Coding Challenge: Plane Deformations

Quick n' easy coding challenge: Plane deformations (used a lot in old-school demos)

The idea is very simple. Find a source image. Create an empty canvas. Fill every pixel in the canvas with a color picked from an offset position (found using simple math expressions) in the source image.

Possible ways to expand the coding challenge:
* Animate the source image to make weird psychedelic effects
* Use look-up-tables (LUT) to precalculate the deformations and speed up rendering
* Generate math expressions randomly to explore new effects (possibly involving infix/postfix notation = out of scope?)

Online example:
http://mrdoob.com/lab/javascript/effects/plane_deformations/

Here is a good write-up by Inigo Quilez on the topic: http://www.iquilezles.org/www/articles/deform/deform.htm