I was under the impression that there is something weired with the current implementation; but I wasn’t sure at all.
So today I quickly wrote a simulation with the hybrid method as currently implemented. Here is the outcome:
– x-axis: input intesity, y-axis: output intensity (absolute top, relative to input bottom)
– blue curves: multiplication, red curve: subtraction
– from left to right: hybrid off, low, med and high
And yes, there is a inconsistance. Exactly where scanline-strength = (hybrid-contrast)*input the scanline completely disappears. This can be seen in the image and does not feel good to me.
Thus one has to either scanline strength high or hybrid contrast low.
After modifying the math a bit, I came up with this:
Actually I considered the scanlinestrength in the hybrid calculation. This ends up that a) the darkening does not disappear and b) there is no discontinuity.
I do have a similar HDL implementation ready but want to test it before push it for others to test.