ffmpeg 709 Colors

[poisondeathray]

Originally Posted by jay123210599

How are they different? Which one will have the higher quality?

You can compare them. They will be similar in quality, but they are not bit identical.

Difficult to say which is "higher quality", because they are both technically lossy compared to the source. 8bit RGB is a lossy converted representation of 8bit 4:2:0 YUV data - and you cannot get back the original values - so an 8bit (or 16bit) PNG is lossy compared to the source by that definition

The main differences are due to the chroma upscaling algorithms used (if you test using a 4:4:4 source, the differences are reduced) , but there are other differences as well

Originally Posted by Z2697

Yeah... and zimg also scales chroma when performing transfer conversion, so keep YUV won't actually "save the chroma" anyways, well, unless you use point resize in the conversion, but then you do downscale, it doesn't really matter after all, better just go RGB.

You can repeat with YUV 4:4:4 src tests with no chroma scaling for the RGB step and you get similar findings

Originally Posted by GeoffreyA

Apart from the increase in saturation, which is visibly off, the linear-Y path seems slightly sharper: at least on the hairs. The brightness on the eyes has also gone up. This is a source that I am going to keep and experiment with. Earlier today, when I put together the revised command, I tested a shot from Mulholland Drive and all looked identical, even scaling in gamma light.

Yes , and just because there is one proposed method of linear gamma scaling , it doesn't mean you should use it. Use whatever works for your goals . Some people like merging the extracted Y from the linear-Y path with the extracted CbCr from the linear-RGB path with a weighting , for example, or whatever combination.

BTW , the original jpg (stored as YUV444 fullrange) src image
https://en.wikipedia.org/wiki/File:C...p_Portrait.jpg

Also, it's often advised to perform calculations or processing in RGB because of the maths.

Personally, I prefer using RGB for color manipulations . RGB is an additive model. It makes intuitive sense to me 1+1=2. Some people are able to do it successfully fully in YCbCr... I find it more difficult to do in YCbCr for more than simple manipulations

[Z2697]

I mean, I totally agree that doing it in RGB is the right way, I added some point to it: chroma scaling is still involved so the performance and sharpness (of chroma) will still be affected, unless (maybe) point resize is used.
YUV is weird, man. It's a legacy from analog era, it serves... virtually nothing in modern times.
Well, subsampling saves encoding and decoding time, and the encoder is more efficient in compressing YUV in contrast to RGB, but what if we have switched to RGB long time ago? Things will be designed around RGB and maybe not subsampling, but encoders will be better at RGB.

It's just that I always hesitate to convert back and forth bwtween YUV and RGB during process, when 99.9% of the source we can get are already YUV420.

[huhn]

while subsampling is just counterproductive YCbCr is not for lossy encoding.
the power to use less bit rate for Cb and Cr is to powerful and can not be beaten or reached with RGB.

there are other types that make converting back and for easier but using "lossy" complex one like ITP should be the future.

[GeoffreyA]

Originally Posted by poisondeathray

Yes , and just because there is one proposed method of linear gamma scaling , it doesn't mean you should use it. Use whatever works for your goals . Some people like merging the extracted Y from the linear-Y path with the extracted CbCr from the linear-RGB path with a weighting , for example, or whatever combination.

I suppose like most things, the "best" approach is often a hybrid method, combining the best of each.

BTW , the original jpg (stored as YUV444 fullrange) src image
https://en.wikipedia.org/wiki/File:C...p_Portrait.jpg

Thanks.

Originally Posted by Z2697

I mean, I totally agree that doing it in RGB is the right way, I added some point to it: chroma scaling is still involved so the performance and sharpness (of chroma) will still be affected, unless (maybe) point resize is used.
YUV is weird, man. It's a legacy from analog era, it serves... virtually nothing in modern times.
Well, subsampling saves encoding and decoding time, and the encoder is more efficient in compressing YUV in contrast to RGB, but what if we have switched to RGB long time ago? Things will be designed around RGB and maybe not subsampling, but encoders will be better at RGB.

YUV is confusing, whereas RGB makes practical sense, reflecting what we learn about the primary colours in everyday life, and even a child could understand it. Though a relic of the past, YUV more closely reflects the way our eyes work and exploits that, similar to audio compression paying more attention to the frequencies ours ears are most sensitive to. But I agree that life would be easier with RGB.