[FFmpeg-trac] #11182(swscale:closed): yuvtestsrc and yuv444p->rgba->yuv444p conversion result in huge difference

[FFmpeg]

#11182: yuvtestsrc and yuv444p->rgba->yuv444p conversion result in huge difference
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             Reporter:  Andrew-R     |                    Owner:  (none)
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:  swscale
              Version:  unspecified  |               Resolution:  invalid
             Keywords:  colorspace   |               Blocked By:
  color_primaries                    |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by Balling):

 MasterQuestionable, it is never that simple with this stuff... You did not
 understand the main factor. In the case with full range RGB to full range
 YCbCr... There are some values in YCbCr that will be negative R', G', B'.
 (For example in limited range YCbCr BT.709 values 139, 151, 24 will be
 limited (!) RGB -21, 182, 181 and full RGB -43, 194, 192.)

 >Full range would be as well 256^3.

 No, it will not be. In YCbCr full range 0, 128, 128 would be the same for
 all x, y values of 0, x, y. All of the are just black.

 >It's artificially limited range.

 Limited range is not artificial. It is used everywhere except for Dolby
 Vision profile 5 IPTPQc2 and s-Log used in Sony cameras and V-Log used in
 Panasonic cameras. That is all I know of.
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Ticket URL: <https://trac.ffmpeg.org/ticket/11182#comment:14>
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