The choice of optimal filters for our CRT emulation was done by KiDra in March 2022.
Release 1 of C64MEGA65 only supports horizontal and vertical filters for performing the CRT emulation. There is no gamma correction and no shadow mask.
This leads to Scan_Br_120_80.txt being a bit too bright but the "pure"
version Scanline_80.txt being a bit too dark. We found Scan_Br_110_80.txt
being optimal for our purposes - at least as long we are not supporting
gamma correction and shadhow mask: The +10% in brightness compensates the
perceived -10% in brightness due to the emulated scan lines.
"It is the option where you set what upscaling method to use. I use lanczos2_12.txt, because it adds a bit of blur and imperfection around edges, without going too blurry (it does not replicate composite blending)."
"This one adds the scanlines. Br_120 increases the brightness and thus counterbalances the darkening of the image caused by the Shadow Mask filter. 80 is rather mild in scanlines, because I do not like these overblown dark scanlines some folks use."
"It corrects the gamma curve, because CRTs and LCDs have different gamma
curves and without correction dark parts of the screen would be too bright.
The CRT Simulation version creates nice, crisp colors."
https://github.com/MiSTer-devel/Filters_MiSTer/blob/master/Gamma/CRT%20Simulation.txt
"The shadow mask adds the aperture grill / slot look. VGA squished is one of the most finely granular shadow masks and to me adds the delicate look of a classic crt screen."
"Commodore 1084 - I would not use that setting, but here the file so you can experiment with it ... pattern is too prominent ..."