Collection of Tools & Utilities/Collection of Tools and Utilities.iso/graphic/gds202.zip/GDSINFO.DOC

Text File | 1991-07-08 | 27KB | 528 lines

INTRODUCTION    Graphic Display System - GDS

  One day, I was working on a simple card game and needed a variety of
cardback graphics.  I referred to a library of GIF files for some good
scenery to put on the backs of cards and found about 30 files which had
nice scenery and pieces which could be used quite nicely.

  First, I converted a set of GIFs into IFF format and loaded them into
Deluxe Paint II Enhanced.  Deluxe Paint is one of the more powerful paint
programs, and I was very surprised to find that the brush size is limited
to 64K (a forgivable programming limit).  After messing around with grids
and reducing chunks of images down in a nice orderly fashion, I did not get
the results that I wanted, I deleted the whole bunch.

  I was very happy to find a program called GIFDESK on a bulletin board.
It seemed to be just what I was looking for, and it solved another problem
for me also.  The documentation said it could reduce GIFs, but it was
designed for cataloging pictures, rather than just image reduction.  Great!
Now I could get the graphics done, and I could catalog my 150 megabytes of
GIFs!

WRONG.  GIFDESK is great for a simple catalog program, but it doesn't do
much for preserving images.  The version I have simply grabs dots from the
original and slaps them in a reduced space.  Although I'm not sure, it
seems to also use a generic palette which further reduces the quality.
In short, all images get stomped on, some are very simply unrecognizable.

  Another problem which was mounting in the back of my mind was that every
GIF viewer I've seen either has mounds of technical problems/ quirks/bugs,
or a user interface that would scare the average user.

  I was disgusted, in between projects, and wired on coffee.  I downloaded
CompuServe's GIF file specifications for encoding and decoding and got to
work.  A day later, GDS 1.00 was a reality.

  I make no claims that GDS is everything.  The general outline of the
program is based around a very few simple concepts, and there is certainly
room for improvement.

  Ironically, many users keep a collection of viewers available in case
they run into this well known scenario:
     "Oh that picture!  You have to use this viewer for that one..."

  GDS overcomes a lot of common problems like "odd aspect ratios" and
enormous pictures.  I have many VERY large or odd shaped GIF's that I had
never seen completely before I wrote GDS.  GDS handles images up to and
including 2048x2048, and should be able to reduce any 2048x2048 image down
to 32x32 with no problem (300 would fit on a single 640x480 screen)!

  The last but not least effort before version 1.07 was to support the
GIF89a file format.  Reading and writing these files was no problem, except
that we couldn't find another viewer that would display '89a images
properly.  So . . . GDS will continue to write GIF87a files until the other
viewers are up to speed.

  It has now been several weeks since the first releases of GDS, and the
response thus far has been overwhelming.  Only three weeks after the
release of GDS 1.07 on CompuServe, GDS107.ZIP received over 190 downloads!
That level of interest is phenomenal on CompuServe since the existence of
GDS is not publicly advertised in any forums, BBS's, etc.  When I first
wrote GDS, I had no idea how much all of you wanted it.  Now I do, and this
latest version demonstrates how I intend to continue improving it.

  Many thanks go to all of you who have been invaluable in helping solve
hardware and software problems, and becoming part of the GDS family of
registered users.



REVISION HISTORY

1.00    02-10-91        The "First Release; Hope You Like It" Version
-->     No bugs reported yet.  (I'm plugging my ears.)


1.01    02-11-91        The "Wow! that was fast!" Version

-->     "Sort:" menu in earlier versions could easily lock up GDS when
used to sort by "Bits per pixel" or "Resolution" if GDS had not yet read
file information for all files in file list.  Although I haven't seen it,
this bug may cause stack overflows, 386 exceptions, and all sorts of
other unpredictable stuff.

-->     Palette generation for array images is much more accurate for
images with varying numbers of bits per pixel.  In prior versions, images
with fewer bits per pixel were not represented equally among pictures
with many bits per pixel.  This problem has been eliminated by padding
smaller palettes to bias the importance of their individual color ranges.

-->     When displaying a 2, 4, 8, or 16 color image in single view mode
and the screen format used to display the image was an EGA mode, some VGA
boards would handle the EGA palette and VGA color registers
inconsistently.  This occasionally caused a color or two to be incorrect.
GDS now resets all EGA palette registers and all VGA color registers
every time the palette is set, which seems to have corrected the problem.
NEW!    Changed behavior of mouse clicks in file list when "View:" mode
is set to "Slides."  Users tend to want to point at a file and add it to
the list rather than deselecting all other entries in favor of the one
their clicking on.  So from now on, when you're doing slides, remember
that the mouse toggles files!

-->     Fixed small moving button click problem in array setup.


1.02    02-12-91        The "QUIX RIX FIX" Version

NEW!    Added RIX support through the ALT-R command.  Note that GDS can
only support the UNCOMPRESSED RIX file formats as RIX Software is not
releasing any information about their compressed file format.  If you
would really like to see support for compressed RIX files, don't ask me--
ask RIX Software.

-->     Fixed PCX file write for 16 color screen modes.  In previous
versions, GDS would write odd images with the bits in the bytes flipped
around, and possibly the plane order reversed.  This bug may be a
reflection of how much time I spent writing PCX support.  GDS now reads
and writes PCX files correctly in all screen modes.


1.03    02-13-91        The "New and Improved Slideshow" Version

-->     Corrected bug in slide shows which could incorrectly display
images which had been read completely into EMS before being displayed.
This bug is more common when the user hits the space bar to bypass the
slide show delay.  Earlier versions of GDS could display slide shows with
image misalignment/fracturing or even garbage in horizontal bands of
images.

-->     Corrected bug in array generation which could crash a system.
The bug occurs when the individual array images were reduced to less than
1:32 of the original image size.  This limitation was not protected
against in prior versions of GDS.  GDS is now capable of 1:64 image
reduction and limits the size of array images to prevent users from
reaching this limitation.

-->     Corrected many bugs in ALT-Z zoom function during single image
viewing.  In prior versions, the zoom feature would inversely compensate
for the aspect ratio of the screen.  This version should handle the zoom
feature as one would expect.

-->     Corrected nasty bug in two dimensional antialiasing when
displaying zoomed areas.  This bug would skew some lines in the display
to the left of where they should have been drawn.  The severity of the
display problems depended on the level of zooming, the aspect ratio of
the original image, and the position of the upper left zoom rectangle
corner.

NEW!    Added READMAC file format to list of supported formats.
Readmac files (.MAC) can be read, but not yet written.  Anybody out there
want to write these files?  Let me know.  NEW!    Added color control to
single and array views.  The overall color level in the palette can be
adjusted with the ',' and '.' keys (normal case of '<' and '>').  To
reset the color level, just hit Shift-',' or Shift-'.' ('<' or '>').
This feature, along with the other image palette options gives the user a
surprising amount of control over problem images.

NEW!    Added page display compensation when generating arrays and using
ALT-F to fit an image to the display.  In pr