Im not to sure burn in is that much of a risk with this shader - I could be wrong though so maybe worth ering on the side of caution. The reason I say that is that only 3 in 12 sub pixels horizontally are on and only 1or 2 out of 10 pixels vertically are at max. Presumably burn in is caused by heat due to surrounding sub pixels being on and pushing over an individuals subpixel heat limit over its individual limit and because most of the display is actually off with this shader the risk of burn in is presumably low. Its just my guess though I have no hard proof or tests.
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Superb I do like the ntsc look sometimes - it gives a different air to things. Much smoother gradients and the like but also a bit vaseline-y.
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Yes personally I wouldn’t be too worried about burnin with this shader as the screen is mostly off/low BUT I can guarantee it so be careful using whatever method!
Also with the min/max/attack scanline that makes complete sense to me as we’re simulating 30 year old CRTs whose scanlines have invariably degraded over time and shifts the overall colour in different directions. My 2730qm has a stronger red scaning beam and so thats what I modelled in this shader. Setting all the scanlines to thevsame length and attack should fix that. But then thats those defects are now part of the crt look. What I will say is that on an old crt this changes across the whole screen - some areas green is stronger some blue so theres no right solution and I doubt many people have the patience to model it down to this level - famous last words… 
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Probably but for me this is a very important piece of the nostalgia pie. For others it might be reproducing curvature or blurriness err…vaseline-iness. Lol
They say ignorance is bliss so maybe it’s a good thing that I use CRT shaders exclusively and trust my memory and my imagination to determine what looks and feels right but I honestly don’t have any issue with colours using Mask Accurate Mode anymore with the shader.
On another note, you see that I was able to figure out how to capture hybrid HDR/SDR screenshots in jxr format using the shader.
My next challenge is how to record HDR video while using the shader but this is proving to be even more elusive.
On my system, I can’t use NVidia Shadow Play to capture HDR video, only SDR.
If I try to use OBS the only options that I’m being allowed to use to capture HDR are P010 (10-bit, 4:2:0) Colour Format and Rec. 2100 PQ or Rec. 2100 HLG.
Obviously this is unacceptable due to the Chroma Compression.
I think I might be able to work around these limitations by using the shader in SDR mode, then making my recording using RGB 4:4:4 or whatever Colour Format nVidia ShadowPlay uses.
I’ve never had a problem with ShadowPlay applying Chroma Compression to my SDR captures.
After making my SDR video, I would then like to apply the same principles and techniques of Inverse Tonemapping sRGB or (whatever SDR Colour Space Megatron Tonemaps from) into Rec. 2020 (or whatever HDR Colourspace Megatron Tonemaps into).
I would like to do all of this using video editing software for example, Premier Pro, DaVinci Resolve, Hit Film or Kdenlive.
Is it possible for one or more of you more learned folks here to assist me with some tips as to how I might go about this and if it’s even possible?
So basically I would like to start with Megatron in SDR mode but end up with a video at the end that looks like I recorded it using the shader in HDR Mode.
I’m including @Dogway, @Azurfel, @Dennis1 and @rafan in my list of persons who might possibly be able to assist.
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If youre on Windows 11 it might be best just to use auto hdr it provides and have the shader in sdr mode. Presumably OBS works with this feature but I dont know.
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Thanks for the tip. Ultimately I would like to have a properly inverse tonemapped from SDR to HDR file that is Rec. 2020 and HDR10 compliant so that when played back or uploaded to YouTube it would trigger the playback device to switch into HDR Mode and look similar to how it looks when using the shader in HDR Mode.
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I would suggest going to the HDR channel on the Special K Discord and see if they have any idea how you can force Shadowplay to record HDR footage in 444.
Failing that, it may be best to wait until Megatron’s gamut overshoot issues have been resolved, because based on my recent experiments, i think it is highly likely that the solution will involve changing the way inverse tonemapping works in Megatron.
Also, before you spend any more time on this, are you 100% certain that Youtube will ingest and play back 444 HDR uploads in 444? Because i’m not finding confirmation that it will right off, and if it won’t, then the whole endeavor is unfortunately a non-starter.
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Thanks. I’m using a GeForce GTX 1070. Shadow Play doesn’t record in HDR on that GPU period. It can do HDR stills in jxr format though. My SDR recordings don’t seem to have issues with Chroma Subsampling though so I’m assuming that it does record SDR footage in 4:4:4.
I’ll check them out. I was just wondering if I could just record full range 4:4:4 using Shadow Play then inverse tonemap that recording in editing or post and have a similar result as Sony Megatron HDR. So I wanted to know if there are any tips you could share regarding which colour format to choose or how to go about tonemapping because I’ve never done anything like that before but I can probably wait and see where things end up however I’m pretty cool with the way things are looking now after my tweaking.
