Yes good idea, I have a feeling my PVM doesn’t have a brightness control when taking scart though.
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It would be very unusual for a studio monitor not be able to control brightness. Being connected via scart should have nothing to do with it?
According to the manual of your Sony PVM 2730QM on page 5 and on page 3, you can control Brightness (black level I think) with button “4” and “Picture” level (meaning old fashioned “Contrast” I think) with button 14.
See page 3 here: https://archive.org/details/sony_PVM-2730QM_Service_Manual/page/n1/mode/2up
And page 5 here: https://archive.org/details/sony_PVM-2730QM_Service_Manual/page/n3/mode/2up
It does say that some controls only work when “Set the MANUAL CONTROL switch on the rear panel to ON” (see page 4 and 2 at the bottom).
EDIT: and on page 2 there’s additionally under “Troubleshooting”:
Symptoms: No controllable keys although the POWER switch is turned. Corrections: Press the CONTROL key.
Page 4 note: Press CONTROL key after power is turned on to illuminate the control keys or indicators
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Yes as I say it was a feeling, you could well be right but I do know for certain some controls dont do anything and I have two of them that work that way. Having said that maybe it’s the ‘hue’ controls. I’ll have a play around.
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So just just played around with brightness and whilst I was wrong in that its disabled, I was right one way, in that lowering it doesn’t do anything (not that I could perceive in a lit room at any rate) i.e it’s at its darkest but who knows in combination with contrast and a dark room maybe I can get some leverage our of it.
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Just curious, did you try both Brightness (button 4 in manual) and Picture (button 14 in manual)? Especially the Picture button should work on Luminance, did you try this button on the right side of your screen?
To make it clear what we call “Brightness” these days with LED monitor, it is the equivalent of “Contrast” or “Picture” control from the CRT days. So if you want to lower the max luminance/brightness on a CRT you actually need to lower “Picture” or “Contrast” and not “Brightness” (which on a CRT controls the black level and does little to max luminance).
I can only say that if you can’t turn the screen close to entirely black, something is definitely wrong with your PVM.
Edit: so yeah you need to lower “Picture” on your PVM (button 14 on the right) to lower the brightness. That should do the trick.
If you want to read up on the (confusing) terminology used in the CRT era, read this from Charles Pontyon, the CRT expert, here CRT “Brightness” and “Contrast” (Picture) controls
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Yes I was just saying brightness doesn’t go lower. I don’t tend to do any calibration stuff during the day and so that’s why I havent taken further steps - the problem is at night is the only time I get to work on other projects and so finding time is difficult.
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Hi @MajorPainTheCactus !
I’ve been doing some extended testing and have some good news! I’ve now been able to also get a balanced Gray Ramp in HDR mode!
Just for the sake of completeness I’ve tested all three SDR modes (709, sRGB, DCIP3) since they each use a different gamma curve and tested HDR mode. I’ve used the 2730-sdr preset for SDR and the 2730-hdr preset for HDR. So four tests in total.
After loading the preset I changed the “Brightness” +0.15 to “0.00” and TVL to 1000 in all four test, additionally I tweaked CRT gamma in the three SDR tests and for the HDR test tweaked Max Nits, Paper White Nits and CRT Gamma.
To get right to the issue, to get a balanced Gray Ramp in HDR mode I needed to lower CRT gamma from its default 2.4 to 1.9 and then lower max and paper white nits to around 300 each (even though my monitor is HDR 400) and then I get a balanced Gray ramp, while remaining a bright enough screen as well!
So what I’ve noticed is that your 2730-SDR and 2730-HDR preset differ in their preset CRT gamma, the 2730-sdr version sets a preset value of CRT gamma 2.00 but the 2730-HDR preset doesn’t set a preset CRT gamma, so it defaults to the parameter.h default of 2.40!:
2730-sdr preset
loads "#reference “shaders/crt-sony-megatron-sdr.slangp” which has a gamma_in preset value:
#reference "crt-sony-megatron.slangp"
hcrt_hdr = "0.000000"
hcrt_gamma_in = "2.000000"
2730-hdr preset
loads "#reference “shaders/crt-sony-megatron-hdr.slangp” which does not have a gamma_in preset value:
#reference "crt-sony-megatron.slangp"
hcrt_hdr = "1.000000"
I think if you add the " hcrt_gamma_in = “2.000000"” also to your 2730 HDR preset, it may save a lot of headaches for people.
Because, if I change CRT gamma to anything above 2.1/2.2 let alone its default 2.4 there’s just no way I can get the gray ramp balanced, the whites will always be blown out or the whites will be good when lowering paper white to something about 170, but then the darks and the whole screen will be way to dark.
