JPG Chroma Subsampling

No matter what quality is used, the jpg export always produces a visible quality loss in solid colors (specially visible in reds, for instance). I think the problem is caused by an aggressive chroma subsampling.
Sometimes the texture in photographic images hides the subsampling, but when exporting designs with both photos and solid colors the subsampling is more evident.

Phatch should allow to export good quality JPGs, and I guess an extra option to set the desired chroma subsampling should be a great addition for those who need to process high quality images.