Nope, i think it is not what he is trying to achieve, anyway for it it there is a strength parameter which affects all of the NTSC artifacts. Highering it will put more artifacts over the treshold that will allow to blur them or not.
Thinking out loud, I don’t know if it could be useful to completely cancel artifacts under a certain ‘strongness’
I’m thinking it might be useful to control or balance the blur artifacts vs the colour artifacts independently.
I think that’s what @ROBMARK85 might have been getting at.
He seems satisfied with the level of NTSC Blur but in some cases the colour alteration might be a bit to strong for his (and my) liking.
So what would one have to do to keep everything else the same but reduce the intensity of the colour artifacts alone?
Eh, once we have identified an ‘artifact’, we can blur it (blend the waterfall) or not (keep the waterfall sharp)
If you scroll some posts ago, where I explained the workflow, you can see the artifacts mask.
Notice that the waterfall mask is not a solid color, unfortunately, it contains various levels of artifacts, stronger and weaker.
So to blend it good, we have to blur something else too.
Yet, the blur radius depends on the artifact strength (dumbly calculated as a difference versus the original color), this helps at least.
So, the method is the same already described. With the help of the debug mask, one can select a particular treshold under which (black areas) apply less artifacts blurring and optionally less chroma bleed.
Those settings in the ntsc presrt are tuned by me for sonic, and i think they would work good for other megadrive games.
edit:
As a reminder, NTSC artifacting code on koko-aio only works ok for megadrive; for nes/snes one, I suggest to use just chroma bleed. (bandwidth limited chroma)
Hi guys. @Cyber 100% hit what I was looking for, and @kokoko3k’s idea out loud about canceling artifacts below a certain threshold, I think is a great idea when using NTSC color artifact with Megadrive games. In the meantime, following @kokoko3k’s advice, I used the Chrome bleed option by changing its strength to 0.70, also activating FXAA and leaving all the remaining default values unchanged. The reference preset is the “Monitor-ScreenLevel_HMaskWide-Corelevel_SlotMask.slangp”. I’m undecided whether to raise the strength of the Chrome bleeding to 0.80, but not beyond because the value to 1.0 together with the deconvergence and the FXAA would blur the final image too much. Here are some examples using the mythological Castlevania Dracula X for Super Nintendo. Let me know what you think and thanks again for your work @kokoko3k. As soon as I get a decent computer I will enjoy those from @Cyber too, having all these options is exciting because you can play the old games with different “filters” always making the experience different from the other times, Thanks guys.
After various attempts, even experimenting with Marvel Super Heroes for arcades (too bad I have difficulty sharing screens) I saw that both with slotmask and with aperture grill the ideal value of Chroma bleeding strength (at least on the smartphone screen) is 0.75. However, in conclusion, I wonder if it is better to keep or disable the deconvergence at this point. Or maybe keep it turned on for 8 and 16 bit titles only.
To me it’s natural for a CRT screen that has some age and wear and tear to have at least a tiny bit of deconvergence. It’s an interesting setting to play around with. I tend to feel funny about a preset with deconvergence completely disabled but it probably aligns better with LCD subpixels and looks nice in screenshots this way.
Yeah, I think deconvergence has a great appeal and a great retro-feel at first , but still, everytime i disable it, my eyes feel refreshed.
So it is down to personal taste, as usual 
@ROBMARK85, loving the screens, i prefer 0.70, but again, it is good as long as it pleases you.
Also, tuning presets on android is not the best experience, speaking by experience!
Thanks for the advice and help.
Did it, here you see ntsc artifacts pushed way too much (3x), just to show the new feature:
Then, now you can use the treshold to cancel artifacts falling below it:
And there you see the result:
It cancelled almost everything, leaving some green eye and blanka’s hairs. I hope starting from a normal artifact strength will produce better results, let me know!
Also, i noticed that i’ve had disabled the chroma bleed cancellation feature by mistake, so thank you for give me the opportunity to fix that too
And, modified the parameter names and documentation to hopefully be more understandable:
Consider artifacts above this treshold:
Tune this to select more or less artifacts, depending on their strength.
Show the mask of selected artifacts (debug)
This will show only the part of the image that contains artifacts.
Use it to for a better visual feedback of the following parameters
1* Under treshold: Cancel blur (Glow)
How much the glow/blur function will skip blurring "unartifacted" areas.
2* Under treshold: Cancel Bandwidth limited chroma"
How much the Bandwidth limited chroma function will skip blurring
"unartifacted" areas.
3* Under treshold: Cancel artifacts
How much the artifacts under the treshold will be completely removed.
Edit: Ah, another thing, if you’re not interested in the artifact colors, you can even put the artifact strength to 0.0, and since this will not clear them from the artifact mask, it can be still used to modulate the blurs:
Great show, thanks for this nice upgrade @kokoko3k. Now the artifact is barely noticeable and not annoying at all. Thanks for your immense work.
Great job. For me, this seems like one of the last bits of the puzzle now solved - to recreate what the devs exploited using an analog chain, witthout making too many sacrifices in the process.
Eh, i’d like this statement to be true.
Unfortunately per game tweaks may still needed, but at least the basal result should be now a bit higher 
Looks pretty good here with the other tweaks i’ve made.
Mask stagger is a bit misaligned for screen zoomed masks; it seems to happen in the middle of the triad (worse, in the middle of the phosphor), will check it out today.
-OK- fixed that, even if nobody noticed
This returns every there and then, hopefully this will finally fix it.
Spot the difference!
Don’t be shy then 
1080p output on a 4k OLED (in PC mode):
EDIT - wrong one posted, now corrected.
Have you recently made any changes to/or could impact tate mode?
Not that i can remember, do ypu have problems? It could be helpful to know when they started, but i will check if here is all right.
-EDIT- Confirmed, works good here in auto mode with mame 2003 plus, or whatever with forced mode.
Maybe in the last day or so - forced tate mode throws out the vertical scanlines. You should be able to spot it.
Is it possible that you’re confusing vertical mask at core level for scanlines? They would look very similar.
