Originally Posted by mark haflich
I suspect the few even know what color subsampling even is. i suggest you elucidate exactly what it is. Myself? I don't know what it is either. Why is it bad also?
Color subsampling is video processing where the display processes color information at a lower resolution than luminance. It's a technique that has been used for decades with NTSC for reducing video broadcasting bandwidth. It takes advantage of the eye's lesser ability to discern differences in color between adjacent pixels, compared to brightness.
Computer monitors and data projectors do not use color subsampling because,
1) Video bandwidth is not at a premium (computer straight to monitor)
2) It degrades the image quality by smearing colors
3) Users generally sit closer to a computer monitor or projected data screen than a television, and the eye can pickup degradation in color bandwidth.
Signals without color subsampling are also called 4:4:4 color.
A Blu-ray disk has 4:2:0 color, so for every four pixels on the even scan lines there is color information for every two pixels, and no information for the odd scan line pixels.
Blu-ray players upscale the 4:2:0 information on the disk to 4:2:2 color which is sent to the display, which means for every four pixels on even and odd scan lines, there is color information for every two pixels.
Some Blu-ray players also have the option to output in 4:4:4 color. If the display device down samples to 4:2:2, then you have lost the upscaling that the Blu-ray player did potentially with higher quality.
So a projector which does not perform color subsampling gives you the option to upscale in the Blu-ray player (may be better quality), or with an video outboard processor (also potentially with better quality), and the projector leaves that output untouched.
I highly recommend an article in the Dec. 2010 issue of Wisescreen Review called "Choosing a Color Space". It gives a lot of information on color space, and processing.
I hope this helps.