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0 pointsjheriko9y ago0 comments

you are right, there is a weird grainy sharpness kind of 'feeling' when chroma is not subsampled...

but you get the exact same effect from higher resolutions, e.g. going from SD->HD->2K->4K we see the same thing... and we are still doing it, so i would question highly that it is subjectively better in a long-term sense given this continuing trend.

i remember hearing people discuss this sort of thing when HD was new, and they stopped after while - i suspect because they got used to it, and they now realise how low the quality of the SD image was. i noticed this in myself as well...

edit: incidentally there is a discussion about this here (first google thing i found): http://www.neogaf.com/forum/showthread.php?t=1308591

its seems either nobody or very few are taking the perspective that 4:2:0/4:2:2 looks better, and there are even a few descriptions of precisely what they notice as being worse.

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haasn9y ago

I believe you are misunderstanding the issue.

Nobody is trying to argue that 4:2:0 video looks objectively superior to 4:4:4 video if given a free choice. Obviously, full chroma information will always be better, such as is the case for something like a PC monitor vs a TV with subsampling.

The problem is that 4:4:4 chroma requires more bits to compress, so when you're designing a video/image codec, you have to ask yourself whether the difference in bitrate between 4:2:0 and 4:4:4 is worth the difference in quality, and the answer seems to be “no”.

This means that when you're serving, say, a 5 Mbps youtube video where the bitrate is already fixed, 4:2:0 is going to give you more bits to put into useful stuff (e.g. luma plane) instead of having to waste them on mostly-redundant chroma information.

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