Sony Megatron Colour Video Monitor

[MajorPainTheCactus]

Thanks!

So the main reason the water is now blue is because I put the white point up to D93. I find this a bit strange as it kind of says my PVM has a white point of D93. I suppose it might have as Sony is Japanese but the PVM is a PAL region PVM. It’s a bit odd - I reset all the options to ‘NORM’. I have two of these PVMs so I might see if it’s been effectively fused off to D93 by someone ‘fixing’ it over the years.

The other thing it could be is that it’s playing Secret if Mana that was developed in Japan. But this is the NTSC version playing on an NTSC SNES.

That’s a lot of colour systems there!

[MajorPainTheCactus]

Thanks for your kind words - it really means a lot to me. Funnily enough Im getting to that conclusion too - I actually prefer the LCD version. I won’t say that in front of my old two girls (the PVMs that is ) though - I will always love them.

In motion they are slightly better - my Eve Spectrum seems to be quite good at reducing blur compared to other LCDs. I think the Blur Busters did a good job calibrating it even without back light strobing - maybe? It’s the poor no. Of darkening zones that let it down in HDR though.

As for the name I think you’re right. The only thing is though that I get quite boring names unless I make it some general name that doesn’t really describe what it does. Hmm have to have a think - any ideas are welcome!!!

[MajorPainTheCactus]

Right so another attempt at getting the colours right! I think we’re basically there - but see what you think - we’re a smidgen out.

Ok so I added in the option to tweak the gamma value and between that and pumping brightness and contrast up I could get the CRT to look quite a lot like the LCD in terms of the colours at exactly the same camera settings.

I do think though in person this isn’t as nice as slightly lower settings more saturated settings on the LCD.

What this is causing headaches with is what are LCD pictures and what are CRT (one give away clue by the way is that some photos have the blue ‘on’ light of the LCD below. Its a nice problem to have at this point as it means I’ve pretty much reached my goal. I’ll keep tweaking this though.

One thing to point out is that the camera on the LCD screen gives a red halo around the center of the screen so thats why the door frame is slightly more red - its not visible with the eye.

CRT Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 200, WB 6500K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

LCD Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 200, WB 6500K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

[hunterk]

that’s really beautiful, man. I think we can finally put to rest the old “crt shaders are cool, I guess, but they don’t look real” adage. Even the close-close-up shot is indistinguishable unless you know exactly what to look for.

[MajorPainTheCactus]

…and just for fun Sonic in the waterfall - this probably fails the transparency test even on my PVM because the signal is too clean.

CRT Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 200, WB 6500K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

LCD Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 200, WB 6500K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

[Cyber]

@MajorPainTheCactus

…and just for fun Sonic in the waterfall - this probably fails the transparency test even on my PVM because the signal is too clean.

That effect is not just about simulating screen characteristics but also signal characteristics, which can vary depending on the input type used on the display as well as the characteristics and quality of the output circuits of the different consoles themselves.

Now that you’ve conquered PVMs and Slot_Masks you’ve basically created a great foundation. It would be nice to see you tackle some of the other “problems” that still exist in a similar, patient and systematic fashion.

So maybe getting not just rainbow effect or de-dithering but Genesis Composite and RF out right might be a nice next step. It could be modular in that one module can be for the TV input side of things that remains constant across consoles and the other module can be unique to the different consoles’ output qualities themselves.

I think the PC Engine also did some unique tricks at the output level in order to display additional colours which is why they added a Composite/RGB toggle in Mednafen/Beetle.

[Cyber]

I’m seeing some small but not insignificant differences here in these comparison shots.

The vertical gaps between the jailbars seem wider and the black background seems darker in the LCD vs the CRT. Also the width of the jailbars themselves seem thicker than the width of the jailbars in the LCD. So there’s a difference in ratio. The LCD looks more 1:0.8 or 1:0.75 between the Jailbars and the gaps but the CRT looks closer to 1:0.6 or 1:0.5 not exactly but 1:(something less than what the LCD is)

The black level seems lower on the LCD also. It could be as a result of this or some other reason.

Be sure to zoom in on the cropped screenshot to better see what I’m talking about.

[Nesguy]

@Cyber

It would be nice to see you tackle some of the other “problems” that still exist in a similar, patient and systematic fashion.

It’s an elusive goal because the way any composite signal actually looks depends on the quality of the comb filter used by the TV, which varied widely, so choosing a reference is hard and partially depends on what the desired look is. A PVM might be perfect for this as it has no comb filter, meaning all the composite video artifacts are present and dithering is completely blended (If the dithering isn’t blended, I don’t really see the point).

