On Mon, 2 Apr 2001, Ben Bridgwater wrote: > Trent Piepho wrote: > > > > 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!!! > > > > That doesn't make sense. You say "RGB to Y'CbCr" routine, and then converted > > YUV video. If you take YUV as input, you need a "Y'CbCr to RGB" routine. > > I have both ways conversions: Y'CbCr <-> RGB, and both according to the newer > colorspace FAQ coefficients/terminology are really Y'PbPr. I havn't tested the > RGB -> Y'CbCr direction, but the Y'CbCr -> RGB converts bttv YUV data and the > colors look normal. Are you getting the data directly from the driver, or from some application that might be modifiying it? Try capturing a colorbars test pattern in RGB mode and then YUV mode, and convert using the Y'PbPr formula. Then try converting using the formula in the bt848 datasheet. See which one looks more like the RGB output. You can get the bt848 to generate a colorbars pattern internally, but you need to hack the driver.
