Fantastic - I thought we might have been dealing with some custom renderer when you said this. Ok we’re all good.
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hello, thansk for the lovely shaders. as my system is not so powerful i wanted to know, if you people know why crt-guest-advanced-fastest is just flickering wildly. i hope the shots make it somewhat clear… thx…
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Hello there!
The shader contains some modern speedup techniques, but otherwise is should work quite nicely with the glcore driver. I guess there are some issues with vulkan/d3d which would require some nitpicky polishing.
Alright thanks. I ll just use venom normal instead
- are the default shader presets of dr.venom and advanced a recreation of a certain tv?
- is it possible to recommend royale-kurozumi over venom-advanced or vice-versa or are they different shaders for different purposes?
- could someon give me a hint on how to use afterglow sort of correctly i’m a tad overwhelmed w that feature…? thx
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I stated a couple of times that the default presets are a bit “shy”, not aiming for a specific crt tv model and mostly suitable for a 1080p display. It’s so on purpose.
I guess the “kurozumi” preset could get a better tweak with the new iteration on the shader than the older guest-dr-venom, but the purpose is quite the same as the royale-kurozumi that’s to achieve a PVM crt look. But ofc. you can tweak further both if you like. 
Tweaking afterglow:
- more persistence means longer trails
- if unsure persistence for different RGB values is best the same
- afterglow manifests itself on black pixels/areas (for authenticity)
And that’s not too hard i guess. Ofc afterglow looks better with some games which use black background etc.
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I think you need a high refresh rate for afterglow, otherwise it’s just blur city.
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Just a friendly reminder phosphor persistence/afterglow happens on any color that contrasts enough is my guess (doesn’t care if it’s black).
I was playing a NES game while back on CRT can’t remember which game, I posted a long drawn out comment in on the the shader threads about it. Regardless, it had blue backgrounds, and I don’t mean dark blue, I mean like baby/sky blue and I was able to see afterglow from 6ft away to the point that I decided to confirm by getting closer 
Granted that CRT is like almost 14-21 years old at this point, and I haven’t had either serviced. (I can’t remember which of my two CRTs I used, I’m going by their manufacturing dates btw)
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Synced displays (for example) are quite fine for afterglow with ordinary framerates, since crt’s also didn’t produce continuous effects between movements. I guess the base effect is as good as it gets.
Afterglow is definitely manifesting on black background on many types of crt displays. Didn’t notice it on my crt tv’s though as a general ghosting effect though. I could get a bit more nitpicky here, treating afterglow per color component instead.
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Yeah this persistence vs afterglow is a tricky one.
@hunterk has mentioned that on his crts that he has only seen it appear over black
Long persistence, like you see on old LCDs the glow appears equivalently over brighter and darker colors, so looks blurry in movement. The afterglow on the other hand seems to only noticeable on darker areas. I’m no expert on this, just what I’ve observed…
One thing that I’ve seen about the afterglow in GDV is that the cutoff between what is considered black and where afterglow appears and where lighter colors start to appear and no afterglow appears can be abrupt and cause a harsh edge between them. So you can end up with the afterglow being much brighter than the area it is right next to (which is almost black)
I think the ‘Raise Black Level’ is also hooked to this identification of what was black, so can give a weird result too if it is increased depending on the game if there are gradients close to black, I’m sure it would work quite well for something like Pacman.
Here’s an example of when the
I haven’t played with this stuff for a while though, so hopefully that’s all still accurate
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Yeah, the way it seems to work (which is unfortunately very hard to express in code) is: the phosphorescence decays almost instantly on blue and green but the reds last longer and exhibit a long tail of up to a couple of seconds, depending on the phosphor material. If a given pixel is re-lit during that falloff period, anything greater than the current fading value completely overrides it (i.e., there’s no additive brightness from the previous decay). There will be some visible rolloff even on nonblack stuff, as long as it’s a brighter->darker transition, but due to the big-initial-drop-with-long-tail behavior, you’re never going to see it unless the darker pixel is very dark indeed.
I’m also not sure how/if different follow-on colors affect things (e.g., red decay followed by bright green) and/or chromatic aberration.
I agree that anything using thresholds looks bad the closer you are to that threshold, but I’m not sure that a better, more realistic method is feasible.
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This looks really good! I think it’ll be a great addition!!
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Thanks for the answer. I didn’t want to appear lazy or something…
I tried to search for these things before asking. But I didn’t use the search function. Just tried to manually read through this bigger thread.
I am thankful for your work on these shaders and the detailed answers, I’m just rather new to a more technical approach of using shaders…
Sadly the kurozumi-guest.slang preset doesn’t work anymore on my macbook air 2015. These days I use kurozumi-royale or your guest-venom version.
I did’t want criticize your default preset. Just curious.
I think I’ll just leave out the afterglow feature for now. I first want to get colors as right as possible, but I’m struggling to be satisfied.
Maybe another question: would you guys prefer to use the lut parameter, or the crt-color-profile for adjusting your color settings? I couldn’t get the saturation parameter to anything I wantrd. Is it advisable to crank scanline saturation up to 2 or do I have to bear artifacts in mind? Same for scanline-spike-removal?
So thanks for the work and this nice thread.
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I like the addition of the mask aperture trinitron style. But is it possible to know more about it? I tested the revision1 guest advanced… The mask had some strange things, like ssss and dollars as mask pattern… But with revision 2 everything is fine… 1/ was this due to my oled structure wrvb vs rvb? Or was it not intended to work this way? 2/ without bothering guest I wanted to know if he had a personal version with more settings? Because I saw a post where they were looking for 4k optimization, and lightened up the options for the users ease. But my question is if there is a guest advanced rev2 version with more settings? Just a question, why? Because I’m working on a shader preset that offered me 4 gammas to fine tune the colors contrast luminosity… The result is a bright image with good contrast. Example shader misc slang ( 4 gamma settings at different places)
game embedded gamma/ crt electron gamma/ simulated crt gamma /your display gamma
crt royal simulated crt gamma/your display gamma
So is it possible to have this versatility of gamma settings in guest advanced rev2? Or do you have your own shader that you reserve for yourself because you think it would be difficult for the end user? Because it makes a difference to me all the way through the image process, with the integration of mask and ensure a bright and clear image, not dark and dull. Again bravo for the shader, because I use it now, must redo the work from scratch, 1 month of work lost… No big deal, for now I’m having trouble matching the color brightness of guest advanced v2 to the basic misc slang.p preset (because less gamma adjustment) The preset I used available to all at retroarch I post here that you can see what I am talking about gamma… My preset genesis.i don’t remember exactly its name at retroarch but this is the one… Preset for 4k slot mask ( instead of aperture grill so I start from scratch with guest advanced v2) Custo 8x9 is for the correct format without artifact on 4k oled tv ( preset that has a trinitron border so image framed ).
https://drive.google.com/file/d/1oOOX7uG59pKejCNN8iXfBqfOX4_i-bnv/view?usp=sharing
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I’m not sure if you have already tried this out or not, but some OLEDs have a Peak Brightness setting which when turned on uses the white sub pixel and when off does not.
There was some discussion a while ago where it seemed that turning the white subpixel off might result in better per mask display.
I haven’t tried this myself on an OLED though so this may just be theory… 
Maybe @c9f5fdda06 might have some thoughts on this though.
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Indeed read that somewhere… But my preset uses bfi (black frame insertion) And that my preset takes into account the 40℅ of luminosity loss… And that for that to have 4 gamma allows to adjust more easily the rendering, and that the final image Is bright and contrasted. Thanks
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