Consider using an escrow as well, I volounteer if wanted.
EDIT: Forgot to ask, is it possible for users to make agreements with each other to cooperate if s/he wants to take a day off some time??
Yes! I agree, (up to) 100 images per day to be extracted on a background is really a big day to day project for a one single person. Another suggestion will be, maybe OP can consider to divide the workload into individuals that have the the best approach on the example given. (if(workload == 99)( jayce,GHCoins45,Raja_MBZ = workload/3 )). Well, I think it also depends on the selected designer whether he/she would share Just giving out my idea in here.