We did find that their TCONFIG program has a gamma
slider.  It is set to a value of 1.0 as a default, and can be set to values
below 1 if necessary.  Backing into things, I set 3DS Gamma to 2.2 (your
number from somewhere), shelled out to TCONFIG and dropped their gamma to 0.5
to make the grey boxes match.  However, this was just a test, and I'd guess
that this correction/decorrection combo must trash the adjustment.

Now I just have to hope that my Sony EVO-9650's don't have built in Gamma
correction! Argh.

Thanks again.  - dave


#: 62513 S3/Autodesk 3D Studio
    20-Oct-93  10:42:52
Sb: #62460-#Setting r3 gamma
Fm: Don Landis 71673,3612
To: David Stinnett 70214,774 (X)

Althouigh I haven't gotten this far with installation of r3 I've been
following this gamma problem on the targa+.  It seems to me that one would be
advised to not adjust the monitor to get the gamma to work.  The monitor is
your primary measuring device and as such should be calibrated using a
standard NTSC color bar from a standard source and using blue gun set the
color/tint/brightness/ and contrast for perfect bars.  The bars should be from
a standard source like a signal generator or camera, or, in a pinch recorded
from broadcast TV.  Once the monitor is calibrated leave those controls alone!
Then go in and attempt to use the gamma adjusting setup in r3.  You see, if
you're constantly adjusting your monitor to match what ever the targa+/3DSr3
is putting out you won't be calibrating anything.  It's like trying to get
your car to go faster so in tinkering with the speedometer you're able to
accomplish this, right?  <g>

There are 2 Replies.

#: 62525 S3/Autodesk 3D Studio
    20-Oct-93  11:25:25
Sb: #62513-Setting r3 gamma
Fm: Yost Group 76702,413
To: Don Landis 71673,3612 (X)

Don, you're ABSOLUTELY correct.

                - G

#: 62649 S3/Autodesk 3D Studio
    20-Oct-93  23:17:55
Sb: #62513-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Don Landis 71673,3612

Don,
        Actually, I spit out several images onto the Targa and adjusted the
monitor controls so that I got the best image on all the stills with a single
monitor setting, so now that they're set, I don't need to touch them again. I
certainly didn't mean to imply that I was adjusting the monitor each time a
different image was displayed. That would be rather pointless. Regarding the
NTSC color bar pattern, that is something I should check into. I think there's
one in one of the libraries here, if I remember right. I think it would be
helpful if a color bar targa file was included on the 3ds cd for just this
kind of thing. (maybe next release, Gary?)

                                                David

#: 62524 S3/Autodesk 3D Studio
    20-Oct-93  11:24:45
Sb: #62460-#Setting r3 gamma
Fm: Yost Group 76702,413
To: David Stinnett 70214,774 (X)

You should always have your brightness and contrast controls set at their
normal (centered) position when you adjust gamma values.  It sounds like your
Targa board is still doing gamma correction, if the outer box is always darker
than the inner box.  You can try running to the monitor via the NTSC signal
instead of the S-video signal... that might give you a better idea of what's
going on.  Since you say that you're setting your display gamma to 1.8 and
your samples are "much too dark", it sounds like you're either setting your
brightness and/or contrast too low (off the center position) or that
something's wrong with your monitor.

Are you going out to videotape with this setup?  If you aren't, you might want
to try turning gamma off and seeing if that makes life easier for you.

                - G

There is 1 Reply.

#: 62650 S3/Autodesk 3D Studio
    20-Oct-93  23:18:05
Sb: #62524-#Setting r3 gamma
Fm: David Stinnett 70214,774
To: Yost Group 76702,413 (X)

Gary,
        All the controls on both monitors were pretty much centered when
setting the gamma (and still are). If the Targa is doing correction on its
own, I don't know, But a tconfig batch set to 1.0 is run before starting 3ds.
I'll try to use the composite out of the Targa and see if that has a different
effect. I do plan on sending a bunch of stuff out to be laid to tape in the
next few months, so I would like to keep the 3ds gamma on, rather than not
dealing with it.
        The controls are also centered on the NEC 5FGe, and everything looks
fine in Windows and other programs, including the 3ds modules, with the single
exception of the rendered spheres in the mat editor, which don't look nearly
as vibrant as the screenshot of the mat editor on the 3ds box. However, since
I'm rendering those to the Targa, I'm not that concerned with that.
        This whole gamma thing brings up another question. When a shot is
rendered in 3ds and brought in to another program such as Photoshop for
touchup, what Photoshop gamma setting is ideal, none, 1.0, (same?) 1.8, or
simply whatever looks best (1.8)? A whole book can probably be written on the
subject, if it already hasn't! Well, I think I'll go read the gamma section in
the advanced users guide again.


                                                David


There is 1 Reply.

#: 62683 S3/Autodesk 3D Studio
    21-Oct-93  08:38:28
Sb: #62650-Setting r3 gamma
Fm: Yost Group 76702,413
To: David Stinnett 70214,774

Based on my experience with PhotoStyler, which is very close to Photoshop, you
would adjust their monitor calibration in much the same way as in 3dsR3, and
then just leave it alone. They also have a method of applying gamma curves to
the bitmap image, which you should avoid since they work in 24-bit color
space.

        - Jack

#: 62534 S3/Autodesk 3D Studio
    20-Oct-93  11:46:47
Sb: #62343-#Setting r3 gamma
Fm: David Rhoten 71450,2654
To: Yost Group 76702,413 (X)

Gary:

Yes, I checked the batch files that TConfig had created, and they were made
with Gamma set to 1.0.  My monitor is a little 13" Panasonic TV set that has a
composite video in.  I will try the following:  I will run the gamma config
from 3DS and set it to 2.0.  Then, using the black level control on the
Panasonic, I'll try and get the greys close.  I'll let you know.

Yes, I'm trying to set this for video.  When I'm doing something for print
(dye-sub) and film (slide/4x5), should I use a 1.0 setting, and then let
PhotoStyler or whatever I'm using to print from correct the gamma?

Dave



There is 1 Reply.

#: 62596 S3/Autodesk 3D Studio
    20-Oct-93  18:53:14
Sb: #62534-Setting r3 gamma
Fm: Yost Group 76702,413
To: David Rhoten 71450,2654

If you look at the 4-color section in the 3DSr3 reference manual, on the top
of the 3rd page of that section you'll see gamma tests for print output.
We've found that a gamma value of 1.8 provides the best balance of contrast
for print.  You definitely want to get as close as possible in 3DSr3 instead
of doing all the gamma correction in PhotoStyler.  Why? Because once the
24-bit image is in a paint program, you'll be quantizing the colors when you
do gamma correction to it (since it's out of the 3DS 48-bit color domain).
That's BAD.

                - G

#: 62535 S3/Autodesk 3D Studio
    20-Oct-93  11:46:48
Sb: #62389-Setting r3 gamma
Fm: David Rhoten 71450,2654
To: David J. Marks 72172,1036 (X)

Okay, I'll play around.  See my reply to Gary.


Dave


#: 62527 S3/Autodesk 3D Studio
    20-Oct-93  11:26:20
Sb: #62452-#Setting r3 gamma
Fm: Yost Group 76702,413
To: Mark Bessette 71572,3251 (X)

Are you referring to framebuffer gamma or display gamma?

If your center grey box is changing from too dark to too light at 2.00, that's
_probably_ what your optimal gamma is.  Set it to the point at which it starts
changing, stand back about 4 feet from the monitor, and squint.  That will
give you your best shot at viewing the gamma setting.

If you're rendering with a gamma of 2.00 and your images are very dark, then
either: 1) your monitor controls are adjust lower than their center-point (you
need to leave them at their center-point) or 2) you don't have enough lights
in your scene, or 3) one of your hardware devices (framebuffer, monitor,
encoder, etc) is doing something weird to the gamma.

                - G

There is 1 Reply.

#: 62633 S3/Autodesk 3D Studio
    20-Oct-93  21:09:44
Sb: #62527-Setting r3 gamma
Fm: Mark Bessette 71572,3251
To: Yost Group 76702,413 (X)

>Are you referring to framebuffer gamma or display gamma?<

Setting-up the display gamma.

When setting-up display  gamma with Photostyler there is a smooth transition.
It is hard to pick the correct gamma. It takes a little practice.

What I'm seeing is from 1.99 and below (dark gray) from 2.00 up (light gray).
There is no point or transition where it starts to change. It is very abrupt.

Changing monitor brightness might help with some of the renderings. I'll try
it.  I'm using a NEC 3FGe monitor. The monitor does not have an indent that I
can find. Maybe I'll turn the monitor upside-down.(g)

I'm going to set the display gamma for 2.00 (the point it changes) and see how
well everything works.

I was dreading getting another version because set-up of a new program always
has problems. I read most of the installation guide and went through the
install.

EVERYTHING RAN WHEN I TYPED 3DS! Still have a small glitch with memory but
that might be QEMM.

I can't wait to start using some of the new features. Congrats!

mark


#: 62526 S3/Autodesk 3D Studio
    20-Oct-93  11:26:02
Sb: #62354-Setting r3 gamma
Fm: Yost Group 76702,413
To: Phillip L. Miller 74710,3061 (X)

Correct... The gamma setting control will only work with a 24-bit display.

Regarding our grey-scale gamma setting vs Photoshop's seperate RGB gamma
controls... good question.  We did quite a bit of research with this and found
that we got the same results using the Photoshop/Photostyle method and with
our grey-scale method.  We also asked a number of experts in the field (ie:
Roy Hall, Don Brittain, and others) and everyone agreed that the grey-scale
method would be fine.  On my NEC Multisync 5FG monitor, the Photoshop-style
gamma system reads 1.65, and so does the 3DSr3 gamma setting dialog.

                - G

#: 62540 S3/Autodesk 3D Studio
    20-Oct-93  12:22:50
Sb: #Setting r3 gamma
Fm: Phillip L. Miller 74710,3061
To: Yost Group 76702,413 (X)

Thanks for the gamma info. One gets the hang of it after perfecting just
the right combination of squinting and looking slightly cross-eyed at those
squares <g>.

Do you know if app's such as PhotoShop save/use gamma info any differently? -
or is always split to 3 channels and used by all the same?

- Phil


There is 1 Reply.

#: 62597 S3/Autodesk 3D Studio
    20-Oct-93  18:56:26
Sb: #62540-Setting r3 gamma
Fm: Yost Group 76702,413
To: Phillip L. Miller 74710,3061 (X)

The primary difference between the way PhotoShop uses gamma and the way 3DSr3
uses gamma is that 3DS does its gamma computations in 48-bit color space (64,
including the alpha channel), and then it samples down to 24-bits.  PhotoShop,
on the other hand, doesn't have any extra color data to work with, so it must
do everything in 24-bits, producing quantizing/banding artifacts.

                - G

#: 62673 S3/Autodesk 3D Studio
    21-Oct-93  06:25:26
Sb: Setting r3 gamma
Fm: Phillip L. Miller 74710,3061
To: Yost Group 76702,413 (X)

Thanks again for the clarification. You have good reason to be proud of
3DSr3's color rendition! Gradients are exquisite with their all so subtle
dithers.

- Phil

#: 62736 S3/Autodesk 3D Studio
    21-Oct-93  14:45:45
Sb: #62649-#Setting r3 gamma
Fm: Don Landis 71673,3612
To: David Stinnett 70214,774 (X)

I uploaded an NTSC colorbar from a test generator and grabbed as a targa file.
It would be ok to use to adjust your targa gamma but not for monitor
adjustment.  You really need a standard CB source.  Actually, to adjust the
targa you really need the match gray panels test that you have been using.
Your adjusting the monitor with unknown source targa files would still be
guess work in my book.
  I'm currently trying to match gamma between TOPAS output and 3DS.  The
strategy I'm using is to match each to a standard monitor and hope for the
best.  However, I might have to use TOPAS as the standard since 3DS has more
user control over this setting, especially r3.  I'm using both packages to lay
tga's in sequence using effects from each for the project.

