LizardTech makes MrSID, an imaging environment which has at its heart a wavelet based image compressor. The MrSID compressor evolved over many years at Los Alamos National Laboratory from the simple observation that an image is a function and that compression is a form of numerical approximation. This talk will look at some of the unexpected mathematical concepts which have found their way into a code which from the outside appears to be just "pixels in and pixels out" but inside looks more like a giant differential equation solver.