Motown

alfuso asked, about the preceding picture (blue fish), and presenting a negative image; "how does it work?"

Well…. here's a real simple example. I while looking at the sketch following this, did a real quick sketch on red paper using white oil pastels. So! The white becomes black. The red becomes green. Then using photoshop or and other digital image manipulator (I use Graphic Convertor) one can simply invert the colors in the picture, -which does exactly the same the same thing as we used to do in the darkroom when we'd print a color picture from a color negative. Each original color becomes it's complement when printed. Wikipedia gives a quick, concise, explanation of complementary colors.