Generation PHP

On this page below lies Flyer. It is generated by “on the fly.” How to make the same thing on PHP?
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Answer 1, Authority 100%

Most likely GD For drawing such a picture plus gravatar to get the avatar itself. The point is not particularly cunning.

Answer 2, Authority 50%

I wrote a similar garbage to the sake of interest.
If I wonder, I can send all the code (warning: it is unguarded)

In short – we take a hash from some kind of unique value (for example, e-mail), divide it into blocks. The first 6 characters – we give under the color of the background, the rest of the division is equally between the coordinates of the points (Gravatar Kaleidoscope does a little differently: he originally all patterns are set), then spread it with a rotation four times.