There is 1 Reply.

#: 62823 S3/Autodesk 3D Studio
    22-Oct-93  02:59:32
Sb: #62736-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Don Landis 71673,3612

>>to adjust the targa you really need the match gray panels test that you have
been using.  Your adjusting the monitor with unknown source targa files would
still be guess work in my book.<<

        Unfortunately, the gray panels test simply won't work. If the
brightness/contrast controls are close to centered, the grays can't even come
close, and if the monitor's controls are adjusted to let the grays kinda
match, then the images displayed are much too dark. Everthing seems to look
good now, so I'll try rendering some of the sample scenes on the cd, and if
they look good without adjustment, I should be set.

                                                Thanks,
                                                        David

#: 62737 S3/Autodesk 3D Studio
    21-Oct-93  14:54:53
Sb: #62649-#Setting r3 gamma
Fm: Kevin Krell [CSA] 76077,2774
To: David Stinnett 70214,774 (X)

David,
       There is a color-bar .GIF (which, considering the colors used, is just
fine) included on the 3D Studio R3 CD.

               Kevin Krell - Computer Support Associates

There is 1 Reply.

#: 62824 S3/Autodesk 3D Studio
    22-Oct-93  02:59:42
Sb: #62737-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Kevin Krell [CSA] 76077,2774

Could you tell me where and under what name? I looked but couldn't find
anything.

                                                Thanx,
                                                        David

#: 62775 S3/Autodesk 3D Studio
    21-Oct-93  19:40:49
Sb: #62650-#Setting r3 gamma
Fm: Yost Group 76702,413
To: David Stinnett 70214,774 (X)

As Jack said, you want to get the gamma right in 3DS, and then leave it linear
in Photoshop.

                - G

There is 1 Reply.

#: 62822 S3/Autodesk 3D Studio
    22-Oct-93  02:58:57
Sb: #62775-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Yost Group 76702,413

Gamma in Photoshop is set at the default of 1.8, and stuff looks fine, so I
don't think I'll mess with it.

                                                Thanks,
                                                        David

#: 62690 S3/Autodesk 3D Studio
    21-Oct-93  09:41:13
Sb: #62596-Setting r3 gamma
Fm: David Rhoten 71450,2654
To: Yost Group 76702,413 (X)

Thanks Gary!  Yeah, I forgot about the little gamma illustrations.  I
appreciate it, and await the results of your conversation with the Truevision
techs.

Dave



#: 62727 S3/Autodesk 3D Studio
    21-Oct-93  13:01:35
Sb: #62581-Setting r3 gamma
Fm: krazy images 72724,3111
To: David J. Marks 72172,1036 (X)

Wow! 3 guys, 1.5 hours? And someone say that there are no Truevision support.
<g>

ana /krazy images


#: 62864 S3/Autodesk 3D Studio
    22-Oct-93  12:03:30
Sb: #62823-Setting r3 gamma
Fm: Don Landis 71673,3612
To: David Stinnett 70214,774 (X)

I havn't spent much time this past week with 3DSr3 due to three projects
finishing up on r2.01 and evaluating Topas.  I did look at the Targa+ output
gamma test and it matched perfectly at 1.0.  I have the gamma adjustment in
tconfig at 1.0 if I recall.  My monitor is calibrated with NTSC CB from a
signal generator.  I'll play with it some more this weekend when I finish
these projects.  No work for the next two weeks so I should have some time to
play and update my resume tape.

#: 62867 S3/Autodesk 3D Studio
    22-Oct-93  13:01:53
Sb: #62824-#Setting r3 gamma
Fm: Kevin Krell [CSA] 76077,2774
To: David Stinnett 70214,774 (X)

David,
       Where what & under what name what?  It figures - just when you want
people to cut down on extensive quoting of previous messages...

               Kevin Krell - Computer Support Associates

Lost in an impenetrable forest.

There is 1 Reply.

#: 62941 S3/Autodesk 3D Studio
    22-Oct-93  21:56:50
Sb: #62867-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Kevin Krell [CSA] 76077,2774

Kevin,

>> Where what & under what name what?  It figures - just when you want people
to cut down on extensive quoting of previous messages...<<

        I was asking about....

 >> There is a color-bar .GIF (which, considering the colors used, is just
fine) included on the 3D Studio R3 CD.<<

        Thanks.

>>Lost in an impenetrable forest.<<

        Have you tried leaving a trail of bread crumbs? Or does that only work
in caves?<g>

                                                David






#: 62855 S3/Autodesk 3D Studio
    22-Oct-93  10:47:01
Sb: #62822-Setting r3 gamma
Fm: Yost Group 76702,413
To: David Stinnett 70214,774 (X)

I'd agree with you that if everything looks fine, leave it.

                - G

#: 63280 S3/Autodesk 3D Studio
    25-Oct-93  14:40:22
Sb: #62941-#Setting r3 gamma
Fm: Kevin Krell [CSA] 76077,2774
To: David Stinnett 70214,774 (X)

David,
       The file you want is actually distributed on the R3 diskettes.  In your
3DS3\IMAGES directory, look for TESTPAT.GIF.  It is a low-res version, though
- I guess 320x200.  It includes RGB, CMYB and grey-scale.

               Kevin Krell - Computer Support Associates

There is 1 Reply.

#: 63384 S3/Autodesk 3D Studio
    26-Oct-93  00:02:14
Sb: #63280-Setting r3 gamma
Fm: David Stinnett 70214,774
To: Kevin Krell [CSA] 76077,2774

Found it. Thanks.

                        David

#: 63695 S3/Autodesk 3D Studio
    27-Oct-93  10:14:03
Sb: #Gamma correction
Fm: McDOWELL OWENS 75250,461
To: all

We are currently using release 3.0 with a Truevision Targa+64 framebuffer.
Using the Gamma correction feature in 3.0 we have set the framebuffer Gamma to
1.0 with a tconfig.bat file.  The on screen set command for the framebuffer is
also set at 1.0 for the closest match on a NTSC monitor. Is this correct?
What about the 2.2 recommended for output to NTSC? please help!

There is 1 Reply.

#: 63702 S3/Autodesk 3D Studio
    27-Oct-93  10:49:56
Sb: #63695-#Gamma correction
Fm: Yost Group 76702,413
To: McDOWELL OWENS 75250,461 (X)

If your onscreen gamma in the 3DS framebuffer gamma SET dialog is showing 1.0,
it means that your Targa board is doing its own gamma correction, and that you
SHOULD LEAVE IT AT 1.0 in Studio (until you figure out how to turn off the
gamma correction on the Targa board, of course).  The problem with the Targa
doing gamma correction is that it will quantize the image (and cause banding
and color problems).  I've got a message into the Truevision folks to get back
to me re this problem.  When I find out how to disable gamma correction on the
T+, I'll let you know.

Just remember, do NOT gamma correct twice.  That's the worst thing you could
do.

                - G

There are 2 Replies.

#: 63737 S3/Autodesk 3D Studio
    27-Oct-93  13:22:13
Sb: #63702-#Gamma correction
Fm: Don Landis 71673,3612
To: Yost Group 76702,413 (X)

Thanks for clarifying this, Gary.  I've noticed the same thing with my targa+
16/32.  The Grays match at 1.0 not 2.2.  My targa+ is set for 1.0 in tconfig.
as well.  I take it then I should shut off the 3DS gamma until you get a
method to shut off the targa+ gamma.  Maybe Kevin Krell could jump in and add
to this.  I haven't had the time to look into it closer but so far 3DSr3 is
pumping out some pretty impressive contrast ratio on a calibrated monitor
across my three peer network so I guess something's working right.

There is 1 Reply.

#: 63804 S3/Autodesk 3D Studio
    27-Oct-93  20:15:15
Sb: #63737-#Gamma correction
Fm: Kevin Krell [CSA] 76077,2774
To: Don Landis 71673,3612 (X)

Don,
       I just never got into using TCONFIG.  I still use the old TMODE 11 6 0
method.

               Kevin Krell - Comptuer Support Associates

There is 1 Reply.

#: 63838 S3/Autodesk 3D Studio
    27-Oct-93  23:50:30
Sb: #63804-Gamma correction
Fm: Bailey Brown 73020,3442
To: Kevin Krell [CSA] 76077,2774

Kevin,

Do you know if using tmode leaves the gamma at 1.0?

Bailey


#: 63782 S3/Autodesk 3D Studio
    27-Oct-93  17:29:31
Sb: #63702-#Gamma correction
Fm: John Ellis 72440,3046
To: Yost Group 76702,413

Gary and all concerned,

It seems that if you use tconfig with the 32+ the default is a gamma 1.00. The
minimum value in tconfig is 0.1  However if you cold boot your system and just
use "tmode 11 6", gamma correction appears not to be active. I have tried both
configurations; using tconfig with the batch file it creates, and cold boot
alone. Using just "tmode 11 6" with a cold boot and adjusting gamma in 3DSR3,
for my monitor I get a gamma adjustment of 2.05, which I believe is correct. I
also have an old 32 which does not have gamma correction internally and on the
same monitor they appear to be adjusted equally. Hope this helps. - JE


There are 2 Replies.

#: 63829 S3/Autodesk 3D Studio
    27-Oct-93  22:58:23
Sb: #63782-#Gamma correction
Fm: John Tissavary 71054,15
To: John Ellis 72440,3046 (X)

Thanks for that message.  I was wondering about that, because although my
grey's do NOT match at 2.2 in R3, the images look WAY better.  I use tmode 11
in autoexec.bat and do not use tconfig, though I did jump in and notice the
gamma slider which made me nervous.

I ended up using what I though looked best despite the grey boxes, and that
was 2.2 for NTSC.

Thanks,

John Tissavary (La Luna cie)

There is 1 Reply.

#: 63857 S3/Autodesk 3D Studio
    28-Oct-93  01:22:33
Sb: #63829-Gamma correction
Fm: John Ellis 72440,3046
To: John Tissavary 71054,15

John - I'm sure we'll learn more from Truevision, but as you say it looks WAY
better! I'm so impressed with R3. The colors POP out, I've got Red that looks
RED, nice deep and rich. The images have so much more depth. If I find out
more I'll let you know. BTW if you need to adjust any of the other registers
they can be accessed outside the tconfig.exe manually. I'm having a blast,
hope you are too :-)  -JE


#: 63874 S3/Autodesk 3D Studio
    28-Oct-93  06:32:43
Sb: #63782-Gamma correction
Fm: Martin Enthed 100277,1272
To: John Ellis 72440,3046

If I understand you, will tconfig with gamma set to 1.00 do gamma correction
on a Targa+ 16/32. I use tconfig on my targa+ card with gamma set to 1.00, and
get a gamma correction at 2.10 in 3DS. As I see it the gamma 1.0 in tconfig is
the same as NO gamma correction. When I tried to set it as low as possible, I
got a BLACK screen, so it looks like values below 1.00 produce an inverse
gamma correction.

Please correct me if I'm wrong ! :-)




#: 63959 S3/Autodesk 3D Studio
    28-Oct-93  13:12:22
Sb: #63838-Gamma correction
Fm: Kevin Krell [CSA] 76077,2774
To: Bailey Brown 73020,3442 (X)

Bailey,
       It seems to be 1.0.  At least, Targa images come into the ATVista and
look right @ 1.0 rather than if created on teh Vista @ 2.2.

               Kevin Krell - Computer Support Associates

#: 63941 S3/Autodesk 3D Studio
    28-Oct-93  11:47:38
Sb: #63737-#Gamma correction
Fm: Yost Group 76702,413
To: Don Landis 71673,3612 (X)

John Ellis is suggesting an interesting way of inhibiting the T+ from doing
gamma correction.  Just use the tmode 11 6  command and don't use tconfig.
Check out his message number 63782.