For me, YouTube compatibility is secondary so whether or not it accepts 4:4:4 HDR - which I wouldn’t be surprised if it doesn’t, I’ll still do my videos and share them via regular download links if I need to - which is what I’m used to doing.
I guess I could use the information contained in this post you shared to help guide me. I think I should be able to get this to work because it seems to make sense that it should be doable in theory.
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RetroArch’s internal video dumping does RGB 4:4:4 in lossless mode. However, AFAIK it’s not hardware-accelerated, so it encodes (much) slower than real-time. Depending on the core, you may be able to use RetroArch’s input recording/playback to do it unattended. I don’t know whether these dumps would be detected as HDR content on playback, either.
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Thanks, I have a question, is my understanding of the attack parameter correct in the pic? Higher number means slower?
And that it requires lower content res than the effective “Vertical TVL” (I know that’s not a thing) of the mask? “4k/600TVL/Shadow” settings gives a 360 (4 pixel tall mask÷1440p) “Vertical TVL” on my 1440p. Meaning that 360p and higher content (without overscale) won’t work well with the attack setting on my monitor, am I correct also in this?
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Here’s the best explanation I have for it: https://editor.p5js.org/majorpainthecactus/full/skwKYZu7Q
If you put 100 into one of the text box that’s equivalent to putting 1.0 for attack in the shader. The image in the background is a gaussian distribution on the scanline (take the image with a grain of salt though as its no doubt been warped by processing and photography).
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Just updated the default and 2730QM presets on Github to be colour accurate with my PVM (at least by eyeballing it). These are the closest I’ve got to matching my 2730QM PVM and pretty spot on. I need to use a spectrophotometers to get closer.
You will still need to adjust your peak and paper white brightness.
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I just had time to test dylanraga’s win11hdr-srgb-to-gamma2.2-icm profile and I am very happy with the result. I did some measurements with HCFR and my i1 Display Pro Colorimeter and I can get very good results with Windows 11 set to HDR and the SDR slider at maximum. The icm profile raises the lower steps of the gamma curve (between 0-20 IRE) a bit to prevent the washout, which is present without the profile.
This is the measurement without the profile:
This is with the profile:
Until these measurements I thought it will be difficult without a LUT to straighten the Gamma curve, but after I activated the dynamic tonemapping function of the LG GX OLED TV, I got a very surprising result with a Gamma curve, which measures between 2.2 and 2.3:
And after the gamma measurement I had also to measure all color points:
As you can see, the results are just great. For me personally, there is no need to use any of the HDR tonemapping solutions, which we discussed before. Just Windows 11 set to HDR, the SDR slider to maximum, the sRGB to gamma 2.2 profile installed and dynamic tonemapping activated on my OLED is all what’s needed to get a bright enough and pretty accurate picture with the Megatron shader, which is set to SDR. And this solution is thankfully compatible with any emulator using the reshade port of Megatron.
Thank you again @ Azurfel for the hint with the sRGB to Gamma 2.2 profile 
The only thing I am curious about is how a UHD LCD IPS panel with RGB subpixels or VA Panel with BGR subpixels would perform with the Megatron shader, as the “400” lines setting (resolution set to 8K and 800 TVL) within Megatron, which is my favourite, has some minor issues with overlapping phosphors on my LG OLED as you can see here:
But I think the difference will be so minor, that it will not be visible to the eye from the distance I play games. I think those new Mini LED TV’s with good black levels are a good choice too for Retrogaming and CRT emulation and these bright TV’s should even work in normal SDR mode without any of the workarounds the OLED TV’s need.
I have also the idea to buy a Sony Trinitron CRT in the future, just for the purpuse of comparing to the Megatron shader and perfecting the settings. The Megatron shader just rocks !!!
I have to edit my post, because I have mistaken dynamic tonemapping with HGIG: This measurement is with the LG OLED set to HGIG and not Dynamic under the Dynamic Tone Mapping section of the TV:
Tonemapping Off or Dynamic has those weird gamma curves I posted above which goes toward 1.2 at the higher brightness levels. So HGIG is the way to go for a straight gamma on LG OLED TV’s or at least this specific GX model.
I therefore repeat the statement I made above in a corrected way:
Just Windows 11 set to HDR, the SDR slider to maximum, the sRGB to gamma 2.2 profile installed (I use the 400 nits icm file currently) and HGIG under dynamic tonemapping settings on my OLED is all what’s needed to get a bright enough and pretty accurate picture with the Megatron shader, which is set to SDR.
