Hi, for a program, I need to map the location of all the back pixels in an image into some kind of structure. The program later uses the structure to select a random pixel location. It then removes the location, to prevent it being used again. The problem is, there is a huge number of black pixels (close to 40,000) so an ordinary array takes forever to search for and eliminate the "used" pixels. Is there some other "Faster" data structure?

>Is there some other "Faster" data structure?

Yeah! but tell me about your plan and currently used "data structure".

instead of saving all the pixels separately, you could instead save less arrays containing four coordinates in which between are only the same color, or as i like to call it "same-pixel-quadrants". so if you have a piece of image that's only black containing 40.000 pixels, make much less squares covering the whole piece.

I thought of that, but the program randomly picks a point, and then does a random length flood fill, removing points from the list. My thought is to make a nested array. Then the program can randomly choose a sub array, and then a point from there.... and confine itself to those points....