[Tig] green in YUV

Martin Euredjian ecinema
Mon Dec 3 14:52:58 GMT 2001


From: "Rob Lingelbach" <rob at film.calarts.edu>

> YUV colorspace?

Good discussion ... but I wonder, did you mean Y Cb Cr?
Probably a minor point. They are different.

YUV and YIQ are scaled for analog composite PAL and NTSC.  They are not used
in the digital world. It is common to find image files names "something.yuv"
that, in reality, are YCbCr/YPbPr.  YPbPr is a scaled version of YCbCr.
This is done to get equal excursions on all three sampled quantities.  While
the internal workings of a a device might be YCbCr, you want the analog
output to be scaled to YPbPr --a camera or VTR, for example-- such that the
receiving device's A/D converters can all be scaled equally and have the
same reference (they all expect a 1 V peak-to-peak signal on all three
channels, for example).


-Martin Euredjian
eCinema Systems, Inc.
(661) 305-9320
ecinema at pacbell.net

BTW, I omitted the tick mark denoting "gamma-corrected" from the above
designations to a) simplify things and, b) because gamma issues have no
relevance to the distinction I am making.







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