(Don't tell anyone, but this fractal type is not really a fractal!)
Fascinating Moire patterns can be formed by calculating x^2 + y^2 for each pixel in a piece of the complex plane. After multiplication by a magnification factor (the parameter), the number is truncated to an integer and mapped to a color via color = value modulo (number of colors). That is, the integer is divided by the number of colors, and the remainder is the color index value used. The resulting image is not a fractal because all detail is lost after zooming in too far. Try it with different resolution video modes - the results may surprise you!