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What is Color Banding? And what is it not?

simonschreibt.de

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Re: What is Color Banding? And what is it not?

#5
That video itself has a lot of color banding, posterized or quantized look. Chrome on 2015 Macbook Pro Retina 13". Same happened on Safari.

I thought this was intentional and expected the author to mention about it at the end of the video, but... nothing.

Re: What is Color Banding? And what is it not?

#6
post #2

Dithering is seen so often in 90's 256-color images, but why so rarely in the ugly banding of 24-bit RGB images?

The alternatives to dithering a 256 color image both end up with undesired results. You can either create a palette specific to your image or application (which makes the rest of a multitasking system look like a tie-dye shirt), or have really, really ugly banding since you have a mere 256 colors to work with (minus reserved colors) instead of 2^24

24-bit images are 'good enough' and dithering would just add another step to the asset workflow.

I can remember the days with a 1MB video card and Windows 95 - switching between 16-bit color at 800x600, or 8-bit color at 1024x768. Resolution vs dithering...

Re: What is Color Banding? And what is it not?

#7
post #5

That video itself has a lot of color banding, posterized or quantized look. Chrome on 2015 Macbook Pro Retina 13". Same happened on Safari. I thought this was intentional and expected the author to mention about it at the end of the video, but... nothing.

The video looks bad because YouTube's encoder butchers video content. Add to that the reality that video decoders typically apply filters to a video post-decode to compensate for the artifacts introduced by encoders. Those filters can add banding, and the encoder already quantized the video.

It would look better if the video had been uploaded at 1080p60 or something ridiculous, because that increases the bitrate budget, and the smaller video macroblocks cover less important image information. But that's kind of an awful hack.

You can observe this clearly with youtube clips of classic games, like those at TASVideos ( https://www.youtube.com/channel/UCFKeJVmqdApqOS8onQWznfA ) the source games are 480i or 240p at best, but the quality of the youtube 480p bitrate is significantly compromised in ways you can see. If you watch it in 1080p it looks much closer to what you'd see in an emulator (or off the hardware when connected via RGB/component.)

Re: What is Color Banding? And what is it not?

#8
post #2

Dithering is seen so often in 90's 256-color images, but why so rarely in the ugly banding of 24-bit RGB images?

Well, like the video explains, I think a lot of people don't recognize the problem, because it's less obvious with 24-bit color. And, if they do recognize the problem, they might think it can't be fixed, or they might not think subtle bands are worth fixing.

I've used the following in the past with a lot of success, for one-click fixing Photoshop banding.

http://nomorebanding.com

Re: What is Color Banding? And what is it not?

#9
post #5

That video itself has a lot of color banding, posterized or quantized look. Chrome on 2015 Macbook Pro Retina 13". Same happened on Safari. I thought this was intentional and expected the author to mention about it at the end of the video, but... nothing.

He mentions YouTube compression at 3:28.

Re: What is Color Banding? And what is it not?

#10
post #2

Dithering is seen so often in 90's 256-color images, but why so rarely in the ugly banding of 24-bit RGB images?

I can't say for sure, but one of my guesses would be stability. By that I mean that the noise is acceptable for a single static image, because it doesn't change - but distracting in an animation if the dithering completely changes from frame to frame.

I might be a non-issue - either not noticeable or not distracting - and the real reason is that people just don't see banding as a problem or that the rendering overhead per-frame is too much.

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