Based on this question for imagemagick, what is the equivalent for graphicsmagick? Recipe for creating Windows ICO files with ImageMagick?
Also I just want to generate a fully transparent ico file with multiple sizes. I found that there's an xc:none
option that works for both, but is there one single command that generates ico files with multiple sizes that is transparent? Otherwise I would have to first create a transparent png file, then create ico files from the png file.