The bottom line is if the grays match in the 1.0 range, it means your
framebuffer is definitely gamma correcting and you shouldn't do additional
gamma correction in 3DS until you figure out how to turn the fb gamma
correction OFF.  Once doing that, use the 3DS gamma correction for much better
results.

                - G

There is 1 Reply.

#: 64021 S3/Autodesk 3D Studio
    28-Oct-93  21:35:48
Sb: #63941-#Gamma correction
Fm: Don Landis 71673,3612
To: Yost Group 76702,413 (X)

I'm using tmode 11 but not tmode 11 6.  I'll try that next.  I don't know what
the _6 does.  So much undocumented stuff about the targa+.  Such a mystery!

There are 2 Replies.

#: 64122 S3/Autodesk 3D Studio
    29-Oct-93  10:52:32
Sb: #64021-Gamma correction
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612

Don - You need the "6" if you're using external sync, which I assume you are
as you have your own video environment. It has no effect if you aren't using
external sync as it automatically locks to internal if it doesn't get an
external signal. -JE


#: 64156 S3/Autodesk 3D Studio
    29-Oct-93  12:44:37
Sb: #64021-Gamma correction
Fm: Kevin Krell [CSA] 76077,2774
To: Don Landis 71673,3612

Don,
       I don't know what you mean about Targa+ info being undocumented.  The
TMODE parameters are right in the manual.  Where do people think I get this
stuff?

               Kevin Krell - Computer Support Associates

#: 64005 S3/Autodesk 3D Studio
    28-Oct-93  19:33:40
Sb: #63857-#Gamma correction
Fm: John Tissavary 71054,15
To: John Ellis 72440,3046 (X)

I'm so thrilled with the new renderer.  It is the most outstanding feature of
3D Studio, as far as I'm concerned.  I've been comparing Abekas/R2 output to
R3/Targa+/SVO 9600, and the latter looks WAY better!  Can't wait to get to the
Abekas with R3 targas!

Thanks for the word on TMODE.  I don't use TCONFIG anyway, so it's no big
deal.  What's the "6" for?

John Tissavary (La Luna cie)

There are 2 Replies.

#: 64017 S3/Autodesk 3D Studio
    28-Oct-93  21:05:35
Sb: #64005-Gamma correction
Fm: John Ellis 72440,3046
To: John Tissavary 71054,15 (X)

John - I agree it's absolutely gorgeous. I think there are a lot of terrific
new features for the animator/modeler in this new release, but in the end IT
IS the output that counts. Hmmm maybe I'll do an ice-cream cone.... <G> -JE


#: 64129 S3/Autodesk 3D Studio
    29-Oct-93  11:27:08
Sb: #64005-Gamma correction
Fm: Yost Group 76702,413
To: John Tissavary 71054,15

Note that I found that a gamma of 1.8 worked best for Abekas output. (and the
_6_ is for turning on external genlock synching)

                - G

#: 63945 S3/Autodesk 3D Studio
    28-Oct-93  11:57:47
Sb: #63874-Gamma correction
Fm: John Ellis 72440,3046
To: Martin Enthed 100277,1272 (X)

Martin E. - Some people have had problems with TCONFIG, maybe for just the
reasons you mentioned, ie: they tried turning Gamma below 1.0  TMODE 11 6
works and uses the default setting. Your gamma correction of 2.10 seems like
its in the correct range for RGB, you might want to boost it to 2.2 for NTSC
output. Try using TMODE 11 6 alone and if your rendered image looks the same
with the Gamma correction you've already set in R3, I would say you're
speculation is correct. I'm getting excellent results with whatever the
default is. My intention was to provide a working solution until there is a
definitive answer from Truevision, which I hope will be today. -JE


#: 63963 S3/Autodesk 3D Studio
    28-Oct-93  13:42:59
Sb: #63874-#Gamma correction
Fm: John Ellis 72440,3046
To: Martin Enthed 100277,1272 (X)

Martin - In answer to your question, by using tconfig.exe and setting it for
512x486 you're putting the Targa in gamma correction mode even though your
setting is a 1.0 which is neutral (as opposed to off). Its still going through
the circuitry. Ideally you'd like to bypass the circuitry. You'll notice that
if you set your Targa 32+ to 512x400 and click on Targa32+ in the Operation
mode that gamma will go to zero. But if you click on 512x486 it automatically
goes to 1.0  Which means that tconfig by default activates gamma correction
even though it is neutral. The best way is TMODE 11 6 which leaves gamma
turned off. If you need to adjust any of the other parameters you might want
like hPhase you can use Targedit instead to initialise those functions. -JE


There is 1 Reply.

#: 64076 S3/Autodesk 3D Studio
    29-Oct-93  06:32:18
Sb: #63963-#Gamma correction
Fm: Martin Enthed 100277,1272
To: John Ellis 72440,3046 (X)

>Martin - In answer to your question, by using tconfig.exe and setting it for
>512x486 you're putting the Targa in gamma correction mode even though your
>setting is a 1.0 which is neutral (as opposed to off). Its still going
through >the circuitry.

I havn't tested the 512x486 resulotion as I wan't PAL not NTSC output ! I have
used 512x576 (tmode 15) for my animations.

I live in Sweden, that's way I'm not a NTSC fan ! :-)

regards, Martin





There is 1 Reply.

#: 64126 S3/Autodesk 3D Studio
    29-Oct-93  11:22:39
Sb: #64076-Gamma correction
Fm: John Ellis 72440,3046
To: Martin Enthed 100277,1272

Martin E. If you're using TMODE 15 then your board will not be setup for Gamma
Correction, which is what you want. Earlier you mentioned using tconfig with a
setting of 1.0  Most of here are not NTSC fans either <G> but its what we have
to work with for the time being :-) So what type of work are you doing in
Sweden? Do you have many 3DS users? Just curious. -JE


#: 63940 S3/Autodesk 3D Studio
    28-Oct-93  11:46:40
Sb: #63782-#Gamma correction
Fm: Yost Group 76702,413
To: John Ellis 72440,3046 (X)

This is great news!  Just the information I've been looking for.
Coincidentally, I just got through to Jamie at Truevision and he confirmed
what you said.  Plus, he said that if you absolutely need to use tconfig, you
can turn off the automatic gamma correction afterwards by doing a

targedit Byplut 1

Basically, the simplest way to not invoke automatic T+ gamma correction is not
using tconfig then... just use the tmode 11 6 parameter and all will be fine.

Fantastic!  Thanks again for the info... a major Targa mystery revealed.

                - G

There is 1 Reply.

#: 63946 S3/Autodesk 3D Studio
    28-Oct-93  12:07:59
Sb: #63940-#Gamma correction
Fm: John Ellis 72440,3046
To: Yost Group 76702,413 (X)

Gary - You're very welcome and thank you for the new 64 bit renderer - the
colors are beautiful! -JE


There is 1 Reply.

#: 63947 S3/Autodesk 3D Studio
    28-Oct-93  12:26:37
Sb: #63946-#Gamma correction
Fm: Yost Group 76702,413
To: John Ellis 72440,3046 (X)

I'm glad you appreciate them!  <g>

BTW, I made a mistake in the last email re the targedt command line argument
for bypassing the automatic gamma if you MUST use tconfig.  It's really:

targedit lutByp 1

There ya go,

                - G

There are 2 Replies.

#: 63975 S3/Autodesk 3D Studio
    28-Oct-93  15:02:10
Sb: #63947-#Gamma correction
Fm: John Ellis 72440,3046
To: Yost Group 76702,413 (X)

Gary << BTW, I made a mistake... >>

I hear the vacation Sirens calling... Ancient Ruins, sandy beaches... quite a
distraction. <G>

-JE


There is 1 Reply.

#: 64130 S3/Autodesk 3D Studio
    29-Oct-93  11:27:59
Sb: #63975-Gamma correction
Fm: Yost Group 76702,413
To: John Ellis 72440,3046 (X)

Two weeks and I'm outahere.

                - G

#: 64006 S3/Autodesk 3D Studio
    28-Oct-93  19:33:43
Sb: #63947-#Gamma correction
Fm: John Tissavary 71054,15
To: Yost Group 76702,413 (X)

The renderer is my favorite new feature in R3.  I've been comparing my
R2/Abekas stuff to some R3/Targa+/SVO 9600 tests and the latter is WAY better.
Wow.

Thanks,

John Tissavary (La Luna cie)

There is 1 Reply.

#: 64131 S3/Autodesk 3D Studio
    29-Oct-93  11:28:29
Sb: #64006-Gamma correction
Fm: Yost Group 76702,413
To: John Tissavary 71054,15

Your welcome!  (the bottom line is always OUTPUT QUALITY)

                - G

#: 63038 S3/Autodesk 3D Studio
    23-Oct-93  21:57:07
Sb: #R3 Render
Fm: Mark Bessette 71572,3251
To: all

I installedR3 a couple of days ago. it looked ok but I have some problems. I'm
using Vibrant driver for IBM 8514A Graphics board.Display is set for 256
colors at 640x480.

 When I render an object it looks terriible. It looks as if there aren't
enough colors or something.

I went back to R2 and everything looks Ok.

Any suggestions?

mark

There are 2 Replies.

#: 63065 S3/Autodesk 3D Studio
    24-Oct-93  00:05:18
Sb: #63038-#R3 Render
Fm: John Tissavary 71054,15
To: Mark Bessette 71572,3251 (X)

Have you adjusted the gamma correction settings properly?  There is a
description on how to do this in the installation guide.  If incorrectly
adjusted you're images could appear too dark or too light.

Regards,

John Tissavary (La Luna cie)

There are 2 Replies.

#: 63079 S3/Autodesk 3D Studio
    24-Oct-93  10:27:44
Sb: #63065-R3 Render
Fm: Mark Bessette 71572,3251
To: John Tissavary 71054,15 (X)

I tried to adjust display gamma but I'm having problems with that too. The
small box on the display gamma is dark or light. It is dark at any settings
from 1.99 and below. When I get to 2.00 the box shifts to a light gray. There
doesn't seem to be a close match. I've set the gamma at 2.00. I'm going to
turn the gamma off and see what happens.

mark

#: 63080 S3/Autodesk 3D Studio
    24-Oct-93  10:49:27
Sb: #63065-R3 Render
Fm: Mark Bessette 71572,3251
To: John Tissavary 71054,15 (X)

I turned display gamma off. rendering in the materials editor seems ok but a
little dark. I've set my display as bright as I can without the lettering
bluring. I'm not sure what is happening but maybe 3ds is using 16 colors to
render?

mark

#: 63146 S3/Autodesk 3D Studio
    24-Oct-93  20:00:18
Sb: #63038-#R3 Render
Fm: Martin Foster[Animatrix] 70303,456
To: Mark Bessette 71572,3251 (X)

Mark,

I suggest deleting your 3dadi.cfg, running 3ds vibcfg, and going through the
main-display, render-disply and materials display again. Do a video mode TEST
on each choice. When you are in 3ds make sure your device is VIBRANT. Let me
know if it helps.

There is 1 Reply.

#: 63147 S3/Autodesk 3D Studio
    24-Oct-93  20:08:51
Sb: #63146-R3 Render
Fm: Mark Bessette 71572,3251
To: Martin Foster[Animatrix] 70303,456 (X)

Martin

I'll give it a try. I won't be able to try it until tue. night . I'll let you
know if it works then.

thanks - mark

#: 63345 S3/Autodesk 3D Studio
    25-Oct-93  20:27:05
Sb: #63146-#R3 Render
Fm: Mark Bessette 71572,3251
To: Martin Foster[Animatrix] 70303,456 (X)

Martin,


I did get a chance to try your suggestion Monday night.

I deleted 3dadi.cfg and ten ran 3ds vibcfg. I went through the main display,
render-display and materials display again.

