On Wed, 28 Mar 2001, Ben Bridgwater wrote: > Trent Piepho wrote: > > The blue tone you see might be the result of a different YUV color spaces. > > Unfortunately, people use YUV to refer to more than one different color space. > > For instance the YUV data from the bt848 isn't exactly the same as the YUV > > colorspace used in JPEG files. If you make a JPEG file using the YUV data > > from a bt848, or probably any other TV based capture card, the image looks > > wrong. I don't remember exactly, but I think it comes out too green. > > Bt848/V4L use Y'CbCr, not YUV, but I think this sloppy usage of "YUV" is understood. > > AFAIK, JPEG and MPEG also use Y'CbCr. The Rec.601 Y'CbCr colorspace used by bt848 is different than that used by the JFIF standard. It would be better to call the colorspace used by jpeg Y'PbPr. If you take the "YUV" data from a bt848 and try to jpeg encode it without modifiying the data, your JPEG will look wrong. Been there, done that, wrote a Y'CbCr -> Y'PbPr converter so my JPEGs would look correct. Sections 28 and 29 of the colorspace faq describe the two colorspaces.
