Hi. I'm interested how the composite fuction "after light???" (my gimp talks german to me - so it's "nachbelichten" - i think i should be dodge?!?) works. I checked the code, but the function (A * 256) / (256 - B) doesn't seem to be the proper one (as e.g. overlaying a picture with a white color (A) in this mode doesn't change the picture (B) anyway) If anyone could tell me, how this is done, or where i can find the proper code: Thanks Thomas -- Think, think different. But essentially: Think! ps: don't worry, i'm not working on some kind of counter program, but i want to use this function to highlight something in my app.