 I picked 640x480 256 colors for each with the VIBRANT driver for my board
(8514A). Unfortunately I still have the same symptoms. Can't seem to pick a
correct display-gamma and the colors are all blocked-up. It seems to work fine
with gamma off.

I am losing about 2 Meg of RAM. I only have 8 so it hurts. Is this normal?

I have QEMM but I haven't done anything since installing R3.

I lost about the same in R2 but I was using Turbo DLD for my graphics board.

mark


There is 1 Reply.

#: 63374 S3/Autodesk 3D Studio
    25-Oct-93  22:50:41
Sb: #63345-#R3 Render
Fm: Martin Foster[Animatrix] 70303,456
To: Mark Bessette 71572,3251

Mark,

I don't have any other ideas. If you tested the video mode during the 3ds
vibcfg stage and it looked OK, then I'm not sure what it's doing wrong inside
the package. What gamma do you the main display set at? My monitors seem to be
around 1.1 for display and my targa+ 16/32 I just assume 2.2 for NTSC.

I have 16mb (16384 bytes) in my 486/50 and 3dsr3 reports 14832, so I'm losing
1.5mb. You might want to read the performance and installation guide on how to
configure pharlap. FWIW, some bios' steal a few hundred K's to put something
in; also, some software cache programs (like Smartdrive) may steal some RAM.
Release 3 will chew up 8mb of ram in no time flat! If you find yourself paging
a lot, it's highly recommended to get more RAM.

There is 1 Reply.

#: 63403 S3/Autodesk 3D Studio
    26-Oct-93  02:09:23
Sb: #63374-R3 Render
Fm: John Tissavary 71054,15
To: Martin Foster[Animatrix] 70303,456

BTW, how do you turn Targa's gamma correction off to arrive at 2.2?  If I do
2.2 everything looks like utter CR*P.

Thanks,

John Tissavary (La Luna cie)

#: 63496 S3/Autodesk 3D Studio
    26-Oct-93  13:59:15
Sb: #63403-#R3 Render
Fm: Martin Foster[Animatrix] 70303,456
To: John Tissavary 71054,15 (X)

John,

It's probably more a case of what I do _not_ do. I just boot-up with the
targa+ driver and run tmode 11. I don't do anything else. Seems like running
other commands will cause gamma correction to be used. I'm just guessing I
don't know much about it. I may even have to RTFM <g>.

There is 1 Reply.

#: 63654 S3/Autodesk 3D Studio
    27-Oct-93  02:45:52
Sb: #63496-R3 Render
Fm: John Tissavary 71054,15
To: Martin Foster[Animatrix] 70303,456

I do the same thing, but when I set gamma in 3DS it acts like there's already
correction going on.  And when I run TCONFIG it shows some sort of gamma
correction.

John Tissavary (La Luna cie)

#: 63607 S3/Autodesk 3D Studio
    26-Oct-93  21:09:39
Sb: #63374-#R3 Render
Fm: Mark Bessette 71572,3251
To: Martin Foster[Animatrix] 70303,456 (X)

Martin,

Thanks for your input.

Monday Autodesk is going to be in Boston for a kickoff forum on R3. I think
I'll output to video, see how it looks and bring it to to this forum. Maybe
someone from Autodesk will be able to help.

Your right about R3 eating up memory. I need a new computer but can't get one
until next year.

When I find out what's causing the problem I'll let you know.

mark

There is 1 Reply.

#: 63633 S3/Autodesk 3D Studio
    27-Oct-93  00:19:01
Sb: #63607-R3 Render
Fm: Yost Group 76702,413
To: Mark Bessette 71572,3251

What does your framebuffer gamma setting end up being after you match the grey
pattern with the surrounding grey field?  Don't assume that your gamma is 2.2
without having them match at 2.2.  If you can't get them to match, try to turn
the gamma correction in your video chain (framebuffer, encoder, whatever) OFF,
and if you can't do that, turn off gamma correction in 3DS.  The worst thing
in the world to do is gamma correct an image TWICE.  You should definitely
read the section about gamma correction in the AUG that comes with r3.

Regarding the Boston forum, there won't be any tech support people there.

                - G

#: 63728 S3/Autodesk 3D Studio
    27-Oct-93  13:00:41
Sb: #63654-#R3 Render
Fm: Martin Foster[Animatrix] 70303,456
To: John Tissavary 71054,15 (X)

John,

sounds like I really need to read the manuals - don't want double
gamma-correction!

There is 1 Reply.

#: 63827 S3/Autodesk 3D Studio
    27-Oct-93  22:58:16
Sb: #63728-#R3 Render
Fm: John Tissavary 71054,15
To: Martin Foster[Animatrix] 70303,456 (X)

Today I reset the gamma to 2.2 and it looks much better than gamma OFF, double
gamma or not.  Perhaps without hitting "DO MODE" in TCONFIG it leaves gamma
correction off.  Anyone out there know the answer?  The manual is very vague
about this.

John Tissavary (La Luna cie)

There is 1 Reply.

#: 63851 S3/Autodesk 3D Studio
    28-Oct-93  00:12:15
Sb: #63827-R3 Render
Fm: Martin Foster[Animatrix] 70303,456
To: John Tissavary 71054,15 (X)

John,

John Ellis suggested rebooting and starting the targa+ with "tmode 11 6"
command to switch off gamma correction. Give it a try. I will try it too.

#: 63877 S3/Autodesk 3D Studio
    28-Oct-93  07:01:05
Sb: #63607-#R3 Render
Fm: David  Hogan 73143,1772
To: Mark Bessette 71572,3251

Where and when will 3DS Boston pitch be?

There is 1 Reply.

#: 63884 S3/Autodesk 3D Studio
    28-Oct-93  08:19:29
Sb: #63877-R3 Render
Fm: TED BOARDMAN 71022,3001
To: David  Hogan 73143,1772

David,

PMJI, The place is The Charles Hotel, 1 Bennett St. Cambridge. I believe it is
at 9 am but you can call Tamar at Wentworth 617.442.9010 x376 if Mark doesn't
correct me by Friday.

TedB

#: 63989 S3/Autodesk 3D Studio
    28-Oct-93  18:19:42
Sb: #63877-R3 Render
Fm: Mark Bessette 71572,3251
To: David  Hogan 73143,1772

David

The Boston (actually Cambridge) forum (pitch) is at the Charles Hotel, One
Bennett St. It's about 3 or 4 blocks from Harvard Sq.

It runs from 8:30 - 11:00.

You should call 800-225-1149 to register.

mark

#: 63994 S3/Autodesk 3D Studio
    28-Oct-93  18:38:34
Sb: #63851-#R3 Render
Fm: John Tissavary 71054,15
To: Martin Foster[Animatrix] 70303,456 (X)

What does the "6" do?

John Tissavary (La Luna cie)

There is 1 Reply.

#: 64012 S3/Autodesk 3D Studio
    28-Oct-93  19:44:06
Sb: #63994-R3 Render
Fm: John Ellis 72440,3046
To: John Tissavary 71054,15 (X)

John - >> What does the "6" do? << That's for genlock to an external source
which you may not need depending on your setup. -JE


#: 64181 S3/Autodesk 3D Studio
    29-Oct-93  15:07:50
Sb: #R3 Render
Fm: David J. Marks 72172,1036
To: Yost Group 76702,413 (X)

>>The worst thing in the world to do is gamma correct an image TWICE.

Have you gotten any feedback from Truevision on disabling built-in correction
on Targa+ cards?

- Dave



There is 1 Reply.

#: 64272 S3/Autodesk 3D Studio
    30-Oct-93  09:44:54
Sb: #64181-R3 Render
Fm: Yost Group 76702,413
To: David J. Marks 72172,1036 (X)

Sure have.  We've been talking about it here in the forum for a few days now
(have you seen the message threads about it?).

Basically, the problem (according to Jamie at Truevision) is that using
tconfig automatically invokes the gamma correction circuitry. Just don't use
it, and use tmode (ie: tmode 11) instead.  If you must use tconfig, he says
that you can turn off gamma correction by doing a: targedit lutByp 1 (or
lutBypass 1).

Since I use an old Targa24, I can't test this here, but the consensus is that
it seems to work.

                - G

#: 64182 S3/Autodesk 3D Studio
    29-Oct-93  15:07:53
Sb: #64012-#R3 Render
Fm: David J. Marks 72172,1036
To: John Ellis 72440,3046 (X)

John,

Regarding the Targa+, I've had no success in disabling its built-in
correction.  I was on the phone about a week ago with Truevision tech support
for nearly an hour and a half.  They said that the board uses "look-up tables"
which are "optimized" for NTSC output.  Sounds like built-in gamma correction.
They couldn't tell me how to disable it.

They exactly duplicated my results with the 3DS Gamma correction squares: a
setting of near 1.0 for optimum output, meaning no 3DS adjustment.

They wanted to discuss this with the Yost Group directly, and I've passed on
all the information via email.  No word yet, though.  Stay tuned...



There are 2 Replies.

#: 64198 S3/Autodesk 3D Studio
    29-Oct-93  17:02:51
Sb: #64182-#R3 Render
Fm: John Ellis 72440,3046
To: David J. Marks 72172,1036 (X)

David - I'm not sure who you've been talking with at Truevision, but my
understanding is that the default has no Gamma Correction. I and several
others have been getting great results using TMODE 11. If you haven't tried
it, please do. Seriously, the output is fantastic. Here is how to do it. If
you are using a batch file produced from TCONFIG placed in your autoexec.bat
"rem" it out, and reboot your system. If you are initializing your Targa after
you boot up by manually typing in the name of the batch file, just don't use
it. Instead at the C:\ prompt type TMODE 11. (This assumes that TPLUS is in
your autoexec path statement.) And then run 3DS as you normally would. Once
in, do your gamma adjustment for the framebuffer. Render ADLOGO.3DS, the
colors are extrordinary! Let me know how it goes. -JE P.S. If you're using
external sync type "TMODE 11 6" instead.


There is 1 Reply.

#: 64246 S3/Autodesk 3D Studio
    29-Oct-93  23:17:43
Sb: #64198-#R3 Render
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

John & David:

I found no difference between tconfig gamma 1.0 and tmode.  Using a
vectorscope and visually.  Seems like you're telling people that 6 inches is
longer than a half a foot. <g>  Point is 3DSr3 just plain does fabulously good
output!  I even tried tmode 25 for a change and was astonished at the
resolution.  I might try it on some of my broadcast jobs in the future.  I
couldn't detect any banding of the 16 bit color at all.

There is 1 Reply.

#: 64257 S3/Autodesk 3D Studio
    30-Oct-93  02:51:20
Sb: #64246-#R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)

Don - There is a difference between the tconfig setting of 1.0 (which is
supposed to neutral) and tmode 11 with its default of no gamma. While visually
you may not be able to see a difference, electronically and functionally there
is.

I too have tried the results both ways, and this is the test I put to you.
Render the ADLOGO.3DS If you think the colors are supposed to be dark and more
saturated, then I suggest using your approach which I do not find
aesthetically pleasing. If on the other hand they are supposed to be a rich
vibrant pastel (almost electric) then I suggest using TMODE 11 or TCONFIG.EXE
and turning off the gamma with targedit lutByplu 1. Which, BTW Jamie at
Truevision recommended; if you HAD to use tconfig.exe. I don't think he would
recommend it for no reason, and it begs the question why have a command to
turn it off if it didn't make a difference? Do you really think this is making
6" more than half a foot? <G> I don't think a vectorscope is going to help
much in this regard, a waveform might if you knew what you were looking for.
(This applies to anyone, not you specifically.)

