use PixelGrabber to record a grid of colors then store it in a 2D array and with the next image get another 2D array of colors from the picture and compare the two arrays to see which part of the grid changed. You still will not have a way to tell the difference from the place were the object was and the color of the current object unless you had a image of the place room screen or what ever it is without objects and compared all other images to that one.