When using exiftool to inspect various images, I've seen lots of different values for the Y Cb Cr Sub Sampling tag. A few examples:
YCbCr4:4:4 (1 1)YCbCr4:2:0 (2 2)
In How is the YCbCr color space represented in a JPEG image?, the meaning of part of this tag's values is explained, but not the whole thing: specifically, it explains the ratios (the 4:4:4 and 4:2:0 parts in my examples) but not the values in parentheses that follow them. I haven't been able to find documentation anywhere about what the full format of this field actually means, much less just the values in parentheses. It's possible that there is no formal spec for this field, and it comes down to the hardware and software used to produce the image file, but I have never seen an example in my research where exiftool did not output the field formatted in this way (nor does their source code seem to have any examples that show otherwise in their test fixtures that would imply it's not a de facto standard format.)
Could someone explain what each numeric value in this EXIF tag means? I'd ask for just an explanation of the values in parentheses since those are the ones I specifically don't understand, but I think that a full explanation would be useful for people searching for more info on this from a web search.
4:2:2independently of its direction (instead of4:2:2and4:4:0) so I suspect that the numbers in parentheses are just telling the H and V sampling factors (and are important and different only for halved chroma). \$\endgroup\$