Next step is to generate an .icm profile by myself, which fits with the SDR slider @ 100 or even overdrive the slider via registry to higher luminance values as Azurfel mentioned, to squeeze out even more brightness of my LG OLED and get the gamma more linear towards 2.2 
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That’s what the OLED RWBG Subpixel Layout is supposed to resolve. Also, Colour Accurate Mode also introduces the appearance of overlapping subpixels.
I do agree that the Slot Mask Presets might need some work and further testing even with the OLED RWB Subpixel Layout though.
There are also issues with the scanline patterns when using the Slot Mask with Deconvergence enabled.
I’ve been focussing on Aperture Grille for now because that works perfectly. Maybe later on I’ll try to assist with the Slot Mask and Shadow Mask Modes to get them in line with what I’ve used in my presets in the past with other shaders.
I don’t think my older LG OLED TV has any of those tonemapping settings.
This is great work that you’re doing though. Just using Windows and the display to get the extra brightness and perform the correct tonemapping instead of the shader. It makes sense that it would work. Now how do we apply this to a video editor if we were to record this SDR Megatron to get a similar effect but with the display’s HDR mode being triggered and used when the video is played?
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I tried all, the WRGB subpixel structure does the same overlapping and the BGR overlaps all and looks even worse. With resolution set to 8K and 800 TVL it doesn’t make any difference if mask or color accurate.
On my LG GX the HGIG setting is under the picture settings and then under advanced controls. What I measure here is, that the HGIG setting actually maps the EOTF in HDR mode back to a SDR gamma curve. Maybe dig again in the menu, your OLED may have it too.
Compared to normal SDR mode in Windows 11, the HDR mode with the SDR slider @ value 100 feels like around 25% brighter. Actually, it would still be nice to have more brightness on my GX, but this workaround at least makes it possible to not have the feeling of a too dim picture. Mini LED TV’s and for example the newer OLED’s like the G3 or Samsung’s QLED may not even need the HDR /SDR workaround and work just fine in SDR. But I will try too “overdrive” the SDR slider in Win11, maybe it will help further. The dynamic tonemapping setting of the LG is even brighter than HGIG, but not accurate anymore as you can see in the gamma measurements above. But it’s usable too, if someone does not focus on absolute accuracy.
Good question, at the moment honestly I have no idea as I currently just use my phone to capture. But maybe one idea is, that people who have an HDR capable display just use the same method I am using, just putting the TV manually through the OS in HDR mode and then setting the SDR slider to the maximum of value 100. This will allow also to see the videos / pictures with more brightness.
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Hey everyone:
I acknowledge this is a very dumb and noobish question on my part! I don’t have a deep understanding of the function of all the parameters in the shader; I’ve just been using it because it looks great on my 4K TV! Megatron in my opinion blows every other CRT shader out of the water.
I’ve been trying to use it now on my tablet though which is near 4K, and the results I get seem to differ dramatically depending on which retroarch core I’m using. For example, this is a Snes9x game (PVM 1910 SDR, only settings change I made was to 600 TVL), which looks good to me:
But when I was trying some PSX games or ffmpeg, the same settings give me what I’d describe as intense color banding (this is ffmpeg, identical settings)
Is this dependent on the native resolution of the content? Trying to understand why they look so different on the same settings.
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Fantastic write up - really interesting stuff! Almost makes me want to update to Windows 11! (I really should anyway I know).
With regards to the overlapping phosphors: thatll just be a bug in the shader which should be easy to fix. When I get the time Ill look into it.
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Yeah itll probably be the high resolution of that content. First thing to try is integer scaling. PSX I think is 240p so that really shpuld work without banding/problems so maybe something else is going on there.
What resolution is your tablet? What model is your tablet?
It is indeed, for the most part, but most of the cores support increasing the internal res, which frequently wreaks havoc with CRT effects.
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Thanks! You should really update, as Windows 11 has many improvements in handling HDR signals.
It would be really awesome, if you could fix the overlapping phosphor issue. In the close up picture I posted, you can see, that the blue overlaps the green by one single row:
So the blue has to be moved 1 pixel row to the right (this is with the Display resolution in Megatron set to 8K and resolution set to 800 TVL).
The 4K / 300 TVL setting is just too coarse in my eyes, as the overall picture looks too “rough”. Maybe, for the sake of convenience, you could also just include a 400 TVL setting, as many may not know they can set the Display resolution to 8K in the shader with a 4K display.
I would be also interested about what you think how the Display resolution set to 8K and 800 TVL looks to your eyes on your Display’s. For me this combination is absolutely on point in regards to how the phosphors and scanlines look. Not too coarse and also not too fine like a Sony BVM / PVM, just spot on for me.
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