I have an old Targa 32 and a new Targa 32+. The old Targa definitely doesn't
have gamma correction, we know the new one does. I can do a side by side on
the same monitor. With the old Targa 32 set at the defaults in R3, ie 1.8,
gamma ON in R3 the colors are as I describe. (Interesting coincidence) Using
Tmode 11 6, I can adjust the Targa 32 + in R3 to a gamma value of 2.0 and get
the same result. If automatic gamma correction was a factor the range would be
much different. I attribute the .2 difference to the individual cards.
Following the procedures you outline, my colors are dark and coarse but it's
not suprising as the gamma you specified in R3 is 1.0, I believe the range
should be between 1.8 and 2.2  2.2 is what is needed for output in NTSC.

BTW - Gamma as specified in a video cameras CCU where you would use a
vectorscope for color gun balance and alignment is different than Gamma in the
context we are using it.

I am very satisfied with the results I've been able to obtain by following the
procedure I've outlined. That is TMODE 11 6 and R3 Gamma Adjustment at 1.8 and
2.0 for an RGB Video monitor and NTSC output at around 2.2. The results are
stunning and I think that Gamma Correction done in R3 is far superior to what
the Targa does on its own. Technically and functionally I have proven to my
satisfaction that the TMODE 11 approach is the correct one. I no less a
perfectionist than you are Don. And while the debate rages I'm happily getting
my work done with outstanding results, as is John T. who stated that he
thought the renderer was the best feature of the new release. And to that I
would like to add that in my five years of working with animation and targa
boards I have never seen colors reproduced so beautifully as with R3 and that
includes its Gamma Correction feature. I guess this is one of those rare times
when you and I don't see eye to eye :-) -JE


There is 1 Reply.

#: 64330 S3/Autodesk 3D Studio
    30-Oct-93  13:28:38
Sb: #64257-#R3 Render
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

I wouldn't say we dont see eye to eye at all.  I will try your test and
compare.  I just found the setting of 1.0 to be no change in the picture, nor
on the vectorscope, nor on the waveform monitor.  When setting the 3DS gamma
to higher than 1.0  I found the colors were washed out and in some areas the
borders would run together.  I'll reference the chevy.3ds file in the front
bumper area.  The whites in this file approach 100 in the WFM and the dark
areas are near 15-20 IRE.  There is good spread of color.  With the gamma
adjusted higher say 2.0 the color tends to run between 40 and 100 which is a
measurement of what I see as washing out of the picture.

Although I have used tconfig batches in the past I've been using tmode 11 for
the past 2 months.  It is simpler to work with.  In addition, using tmode 11 I
CAN match the gray panels in 3DS at 1.0 and when I go higher the center panel
goes too white.  Therefore if I use your 2.0 or 2.2 adjustment in 3ds gamma
the gamma set is off as well as the picture is washed out.  If I use tconfig
at gamma 2.0 the same thing happens.  There is something that is inconsistent
here with what I'm seeing and what you're saying I should be seeing.  Maybe I
need more detail in setting up the targa+ but I find it very hard to believe I
could get a more perfect looking image as well as NTSC test patterns than I am
getting with gamma set at 1.0.

BTW I also tried GY's double gamma adjustment by setting the tconfig at lower
than 1.0 and 3DS at higher than 1.0.  I now could get the grays to match at
1.8 and the picture looked OK on brightness but colors were indeed muddy and
some banding was observed.  He accurately predicted the effect.  Now, why am I
not getting the best looking picture at gamma 2.2 as you suggest I should?

There is 1 Reply.

#: 64343 S3/Autodesk 3D Studio
    30-Oct-93  15:16:58
Sb: #64330-#R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)

Don - I really don't know the answer to your question, but there's obviously a
problem some where. How are your monitors terminated, maybe their double
terminated. This seems unlikely knowing your determination to get it right.
Still I'd be curious to know what type of monitor you're using. I'm using a
Mitsubishi Multi-sync for RGB. Are you using one monitor for both rendering
and modeling?  The 2.2 is for final output through the composite or SVHS
cable. In my case its SVHS through the EVO. If you are using TMODE 11 only,
and you go into the Gamma control menu and render at the default of 1.8 - 2.1
on your frame-buffer display and check the composite signal out how does it
look? I'd be happy to work with you and help you crack this nut. -JE Just to
review. Clear out any batch files created by TCONFIG. Reboot your system.
Manually enter Tmode 11. Go into 3DS... go into Gamma correction and "set" for
the Frame buffer, adjust the slider so that when you stare at the box the
boxes blend with the same luminance level. What is the setting you get?

There is 1 Reply.

#: 64394 S3/Autodesk 3D Studio
    30-Oct-93  21:51:50
Sb: #64343-#R3 Render
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)


The hw setup is a two monitor cgi system with IDEK 5317 as the modeling/vga
and a panasonic datagrade NTSC monitor similar to a CT1331Y.  I have
personally removed the termination on this monitor for inclusion in the line
feed to the video bay with the scopes, termination is at the final monitor, a
JVC TM900SU.  Both monitors are calibrated and match results.  In addition, if
the termination would be incorrect it would show up as incorrect peak to peak
video voltage on the waveform.
>>If you are using TMODE 11 only, and you go into the Gamma control menu and
render at the default of 1.8 - 2.1 on your frame-buffer display and check the
composite signal out how does it look?  It looks washed out.  Even the blacks
are approaching gray.
>>Go into 3DS... go into Gamma correction and "set" for the Frame buffer,
adjust the slider so that when you stare at the box the boxes blend with the
same luminance level. What is the setting you get? I think I said before...
it's 1.0.  It's not possible to go below 1.0 in 3DS but I don't think the
match would be any better than what I'm currently getting at 1.0.

BTW how do you calibrate your monitor(s) brightness and contrast?  How do you
measure your line impedance?  If you set it up to what looks fine to you then
that will work as long as you keep to your own environment.  I do work for
many video production post houses and cablecast.  My video levels have to be
right on or the work gets refused.  I wouldn't think of sending my work out
without scoping the video levels.  Gamma doesn't seem to throw the levels off
it just seems to shift the  center contrast of brightness light or dark.  This
is most noticable on the vectorscope, and, on the WFM but to a lesser degree.

There is 1 Reply.

#: 64414 S3/Autodesk 3D Studio
    31-Oct-93  02:44:46
Sb: #64394-#R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)

Don - All the symptoms you describe sound like your composite monitor is not
terminated properly. The symptoms you describe sound drastic. I agree that the
WFM/VS should show this, but it is possible that your monitor is not
terminated and the loop through to your WFM/VS is straight through. Is the
monitor self terminating, ie: does it have a switch. Can you use a BNC
terminator? Would it be a big deal to send the composite signal directly to
the WFM/VS and then into your composite Monitor and use a BNC terminator,
bypassing the internal one? Better yet, try a different monitor.

As to adjusting my monitors for NTSC out, I use color bars and turn on the
blue gun. Then balance the bars for contrast and luminance so that the bars
balance alternately. Standard practice.

Line impedance is 75 ohms and is easy to test with a VOM or oscilloscope. I
rarely have any problems with line impedance. What are you getting at?

As for doing production work, I do my previews on an EVO and final tranfers to
CRV. As you know there is no TBC on either the EVO or CRV, so no cheating. It
gets transferred straight to BETA SP from the component side of the CRV.
WYSIWYG.

I've asked a volume 3DS dealer here about problems with R3 and Targa boards,
he said he'd had none. But he did say he didn't like TCONFIG because it was a
lame way to set up the Targa. He also sells Matrox and has had no problems
with them either. Just to let you know I've done my homework. <G>


There is 1 Reply.

#: 64434 S3/Autodesk 3D Studio
    31-Oct-93  11:03:57
Sb: #64414-#R3 Render
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

>> Is the monitor self terminating, ie: does it have a switch. Can you use a
BNC terminator? Would it be a big deal to send the composite signal directly
to the WFM/VS and then into your composite Monitor and use a BNC terminator,
bypassing the internal one? Better yet, try a different monitor.

I can assure you that proper termination is in place here at all times and is
constantly monitored on the video feed.  I use only composite video so no
chance that, say the green line lost term. or got double terminated.

On the CGI composite monitor the internal termination has been removed.  Only
external termination is used and it is supplied by the final device in the
line, the JVC 9" monitor.  There are several other monitors on the board that
are for A/B/C roll setup but I doubt they would give any different results.
They are all internally terminated.

I don't think trying to solve this gray box mystery is going to be done by
scrutinizing termination.  I'm just too aware of the importance of this simple
requirement to overlook it in my setup and have it be wrong.

>>I've asked a volume 3DS dealer here about problems with R3 and Targa boards,
he said he'd had none.
Respecting and excepting the dealers on this forum, my opinion of dealers is
not very high when it comes to engineering, honesty, and the guts to tell it
like it is to the potential customer.     >>TCONFIG because it was a lame way
to set up the Targa.  Now what kind of statement is that?  I'm surprised you
would even repeat something like that from an annonymous dealer.  I'd much
rather respect your opinion on tconfig vs. tmode.  When it comes to stuff like
this I don't think it's a matter of winning a popularity contest.  I prefer
tmode because it is simpler to do the same thing, and, it prevents one from
screwing around with the setup.  For this reason I think I know why dealers
like Tmode over tconfig.

There are 2 Replies.

#: 64462 S3/Autodesk 3D Studio
    31-Oct-93  13:09:08
Sb: #64434-#R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)

Don - Our threads are getting crossed up, as you recieved my last message
after you had solved your problem. TCONFIG is lame because it makes certain
assumptions. It was designed to be used by people who wanted an easy setup for
the Targa. However this often causes more problems than it solves. There are
lots of registers on the Targa that TCONFIG does not address and herein lies
the problem. This gamma correction issue is a good example. The dealer I was
speaking of is not on this forum. But has been working with Targas as long as
they've been around. Before the creation of TCONFIG all the parameters had to
be set manually. There is a book from Truevision called the developers kit
which lists all the registers and what they do. I think like anything else in
this business its important to know as you much as one can about each
component in a system. TCONFIG is a crutch, and may work well in most
applications, but in our demanding environment, it has its shortcomings. I
don't think of it as a popularity contest either. -JE

Regarding termination, that was a suggestion I was giving before you had found
out that you hadn't clearly understood how to use the gamma correction. The
symptoms you described sounded like termination problems. And even in the most
rigourously maintained environment, when things get moved around, little
things get over-looked. O.K.? -JE

-JE


There is 1 Reply.

#: 64481 S3/Autodesk 3D Studio
    31-Oct-93  17:14:29
Sb: #64462-#R3 Render
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

>> And even in the most rigourously maintained environment, when things get
moved around, little things get over-looked.

You're right there,  when I get called in as consultant on engineering
problems in studios locally termination is often the first thing I have to
correct.  Being a good troubleshooter, it was correct for you to suggest
checking it.

There is 1 Reply.

#: 64489 S3/Autodesk 3D Studio
    31-Oct-93  19:45:24
Sb: #64481-R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612

Don - >>You're right there... << Just trying to look over your shoulder,
without actually being there. <G> -JE


#: 64473 S3/Autodesk 3D Studio
    31-Oct-93  15:38:30
Sb: #64434-R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)




#: 64208 S3/Autodesk 3D Studio
    29-Oct-93  17:18:53
Sb: #64182-R3 Render
Fm: Martin Foster[Animatrix] 70303,456
To: David J. Marks 72172,1036 (X)

David,

here's the good word from Gary and Truevision:

targedit lutByp 1


#: 64597 S3/Autodesk 3D Studio
    01-Nov-93  16:14:18
Sb: #64272-#R3 Render
Fm: David J. Marks 72172,1036
To: Yost Group 76702,413 (X)

>> Since I use an old Targa24, I can't test this here, but the consensus >>is
that it seems to work.  - G

Aaaaaarrrrrghh...  My two Targa+ 64's must be the only two in the known
universe that don't follow the rules!

Following are my only lines pertaining to Targa configuration:

CONFIG.SYS: Device=C:\TPLUS\TARGAP.SYS MD D6 I220

AUTOEXEC.BAT: C:\tplus\tmode 11

3DS.BAT set RDPADI=c:\3ds\drivers\rdptplus.exp

When I run 3ds, select the gamma control d-box and set frame-buffer gamma, the
boxes ALWAYS match at 1.01 -- nowhere near the expected 2.0-2.2!

