"There are a great many barriers that block open source graphic
arts software from making it into the mainstream. There is the
issue of the proprietary elements present in the big print shops.
Adobe, not just Photoshop, but most of their print/image based
products are based on a proprietary color system that large ink
printers use to guarantee color quality. Sometimes called 'spot
color' but the real term is Pantone Color. Pantone is an global
industry standard for professional graphic artists and professional
print shops--and it's proprietary of course..."