Trent Piepho wrote:
>
> For instance, in libjpeg, there is this comment:
>
> * YCbCr is defined per CCIR 601-1, except that Cb and Cr are
> * normalized to the range 0..MAXJSAMPLE rather than -0.5 .. 0.5.
> * The conversion equations to be implemented are therefore
>
> Which would make you think that they use rec 601 Y'CbCr, wouldn't it?
> But then look at their equations:
>
> * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
> * Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
> * Cr = 0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
Well, if one can't trust the specs, then I guess the Bt848 datasheet is
just as suspect... particularly as I just realized that my "RGB to
Y'CbCr" routines actually use the above "Y'PbBr" (using the colorspace
FAQ terminolog) coefficients (I don't remember where I got them from),
yet the converted Bt848 YUV video looks entirely normal to me!!!
Given that MPEG/JPEG/MJPG is the major "consumer" of YUV data, it would
be a bit odd if the Bt848 put out something else... I think for the time
being I'll assume that Bt848=MJPG, and not worry about what it's called!
;-)
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