There are a lot of threads on here about doing that in Photoshop (search the forums for terms like mode, bitmap, ellipse). There was a video that someone linked to as well which went through the whole process, but I don't remember exactly where.I just ordered a color separation program which has not arrived yet so I was wondering if I can separate in photoshop. I need to give an answer soon if I can do the job and want to make sure I can before I commit.
There are at least 8 basic colors in that image; that's before halftoning to make the forty-eleven different shades of each of the basic colors.you could do 4 color process if your really wanted to, but everyone knows spot is the way to go. I would seperate that file into 6 colors and take some of those oranges and greens that are similar and make the lighter ones halftones of the darker colors.