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1991-10-22
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328 lines
D I S P L A Y 4 . E X E
O C T O B E R 1 9 9 1
FOR THE DISPLAY OF UOSAT OSCAR 22 CCD PICTURE FILES
Free Issue Software for Licensed Amateur Radio Use ONLY.
Copyright 1991 AMSAT-Australia
Donations in appreciation of this software package
to assist fund and develop future
Amateur Radio Satellite Programs
may be forwarded to
AMSAT AUSTRALIA
GPO BOX 2141
ADELAIDE
SOUTH AUSTRALIA
AUSTRALIA 5001
This document is to cover the program DISPLAY4.EXE Version 4.1
released 6th October 1991.
Version 4.1 is a significant update of all the previous versions of
DISPLAY.EXE with additional enhancements.
Updates from Version 4.0 include :
1. Ability to read .DLX or .ACT files
2. Recognisation of "non standard" files.
3. Automatic calculation of the exposure time
4. Deletion of Auto white bar fill
5. Inclusion of Manual white bar fill
6. Automatic exposure correction of displayed file
7. General enhancement of Display Screen
8. Eraseable scroll bar to highlight scroll update
FILE CAPABILITY.
DISPLAY4.EXE is designed to display retrieved CCD or IM Series
Picture Files. However after specific requests from users of
previous versions of DISPLAY to have the ability of displaying .ACT
files, I have included that ability. For best display performance
the .ACT file should have the minimum number of holes. However it is
extremely usefull even with only 25% of the total, in being able to
preview the picture with a view towards completing or abandoning the
file. The only limitation on .ACT or .DLX files is that are of the
IM Series, ie: Files 0x0224 and above. The program will work with
earlier files however the picture will be misaligned, but viewable.
Having released Version 4.0, the very next day IM0019 was obtained
and when loaded indicated it was corrupted. In Version 4.1 I have
revised the rules by which a file is recognised to be "corrupt".
The format of the IM Series file makes it extremely difficult to
retrieve should it be corrupt. Therefore I have relaxed the test on
both the CCD and IM Series, and issue an appropriate message. The
penalty is of course that corrupt CCD files cannot be written back
as an uncorrupted file. However should this be the case the use of
DISPLAY2.EXE will overcome this problem.
DETERMINATION OF EXPOSURE TIME
As the file commences to load into memory the program
interrogates the file header information and calculates the exposure
time from the UNIX Time Stamp embedded in the header. This timestamp
is also wriiten to the file display, once the file is loaded.
However while the file is loading, you should record the date and
time displayed so that at a later time you can use your Tracking
Program (eg:InstantTrack) to ascertain where the picture was taken.
Make certain that you include the seconds value, because 1 minute on
UoSat Oscar 22 is a significant distance. Having determined the
location you will generally require an atlas, and the use of the F5,
F6, F7 and F8 keys to achieve the correct picture orientation,
unless the picture is of a notably distinguishable landmark.
WHITE BAR FILL.
The automatic white bar rejector in Version 4.0, did not meet my
personal expectations. I in fact experimented with 4 diferent
functions before settling for a manual solution.
Whilst in the EDIT mode you use the PAGEUP or PAGEDOWN keys.
The PAGEUP Key darkens the bar by 0x01 bytes per key stroke,
whereas the PAGEDOWN whitens by 0x01 bytes. You may require at least
10 key strokes to note a visible darkening in some instances.
Experience will assist you to ascertain the correct balance. On the
pictures retrieved to date it is extremely difficult to obtain an
ideal match. [Also refer the INSERT and DELETE Key Functions].
MEAN VALUE AUTOMATIC EXPOSURE CORRECTION.
As stated in previous notes, I unfortunately managed to include
a "bug" in the original versions of Display. It was not until the IM
Series appeared that I realised that there was a problem. (The
symptom was all those "washed out" white pictures). The paradoxial
situation was that the "bug" in fact enhanced the CCD Series of
pictures. However now is all resolved. Currently the Surrey Team are
experimenting with exposure settings,etc. Consequently the pictures
can vary from "overexposed through underexposed". In version 4.0
this required considerable patience to adjust the contrast manually.
Now as the file is being loaded a MEAN VALUE calculation, is
performed on all the picture bytes. Theoretically within a 64 Grey
Scale Picture the mean value of the picture should be 0x1f, being
the mean value of 0x00(black) and 0x3f(white). Once the MEAN VALUE
is ascertained all the picture bytes are adjusted to achieve a
displayed mean of 0x1f. [For example load IM001A, CCD2(14th Aug),
IM0011 and IM0018 and compare the MEANS.]
