Most of these switches behave more-or-less the same on the
Windows, Linux, and RiscOS versions; some RiscOS-specific issues
are mentioned below. Note that even on the Windows version, the
options must be prefixed with - and not /.
At its simplest, you can
just type intergif and the name of your sprite or film
file, and it'll be converted. Here's a full list of the
intergif [-i] [-s] [-loop] [-split] [-d cs]
[-t [pixel]] [-trim] [-join] [-list]
[-g16 | -g256 | -216 | -256 | -pal palfile |
-best n ] [-dither [-zigzag]] [-c changefsi-options]
[-o outfile] infile
- Produce an interlaced GIF: in other words, one which a Web
browser can render quickly at a low resolution, filling in the
details later as they arrive.
- Looping animation: Normally an animated GIF plays through once and stops. If you
tick this option, you'll get an animated GIF that plays over and
- This option causes InterGif to look for only one frame in the
file you give it, and then look for the next frame in another file
with the numeric part of the file incremented. For instance, you
could have three files called frame000, frame001, and frame002 and
create an three-frame animation by issuing the command
intergif -join frame000 -o
This is, by no coincidence, compatible with the way
POV-Ray names its output files.
- This option causes InterGif to treat "infile" as a text file
containing a list of image filenames to convert.
- -d cs
- Sets the frame delay in centiseconds. This overrides any
frame delays set in the input file or files.
- This splits up the input file into one output file per frame.
Not, I admit, terribly useful, unless you need to import something
into an application that expects lots of one-frame GIFs -- for
instance, Sun's Java Animator applet. The names of the files are
taken from the one you give, with any numeric part incremented as
needed, so if you save a three-frame animation as frame001/gif,
you also get frame002/gif and frame003/gif.
- Use transparency (masking) information from the input file
to determine transparency in the output file (the default is
to use no transparency at all).
- -t pixel
- Use the specified pixel-value from the input file as
- This tells InterGif to remove any wholly
transparent rows or columns from the edges of the input
image. (If the input is an animation, it only removes rows or
columns that are blank on every frame.) This means
that the output image may be a different size from the input
one, which is otherwise never the case.
advise you to do this if you're making a one-frame,
transparent, interlaced GIF: for the reason why, see the
section on Netscape
probably also want to do this if you're converting a Draw
file, as these often end up with one or two transparent rows
and columns at the edges.
- This maps all colours in the input onto the nearest ones
the Macintosh/PC standard 216-entry "web safe" colour cube. This is
useful, for instance, for reducing the size of 256-greyscale
images. Note that InterGif really does map the
image to the new palette: it doesn't do dithering, unless you also
Properly dithered images compress really badly in the GIF
- These options cause InterGif to create greyscale output: 16 or 256
- -best n
- This is the most powerful option: selecting this makes
InterGif calculate the optimal palette for displaying the
input images, and then map to that. You can tell it to
calculate any size palette from 2 to 256 entries. InterGif
uses the "median cut" algorithm to calculate the palette.
this option makes InterGif dither, rather than map,
its input file to the required palette. This only works on
16bpp and 24bpp input files (and Draw files). This feature was
contributed by Martin Würthner.
- Normally the -dither option works left-to-right on every row. But you
probably want it to alternate left-to-right and right-to-left on
alternate rows -- this so-called "boustrophedonic" Floyd-Steinberg
often gives better results, and it's what ChangeFSI uses. The -zigzag
option makes the dithering boustrophedonic.
- -o outfile
- Filename for the output (default is
- A RiscOS sprite, Draw, Complete Animator, or GIF file
(the first two of those only work on the RiscOS version)
RiscOS version only
As well as allowing the conversion of sprite files and Draw
files, the RiscOS version of InterGif supports the following
The default output file is <infile>/gif instead of
- Produce a sprite rather than a GIF
- Map to Acorn standard 256-colour ("mode 15" or "VIDC1")
- Output a "new format" (RiscOS 3.5 and later only) sprite
- -xdpi 180 | 90 | 45 | 22
- Horizontal dpi specification (for new format sprite only)
- -ydpi 180 | 90 | 45 | 22
- Vertical dpi specification (for new format sprite only)
- -pal palfile
- Map to given palette
- -c changefsi-options
- Preprocess each frame with Acorn ChangeFSI, if available
(Note to users
of previous RiscOS versions: the !Boot file of !InterGif sets up
Alias$intergif, so you no longer
need to copy the intergif program into your library directory. In
fact, to avoid confusion, you should go and delete any copy of
intergif in your library directory.)
All Rites Reversed --
Copy What You Like