This program is part of Netpbm.
This program is essentially obsolete; The newer winicontopam is better.
winicontoppm reads a Microsoft Windows .ico file and converts it to one or more PPMs.
A Windows icon contains one or more images, at different resolutions and color depths. Each image has an 'and' mask, which contains transparancy data.
By default, the output goes to Standard Output. If you specify ppmdestfile, output goes into one or more files named as follows. If it's just one file (i.e. you specify the -multippm option or don't specify -allicons), the file name is ppmdestfile.ppm. If it's multiple files, their file names are ppmdestfile_1.ppm, ppmdestfile_2.ppm, etc.
When you specify the -writeands option, the file names above are modified to include the string xor as in ppmdestfile_xor.ppm or ppmdestfile_xor_1.ppm.
winicontoppm can convert .ico images with 1, 4, 8, 24, or 32 bits per pixel. Before Netpbm 10.15 (April 2003), it could not handle 24 and 32.
If you specify neither this nor -bestqual, winicontoppm extracts the first image.
If you specify neither this nor -allicons, winicontoppm extracts the first image.