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! ;-)
