Added module support.
Renamed file.
Made jslint happy.
Removed all progress callbacks.
Lowercase variable.
Added noise and colorDistance function.
Added the main program.
Added packaging information.
git ignore file.
Added module support for img.js
Added example.
Added in options.
Separated rendering functionality from the canvas and layer information.
Added createImageData function.
Add multiple filters to a layer.
Added opacity variable.
Added simple compositing with alpha.
Added basic (context) blending.
The 2d rendering context is able to draw canvases on top of each other.

So conversion to image is not really needed.
Added simple masking functionality.