You could store the combo shapes for 50 images in about 350 bytes. If you want to fix to axis and pick one shape, you can get it down to 300. (That's 256x256 images, for each shape you need two coordinate pairs, or 4 bytes, 1 byte for rotation, 3 values for rgb (15-bit color), and 2 bits per shape for choice between ellipse, rectangle, and triangle