Last 2 versions for now, v2.4 and v2.5 with some further variances. I’d appreciate if you know how to combine this little mod with LUT or make less visible the rainbow lines or any other suggestion to improve this even further with the dithering/composite effect or some other shader.
Have fun
some other picture:
Someone asked for that purpose, and you are yourself. 
I was doing some tests with the Shaders Venon, is achieved quite close but this is wonderful! How nice to remember that time, when technology that limited but creativity was at its maximum expression.
2 new variants:
ok these may be for now the last variants for composite-Rainbow effect. Version 2.7 is for flat screen and v2.71 is with some CRT looking. This time both versions have a less visible rainbow effect which may fit way better compared to the original hardware (pictures below). Hopefully if you know how to improve the composite-dithering even further with this preset, I’d be glad to check that out !
Rainbow effect this time, if ever had to bring a rate then I’d say it’s like 95% accurate in comparison to real hardware composite connection. If it’s anything ever to improve the rainbow lines, I’d say yellow-green bars may need to be a bit more mixed up on screen. I couldn’t notice differences between real hardware pictures and genesis core from distance, but only if you approach to the screen so then you can see little differences with the hardware…
Still, I think it’s a very satisfactory (at least for me) result to get the rainbow effect working to this point. Please feel free to improve this preset even further. I hope you enjoy it as much as I wanted to see rainbow effect in PC to deliver fully experience playing with composite connection-looking with those Sega Genesis classic games. Big thanks to the guys who brought us those shader-presets that I took as a base to make this modding. And big thanks to anybody that would like to give a try to this little mod !
Good luck & Have fun !
Link to v2.7 + v2.71:
Some comparison pictures from real hardware Sega Genesis (model 1) VS RetroArch Genesis Plus GX
Hi, I tested it, but there is a problem for me, it modifies the colors so that the green becomes blue. At least when testing on BlastEm.
That’s the tvout-tweaks TVOUT_RESOLUTION_Q parameter. If you raise it up to around “130.000000”, it should look more normal, color-wise.
The mame_hlsl passes beyond the first 2 aren’t necessary for rainbows, so you can put those 2 passes anywhere the ntsc-adaptive shaders are currently used just by pasting these lines in their place (paths expecting to run from ‘presets’ directory):
shader0 = "../crt/shaders/mame_hlsl/shaders/mame_ntsc_encode.slang"
filter_linear0 = "true"
wrap_mode0 = "clamp_to_border"
mipmap_input0 = "false"
alias0 = "NTSCPass"
float_framebuffer0 = "false"
srgb_framebuffer0 = "false"
scale_type_x0 = "source"
scale_x0 = "1.000000"
scale_type_y0 = "source"
scale_y0 = "1.000000"
shader1 = "../crt/shaders/mame_hlsl/shaders/mame_ntsc_decode.slang"
filter_linear1 = "true"
wrap_mode1 = "clamp_to_border"
mipmap_input1 = "false"
alias1 = "ColorPass"
float_framebuffer1 = "false"
srgb_framebuffer1 = "false"
scale_type_x1 = "source"
scale_x1 = "1.000000"
scale_type_y1 = "source"
scale_y1 = "1.000000"
ntscsignal = "1.000000"
shadowalpha = "0.100000"
avalue = "0.000000"
bvalue = "0.000000"
pvalue = "1.100000"
scantime = "47.700073"
notch_width = "3.450001"
ifreqresponse = "1.750000"
qfreqresponse = "1.450000"Have you tried using the RF preset within guest-ntsc? This gave me rainbow colours in the waterfall in Sonic 1 and also in the pipes in Sonic 2.
Not at my computer to give screenshots at the moment, but it’s a lot more subtle than your screenshots and doesn’t degrade quality too much (still looks a lot clearer than RF does from my memory!).
I have looked up into guest-ntsc presets and this particular option for RF doesn’t seem to give a similar result to the rainbow I was looking for. Still, I’d appreciate the screenshots you just mentioned nor other preset options to look up. Thanks for your reply!
I have looked up into guest-ntsc presets and this particular option for RF doesn’t seem to give a similar result to the rainbow I was looking for. Still, I’d appreciate the screenshots you just mentioned nor other preset options to look up. Thanks for your reply!!
New 2 variants, now palette colors should be way more accurate to original games but with some changes.
v2.8 has intense rainbow lines for whoever may like to see them more intense and v2.81 is the one with accurate rainbow lines with 95% accuracy (from my perspective) since v2.7.
This is some demostration playthrough with my limited 10 years old computer to check the rainbow effect with composite modded preset. https://www.youtube.com/watch?v=sfGsi85zB4w
This is what I meant, it is a slightly modded preset but it should be largely the same just using the RF option. I guess it might not be quite as pronounced.
If I saw it correctly, the lines seem to skip other rainbow colors like yellow or green. Even though the RF option may make them a bit clearer but still, doesn’t manage to expose all the rainbow colors as intended.
Last versions are v2.9 - v2.10 and v2.11 … Pretty happy with the color tweaking here and there. v2.9 and v2.10 just keep the 95% accuracy (in my opinion) and v2.11 got more intense rainbow banding. I just found it cool to expose with more intensity these artifacts from time to time.
I just noticed that Rainbow effect doesn’t expose properly in BlastEm core, so now with v2.2 and v2.3 new variants you shall see the rainbow being exposed properly.
v2.2 will show off the 95% accurate (in my opinion) rainbow or I’d say it’s even a bit more accurate than actually it is for Genesis Plus GX. So this version have the sort of tiny rainbow lines. This version only have some dithering applied with no side CRT effects.
v2.3 have the same version from v2.2 but with intense rainbow lines if you like to see more clearly this particular effect in-game plus some CRT effects.
I explain this here. The genesis has no video artifact. Doesn’t handle transparency in hardware like the snes… What you are trying to reproduce is due to the use of bad video cabling. The genesis is rvb, and does not have a rainbow effect. Anyway I explain it here. But I respect the choice of the users, if they played like that, the nostalgia will make them prefer the bad video signal.
Explanation of the artifacts on genesis, due to a bad cabling.
I played for such a long time with RGB from earlier Sega Genesis emulators like Genecyst, kgen98 and Gens v2.14. Plus in some other seasons with 4xBRz which just enhances the RGB signal (by default in emulators) in my honest opinion … Still, there’s something beautiful about the blurry looking from 90s’ games (for me). What is looking for in this preset is to expose the rainbow effect by composite as much as I could.
I appreciate the link to explain it way better than me.
You’re welcome my friend with pleasure. I also like the rendering, but I am French and have access to a full scart rvb signal. And when I play nes famicom, I use nestopia with the option blargg ntsc… Which degrades the video signal, generates motion and color artifacts… Because that’s how I played the nes in my childhood, because the 2 game consoles that didn’t have rvb in France are the nes famicom, and the n64. Everything else is rvb with the best quality possible. So of course I understand you, and it’s normal to want to find the nostalgia of what you knew. I respect your work, and congratulate you for sharing this with the community, I respect of course the choice of the players. Take care of yourself and thank you.
Hello there. New rainbow presets. This time I took a sample from Hunterk for composite connection in Sega Genesis: https://www.chrismcovell.com/gotRGB/screenshots.html
v2.4 is for Genesis plus GX v2.5 is for BlastEm
Left side sample is real hardware composite from the link above and right side is Genesis plus GX@ynnad4 v2.5 looks amazing with scanlines (overlay) and the scale2x filter on… You have taste man 
The 240P in Genesis is my important and in this video they explain why.