Please tell me I'm not crazy...


There is 1 Reply.

#: 64625 S3/Autodesk 3D Studio
    01-Nov-93  18:03:59
Sb: #64597-R3 Render
Fm: Yost Group 76702,413
To: David J. Marks 72172,1036 (X)

Sorry David. You'll have to wait until December to find out about your sanity.

        - J

#: 64610 S3/Autodesk 3D Studio
    01-Nov-93  17:00:29
Sb: R3 Render
Fm: John Ellis 72440,3046
To: David J. Marks 72172,1036 (X)

David M. You're not going crazy, the boxes won't match for NTSC. See the
Thread GAMMA GAMMA? Basically it boils down to this, you can adjust your SVGA
or RGB if you have it connected, but if you adjust your boxes to match at 1.0
you are disabling GAMMA correction.  You can check this by rendering with it
set at 1.0 and by turning off gamma correction. The net effect is no gamma
adjustment. Don has been vindicated, actually we're both right! You can't
adjust it visually in NTSC but you can in RGB! -JE


#: 64611 S3/Autodesk 3D Studio
    01-Nov-93  17:00:32
Sb: R3 Render
Fm: John Ellis 72440,3046
To: David J. Marks 72172,1036 (X)

David M. If you use TMODE 11 you don't have to worry about it but it is
"lutBypass 1". All this does is by-pass the lookup tables. If you've read the
GAMMA GAMMA? thread you know what to do, I called your office and left my
number if you have any questions. Enjoy! -JE


#: 64607 S3/Autodesk 3D Studio
    01-Nov-93  16:36:43
Sb: #64489-#R3 Render
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

Got your E-mail.

Now, John, when I showed your note to the guys in white coats they decided not
to haul me off to the funny farm. <g>  As far as posting use your own
judgement.  I'm sure this proplem is going to come up even more often than the
confusion with which targa+ exp file to use and vanishing frames with disk to
VTR.  You do need to let GY know because he told me I was the ONLY one that
could have this problem.  You'll have to wait a month for that.

There is 1 Reply.

#: 64612 S3/Autodesk 3D Studio
    01-Nov-93  17:00:36
Sb: #64607-R3 Render
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)

>> Now, John, when I showed your note to the guys in white coats they decided
not to haul me off to the funny farm. << Man and just in the nick of time too
<G> hey sorry about that, I can't bear all the responsibility but alot of
things have been resolved with this one. You can be sure that Gary will be
appraised of the situation. But note too there is a solution. Albiet not
visual. Now that things are clear I don't anticipate any problems really. Its
quite straightforward to correct for Gamma with SVGA or RGB. Take care and
glad we hung in on this one :-) -JE


#: 64600 S3/Autodesk 3D Studio
    01-Nov-93  16:14:24
Sb: #64330-#R3 Render
Fm: David J. Marks 72172,1036
To: Don Landis 71673,3612 (X)

>>Now, why am I not getting the best looking picture at gamma 2.2...

Don, you and I are sharing the same dilusion.  I'm curious if this perhaps
goes much deeper...  Chip revisions/versions etc... Let's see what shakes out
in the next few days.  I've placed another call to Truvision and we'll see
what happens.



There is 1 Reply.

#: 64629 S3/Autodesk 3D Studio
    01-Nov-93  18:25:04
Sb: #64600-R3 Render
Fm: Don Landis 71673,3612
To: David J. Marks 72172,1036 (X)

No dilusion,  I spent quite a bit of time doing multiple configs on the
targa+, numerous monitors, and test instruments.  Your 1.01 is quite on the
money!  But, not the correct gamma.  I believe there is an insect lurking in
3DS with respect to NTSC monitors, targa+ and 3DS gamma measuring system.
Maybe this one will be added to the 3.01 release.  I think more people have to
duplicate it to be a bonafied candidate for the exterminator though.

See ya! I'm out a here.

#: 64628 S3/Autodesk 3D Studio
    01-Nov-93  18:24:45
Sb: #R3 Render
Fm: Don Landis 71673,3612
To: David J. Marks 72172,1036 (X)

Just quickly, now.  I saw your messages and just wanted comment.  I read the
other messages from you as well.

With your setup use gamma on and set it for 2.2 or what ever is pleasing to
your eyes on your NTSC monitor.  Very important that you also set the input
file gamma to the same value as your frame buffer setting.  To pick a correct
value for the frame buffer in your situation I'd render the file chevy.3ds on
metal and set the gamma(s) both to that which will give you a good shadow off
the front bumper without washing out the chrome detail on the bumper.  Be sure
you reload the 3ds file with each change of both settings as the input file
gamma won't do you any good after the file is loaded.  Don't worry about the
output file gamma for now as that has to be set depending on the output medium
you're doing.

Without proper test gear this is the best suggestion I have for you.  Oh yes,
before you do any of this stuff be sure your monitor is properly calibrated
with a known video signal.  most of us use NTSC color bars but in your case
just be sure the picture is pleasing with a good broadcast type signal.

There is 1 Reply.

#: 64681 S3/Autodesk 3D Studio
    02-Nov-93  00:54:42
Sb: #64628-R3 Render
Fm: Greg Pyros 73027,3632
To: Don Landis 71673,3612

Don:

>>  Be sure you reload the 3ds file with each change of both settings as the
>>  input file gamma won't do you any good after the file is loaded.

I thought that 'input file gamma' only had to do with targa files that are
being used as maps, not 3DS files you are loading?

Greg Pyros

#: 64701 S3/Autodesk 3D Studio
    02-Nov-93  09:20:41
Sb: #64597-R3 Render
Fm: David Rhoten 71450,2654
To: David J. Marks 72172,1036 (X)

David:

That's odd, because I switched (my Targa+64) from using a TConfig generated
batch file to just TMode 11, and I DEFINITELY see a difference. I won't say
that I think the two rectangles look "alike" at 2.2, but it did shift
"closer", and the 1.0 center square is muy darker now.

So, I'm sorry David, but you're crazy!<g>

Dave



#: 64712 S3/Autodesk 3D Studio
    02-Nov-93  10:02:26
Sb: #64612-#R3 Render
Fm: David J. Marks 72172,1036
To: John Ellis 72440,3046 (X)

>>Now that things are clear...

Not!



There is 1 Reply.

#: 64721 S3/Autodesk 3D Studio
    02-Nov-93  10:41:18
Sb: #64712-R3 Render
Fm: John Ellis 72440,3046
To: David J. Marks 72172,1036 (X)

David > Now that things are clear...<  >> Not! <<

You've at least got a good starting point, no? What questions do you have? For
sure its alot easier with an RGB monitor. There are some specific questions
I'd like to have answered by Truevision but all it all its not that
complicated. -JE


#: 64713 S3/Autodesk 3D Studio
    02-Nov-93  10:02:27
Sb: #64629-R3 Render
Fm: David J. Marks 72172,1036
To: Don Landis 71673,3612

>>I think more people have to duplicate it...

I had 3 guys on speaker phone from Truevision duplicate it.  (That's when GY
placed his phone call.)



#: 64707 S3/Autodesk 3D Studio
    02-Nov-93  09:37:17
Sb: #64681-#R3 Render
Fm: Don Landis 71673,3612
To: Greg Pyros 73027,3632 (X)

I found it makes a difference!

There is 1 Reply.

#: 64808 S3/Autodesk 3D Studio
    02-Nov-93  23:31:48
Sb: #64707-R3 Render
Fm: Greg Pyros 73027,3632
To: Don Landis 71673,3612

Don:

>>  I found it makes a difference!

Which question were you answering, the one on the input gamma files or the
one on the shininess?

With all due apologies to my esteemed colleague Mr. John Foust, it sure
would be nice if people used ">" more often!  <g,d,&r!>

Greg Pyros

#: 64853 S3/Autodesk 3D Studio
    03-Nov-93  09:32:31
Sb: #64701-#R3 Render
Fm: David J. Marks 72172,1036
To: David Rhoten 71450,2654

>>So, I'm sorry David, but you're crazy!<g>

Maybe not, thank heavens!  In a voice conversation with John Ellis, we came to
the conclusion that composite NTSC monitors may be the source of my problem.
He reproduced my results on his NTSC monitor, but WAS able to make the grey
boxes work on an RGB monitor (without changing a thing on the Targa board).  I
may attempt to borrow a studio monitor to "calibrate" my systems, until we can
afford to buy a better one.



There is 1 Reply.

#: 64937 S3/Autodesk 3D Studio
    03-Nov-93  21:40:37
Sb: #64853-R3 Render
Fm: John Ellis 72440,3046
To: David J. Marks 72172,1036

PMJI - The composite signal is the source of the problem, not the monitor. The
NTSC specification has gamma correction built in to correct for NTSC monitors.
Makes sense if you think about it. This way TV's and NTSC monitors are linear,
where they wouldn't be otherwise. This is why your boxes match up at 1.0 If
you can get ahold of an RGB monitor to align your system, I think that's your
best approach to understanding how this gamma correction system works. -JE


#: 65066 S3/Autodesk 3D Studio
    04-Nov-93  20:39:35
Sb: #64629-#R3 Render
Fm: David W. Mennenoh 71561,2343
To: Don Landis 71673,3612

Don,

Seems you've been experimenting with Gamma a lot lately so I thought I'd pose
a question. I've got an NEC 4FG and a Diamond Speedstar 24. I actually can't
ever get the two boxes to match correctly. It's close at about 1.1-1.2 but
still no match. Our Sony Multiscan HG at the office is matched perfect at the
default of 1.8  Any ideas? Even adjusting brightness/contrast doesn't help
enough where they match at all.

Dave Mennenoh

There is 1 Reply.

#: 65078 S3/Autodesk 3D Studio
    04-Nov-93  22:46:27
Sb: #65066-R3 Render
Fm: John Ellis 72440,3046
To: David W. Mennenoh 71561,2343

Hi David - PMJI, I've noticed with my Cirrus Logic that it seems to digitally
increment in that it will go two or three steps before the next increase or
decrease in brightness. Its not right on either but as close as
01 I don't think its anything to be real concerned about. -JE


#: 65281 S3/Autodesk 3D Studio
    07-Nov-93  04:32:02
Sb: #65066-R3 Render
Fm: Don Landis 71673,3612
To: David W. Mennenoh 71561,2343

I've only been experimenting with frame buffer gamma, which seems to have some
problems.  At this point I think Yost group and truevision need to have an
understanding and then release some new proceedures for us to follow.  For
frame buffers the gray boxes do not seem to work when outputting to composite
video from the targa+.  I haven't heard from the ATVISTA people on this nor
the clone people but the targa+ definitely has a reproducible bug with the
gray boxes.  My SVGA monitor is an IDEK 5317 and it matches on both the #9GXI
and the Metheus 928 S3 at 1.8.  I also tried a generic VLB video card but the
card was defective so I never got beyond install.  When you switched to the
Sony I assume you also switched video cards as well.  I don't know whether
this will affect the gamma.  I would guess it would be primarily dependent on
the output device.

#: 65282 S3/Autodesk 3D Studio
    07-Nov-93  04:32:20
Sb: #R3 Render
Fm: Don Landis 71673,3612
To: Greg Pyros 73027,3632 (X)

>>>>>>  I found it makes a difference!

Which question were you answering, the one on the input gamma files or the
one on the shininess?

With all due apologies to my esteemed colleague Mr. John Foust, it sure
would be nice if people used ">" more often!  <g,d,&r!>


Sorry about that!  I was doing some last minute answering before leaving on a
trip to Pennsylvania and got in a hurry.

