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Posted by Richard Crowley on 11/09/06 20:40
"Phil M" wrote ...
> Hi all. I'm trying to figure out if there's any visual (to the eye)
> difference between 4:1:1 and 4:2:2 footage?
>
> I recorded footage from Betacam SX camera master via the SDI port to DVCAM
> and upon playback, I couldn't visually see any difference in colors.
>
> I understand the theory that in 4:2:2 the chroma components are sampled at
> half the sample rate of luma, and in 4:1:1 the horizontal color resolution
> is quartered. But visually, is there anything more that the eye can see
> when NTSC video plays at full motion? Or the difference shows up only on
> color measuring equipment or when one grabs a screenshot still and
> magnifies it?
Or when you want to do chroma-key (greenscreen, bluescreen, etc.)
where the lower color resolution is visible as fuzzy or inaccurate
switching between the foreground and background video. Since
the majority of the "Y" signal is green, it is reputedly easier to get
good chromakey using green when you are stuck with 4:1:1 DV
(at least here in NTSC-land). Dunno if is the same with 4:2:0 in
the PAL-territories?
I had to deal with a consumer-recorded VHS tape the other day
and was appalled at the low quality people put up with back in
the days. The envelope delay (color shifted from B/W image)
was horrible.
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