FixLuminance
From Avisynth wiki
FixLuminance(clip clip, int intercept, int slope)
My VCR has the annoying habit of making the top of each frame brighter than the bottom. The purpose of this filter is to progressively darken the top of the image to compensate for this. If you've noticed a similar problem with your VCR, email me and I'll finish this explanation of how the filter works. Otherwise, you can pretend it doesn't exist.
This filter works only with YUY2 input.
