Sony Megatron Colour Video Monitor

[nfp0]

Pardon if this was talked before in the thread, but a quick search turned up nothing.

I wanted to try this amazing shader now that HDR works on the major Linux desktops (I’m using the KDE Plasma desktop). KDE has a neat HDR calibration tool in the monitor settings, where you set your max luminance and paper-white value. The usual stuff.

After setting those values up, I set the same inside RetroArch on the HDR menu, and then I set them again on the Megatron parameters (so, I set them in 3 places in total).

But I noticed the colors are washed out and the brightest values seem to be clipping into each other. The overall picture looks very wrong.

Then I went again to the KDE monitor settings and set the HDR max luminance to it’s maximum allowed value (2000 nits), and now Megatron looks much much nicer!
Perhaps double tone-mapping is happening? Once in the shader, and twice in the KDE desktop? Anyone else had this experience?

Still, it feels like I still can’t reach an acceptable brightness value. My TV is an LG C1, which has about 720 nits maximum brightness on a 10% window. Am I doing anything wrong while configuring this shader, or is this to be expected on this TV? Help is appreciated!

(I’m using the crt-sony-megatron-aeg-CTV-4800-VT-hdr.slangp preset with everything at defaults except the brightness settings.)

[Cyber]

Sharing photos of the display showing the issue, really helps much more than text descriptions of a visual problem.

The first person I heard from who tried HDR in Linux ended up discovering some bugs in the Linux HDR implementation. Make sure you’re seeing the changes in real-time when you adjust any of these HDR settings.

It’s possible that the default presets you’re trying could look washed out on your display. If all else fails, you can try increasing the Saturation after you get your brightness looking alright.

One thing to remember is that those Peak HDR Brightness measurements for the TV all use the white subpixel. RGB based presets in Sony Megatron don’t use the white subpixel at all so your effective Peak Luminance might actually be a little lower.

For WOLED displays, use the RWBG/WOLED Display’s Subpixel Layout, Set Colour Accurate/Mask Accurate to Mask Accurate and you can try Vivid Mode in the Shader.

Don’t be surprised if you have to set your Paper White Luminance values almost or just as high as your Peak Luminance to get acceptable brightness and don’t be surprised if you have to increase your Saturation a bit before your colours start to look accurate, in particular Red.

Different Phosphor Types also have vastly different Saturation levels.

Feel free to try Sony Megatron preset packs. You might actually have an easier time getting them to look right on your OLED Display as most of them were made using an LG OLED Display.

[nfp0]

@Cyber

One thing to remember is that those Peak HDR Brightness measurements for the TV all use the white subpixel. RGB based presets in Sony Megatron don’t use the white subpixel at all so your actual effective Peak Luminance might actually be a little lower.

Yes! This sounds like a very plausible explanation. Indeed the white pixel is by far the most powerful on these types of WOLED displays. Seeing as Megatron only used the RGB ones, naturally I would need to set the peak luminance value quite lower than the TV’s maximum.

Indeed at lower brightness levels the colors look totally fine in the shader, and it’s only when I try to compensate for the low brightness (by raising the paper-white luminance) that the colors start looking wrong. So I might be hitting my TV’s RGB pixels peak brightness without reaching a satisfactory brightness level for the shader for normal usage.

In this case I might need to use a shader with mask compensation features, like Guest’s and use HDR to boost overall brightness.

@Cyber

For WOLED displays, use the RWBG/WOLED Display’s Subpixel Layout, Set Colour Accurate/Mask Accurate to Mask Accurate and you can try Vivid Mode in the Shader.

Don’t be surprised if you have to set your Paper White Luminance values almost or just as high as your Peak Luminance to get acceptable brightness and don’t be surprised if you have to increase your Saturation a bit before your colours start to look accurate, in particular Red.

Yes, I am using the RWBG subpixel layout.
I will try the other things you suggested and see how close I can get to an acceptable picture. Thank you!

@Cyber

Feel free to try Sony Megatron preset packs. You might actually have an easier time getting them to look right on your OLED Display as most of them were made using an LG OLED Display.

Ah yes! Good idea! I will try your Megatron presets and see what I can get out of those
I will report back.

[Cyber]

When I used to sit far from my OLED TV I used to use 630/630 for Peak/Paper White Luminance.

When I sat closer, I started using 630/450.

I’ve recently observed that decreasing Viewport Size to 6X provides a nice increase in brightness over 8X and higher.

All else being equal, Shadow Mask and Aperture Grille presets tend to be brighter than Slot Mask Presets.

You should be able to get good enough brightness from an LG C1.

For a hybrid approach though, you can check out my CyberLab Mega Bezel HDR Ready presets.