This is the command giftopnm that can be run in the OnWorks free hosting provider using one of our multiple free online workstations such as Ubuntu Online, Fedora Online, Windows online emulator or MAC OS online emulator
PROGRAM:
NAME
giftopnm - convert a GIF file into a portable anymap
SYNOPSIS
giftopnm [--alphaout={alpha-filename,-}] [-verbose] [-comments] [-image N] [GIFfile]
DESCRIPTION
This is a graphics format converter from the GIF format to the PNM (i.e. PBM, PGM, or PPM)
format.
If the image contains only black and maximally bright white, the output is PBM. If the
image contains more than those two colors, but only grays, the output is PGM. If the
image contains other colors, the output is PPM.
If you have an animated GIF file, you can extract individual frames from it with gifsicle
and then convert those using giftopnm.
A GIF image contains rectangular pixels. They all have the same aspect ratio, but may not
be square (it's actually quite unusual for them not to be square, but it could happen).
The pixels of a Netpbm image are always square. Because of the engineering complexity to
do otherwise, giftopnm converts a GIF image to a Netpbm image pixel-for-pixel. This means
if the GIF pixels are not square, the Netpbm output image has the wrong aspect ratio. In
this case, giftopnm issues an informational message telling you to run pnmscale to correct
the output.
OPTIONS
--alphaout=alpha-filename
giftopnm creates a PGM (portable graymap) file containing the alpha channel values
in the input image. If the input image doesn't contain an alpha channel, the
alpha-filename file contains all zero (transparent) alpha values. If you don't
specify --alphaout, giftopnm does not generate an alpha file, and if the input
image has an alpha channel, giftopnm simply discards it.
If you specify - as the filename, giftopnm writes the alpha output to Standard
Output and discards the image.
See pnmcomp(1) for one way to use the alpha output file.
-verbose
Produce verbose output about the GIF file input.
-comments
Only output GIF89 comment fields.
-image N
Output the specified gif image from the input GIF archive (where N is '1', '2',
'20'...). Normally there is only one image per file, so this option is not needed.
All flags can be abbreviated to their shortest unique prefix.
RESTRICTIONS
This does not correctly handle the Plain Text Extension of the GIF89 standard, since I did
not have any example input files containing them.
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