>>2203739yeah, those jagged edges are the ones that anon says you use to extract the color from. you can either do that multiple times or go manually picking them off. I don't know jack shit about this stuff, so maybe there's a better way. you should ask the people on the IMT for input or search YouTube for quick tutorials.
as a bonus, you should always try to use the best quality image as possible. sometimes people here post jpgs or pngs that have been compressed a few times or have been heavily edited by others. a tip is to try and find the original artist's version (PNG is the most common and reliable source) from either their page/patreon/whatever or some quality sources like the boorus (original pictures, not samples), and work from there. Imgur, social networks like facebook, and other sites are known for messing with the quality of the pic, of course places like /b/ are absolutely out of the question as well