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1989-03-25
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Giffer: A program to display GIF images on a mono-ST
Giffer will display GIF images on an Atari ST with monochome monitor
using a variety of dithering methods, including Floyd-Steinberg.
It can be used from a shell or the desktop.
This archive will contain GIFFER.TTP, the program,
and ALBERT.GIF, a sample GIF image.
To use Giffer from the desktop, you should install with these steps:
- select GIFFER.TTP (single click it).
- invoke "Install Application" from the menu bar (under Utilities).
- type "GIF" as the extension (no return).
- click the INSTALL button.
You can now view your .GIF files by double-clicking the .GIF files.
Once the image appears you can press a digit from 0 through 3
to select other dithering methods (see below).
Pressing any other key will return to the desktop.
To use Giffer from a shell, use
giffer [-i] [-v] [-l] [-r] [-[0123]] file ...
After displaying the image, Giffer will wait for a key press
as described above. There are several command options available:
-i: only print information about the image; don't display.
-v: print information about the image before displaying.
-l, -r: rotate the image 90 degress left or right.
-[0123]: select a different dithering method.
Dithering is a technique to display grey-level images on a two-level display.
The dithering methods are:
0: black and white, no dithering. Useful if image already dithered.
1: a 16 by 16 regular dither. This gives 256 grey levels.
Only 30-40 are really distinguishable. This is the default.
2: a 2 by 2 regular dither. This gives 5 grey levels.
3: Floyd-Steinberg dither. This gives many grey levels
but has less loss of detail than the regular dithers.
It is also a bit slower.
Giffer was compiled with GCC and dLibs. Giffer is unrelated to a program
of the same name for the Mac. GIF is a trademark of Compuserve.
Eric Gisin, egisin@math.Waterloo.EDU