@Cyber

So there’s a difference in ratio

That’s really easy to fix, and CRTs weren’t all the same in this regard anyway, since they were calibrated to have different amounts of overscan and such.

@Cyber

The black level seems lower on the LCD also. It could be as a result of this or some other reason.

That’s a plus in my book, one of the reasons why I kinda prefer the LCD shots in some of these comparisons. That’s also easily adjusted. In any case it’s within the margin of difference between individual devices, I’d say.

[Cyber]

@Nesguy

That’s a plus in my book, one of the reasons why I kinda prefer the LCD shots in some of these comparisons. That’s also easily adjusted. In any case it’s within the margin of difference between individual devices, I’d say.

I understand and agree to some extent but these small differences could add up to the difference between dithering effects working properly or not (or not as good) in some instances as well as keeping the shader from achieving what might be perceived as the “natural or analogue” CRT look and feel. Another thing the increased sharpness and contrast might do is cause the LCD version to be ever so slightly more aliased compared to the CRT version. So we’re losing out on some of the natural anti-aliasing that CRTs generally tend to produce. We’re not losing it completely just reducing it slightly.

These differences are so subtle that they could be due to differences in the photography and even though some might prefer the LCD image, the difference is there so if we’re going for the ultimate Pepsi challenge shader with this particular model and sample PVM there can still be a few adjustments to make to make it even closer to that goal.

@Nesguy

the way any composite signal actually looks depends on the quality of the comb filter used by the TV, which varied widely, so choosing a reference is hard and partially depends on what the desired look is. A PVM might be perfect for this as it has no comb filter, meaning all the composite video artifacts are present and dithering is completely blended (If the dithering isn’t blended, I don’t really see the point).

In this case whoever is up to the task can just select a TV which displays the said effects to their liking and use that as their reference. A set can be selected via many different means. It could be random based on photos, memories, a poll, a competition. Criteria could be supplied and screenshots or suggestions submitted. This could be done in so many ways.

Ultimately it might just boil down to whatever reference set the shader creator has access to that can give the output that we’re trying to achieve.

Another desireable side effect of slightly widening the jailbars and reducing the gaps would be slightly improved brightness.

[Nesguy]

@Cyber

…keeping the shader from achieving what might be perceived as the “natural or analogue” CRT look and feel.

I think any difference in black level or ratio between the LCD and CRT at this point is well within the margin of difference between individual CRTs.

@Cyber

Another thing the increased sharpness and contrast might do is cause the LCD version to be ever so slightly more aliased

I’m not seeing any difference in sharpness between the two at this point. If anything I think the CRT might be barely sharper, but again, the variation here is within the range of variation between CRTs.

@Cyber

Ultimately it might just boil down to whatever reference set the shader creator has access too that can give the output that we’re trying to achieve.

This is another good reason to choose the PVM, since @MajorPainTheCactus has access to one already.

There are several types of comb filters and several manufacturers of each and they all look different depending on the manufacturer.

Basically a comb filter recovers lost signal and reduces artifacts. A PVM lacks a comb filter and just displays the raw signal. So if we start with a PVM and get that dialed in, we can then emulate the entire range of variation in composite output among CRTs by reducing the composite video effects, however they’re implemented.

[Cyber]

@Nesguy

So if we start with a PVM and get that dialed in, we can then emulate the entire range of variation in composite output among CRTs by reducing the NTSC effects.

This is precisely what I meant when I said this:

@Cyber

Now that you’ve conquered PVMs and Slot_Masks you’ve basically created a great foundation.

[Nesguy]

To clarify, I meant “if we start with a PVM showing composite output” using the same methodology employed so far in this thread. That would seem a logical place to start, IMO.

[MajorPainTheCactus]

Yeah so yes you’re right there does seem to be some softness in the CRT than the LCD. I’d want to rule out the camera focus to be definitely sure it’s the shader but I think you might be on to something. I’ve got the original pictures zoomed in here so we can see in more detail than those high level ones:

Hmm I think some of this maybe over exposure. I’m going to go back and take a lower ISO shot to see what’s what.

[rafan]

@MajorPainTheCactus

So the main reason the water is now blue is because I put the white point up to D93. I find this a bit strange as it kind of says my PVM has a white point of D93. I suppose it might have as Sony is Japanese but the PVM is a PAL region PVM. It’s a bit odd - I reset all the options to ‘NORM’. I have two of these PVMs so I might see if it’s been effectively fused off to D93 by someone ‘fixing’ it over the years.