I found it makes a difference with the input file gamma, ie.  Set the input
file gamma to the same value as your frame buffer when loading *.3ds files.  I
don't care what the manual says, following the above will yield more
consistent renderings with different files being loaded.  I'm not sure what
happens with compositing meshes but it should work just as well.

I thought I sent you an answer on the shininess question separately.  Had to
do with using the matte colors from the default Mat Lib as a starting point
and then I just tweaked from there.  I didn't really pay attention to the
shininess sliders just to the rendered results in the scopes.

There is 1 Reply.

#: 65293 S3/Autodesk 3D Studio
    07-Nov-93  11:47:22
Sb: #65282-R3 Render
Fm: Greg Pyros 73027,3632
To: Don Landis 71673,3612 (X)

Don:

Thanks for the info.

When doing any gamma testing, I just exit 3DS, change my 3DS.SET file (I
have a few versions) and fire it up again with a mesh, not a project.  I too
have seen different results when loading depending on the gamma settings and
when you change them.  This is the safest way, I have found, guaranteed
100% not to have _that_ problem!

The shininess sliders don't make any difference when used with a 100% self
illuminating material that I could see, especially when there are no lights
in the scene!

Thanks again,

Greg Pyros

#: 65200 S3/Autodesk 3D Studio
    06-Nov-93  05:13:54
Sb: R3 Render
Fm: Phillip L. Miller 74710,3061
To: David W. Mennenoh 71561,2343

David,

PMJI, but make sure that you are putting the display into a 24-bit color
mode while setting gamma correction. Your incremental adjustment will not be
correct for those troublessome little squares otherwise.

- Phil

#: 64244 S3/Autodesk 3D Studio
    29-Oct-93  23:16:50
Sb: #64122-Gamma correction
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

Thanks for the clarification on the "6" parameter.  I do have a video
production suite but the CGI stuff is separate.  I use the Targa+'s sync out
to genlock the diaquest DQ50P.  The method described in the diaquest manual
was not as stable as the wiring I'm using.  Diaquest method produced a dropped
frame about 1 in 400-500 frames.  Their engineer agreed with me that what I
did was superior to their documented method for reduction of the time delay of
the sync signal.  I havn't dropped a frame since sept. 1992!

I've spent some time with this gamma thing and the jury's still out.  Seems
that tmode 11 w-w/o "6" produces the same gamma level as tconfig setting at
1.0 and 3ds on or off at 1.0.  For my understanding at this time I'll define
gamma anywhere as unity adjustment at 1.0.  Meaning that 1.0 seting anywhere
is as good as no gamma delta or change.  Gary is correct in that any double
deviation from the unity figure as being detrimental to the picture quality.
The targa+ manual briefly discusses gamma as "what looks good".  Rather than
rely on even a calibrated monitor to determine what looks good I've attempted
to use the NTSC color bars tga file that I uploaded to the forum some months
ago.  At unity gamma the color bars produce a perfect vector image and as I
adjust the gamma higher the NTSC bars shift outside the boxes on the vector
scope.  This NTSC bars file was originally created using a tektronics signal
generator and fed to the targa+ composite input with gamma set to unity for
generating a 24 bit file.

FWIW a rendering of the CHEVY.3ds produces the best looking image at 1.0 on
the targa+ either using tmode or tconfig at 1.0 setting and no gamma in 3DS3.
If I turn on gamma in 3DS3 with a setting of 1.0 the lighter colors get
darker. If I adjust the gamma slider to 1.3 it about matches the no gamma
setting.  I think I'll have to just develop a self illumination NTSC color
bars as real rectangle objects for 3DS to render and evaluate with the
vectorscope.  I believe this will be the only way to accurately measure this
gamma thing.  The matching grays just tells me to set everything to 1.0 but
I'm not sure that produces the best looking and most legal picture.

#: 64376 S3/Autodesk 3D Studio
    30-Oct-93  18:33:38
Sb: #64156-Gamma correction
Fm: David Stinnett 70214,774
To: Kevin Krell [CSA] 76077,2774

Kevin,

>> I don't know what you mean about Targa+ info being undocumented.  The TMODE
parameters are right in the manual.<<

        Just to let you know, I can't find a single reference to TMODE in my
Targa+ 16/32 reference guide, however, it is documented fully in a readme file
in my tplus directory.

                                                David

#: 64193 S3/Autodesk 3D Studio
    29-Oct-93  16:17:04
Sb: Gamma correction
Fm: Bailey Brown 73020,3442
To: Yost Group 76702,413 (X)

Gary,

My version of targedit doesn't like lutByp, but it works with lutBypass.

Bailey


#: 64177 S3/Autodesk 3D Studio
    29-Oct-93  15:07:40
Sb: Setting r3 gamma
Fm: David J. Marks 72172,1036
To: David Stinnett 70214,774 (X)

DS: ...the gray panels test simply won't work... the grays can't even come
close... I'll try rendering some of the sample scenes on the cd...

Don't waste too much time on it yet.  Truevision told me that they "optimize"
their boards for NTSC output.  To my limited understanding of video, that
means that they are gamma correcting on board.  You'll probably find that the
3DS grey boxes match near 1.0 (no adjustment).  Unless the Targa+ adjustment
can be disabled, it just won't work.

Stay tuned.  The Yost Group was going to contact Truevision and try to get all
the details.


#: 64245 S3/Autodesk 3D Studio
    29-Oct-93  23:17:20
Sb: Gamma correction
Fm: Don Landis 71673,3612
To: Kevin Krell [CSA] 76077,2774

Excuse me! but there is ABSOLUTELY no mention of "TMODE" in the release 3
Truevision manual I received.  I just went through it specifically looking for
it because it was not listed in the index.  In all fairness to you though, I
did find a reference to tmode in the readme file as obsolete-replaced by the
tconfig.  The number list was there but the "6" was just stated as "use for
targa+"  Newer manuals have probably deleted this documentation but the disks
still have it.  I learned about the tmode use from this forum, not the
truevision manuals.

#: 64251 S3/Autodesk 3D Studio
    30-Oct-93  00:29:11
Sb: #Setting r3 gamma
Fm: John Ellis 72440,3046
To: David Stinnett 70214,774 (X)

David S. - Gary has already spoken with Truevision, check the gamma correction
thread 2 days back. All the details are there. You can turn Gamma off, its
fairly straightforward. -JE


There is 1 Reply.

#: 64379 S3/Autodesk 3D Studio
    30-Oct-93  19:25:53
Sb: #64251-#Setting r3 gamma
Fm: David Stinnett 70214,774
To: John Ellis 72440,3046 (X)

John,
        I've been following this and have tried only using Tmode 11 (after
removing a Tconfig batch from my autoexec.bat and rebooting) but something's
still goofy. Setting the framebuffer gamma to 2.1 gives me the best results,
and this is what I've got it set at presently. The outer box at 2.1 is dark
gray and the inner box is a much lighter gray. If I slide it down to 1.0 they
get closer, but the inner box is still a lighter shade than the outside. When
I set it to 1.0 and view various renderings, the images are much too dark.
        The targa is going straight to an RCA colortrac NTSC monitor with an
S-video hookup. Is it possible that the monitor is doing some sort of gamma
correction on its own?
I don't have time at the moment to pay too much attention to this, but I'll be
taking some major time off starting in a few days, so I'll do some fiddling
then (trying different monitors,
laying stills to tape to compare output, etc.).
        Until then I'll keep my eyes open here. Thanks for your help.

                                                David

P.S. Is anyone else still having trouble matching those annoying little
squares? The display gamma squares match perfectly at 1.8, but even though the
framebuffer output looks great, something in the back of my head says
somethings not right if I can't get a match!

There are 2 Replies.

#: 64437 S3/Autodesk 3D Studio
    31-Oct-93  11:41:36
Sb: #64379-Setting r3 gamma
Fm: John Ellis 72440,3046
To: David Stinnett 70214,774 (X)

David - The monitor seems to be the only difference between each system. I
suspect some monitors are doing some strange things. If your frame buffer
output looks good, leave the setting where you have it. Then do some recording
to tape. Check the output to tape on playback through your NTSC monitor, if it
looks good, then your framebuffer setting is probably pretty close and you
probably won't be able to use gamma adjustment on your NTSC monitor. I'd
strongly recommend getting a RGB monitor for your framebuffer, this would
enable you to set gamma correctly. -JE


#: 64458 S3/Autodesk 3D Studio
    31-Oct-93  12:24:41
Sb: #64379-Setting r3 gamma
Fm: Roger Danielsen 70323,3034
To: David Stinnett 70214,774 (X)

David,

First of all, I'm not a video engineer, and I haven't been able to reach mine
yet to confirm all this, but here are some of my observations. Observations
may be all we have to go on this since we are working on NTSC (never twice the
same color).  For testing purposes, I've hooked up every tv and monitor I own,
and the only one that seems to be able to be gamma corrected properly with T11
6 or tconfig is my the monitor I'm using for my primary video display, a Sony
PVM-1344Q, which I can gamma correct in composite, s-video, or RGB.  Whereas,
my Mitsubishi, which is supposed to be a high quality s-video monitor, no
matter where I put the sliders, it doesn't seem to help.  I have another
Mitsubishi which is better, and a large screen Sony which is about the same.
This indicates to me that some monitors/tvs are so far off they shouldn't be
used as final output test color barometers.  I originally bought the Sony
because when I was taking my stuff into some video houses, my output colors
weren't matching what they were seeing.  This Sony series is very widely used
in video production. An additional observation is that setting the gamma to
2.2 does make my final output look better on even the Mitsubishi.  Hope this
helps.

Roger D.


#: 64413 S3/Autodesk 3D Studio
    31-Oct-93  02:21:04
Sb: #Gamma
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

John:

I just completed the NTSC colorbars mesh file and spent some time running some
tests of the gamma adjustment and I made some interesting discoveries.  All
tests done with tmode 11. Composite video out.
1. The correct gamma setting for my system is indeed 2.2.  The wash out effect
I observed earlier on 3DS files was due to a misunderstanding on my part of
how gamma is applied in 3DS.  Reading pages 4-7 of the advanced user's guide
it became clear.  One must set the input file gamma to the same value as the
framebuffer setting so that the colors in the 3ds file will be de-gammaed.
Once I did this and reloaded the file 2.2 no-longer washed out.  Instead the
detail in the shadows was enhanced furtherthan before.
2. The gray boxes do not work on my system.  They still match up at 1.0.
Which, when coupled with input gamma setting produces much darker images.
3. The vectorscope indicates that green is most affected in the picture by
gamma adjustment.  The 3DS manual describes this also.  Therefore, adjusting
gamma will shift the balance of color on an NTSC color bar.  I then was able
to confirm that whatever the gamma setting you input a file at you should
render that same file at the same gamma on the frame buffer to prevent color
shift as well.   The actual setting is unimportant and can be set to whatever
is yielding the best image to personal preference.
4. I could find no adjustment 1.0 through 2.5 that made any color go illegal.

5. I did not do any tests of the output file gamma.  By the manual it appears
that some experimentation is in order to determine this number based on each
output media eg.  different type films, video, and color print.  The manual
did say that print is linear but I have my doubts.  I know that the best
prints I do on the canon BJC-800 are those with some gamma correction.

Conclusion:  The only negative I found is the gray boxes seem to be totally
useless on the targa+ in my system.  They do work on the VGA monitor.  I have
confirmed that 2.2 will work for excellent results on my system too.  The
secret being to use the same input gamma setting as the frame buffer setting
when loading files for rendering.



There are 2 Replies.

#: 64415 S3/Autodesk 3D Studio
    31-Oct-93  03:32:44
Sb: #64413-#Gamma
Fm: John Ellis 72440,3046
To: Don Landis 71673,3612 (X)

Don - I'm very glad to hear that you solved the problem. It sounds as though
you aren't using a dedicated RGB monitor out of the Targa board. A dedicated
RGB monitor would enable you to use the framebuffer gamma adjustment and the
boxes would match. I use one SVGA monitor for modeling, one RGB monitor out of
the Targa for rendering, and one NTSC monitor for the composite signal out of
the EVO. I also use custom switch boxes to share monitors with each system. It
works very well. And R3 and the Targa + is once again vindicated! -JE P.S.
Just had to throw that in there, didn't think you'd mind. Anymore tough
critics out there, talk to Don, I've earned my wings :-)


There is 1 Reply.

