Reply To: Hybrid Scanlines


Two fun facts beforehand:
– We talk about ‘scanlines’ but we mean off-scanline, which is the line to be darken. But I will keep our false friend 😉
– Multiplication and subtraction are both linear operations

The new hybrid method vs current method is like multiplication vs subtraction so if you want to keep that maybe you can set multiplication to use the new method and subtraction to use the current method?

Give me one good reason why keeping your origin hybrid approach?
The main drawback in my point of view is that the saturation point (point where the scanline completely disappears) massively depends on the scanline strength.
My modification on your approach resolves the problem (yes, it is a problem in my point of view). And as said, it can be overdriven without any problem such that the saturation is before intensity equals 1. See the comparison here:

In this perspective one could call this option hybrid strength and make this a variable number from e.g. 0 to 15, where 0 is off and 8 is 100%.

Linear with old hybrid produces the most convincing (CRT like) scanlines but the gamma is too high (dark image).
Multiplication will have more correct gamma but the scanlines do not vary with brightness enough.

In the same way the multiplication can be overdriven, too. This would allow the user to set the output to zero right for small intensities.

Gamma in the scanline is atm only possible by either tailor approximation or piecewise linear interpolation. I would delay this for now.

And what now? I corrected the GitHub branch. Hybrid contrast is still the modified approach with example values off = 0, low = 50%, med = 100% and high = 125% -> (RLPF also corrected)

I also want to mention that the discoloring observation by @retrorunner with subtraction method for scanlines does not come from his TV. I build a firmware where you can see, what the scanline really looks like.
it can be downloaded here:
Just set the scanlines to manual and vertical to draw all lines as like as they were scanlines. You can definitely see the discoloring effect which is increased in certain circumstances with hybrid scanlines. And no: do not compare with pure color bars, compare at ‘ordinary’ material, where you have mixed colors. E.g. the logo in F-Zero will become red with the subtraction method.