I really like this shader, but I’m using it in a way that causes the screen to become too dark. I can make an overlay that does something very similar but doesn’t darken the screen the same way, so I assume that gamma correction is the culprit.
Would it be possible in a future update to either enable gamma parameter settings, or turn off the gamma correction altogether?
I don’t see any gamma stuff happening in there. Just scanlines, mask and scaling.
Ah, I see what’s happening- I was comparing zfast to an overlay that I thought was doing the same thing, but the scanlines in zfast are actually quite a bit darker/thicker, so that would explain it. 
Did you try to adjust the scanline parameters? The mask fade and both scanline parameters effect apparent brightness. (Mask fade pulls double duty for speed. It’s not just for the aperture mask effect).
I tried playing around with them some, but I’m still not clear on the exact relationship between these settings, so it’s just been a lot of trial and error.
Ideally, the scanlines should be as close to 1:1 as possible (a 50% reduction in objective brightness per line).
I don’t mind a bit of vertical blending between lines if it will help brighten the image, since phosphors on a CRT would bleed into the gaps depending on how bright they were.
Right now I’m using the following settings: Scanline darkness low - 9.00 Scanline darkness high - 8.00
Everything else disabled, nearest neighbor scaling. Increasing dark pixel brightness boost results in clipping, since my monitor is already at the limit of what it’s capable of. I can eke out a bit more brightness with mask fade at 0.60; more than that starts to look overbloomed IMO (scanlines should still be clearly visible over white).