Crossfade Using Pixelbender

I am currently doing some work for a client which involves background subtraction. I have been getting into using pixel bender to calculate filters in flash for a while now, but doing some research I found there is actually huge scope for using pixel bender to carry out other calculations (see this article).

The following example uses pixel bender as a part of the background subtraction process. Consecutive frames from the webcam are blended with all previous frames. The eventual result is to produce a good estimate of the background pixels. The example uses the blendShader property of a display object with blend mode set to BlendMode.SHADER, and a custom Pixelbender shader that mixes pixels. Check it out (click to launch):