Rewrite of various elements of Lumise Product Designer tool

We want a rewrite of several key modules of the Lumise product customisation interface which runs on javascript and PHP, using HTML5 canvas on the client side. The key points that need to be achieved are:

1) Write function to parse .lumi file (encoded JSON object), into:
o Lightweight human readable JSON
o Scaled down .lumi file
o Image files from embedded dataURIs

2) Modify customer facing interface:
o to load scaled down .lumi file
o add HTML/CSS overlay of the editable canvas
o add rebuilt mobile view

3) Various supplementary functions

This is a somewhat complex project as it requires quite specific modification of an existing application. Experience with javascript and PHP a must. HTML5 Canvas experience would help but may not be needed if you are expert in javascript. Lumise-specific experience would be great, but again is not required if you possess the former skills.