It is supported in JPEG! It can reduce color bleeding along the axis that each chroma channel controls. For example, if you make sharp Cr and low-res Cb, you'l

It is supported in JPEG! It can reduce color bleeding along the axis that each chroma channel controls. For example, if you make sharp Cr and low-res Cb, you'll get sharper red edges with some yellow bleeding instead of completely blurry red edges if Cr was subsampled.