[FFmpeg-trac] #3794(swscale:new): SWSCALE: Quantization Errors in Y Studio Range
FFmpeg
trac at avcodec.org
Tue Jul 29 03:01:35 CEST 2014
#3794: SWSCALE: Quantization Errors in Y Studio Range
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Reporter: troy_s | Owner:
Type: defect | Status: new
Priority: normal | Component: swscale
Version: git-master | Resolution:
Keywords: range | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by troy_s):
Attaching the matrix used for conversion.
{{{
0.1825858824 0.6142305882 0.0620070588 +0.062745098
-0.1006437324 -0.3385719539 0.4392156863 +0.5019607843
0.4392156863 -0.3989421626 -0.0402735237 +0.5019607843
}}}
The above is the float version of:
{{{
0.2126*(219/255) 0.7152*(219/255)
0.0722*(219/255) +(16/255)
-(0.2126/1.8556)*(224/255) -(0.7152/1.8556)*(224/255) 0.5*(224/255)
+(128/255)
0.5*(224/255) -(0.7152/1.5748)*(224/255)
-(0.0722/1.5748)*(224/255) +(128/255)
}}}
(For the curious, the 1.8556 and 1.5748 is nothing more than (Coeff.Red +
Coeff.Green) * 2 and (Coeff.Blue + Coeff.Green) * 2 to normalize the
values around the origin.)
--
Ticket URL: <https://trac.ffmpeg.org/ticket/3794#comment:13>
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