On Thu, 29 Mar 2001, Ben Bridgwater wrote:
> > Trent Piepho wrote:
> >
> > >
> > > 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.
>
> I just checked the color space FAQ:
>
> http://www.neuro.sfc.keio.ac.jp/~aly/polygon/info/color-space-faq.html
Try a newer one, like http://www.landfield.com/faqs/graphics/colorspace-faq/
that faq is from 1994. The colorspace used by JPEG is in section C-28, while
that used by the bt848 is in C-29. You're welcome to try it yourself, but you
will see that I am correct. You can look at the transformation equations in
the libjpeg source and the bt848 manual, and see that they are different.
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