How to create new Icon for Character?

To help speed things up and help figure out who is who my DM is enlisting me to help draw easy to see pixel art for my party. I will make a recognizable headshot for each character, nothing fancy.  So.... how do I do this?  Specifically, what is the best dimension for the icon pictures and how do i change them for each person? Also do I have to save as .pdf?

I think this part of the wiki probably can answer your size and format questions.&nbsp; <a href="https://wiki.roll20.net/Creating_Marketplace_Assets" rel="nofollow">https://wiki.roll20.net/Creating_Marketplace_Assets</a>&nbsp; As far as how to go about it, GIMP and Photoshop can certainly make tokens from images.&nbsp; I know there are specific programs out there for making tokens as well, but I have never used them.