#3643: XYZ to RGB color space
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Reporter: TTeam | Owner: (none)
Type: enhancement | Status: open
Priority: normal | Component: swscale
Version: git-master | Resolution:
Keywords: xyz | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by Balling):
Related
https://patchwork.ffmpeg.org/project/ffmpeg/patch/20241216112118.424999-8-ffm...@haasn.xyz/
I do not understand this patch at all, Haasn. It is correct to tag it as
SMPTE primaries, those are fake primaries (centre white), they are not
used ''as XYZ HAS NO primaries''.
>XYZ to RGB colorspace conversion use only sRGB matrix
It is correct for typical HD video, that has BT.709 primaries, you must
use BT.709 primaries XYZ matrix as specified in Nvidia docs or here:
https://en.wikipedia.org/wiki/SRGB#Correspondence_to_CIE_XYZ_stimulus (The
2003 amended version of the sRGB standard points out that higher accuracy
is needed when the samples are encoded with more than 8 bits. **It
provides the matrix**), the primaries in BT.2020 will have to be converted
to BT.709 or different XYZ matrix will have to be used.
If **I do not understand something** please tell me so (what does it mean
in your patch "possibly simply by using a more fitting
RGB intermediate like SMPTE428"), also see page 7 of https://5253154.fs1
.hubspotusercontent-na1.net/hubfs/5253154/st2067-40-2021.pdf
Also this is how you get YCbCr two cofficients from primaries, as such:
https://imgur.com/a/i6742tj
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Ticket URL: <https://trac.ffmpeg.org/ticket/3643#comment:6>
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