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

bluedino 11y ago
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...
- kuschku 11y ago
  And there is one alternative: 30bit (+alpha) colors. But that’s currently only used by designers.
  - exDM69 11y ago
    30 bit color means 10 bits per channel equals 1024 discrete values. If you do a full-screen gradient from, say, red to black on a large resolution monitor, there will be color banding. It's better than 24 bit color but doesn't solve the problem.
    - kuschku 11y ago
      Current movies use 36 bit – that’s enough for 4K usually.
Guest192038 11y ago
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 http://nomorebanding.com
stefs 11y ago
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.
- im2w1l 11y ago
  Dithering seems to work for animated gifs.
  - kuschku 11y ago
    It’s very complicated there, too, though. As this article [1] shows, even with animated gifs you have often unstable dithering with artifacts somewhere in the image. [1] http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html

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...

kuschku 11y ago
And there is one alternative: 30bit (+alpha) colors. But that’s currently only used by designers.
- exDM69 11y ago
  30 bit color means 10 bits per channel equals 1024 discrete values. If you do a full-screen gradient from, say, red to black on a large resolution monitor, there will be color banding. It's better than 24 bit color but doesn't solve the problem.
  - kuschku 11y ago
    Current movies use 36 bit – that’s enough for 4K usually.

Guest192038 11y ago

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 http://nomorebanding.com

stefs 11y ago

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.

im2w1l 11y ago
Dithering seems to work for animated gifs.
- kuschku 11y ago
  It’s very complicated there, too, though. As this article [1] shows, even with animated gifs you have often unstable dithering with artifacts somewhere in the image. [1] http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html