You cant go frame by frame in photshop cause once you animate it the areas you changed it'll have "squiggly" un-even edges, you have to track/mask with bezier tools in a motion graphics program, such as After Effects or better yet, Mocha.
ITs hard peoiple, REAL f'in hard to do it, especailly on cloth.... sometimes almost impossible without all the orig elements sperated and rebuilt/re-composited together, I know it all sounds well and easy in theory, but go rotocope cloth or hair somtime you'll see what its like. Things like lightsabers and lasers are much easier to do cause they are simple flat edged shapes, but once you have say.. young Bobas hair against a white background, HOW are you gonna trap that element? What you need is his actual green screen footage so you can color manip that seprate element in AE or Mocha. Again I use Photoshop everyday for work and I have pretty good expierience rotoscoping in AE, im telling you ships and lasers are one thing, but moving cloth and hair... THATS no fun at all and in some case impossible without un-composited elements to draw from, aside from a global color correction.
However.... One small workaround you can do... sometimes... is take two versions of the same clip, color correct them so Obi looks good, and Boba looks desaturated, then mask out the Boba from the Obi clip, and the Obi from the desaturated Boba clip, hopefully the BG wont be too different to tell... but uh... to anyone who wants to try it with acutal footage, not photoshop imags, then you got my repsect.