#: 64435 S3/Autodesk 3D Studio
    31-Oct-93  11:04:11
Sb: #64415-#Gamma
Fm: Don Landis 71673,3612
To: John Ellis 72440,3046 (X)

>> A dedicated RGB monitor would enable you to use the framebuffer gamma
adjustment and the boxes would match

So what you are saying is that the gamma adjustment using the gray boxes only
works if one uses an RGB monitor but not a composite monitor off the frame
buffer.  I checked again for documentation on this but couldn't find it in the
3ds manual.  This is an important announcement so could you elaborate?  Is
there some reason why RGB works and composite doesn't on the gray boxes from
3DS gamma?

There is 1 Reply.

#: 64441 S3/Autodesk 3D Studio
    31-Oct-93  11:54:59
Sb: #64435-#Gamma
Fm: Yost Group 76702,413
To: Don Landis 71673,3612 (X)

Not true.  We've done tests with the gamma adjustment on dozens of monitors
(there are a lot of computers at Autodesk) and it works fine on RGB,
composite, and Y/C monitors.  There's something unique and bizarre about your
rig that none of us are going to understand without coming over to your house.
(or, you could pack everything up and fly out here to Autodesk with it... I'd
be happy to meet you up in San Rafael for lunch <g>)

                - G

There is 1 Reply.

#: 64478 S3/Autodesk 3D Studio
    31-Oct-93  17:13:32
Sb: #64441-Gamma
Fm: Don Landis 71673,3612
To: Yost Group 76702,413 (X)

I'm honored by the invitation but if Adesk is up to the cost of the trip I'll
contribute the time. <G>

Seriously, I didn't think for a moment that an RGB gamma display should be any
different than a composite ( one work/ one doesn't) It just sounded that way
from John's statement.  Gary, I've looked at the output on 5 different
monitors now with several different setup configurations for the targa+.
tmode 11, tmode 25, tconfig with several setup batches and tplusini method.
They all match grays at 1.0.  The VGA main display monitor at 1.8.  The real
common denominator is the single targa+ board I have to work with.  If I could
find someone else in Jacksonville with a 3DS3/video setup I might be able to
have something local to compare to.  I'm sure you read my results and it
appears that the best looking picture is with gamma set to 2.2 on both file
input and frame buffer.  With gamma off shadows get lost in the dark areas
such as the one in front of the bumper of the chevy.3ds file.  If I don't set
the gamma to 2.2 on input file and use 2.2 on the frame buffer the whole
picture washes out when I render.

#: 64448 S3/Autodesk 3D Studio
    31-Oct-93  11:58:53
Sb: #64413-Gamma
Fm: Yost Group 76702,413
To: Don Landis 71673,3612 (X)

I wish I could come over to your house and look at this setup.  I have a
feeling that something still isn't right, because your grey boxes aren't
matching up.  Too bad you don't live in SF...

                - G

#: 64519 S3/Autodesk 3D Studio
    31-Oct-93  23:51:42
Sb: Gamma
Fm: Greg Pyros 73027,3632
To: Don Landis 71673,3612

Don:

>>  I e-mailed the ntsc cb to Greg P. and let's see if he thinks the colors
>>  are wacky or on the money.

Oh, oh!  I wanted to use your color bars as a base to do some testing with a
system that I am trying to tweak.  If you aren't sure of them, it looks like
I am going to have to rent some hi-end testing equipment for a few days to
test everything out.

My goal was to get a good set of color bars inside of 3D Studio so that
after I rendered them, I could put it on the head of a tape before sending
it off and know that if they looked good, everything else would, also!  Now
with all these other questions coming up, I may have to do it the hard way!

But to let you know, that to my eye and the blue-gun on the Sony PVM-1944,
your bars look pretty good - if I assume they are right on, I could easily
adjust the rest of my system around them.

Greg (no rest for the weary) Pyros

#: 64439 S9/What's New/Want Ads
    31-Oct-93  11:45:46
Sb: #NTSC color bar prj file
Fm: Don Landis 71673,3612
To: Greg Pyros 73027,3632 (X)

The color bars prj file has been sent to you--e-mail per your request.  If you
think it appropriate I might upload this to the library.  It's much smaller
than the tga I uploaded last spring.

Thanks for your interest.  The file has a black bar that is hidden because I
didn't take the time to adjust its levels.  I found the background = none to
be 7.5 ire so I just use that for the black.  Important:  I found the file
must be loaded after you set the input file gamma setting to = what you have
in your frame buffer setting.  This should adjust for any gamma correction i
had on my system when I created the mesh colors.  The colors were adjusted in
the mat ed. with the wfm peak to peak voltages for each color and the
vectorscope.  The colors could use some final tweaking but I need a bigger
scope screen to do this.<g>  The white (gray) bar should be at 77 ire and
black at 7.5.

BTW the renderer in the materials editor is really a time savor.  Yost really
outdid himself with this productivity package!

There is 1 Reply.

#: 64465 S9/What's New/Want Ads
    31-Oct-93  14:12:26
Sb: #64439-NTSC color bar prj file
Fm: Greg Pyros 73027,3632
To: Don Landis 71673,3612 (X)

Don:

Thank you for the color bars project file!  That is exactly what I've
needed.

>>  If you think it appropriate I might upload this to the library.

I's sure it would be not only appropriate but appreciated by all!  You might
want to include a text file explaining how to use it, basically the two
e-mails you have sent me, and delete the black object since the background
works as black!

Thanks again,
Greg Pyros

#: 64576 S3/Autodesk 3D Studio
    01-Nov-93  12:52:57
Sb: #64376-Gamma correction
Fm: Kevin Krell [CSA] 76077,2774
To: David Stinnett 70214,774

David,
       Interesting.  Must be a different version of the manual.  Maybe it was
changed when TCONFIG shipped - my bopard is from the original release (as
dealers got the first boards shipped after the Siggraph announcement of the
Targa+).

               Kevin Krell - Computer Support Associates

#: 64604 S3/Autodesk 3D Studio
    01-Nov-93  16:14:31
Sb: #64448-#Gamma
Fm: David J. Marks 72172,1036
To: Yost Group 76702,413 (X)

>>I wish I could come over to your house and look at this setup.  I have a
feeling that something still isn't right, because your grey boxes aren't
matching up.  Too bad you don't live in SF...

Maybe DonL and I should pack up our stuff and meet you in Belize.  Somehow
gamma correction wouldn't seem so important out there, tho'.



There is 1 Reply.

#: 64630 S3/Autodesk 3D Studio
    01-Nov-93  18:25:18
Sb: #64604-Gamma
Fm: Don Landis 71673,3612
To: David J. Marks 72172,1036 (X)

>>Maybe DonL and I should pack up our stuff and meet you in Belize.  Somehow
gamma correction wouldn't seem so important out there, tho'.


Now you're talking.  What's important in Belize?  Sunscreen and a good  air
compressor.

#: 64606 S3/Autodesk 3D Studio
    01-Nov-93  16:36:29
Sb: #64519-Gamma
Fm: Don Landis 71673,3612
To: Greg Pyros 73027,3632 (X)

>>Oh, oh!  I wanted to use your color bars as a base to do some testing with a
system that I am trying to tweak

It's close enough for G work!  I just won't make any claims because as soon as
I do some wise guy will come in and advise me that my cyan is out by  0.05vpp
as measured on a Scientific Atlanta analyzer or something.  I thought you had
scopes there??  If you only have a WFM I can give you the p-p voltages of what
the colors should be but I'm sure you have all that stuff.

#: 64590 S3/Autodesk 3D Studio
    01-Nov-93  15:29:07
Sb: GAMMA GAMMA?
Fm: John Ellis 72440,3046
To: ALL

This message is regarding Video and the Targa 32/64+ and gamma adjustment.

Only RGB and SVGA can be gamma adjusted with the Boxes to be able to visually
see Gamma Adjustment. In other words only through your SVGA or RGB monitor
will the boxes line up!

NTSC will not show proper Gamma alignment with the boxes. If you set it to 1.0
where the boxes match, you have effectively disabled or neutralized Gamma
Correction in NTSC. You can check this by rendering ADLOGO at 1.0 with Gamma
on and then re-rendering with Gamma off. They are identical.

If you set your framebuffer Gamma to 2.2 you will not see boxes that match on
your NTSC monitor but your NTSC will be gamma corrected. In fact on your NTSC
monitor the inner box will be bright.

RGB and SVGA will Gamma correct in that the boxes will match. I would
recommend that you make your gamma adjustments for either of these two
monitors or between 1.8 - 2.2 to suit your taste. While not explicitly stated
the Advanced User Guide does say "The standard gamma value for NTSC video
output is 2.2", it does not state however how one is supposed to arrive at
that, and the assumption has been that by getting the boxes to match up you
would have proper gamma adjustment. This assumption is incorrect. This only
works for RGB and NTSC.

You also need to check your recording device to make sure it doesn't gamma
correct.  Otherwise you run the risk of double correcting.


#: 64822 S3/Autodesk 3D Studio
    03-Nov-93  02:04:52
Sb: #64590-GAMMA GAMMA?
Fm: David Stinnett 70214,774
To: John Ellis 72440,3046 (X)

        Thank You. This makes me feel better as I was about to spend half a
day switching monitors, gamma settings, and rendering test images just to
match the boxes. No need now.
        I do, however, feel this strange inner hatred for little gray
boxes.<g>


                                                David

#: 64924 S3/Autodesk 3D Studio
    03-Nov-93  18:45:43
Sb: #64822-GAMMA GAMMA?
Fm: John Ellis 72440,3046
To: David Stinnett 70214,774 (X)

David - Your welcome, I think maybe a little too much has been made of these
little boxes as well. Basically it boils down to this, whatever you set your
framebuffer value to set your file input and file output to the same value and
everything will come out fine. A comfortable range is between 1.8 - 2.2 for
video. The NTSC side is already adjusted to compensate for gamma correction on
your NTSC monitor or Television monitor. This is a result of the NTSC
specification and is inherent in any NTSC signal. That's why your boxes match
up at 1.0  Hope this clarifys it for you. -JE


#: 65415 S6/HWare/ADI/OpSys
    08-Nov-93  10:32:54
Sb: #65144-#CRV 3000, 5000, EVO-9650
Fm: David J. Marks 72172,1036
To: John Ellis 72440,3046 (X)

Thanks for the confirmation on that John.  Are you equally certain that a
composite NTSC signal IS gamma corrected?  As we discussed on the phone, that
makes life in grey-box land really confusing.  I can't wait for GY to get back
from vacation and give us his thoughts.



There is 1 Reply.

#: 65475 S6/HWare/ADI/OpSys
    08-Nov-93  14:38:40
Sb: #65415-CRV 3000, 5000, EVO-9650
Fm: John Ellis 72440,3046
To: David J. Marks 72172,1036 (X)

David - I think the term "gamma corrected" with regard to the NTSC signal may
be misleading. The output is linear which means there is compensation to
produce linear results. This is not gamma corrected in the sense that you will
get double gamma correction if you use a setting of say 1.8 in 3DS. But it is
gamma corrected in the sense that it is neutral. Monitors are not linear
devices but with an NTSC signal they are, as evidenced by the boxes matching
up at 1.0 This is a result of the NTSC specification. The Truevision people
who also have 3D Studio have confirmed this. They have worked extensively on
this and you might give them another call for further clarification. The fact
is that when you align your NTSC monitor at 1.0 you are effectively
eliminating the gamma correction provided for in 3DS.