AVS Forum Special Member
Join Date: May 2008
Location: San Francisco - East Bay area
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Just to speak to very specific points...
First... there is no such thing as RGB 4:4:4. You have RGB and you have YCbCr. RGB can be 0-255 or 16-235. YCbCr is output from disc players and other source components in either 4:2:2 or 4:4:4 which tell you how much color decimation was applied. 4:4:4 carries much more color information than humans can see. 4:2:2 would be perfectly fine for high-fidelity video if there were no other issues (like not using all 8-bits effectively). YCbCr is supposed to only exist in the 16-235 digital levels format.
If the video display is well-designed, there will be absolutely NO measurable or visible difference between RGB and YCbCr and it won't matter if the YCbCr is in 4:2:2 format or 4:4:4 format. All 3 formats should measure and appear identical. In the real world, there are displays that simply produce better looking images in either RGB or YCbCr mode -- check both modes, if you don't see any difference, there isn't any difference. It's typically not that difficult to notice so don't spend hours or weeks or months trying to decide if RGB or YCbCr looks better. If you can't tell there's a difference in 5 or 10 minutes, there's no difference worth worrying about.
Incedentally, if you convert RGB data directly to YCbCr without any color decimation, you get YCbCr 4:4:4 -- both color formats contain more data than human vision can make use of. Color decimation is the process of removing superfluous color information... done properly, YCbCr 4:2:2 is completely indistinguishable from 4:4:4 but 4:2:2 requires less bandwidth to transmit across cables or to store in memory (temporarily or permanently). Blu-ray discs are encoded in YCbCr 4:2:0. But 4:2:2 is output from disc players unless you change to RGB or YCbCr 4:4:4. 4:2:2 is the best all-around option unless you happen to own a display that simply looks better when displaying images received in RGB format. All that said... sometime, there's no 4:2:2 option... you can pick RGB or YCbCr 4:4:4 and that's all. Or in some cases RGB may be the only available option (our old DISH receiver was like that). Obviously, you can only work with the choices that are available to you.
"Movies is magic..." Van Dyke Parks
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