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PostPosted: Mon Jun 17, 2013 1:54 pm 
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Googling for "CRT phosphor emulation" and I've found this video:
Emulation of CRT Phosphor + Curved Screen + Fade
But I can't test this GPU shader on my old gma4500

Can anyone test this filter on Stars - Field demo (PD).nes?


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PostPosted: Mon Jun 17, 2013 3:35 pm 
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Do you have some Csound program which can emulate luminofor fading for a single pixel? If it is treated as an audio signal, I wonder what it will sound like?

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PostPosted: Mon Jun 17, 2013 4:37 pm 
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CRT phosphors emit light as either a first or overdamped second order exponential decay¹ after the incoming electron beam radiation has stopped. There will be some complication for the electron beam size, such that a "single" phosphor may actually be struck multiple times in quick succession as the screen is redrawn. Vectorscopes have a different retrace pattern, but are subject to the same caveats.

¹ 'Properties of Fast-Decay CRT Phosphors' by Pfahnl, ftp.helpedia.com


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PostPosted: Tue Jun 18, 2013 4:24 pm 
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What do you think?


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PostPosted: Tue Jun 18, 2013 4:33 pm 
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Looks like motion blur instead of light trails...


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PostPosted: Tue Jun 18, 2013 4:45 pm 
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Quote:
Looks like motion blur instead of light trails...

Yes.

On the my first video you can see that white stars have greenish phosphoric tails.
This effect is similar to "afterglow" but no blur.

I need to make more quality video.
When you see live on real CRT traces looks much longer, brighter and phosphoric.


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PostPosted: Tue Jun 18, 2013 4:54 pm 
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I see. At anyway, even for a single pixel, it's brighter and "bigger" due to his properties in a CRT monitor.


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PostPosted: Tue Jun 18, 2013 5:06 pm 
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Zepper wrote:
At anyway, even for a single pixel, it's brighter and "bigger" due to his properties in a CRT monitor.

Yes... this will be pretty hard so simulate in emulators.


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PostPosted: Tue Jun 18, 2013 5:26 pm 
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Having done a very simple simulation assuming a half-life of 33ms, without any of the electron beam simulations, the effect is fairly subtle:
Attachment:
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This is just "current displayed frame" = maximum("previous displayed frame" * .7,"current notional frame")

(This is a still from the loop that bisqwit made to demonstrate animmerger. Any obvious errors are from it.)


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PostPosted: Tue Jun 18, 2013 7:10 pm 
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I'm shifting right (div by 2) the previous RGB pixel to simulate an exponential decay. Then, I'm adding the new pixel. Well, I see it produced a similar effect from the previous screenshot... ;)


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PostPosted: Tue Jun 18, 2013 8:07 pm 
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You're missing a few points:
1. If the new point brighter than the old one - the new one is drawn just as they are.
2. If the new point darker than the old one - then the strength of the effect will depend on the difference in brightness of the old and the new point. Therefore, the maximum effect will be viewed as a new point - black.
3. Each one has a different color phosphor decay rate. I have already given a link to a video showing it. First fades blue phosphor, then green and red kept the longest. Therefore, it is necessary to work on the sub-pixels separately.


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PostPosted: Tue Jun 18, 2013 10:45 pm 
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HardWareMan wrote:
3. Each one has a different color phosphor decay rate. I have already given a link to a video showing it. First fades blue phosphor, then green and red kept the longest. Therefore, it is necessary to work on the sub-pixels separately.
It looks to me like the half life depicted in that recording is on the order of 100µs for blue, 300µs for green, and 2ms for red. With modern phosphors with those halflives, there will be no visible interframe blurring from the phosphors, only from your eyes.


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PostPosted: Wed Jun 19, 2013 11:09 am 
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So, it's not a matter of interpolating frames or blending pixels at every X ms.
Should I say "outputting pixels whiter than white"? ;)

Funny things ^_^;;


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PostPosted: Wed Jun 19, 2013 11:42 am 
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Zepper wrote:
So, it's not a matter of interpolating frames or blending pixels at every X ms.
Should I say "outputting pixels whiter than white"? ;)

Funny things ^_^;;

This looks nasty, but it's closer than the other approximations above, which are more like motion blur.

Most of what makes the fading phosphor look look like it does is phosphors not going dark instantly.

Eugene.S wrote:
Googling for "CRT phosphor emulation" and I've found this video:
Emulation of CRT Phosphor + Curved Screen + Fade
But I can't test this GPU shader on my old gma4500

Can anyone test this filter on Stars - Field demo (PD).nes?


This looks more like an LCD response time emulator, ironically, from the video.


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PostPosted: Wed Jun 19, 2013 12:39 pm 
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Oh, mein gott :shock:
It's the LSD emulator with psilocybine mushrooms! :lol:

I want to see it on motion


Last edited by Eugene.S on Wed Jun 19, 2013 3:28 pm, edited 1 time in total.

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