Now onto SDR mode…
Previously I already mentioned that SDR mode was fine for me using the DCIP3 colour space with its power gamma, and now I’ve matched up the SRGB and 709 almost through changing the CRT Gamma as follows:
SDR mode:
SDR colour space: DCI-P3, Display Gamma: 2.40, CRT Gamma: 2.30 == perfect gray ramp
SDR colour space: sRGB, Display Gamma: 2.40, CRT Gamma: 1.90 == close to perfect gray ramp (dark values fall off slightly to steeply)
SDR colour space: r709, Display Gamma: 2.40, CRT Gamma: 1.70 == close to perfect gray ramp (dark values fall off slightly to steeply, and even a bit more than sRGB above)
Note how for sRGB and r709 I increasingly need to lower the CRT gamma.
Maybe I’m premature in my conclusion, but it seems, at least for my setup, that with the power law gamma function (which the sdr dci-p3 setting is using as gamma function) allows me to create the most balanced gray ramp in that the darks don’t fall off too steeply, but overal a really great even spacing between the bars from dark to bright. Maybe it would be the same for other users? In that case possibly it could be considered to add an option for the 709 and sRGB colour space, to be able to switch between their spec gamma curves and power law gamma curve.
Anyway thanks again for the shader and putting in all the effort, much appreciated!! 
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As a quick response to the HDR section: so what you have hit upon is the reason why all HDR applications really need a calibration process. Basically because no display can currently display the full rec.2020 spec i.e 10,000 nits and the wide colour gamut (as we’ve discussed before) then what looks good on your monitor may not look good on mine and vice versa.
So as you’ve correctly identified these calibration screens behind the scenes tweak the max nits, paper nits and gamma values of said applications and that is basically what we really need in RetroArch but I didn’t have the time or resources to create those screens when I added HDR support to it.
Basically you need to tweak these values for your screen as these values are for my screen i.e 700 max nits, paper nits and 2.4 gamma (in). These values do give a correct grey ramp on mine so that’s what I’ll keep.
Maybe I need to give these instructions on the shader params screen though.
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This is great work @rafan! What display do you use?
Will you consider packaging a preset pack or at least posting all of your modified preset code as you go along or when you go through all the Sony Megatron Color Video Monitor presets that you use. This would be a great help to users like myself who don’t have as much knowledge and understanding of how colour systems and calibration work!
Brilliant work in improving this awesome shader!
Hi @cyber - that’s my point you can’t make a preset for this with HDR. It’s different for everybody’s display (assuming they have different displays of course).
SDR is different in that a lot of people’s displays are capable of the full rec.709 standard.
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That’s why I asked @rafan what display he uses. His settings won’t work for everyone but they just might happen to work for some with the same or similar displays. They might even work better than the defaults on different displays for some users.
Maybe in time others might share their calibrated presets as well and eventually what started off as a couple presets might someday grow into a large database.
When more and more users start diving in and figuring stuff out about the shader and how to improve the experience on their own then share their presets and findings that’s what will create and generate more buzz and excitement around the shader as the community of users start to grow.
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I don’t know, I think a calibration wizard is the way to go for this. A thousand and one presets would surely just confuse users. At least this is how games deal with this problem.
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Hey @Cyber
It’s a Samsung Odyssey G7. It’s a very nice 1440p monitor. I think somewhere down the road I would want to “upgrade” it to a bright 4K monitor though, as it would be very neat to comfortably use slotmask and lower TVL settings in the shader for an even more close CRT experience. With my current monitor only TVL1000 setting is up there for enough brightness.
In that regard I’m also curious about OLED, since you own one, does it bring a more CRT-like smooth(er) motion with fast scrolling stuff in your opinion? How would it compare to a good LED motion wise?
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Hmmm…my OLED is “only” a 60Hz one. I’ve recently switched between a 4K LED and my OLED and I couldn’t wait to get back to my OLED mainly for the contrast, the better black levels and lack of blooming.
I don’t have any issues with motion clarity on either. I don’t always try to nitpick when I’m immersed in a game though. I have noticed that I couldn’t see the mask pattern clearly in the backgrounds during fast moving or scrolling sections of games. On objects like the main characters (when stationary) or status bars or even static backgrounds in a boss arena or title screen for example it’s not an issue. In general it isn’t an issue at all at least for me as it’s only something I notice if I’m looking for it. Same goes for judder.
I would assume that something that can do BFI properly and still have enough brightness left over so you can see everything properly might be a sight to behold but for me who only has distant memories of CRTs to compare its more than good enough even without.
On my OLED TV, I notice trails from fast moving bright objects on a dark background quite frequently even without tricks like afterglow in my presets.
When I switched back my biggest disappointment was realizing that most of the mask patterns that I used that worked quite well on my LED TV looked really off, incorrect and downright horrible on my OLED TV.
