I want to be create a filter to fade out the edges of an
image, however I'm not sure where to start with figuring out if a
pixel is within the edge fade distance. I've got the attached as a
starter, but I'm not sure where to go for the left and bottom
You need to pass in the width and height of the image as
parameters and use those. Pixel Bender 1.0 doesn't have the
original size of the input image accessible (in Pixel Bender we
only pass in the parts of the input image that are needed).