Why is it that macroblocking seems to be more frequent with the color red, or is more noticeable within the color red? I'm basing this question off my experience with hdtv monitors and responses by many members in several discussions in the hdtv programming thread. Any thoughts? Thanks!

Reds and blues are lower luminance colors and therefore have a high chroma and low luminance values. Chroma DCT blocks are 4x bigger (2H x 2V) than luminance in 4:2:0. Vision is more sensitive to red than blue.