Sony Megatron Colour Video Monitor

Maybe because they have to be refreshed and redrawn and during motion the colours of the phosphors would change and during these transitions between colours of the phosphors (due to motion) typical LCD motion blur due to sample and hold causing persistence of vision can occur. The BFI reduces this motion blur caused by persistence of vision. CRTs don’t suffer from this because they are not sample and hold displays. The whole process of drawing line by line with vblanks in between means that there’s very little in terms of a complete frame for our brains to remember (or is it our retinas to retain).

I notice it all the time once I don’t forget about it by being immersed and not paying close attention to how much better things like backgrounds look when not scrolling.

Perhaps @Nesguy can offer a better and more thorough explanation of this to you.

BFI/Strobing/Motionblur thread reorganized

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Ive just confirmed what I was saying, this in my opinion is absolutely an optical illusion and as such is nothing in inherent in the display.

If you look at my CRT as you scroll in the vertical direction you lose the scanlines. If you go left right you keep them. If you do the same on an LCD with my shaders you get the same effect - it’s slightly lessened if you have larger black gaps between the scanlines.

What clinched it for me is that you can break the illusion by looking at one of the corners in the LCD - there is absolutely no loss of mask or scanline as you scroll. It’s purely an optical illusion that you get on both CRTs, LCDs and probably OLEDs.

You maybe able to help break that illusion with BFI but that is not what happened on a CRT. I will say I think the effect is slightly worse on an LCD over my PVM but then I’d argue it has slightly larger blacks gaps as the display is physically bigger.


Precisely, persistence of vision happens in the eyes, retina and brain. That’s exactly what BFI mitigates. Full frame sample and hold display technology will facilitate this optical illusion much more readily than line by line scanning with vblank technology used by CRTs.

I’m waiting on @Nesguy or @hunterk to chime in on this one and fill in the blanks.

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Hi MajorPain. I don’t want to derail this thread but being that you’re the one who added HDR to Vulkan recently, can you look at my post I made?

There is serious problems when using BFI with HDR enabled. I put a video up to show what is going on.

Anyway back on topic lol.

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Hi great to hear from you! So I’m trying to find the post you made but can’t see it - where did you post it?

If you haven’t already can you tell me the make and model of your display? Also is everything fine when you don’t have BFI on? Also does what you are seeing happen with the stock shader and HDR on?

It’s this one:


Hey just briefly again not to derail but it’s a 65 inch LG C1.

When I turn off BFI, it’s fine. If I keep BFI on and turn HDR off, it’s fine.

So it’s something with how HDR is interacting with BFI. Sadly I REALLY need BFI with my C1. The sample hold time is so instantaneous with motion that only BFI makes things smooth like butter.

Not using any shader at all. That video is with raw pixels and nothing else.


So I’ve posted a reply but the TLDR is that I think this is your local dimming settings. Turn it off and see where you get to.

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C1 is an OLED TV so local dimming is every pixel. Can’t remember seeing any local dimming settings on my OLED TV.

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Are you saying that LCD motion blur is an optical illusion? I think you may want to do some further reading on the subject. Phosphor persistence on a CRT is definitely not the same thing as motion blur on an LCD.

This site has everything you’d ever want to know about lcd motion blur.

When viewing this on a crt the ufos remain perfectly sharp with no loss of detail. Not so on an LCD.

Anyway, I don’t want to derail the thread so that’s all I’ll say on the subject for now.


We can break it off to another thread if needed, but I think what @MajorPainTheCactus was saying is not that motionblur isn’t a thing, but that the apparent disappearance of scanlines on vertical motion and masks on any motion is an optical illusion.

I’ve definitely noticed the same effect with my CRTs, so no matter what’s going on, it’s not just an LCD/sample-and-hold thing.


Oh for sure, you lose scanlines when scrolling vertically on a CRT, but this happens when scrolling at a much slower speed on an LCD.

And yeah a new thread might be good, or the existing BFI/strobing thread.


oh! I get this too. I didn’t connect the dots; just thought the issue was with my TV. I had to disable BFI. @MajorPainTheCactus

Here’s an example:!AmQUGfXPPtq7gw3q-vVZo46cCI5G?e=38B1Ny


Yes thanks! I just remembered that on the other thread! :man_facepalming:

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Ok right I see - thanks!

First let’s take this over to my Vulkan HDR thread.


Yeah so that’s not what the discussion is about - LCD motion blur is of course a thing as in something scrolling across the screen like the spaceship.

What we’re talking about here is the loss of scanlines as you scroll vertically up and down and the mask which do not move.

With respect to my shaders which use black in both cases they are all in fixed positions. As in during an entire play session using the same shader those pixels and masked subpixels never emit light.

So as an experiment if I put two pieces of paper over the screen (LCD or CRT) and just show the black in between the scanlines there is no motion blur caused by scrolling vertically because the pixels never emit any light.

However when you look at the screen without the pieces of paper you absolutely see motion blur as if those black pixels suddenly were turned on. This is very different from the spaceship flying across the screen and traditional response times where a pixel has to change colour radpidly.

Where things get complicated:

What I will say is that I’m not sure I fully understand this optical illusion as it’s definitely worse on an LCD than a CRT. This may well be to do with how LCDs work compared to say an OLED (OLED being near instant on off Vs LCDs much slower blind over a window opening type thing) and BFI is helping the LCD mirror an OLED better which breaks the illusion more. But CRT phosphors are known also to persist as in phosphor after glow so maybe that’s not contributing to this effect. Also why would OLEDs suffer from it? All questions I have yet to answer.


Just uploaded my Sammy Atomiswave simulation to Github. This is probably one of my most favourite cabinets and screens as its large, got scanlines and has a slot mask.

Again possibly the colours are a little off but we’re close.

As always you can find it all under the ‘hdr’ folder in the zip (once its been merged):

Here’s the cabinet I took photos of:

Absolutely amazing cabinet I’m sure you agree and here’s my side by side comparisons of the CRT (first) vs my simulation shader. Note the ISO is now the same on both the CRT and LCD.

Please do click on each to see larger more detailed photo.

CRT Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 200, WB 5000K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.

LCD Photo: OnePlus 8 Pro Camera: Pro Mode, ISO 200, WB 5000K, Aperture Speed 1/60, Auto Focus, 48MPixel JPEG.


we should probably consider using/developing a reproducible methodology for getting pictures of a test image (SMPTE color bars or whatever) to generate color transform LUTs for the various CRTs, too.



Do you know the specs on this monitor? It looks medium-high TVL.

It occurred to me that you can use the 8k mask (RRGGBBX) to get a consumer-grade/average arcade look. TVL would be around 300.


Yes! I’ve got some pictures of a 350TVL PVM I intend to simulate.

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