Seriously both SAI and Photoshop feel insignificant compared to this (In terms of painting and mixing ability) It would be a SIN if I didn't share this with you guys This is the most complex and realistic painting software I have ever come across. Seriously have a look, it's WELL worth it.
Download is here
Information on how to use it
I admit it takes a bit of getting used to, and there are MANY keyboard shortcuts. But personally I'm going to take the time to get used to this software.
He states in the video below that you cannot upload images, that has since then changed btw.
Vthese two don't like youtube videos lol, stealing their space. God I need to learn how to code...