That motivated me to investigate this further and further because others had written off OLED TVs and good colour mask emulation which I wasn’t satisfied with at all and I eventually stumbled upon specific mask patterns that actually worked much better (at least well enough) with OLED TVs.
So no matter which display technology you choose, there’s always going to be some sort of tradeoff.
I think a good 4K miniLED TV might be a good compromise between the two competing technologies.
Specifically one of the new TCLs which has a relatively conservative dimming algorithm which handles difficult for miniLED scenes like starfields very well.
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The photo was to demonstrate the improvement to the mask on my OLED, but the overall image still had clipping/crush issues in the highlights and on similar colours unless using the JVC presets as described here:
However, using the new colour-accurate parameter, all these issues are gone unless pushing the paper-white too high. Everything looks correct with paper-white at around 550 (nits at 720). Thanks for the amazing update!
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Fantastic great to hear! What model OLED are you using again?
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It’s LGs latest 42 inch ( OLED42C2)
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I’m loving the Megatron shader, been doing some more extensive testing with various cores and overal everything works great, but yes I did find one thing that could possibly be improved. Not a bug I think but more something feature related 
The bottom line is that interlaced content does not look right. For example there are many Playstation 1 games that mix low-res (320x240) with hi-res (640x240) and hi-res interlaced (640x480i) content, and this hi-res interlaced content does not look right.
I’ll explain a bit more thoroughly, hopefully it is something that you could look into.
I’m seeing two issues happening:
-
Interlaced content does not look right as scanlines dissappear completely.
-
What I would call “medium-res” (i.e. 640x240) is looking too sharp. I think this is because the shader “sharpness” setting is tweaked for low-res (320x240), but when a game switches to 640x240 in-game the horizontal filtering is not adjusted to this new resolution.
On issue 1 a bit of extra explanation may help. There are some cores that support real-time resolution switching just like the hardware did. Some cores that do this are for example the Mednafen PSX core, BlueMSX core, the Commodore Amiga PUAE core and some others.
As an example of the many oddbal resolutions that may occur here’s a video that lists all PS1 games that use interlaced as the base resolution - in the entire game - (he leaves out games that only occasionaly switch to interlace for title screens etc):
Playstation 1 ALL (?!) Interlaced (Hi-Res) Games
The resolution table that is mentioned in the readme “more” link below the video is interesting:
00:00 Intro
00:05 Hi-Res Mode?
00:35 Debunking 480i Myths
02:18 320x240
02:45 256x480
03:11 312x448
03:34 320x480
04:39 368x480
07:15 382x480
07:45 384x480
08:14 512x478
09:36 512x480
13:52 640x448
14:09 640x480
To not make this post too long and not knowing if you’re already familiar with the technicalities of CRT interlacing the summary is that for correct CRT interlacing simulation you need to weed out the odd and even lines fields from the emulator frames output and have the odd and even lines fields alternating at a slight offset from eachother.
Note that in a CRT the offset is about 0.5 lines. You and I know this is possible because it’s analog television and the phoshpors of the previous field have already died out when the half line offsetted other field is displayed. Rinse and repeat. Through persistence of vision the human eye and brain then sees a 480 tall picture. If you’re interested I could provide more info on CRT interlacing.
As an example this guy explains it nicely. It’s a simple explanation just using his hands and it’s for 1080p/1080i but the idea is the same for 480i CRT:
TV Explained: Progressive and Interlaced . The interesting part is from 3:34, at which the previous link starts.
I know guest.r has done a great job implementing interlacing into his advanced shader that’s virtuously indistinguishable from a real CRT. I’m hoping something similar could be achieved for the Megatron shader.
Possibly the de-interlacing.slang shader from HunterK in the misc folder could also provide some additional idea what’s happening, although this seems to be only for “normal” content and not directly applicable in a shader that has scanlines simulated etc…
I think this could really put the icing on the cake. As always thanks again for the superb Megatron!
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Great investigation, thanks! Yes sure I’m guessing de-interlacing doesn’t work as I haven’t looked at it. I’ll definitely add to the to-do list.
My main focus at the moment with regards to CRT shaders at least, is to get TATE mode working for the d3d9, 10, 11 and 12 drivers. I’ve made some progress but there’s one more thing to fix before I can submit to GitHub. I hasten to add that’s nothing to do with the Sony Megatron shader but the drivers themselves.
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I came across this page that tries to list all subpixel geometries that are used in-practice on modern screens, including phones. Not for any direct use, but since there’s been regular discussion on subpixel types I thought to flag it anyway:
Subpixel Zoo - A Catalog of Subpixel Geometry
Flagging this also to @nesguy and @Cyber for our resident subpixel gurus
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