NOTE! If the exposure contains excessive whites or blacks this
algorithm fails - however this rarely occurs, and should become a
lesser problem as the Surrey Team gain greater experience.
This AUTOMATIC Correction is the DEFAULT setting. Should you wish to
over-ride this function, enter the NOMEAN [option] on the command
line.
When the picture is displayed the PICTURE STATUS in the lower left
of screen, details the calculated mean, and the screen mean value.
In the default setting the screen mean will be displayed as 0x1f.
Should you exercise the NOMEAN Option when initially loaded the
calculated mean and displayed mean will be of equal value. As the
display is manually adjusted the Screen value will increase or
decrease by an amount of +/- 0x04 bytes.
SCREEN ENHANCEMENT
Every picture tells a story. In my case every pretty picture tells a
story, hence the colourisation etc.
Features include EDIT and DISPLAY Fields (Contrast, Brightness, etc.)
PIXEL Information (Blacks, Whites etc.)
PICTURE Information (Mean and Screen Mean Values).
Scrolling EDIT bar to identify line processing locn.
KEY FUNCTIONS
KEY FUNCTION EDIT DISPLAY
F1 Reserved Future Use
F2 Select EDIT Mode X
F3 Reserved Future Use
F4 Reserved Future Use
F5 Normal Display X
F6 Rotate 90 Deg Clockwise X
F7 Rotate 180 Deg X
F8 Rotate 270 Deg X
INSERT Increase Contrast Top to White Bar X
DELETE Decrease Contrast Top to White Bar X
HOME Default-Top 480 lines (640x480 Display) X
END Bottom 480 lines
PAGEUP Increase Darkness of Bar X
PAGEDOWN Increase Whiteness of Bar X
UP ARROW Increase Contrast Total Picture X
DOWN ARROW Decrease Contrast Total Picture X
RIGHT ARROW Increase Brightness Total Picture X X
LEFT ARROW Decrease Brightness Total Picture X X
ALT-X Exit Program X X
NOTE :
F5 or F6 or F7 or F8 Key Strokes exits from EDIT to DISPLAY Mode
COMMAND LINE
The command line looks for an entry as follows :
DISPLAY4 <filename> [options]
DISPLAY4 -> Displays Help Information
<filename> expects CCD???? or IM????
<filename> can include path and directory
eg. DISPLAY4 \UO_22\DISPLAY\IM0012
[options] 800 for 800 x 600 Display (default = 640 x 480)
nomean to negate automatic picture correction
view to view original picture before enhancement
The options may be entered in any order.
PICTURE OPTIMISATION.
The following hints may assist you to optimise the various
pictures retrieved from UO_22. The final result is one of personal
preference.
EDIT MODE
Firstly observe whether the contrast of the picture between the top
of screen and the white bar is the same as below the white bar. Some
of the pictures obtained have a marked difference in contrast.
Should this be the case use either the INSERT KEY to Darken or the
DELETE KEY to Whiten. Eack keystroke varies the pixel byte by plus
or minus 0x01.
Now use the PAGEUP KEY to darken the White Bar. Use PAGEDOWN to
reverse should you "over-darken". Rarely will you get a perfect
balance. Once again it is a personal preference.
Once you optimise the bar you may find that you need to re-optimise
the top section of the picture. (Above the now "non-existent" bar).
With the AUTOMATIC MEAN VALUE correction it is highly unlikely that
you need to adjust the total picture CONTRAST, unless it is highly
unbalanced with an excess of whites or blacks.
Refer the Pixel Indicator.
The Black Value is Qty of Pixel Bytes <= 0x10
The White Value is Qty of Pixel Bytes >= 0x30
The Mid Value is thus Qty of Pixels > 0x10 and < 0x30
To adjust the brightness of the picture use the RIGHT ARROW. Each
key stroke increases the factor by 20% (displayed as Pixel Factor in
units of percentage. Base Value is 100%).
Once you have optimised the picture you can select either F5 through
F8 to place the screen into DISPLAY Mode. The only functions
available in DISPLAY are rotation and brightness. Should you wish to
re-adjust the white bar, contrast etc, F2 will place you back into
EDIT MODE.
Prepared : Colin VK5HI 6th October 1991