A buddy of mine is considering buying a print of my image, “One Fish, Two Fish, Red Fish, Blue Fish” (he’s very smart!). That is one of my favorites, because of what it is, how it came out, and because Dr. Seuss is just way cool.
Each fish comprises 200 cubic Bézier curves. A Bézier curve is one determined by two anchor points, where the curve begins and ends, and (in this case) two control points, which affect the shape. The Wikipedia page has many examples and animations showing how it all works. Basically, four points lead to a smooth curve that starts at one and ends at another.
Each curve is determined by a different set of four points. Look at blue fish, in the upper right corner, and notice the U shape. This curve (which is not actually drawn, but implied) gives the first anchor points for the 200 blue lines. It is also a cubic Bézier curve. Likewise, the sideways U shape in the upper left provides the second set of anchor points. Two more U shapes, unseen in the lower half of the image, provide the control points. For the red fish, there are two anchor U’s in the bottom of the image and two unseen control U’s in the top half. By using the same basic U shape definitions, both fish have the same basic size and shape. But, by changing them slightly, the fish are similar, but not symmetric.
Even though the fish are red and blue, the actual lines used to create them are not. Well, the blue fish is really blue on a white background. But the red fish is on a different layer, which is cyan on a black background. By subtracting the two layers, the red fish is born. Where the two overlap, bits of green pop in. I like this because it’s simple (red, green, and blue being the basic computer graphics colors), and because I don’t much care for a lot of green.