This page implements the worksheet of the Human Shader in javascript. Of course this is blatant cheating, but I wanted to know what a perfect result would look like.
The second image is a high-res version of the first, calculated using the same arithmetic but allowing floating point numbers instead of pure integers.
The remaining three images are the worksheet sections B, C, and D (in that order) but rendered for each pixel. In other words, they are versions of the shader where step A5 always continues to section B, C, or D respectively.