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Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

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Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#31

Post by reactordev »

dylan604 wrote: post #8

I'd love to see an option to have the image pincushion and introduces a buzz in the audio from an video signal that was too strong? That was one of my favorite. Everyone focuses on the interlacing, giant pixels shapes, and the fun with chroma bleed, but some of the most bizarre things could happen when you pushed the analog signal too far. The 1 volt peak-to-peak was a rule for a reason, and going past was possible.…

Also, while the representation of the pixel grid is fairly accurate, it's missing the chromatic aberration from the fact that they were individual electron emitters of red, green, and blue phosphor dots. Pushing the red channel 0.05f and the blue channel -0.05f on the x axis should do the trick.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#32

Post by pdntspa »

I always hated the weird fuzziness, soft lines, and curved image that old TVs imparted on games, it is amazing to me that entire communities have been built up around it. When I started playing games on an emulator and pixels were hard and square and the image was actually flat, I was like YES!!

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#33

Post by foobiekr »

dylan604 wrote: post #8

I'd love to see an option to have the image pincushion and introduces a buzz in the audio from an video signal that was too strong? That was one of my favorite. Everyone focuses on the interlacing, giant pixels shapes, and the fun with chroma bleed, but some of the most bizarre things could happen when you pushed the analog signal too far. The 1 volt peak-to-peak was a rule for a reason, and going past was possible.…

The horrible sound of high frequency CRT screaming meant that I couldn’t go into many electronics areas or stores until the nineties.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#34

Post by foobiekr »

doublepg23 wrote: post #18
karmakaze wrote: post #15

The shadow mask is overly represented. This may work better on a yet even higher resolution display, or perhaps there's an option to reduce the shadow mask effect. The other thing that this emulation can't get right is that phosphor-based displays had more vibrant colors (at lower intensities) than currently popular (IPS) LCD panels. VA panels are better for this.

I was blown away how sharp an Apple ][ display is in person. It’s really hard to get across how cool it looks.

Amazingly, a classic first release Macintosh was vastly worse. Blurry and visible scan lines/interlace.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#35

Post by kloch »

fjfaase wrote: post #2

NTSC was also known for its poor colour reproducability compared to PAL due to how the color signal was modulated. PAL had automatic control where NTSC often required manual adjustment in case the hue was drifted. For that reason NTSC was often said to stand for 'Never Twice the Same Color' or 'Never The Same Color'. I wonder if any of the shaders also has this behavior of randomly shifting the hue or an ability to c…

NTSC colors were bad - really bad - but wideband bayer filters + sRGB are the source of the mediocre colors we see today.

We could have beautiful Kodachrome quality colors If we used narrow-band RGB filters and a wide gamut (Rec.2020, or Rec.2100PQ) colorspace. If you look at the spectral sensitivity specs of Kodachrome film they are fairly narrow-band and closely matched the perceptual sensitivity of human vision (CIE 1931).

If you display an sRGB encoded image with Rec.2020 gamut (without colorspace conversion) the colors will appear very washed out. If you display a Rec.2020 encoded image on sRGB (without colorspace conversion) it will appear oversaturated. Separately, narrower and/or more widely spaced bandpass filters will increase color saturation. It turns out that narrow-band filters approximating the CIE1931 curves are a natural match for the Rec.2020 colorspace. Since CIE1931 approximates how humans perceive color the colors are also more accurate.

It was a "lucky" accident that the properties of CRT phosphors, from which sRGB is derived were a good match for the wideband color filters used in color video cameras.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#36

Post by c-hendricks »

pdntspa wrote: post #32

I always hated the weird fuzziness, soft lines, and curved image that old TVs imparted on games, it is amazing to me that entire communities have been built up around it. When I started playing games on an emulator and pixels were hard and square and the image was actually flat, I was like YES!!

It's interesting, because artists on some games accounted for the fuzziness and used it to their advantage. You should play them how you want of course, but for something like Gameboy emulation I absolutely turn on shaders to avoid the nasty black-and-white.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#37

Post by dylan604 »

reactordev wrote: post #31
dylan604 wrote: post #8

I'd love to see an option to have the image pincushion and introduces a buzz in the audio from an video signal that was too strong? That was one of my favorite. Everyone focuses on the interlacing, giant pixels shapes, and the fun with chroma bleed, but some of the most bizarre things could happen when you pushed the analog signal too far. The 1 volt peak-to-peak was a rule for a reason, and going past was possible.…

Also, while the representation of the pixel grid is fairly accurate, it's missing the chromatic aberration from the fact that they were individual electron emitters of red, green, and blue phosphor dots. Pushing the red channel 0.05f and the blue channel -0.05f on the x axis should do the trick.

There's a fun technique in After Effects to separate the image by channels, and then apply an effect turning the image into grids of small circles. Nudge the red a couple of pixels left, the blue a couple of pixels right, and then the green a couple of pixels up. When these are merged back, you get that very look you've described.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#38

Post by contravariant »

foobiekr wrote: post #33
dylan604 wrote: post #8

I'd love to see an option to have the image pincushion and introduces a buzz in the audio from an video signal that was too strong? That was one of my favorite. Everyone focuses on the interlacing, giant pixels shapes, and the fun with chroma bleed, but some of the most bizarre things could happen when you pushed the analog signal too far. The 1 volt peak-to-peak was a rule for a reason, and going past was possible.…

The horrible sound of high frequency CRT screaming meant that I couldn’t go into many electronics areas or stores until the nineties.

Unbearable high frequency noise does tend to fix itself given a few decades or so.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#39

Post by dylan604 »

contravariant wrote: post #38
foobiekr wrote: post #33

Earlier quoted context omitted.

The horrible sound of high frequency CRT screaming meant that I couldn’t go into many electronics areas or stores until the nineties.

Unbearable high frequency noise does tend to fix itself given a few decades or so.

They were referring the fact that CRTs went the way of the dodo, and flat panels replaced them. This high frequency noise was a unique feature of the CRT.

Re: Cathode-Retro: A collection of shaders to emulate the display of an NTSC signal

#40

Post by dylan604 »

foobiekr wrote: post #33
dylan604 wrote: post #8

I'd love to see an option to have the image pincushion and introduces a buzz in the audio from an video signal that was too strong? That was one of my favorite. Everyone focuses on the interlacing, giant pixels shapes, and the fun with chroma bleed, but some of the most bizarre things could happen when you pushed the analog signal too far. The 1 volt peak-to-peak was a rule for a reason, and going past was possible.…

The horrible sound of high frequency CRT screaming meant that I couldn’t go into many electronics areas or stores until the nineties.

At the end of my day at one of the post houses I was at around this time, I had to ensure all of the monitors were off. I could do it in the dark just by listening for this noise and know if any where on or not. Some of the reference monitors were never turned off though, and I had to ensure they had the correct signal routed to them to avoid burn-in.
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