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Talk:Videos/A Digital Media Primer For Geeks

499 bytes added, 02:52, 25 September 2010
Video vegetables (they're good for you!): chroma samples positioning
::OK, thanks for the clarification Monty... I did not even know that the horizontal crop area existed.
"''[...] most displays use [RGB] colors [...]''". Doesn't that sentence contradict this one : "''[...] video usually is represented as a [...] luma channel along with additional [...] chroma channels, the color''". I don't understand what "''position the chroma pixels''" means exactly. Are we talking of real points on a display ? Thanks, great video ! --[[User:LedavulevogyreLedahulevogyre|LedavulevogyreLedahulevogyre]] 13:59, 24 September 2010 (UTC)
:Display devices use RGB. Most video is actually encoded as YUV, luma plus two color "difference" channels. This reduces the bandwidth of raw video by cleverly exploiting limitations in human perception. Additionally, color samples need not be as frequent as luminance samples. So "chroma pixels" are the color data samples, not the pixels on a real display. --Dryo
 
::Thanks Dryo ! that's what I thought. Then I don't quite understand what this chroma samples positioning/siting is about. Is it actually defining the algorithm you should use to compute RGB pixels from YUV samples ? Is is defining the influence zone of chroma samples over luminance ones ? What I don't get is how you can talk about spatial positioning for something that is, well... not spatial (samples). Thank you again ! --[[User:Ledahulevogyre|Ledahulevogyre]] 09:52, 25 September 2010 (UTC)
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