JPG Export best-quality really chroma subsampling 4:4:4 ?

[hubertmeier]

This is more a question:

My favourite Image Viewer / Organizer shows following info for the chroma subsampling

Sub-sampling 2x2,1x1,1x1

Is this the same like chroma 4:4:4 ? I didn't found any other program which could show this. The export in RT is set

JPG / 8bit / best quality / quality 91

Thank you

[Lawrence37]

Yes, best quality uses 4:4:4 subsampling. Exiftool show
Y Cb Cr Sub Sampling : YCbCr4:4:4 (1 1)