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Old 21st October 2019, 09:12   #113  |  Link
jpsdr
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Join Date: Oct 2002
Location: France
Posts: 2,309
You have a resolution loss because of the non-linear to linear (and back after) transfert function.
Basicaly, with 8 bit, if you have something like this.
(YUV) 0 -> 0 (XYZ)
(YUV) 1 -> 0 (XYZ)
(YUV) 2 -> 1 (XYZ)
(YUV) 3 -> 1 (XYZ)
(YUV) 4 -> 1 (XYZ)
(YUV) 5 -> 2 (XYZ)
....
When you convert back XYZ to YUV, you'll have
(XYZ) 0 -> 0 (YUV)
(XYZ) 1 -> 4 (YUV)
etc...
You loose (1,2,3). Nothing can't be done, except... increase the output (XYZ here) bitdepth, to keep 8 bit resolution for the input (YUV here). But if you stay in 8 bits for all the process, you'll loose resolution, and have less than 8 bit in final result.

And effect is even worse with HDR.
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Last edited by jpsdr; 21st October 2019 at 09:15.
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