The other thing it could be is that it’s playing Secret if Mana that was developed in Japan. But this is the NTSC version playing on an NTSC SNES.

That’s a lot of colour systems there!

According to the service manual of your PVM (2730QM you mentioned), the factory white point is 9300K (D93).

Online: https://manualmachine.com/sony/pvm2730qm/8174091-service-manual/

pdf:

Sony_PVM_2730QM.pdf

Also I’m reading there’s a “HUE” setting on your PVM: two buttons “GRN” and “PUR” that sets skin tone color more greenish or purplish (button above left according to the manual?) that exclusively affects NTSC input signal. Might be something to look at when you’re using NTSC consoles on your PVM.

Good work on the shader, looks better and better with changes. Can you tell something how it is when actually playing side scrolling games etc. How does gaming for a prolonged time on your CRT compare to playing on your LCD with the shader, does the LCD+shader hold up in prolonged gaming sessions versus the CRT?

[MajorPainTheCactus]

Amazing! Good catch! Right there in black and white on the first page! Oh well at least I’m proving my shader matches the real thing! I’ll come back to your other comments.

[Nesguy]

That’s really weird because I’m seeing almost the opposite in other examples- in the closeup of Link for example the partially lit phosphors in the black outline are barely brighter on the LCD compared to the CRT (it’s a very small difference between the two, though).

I’m assuming the PVM is calibrated and you’ve already done a flyback pot adjustment?

[Jamirus]

“I think the PC Engine also did some unique tricks at the output level in order to display additional colours which is why they added a Composite/RGB toggle in Mednafen/Beetle.”

I think that toggle functions more as a correction really, the actual hardware doesn’t output RGB after all without a mod, and the Composite palette accounts for what the internal color conversion actually does. The old RGB palette may still be suited more for some games because of their origin/development process (e.g. Loom was mentioned over at the Pcengineboards as it was ported from different platforms).

[MajorPainTheCactus]

So just played around with the settings and taken photo’s at 100 ISO. So although I think we’re much closer than last night I think the colours are a bit off still. Ignore the fact the LCD is darker for a moment as thats quite fixable its the gradient of the rain drops that is the important thing and proving quite hard to match.

I’m going to implement saturation to fix my original issues but maybe I need to fix those and then come back to this issue as then the colours are calibrated correctly to the PVM.

The jail bar gaps issue is just a horizontal sharpness tweak but I probably need to recalibrate all those settings once the overall colours are correct as it does have an effect on the size and shape of the phosphors and scanlines (and vice versa).

I’ve changed the position of the photos to be more central to the CRT as my PVM’s have larger convergence issues out at the edges which is important in such a image.

Just a single shot of the edge of the waterfall at 100 ISO on my LCD (I’ll try and get the CRT version at a later date):

I will come back to this in due course as its quite a good test case.

CRT Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 100, WB 6500K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

LCD Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 100, WB 6500K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

[MajorPainTheCactus]

Yes I think something is a bit kooky. One thing I will say is that (as with every CRT) my CRT exhibits different issues in different parts of the screen. So this could be just different parts of the screen but I’m not sure on that - further investigation is needed!

When you say calibrated do you mean convergence or colour or both? I tried my best to minimize the deconvergence but with such an old and large CRT its a bit like whack a mole. I think its reasonable though. By flyback pot adjustment I presume thats the HSTAT dial in Sony PVM parlance (I think it is)? If so yes its the first thing I tweaked. As for colour its a very old set and I’m not sure there is an awful lot exposed to be able to tweak. I just set it to ‘NORM’ settings which are supposed to be its standard default settings.

[MajorPainTheCactus]

As to your further points about colour sadly I use a MiSTer through the SCART socket and so those buttons dont do anything. It might be interesting to put an NTSC signal into it though but to be honest I’m not sure how I would do that - there’s not a whole lot of connections on the back.

I’m going to do some video’s at some point to deal with blur. My monitor is supposed to be one of the best LCD’s dealing with it (according to Blur Busters) but I’m unable to switch on the backlight strobing as its disabled for HDR (because backlight strobing dulls the brightness). I’ve asked to get this changed because there are a lot of other reaosns to have it on with backlight strobing but haven’t had any answer. Its supposed to be better than a plasma display at coping with blur but I haven’t been able to test.

In answer to your question I think both are quite close in terms of the experience. The main difference being one is curved and one is flat.