I'm not sure why this is important. Obviously the author is much more knowledgeable than I am, so perhaps I can be enlightened.
As noted in the article, Deep Color is important so that sampling errors do not accumulate while images are filtered, processed & combined. But a television or monitor is the final step, it should be performing very little image processing. (Should is the operative word here, that's not necessarily true).
If you used HDMI to connect cameras to recorders or to connect effects processors, this would be important. Does anybody do this for 4K?
It is possible to see banding at 8bit with a final product. Imagine a flat gradient across the screen from black to white. 255 levels over say 2000 pixels (close enough) on a screen like... 6 feet across. Unless the gradient is dithered (either in the TV, or at the source...), you get ~8 pixel wide bands, which works out to 1/4th inch bands, which is definitely visible in certain situations.
Dithering is certainly a solution, but higher bit depths also works, and in a way that's much cleaner.
EDIT: This implies of course that the final display is also capable of high bit-depth display. Obviously, if the display is limited to 8bit, then it's kinda useless. I think the author's point was that HDMI 2.0 -should- be kinda future proof, and -should- anticipate widespread adoption of high bit-depth displays.
> It is possible to see banding at 8bit with a final product. Imagine a flat gradient across the screen from black to white. 255 levels over say 2000 pixels (close enough) on a screen like... 6 feet across. Unless the gradient is dithered (either in the TV, or at the source...), you get ~8 pixel wide bands, which works out to 1/4th inch bands, which is definitely visible in certain situations.
If you have a RGB image were each color component uses a byte to represent it, you should have a effective Luma bit depth of 8 bit. Well, this is false for LCD screens because they have a effective Luma bit depth of 7 or 6 bits (or worst), so even using a VGA signal (analog signal) you get banding on these screens, were on a old good CRT screen you never appreciate it.
I had always assumed that 8 bits per primary were enough to make the transitions between levels invisible, until I was shown a counter example similar to the author's. I verified with an image editor that the bands were indeed only 1 LSB apart. Given that 8 bits isn't perfect, even if there's no further processing involved, it's reasonable to set a higher goal.
Are you familiar with dithering? While it may seem like cheating, it really works quite well. It's similar to some LED torches, that use PWM to control brightness. They turn on and off really fast, and the more time they spend off, the dimmer the light. Yet you think it's a constant source of light, with a large enough frequency. For dithering, you just need a large resolution.
I'm very familiar with dithering, thanks. It was in that context that I was shown the example - I was wondering why anyone would feel the need to dither down to 24 bits.
As noted in the article, Deep Color is important so that sampling errors do not accumulate while images are filtered, processed & combined. But a television or monitor is the final step, it should be performing very little image processing. (Should is the operative word here, that's not necessarily true).
If you used HDMI to connect cameras to recorders or to connect effects processors, this would be important. Does anybody do this for 4K?