Deprecated: see discussion
FixLuminance(clip clip, int intercept, int slope)
- int intercept = (required)
- Bottom line at which to start correction. intercept should be equal to or smaller than the height of the image.
- int slope = (required)
- Slope of correction function. The top of the picture is made darker by 1 (on a 0-255 scale) every slope lines.
- Maximum darkening (at top line) = intercept / slope
The purpose of this filter is to progressively darken the top of the image; for example, to compensate for certain VCRs which make the top of each frame brighter than the bottom. In practice it only works for NTSC content and it needs its fields separated.
When applying it to an image with height > 255 pixels, you will see a repetitive gradient. So it doesn't work for field-separated PAL content.
This filter works requires YUY2 input.
- Progressively darken top lines.
- Make a ramp test image.