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Old 19th August 2019, 15:39   #102  |  Link
jpsdr
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Join Date: Oct 2002
Location: France
Posts: 2,308
ConvertToRGB(matrix="Rec2020") is not technicaly wrong, you have RGB, but with colorimetry of BT.2020.
After, if you made all your process in RGB, and finalise with
ConvertToYV12(matrix="Rec2020"), you have nothing wrong.
(According of course your input is YUV BT.2020).

What is technicaly wrong, according R-REC-BT.2087 it's that :
ConvertToRGB(matrix="Rec2020")
ConvertToYV12(matrix="Rec709")
This also apply to dither_tools, so, also, they are not wrong.
While you stay within the same colorimetry space (all your data and your video are on the same colorimtry space), nothing is wrong with only matrix.

But when you have different colorimetry spaces :
- Either you convert everyone to the same colorimetry if you're working with datas affected by colorimetry space (or are inside a colorimetry space) (RGB, YUV).
- Either you work with datas which are unafected (or make abstraction or are outside a colorimetry space) by colorimetry (XYZ and probably others i don't know).

According your question :
Quote:
If that's true, I guess I'm asking if I upscale a HD video to UHD and convert the colors, for it to display correctly in an UHD TV's media player, should I be using the "matrix only" method or do it "properly" with the XYZ method.
I must said that i have no knowledge of broadcast or professional environment, and i'm sorry, but i don't know what to answer.
Just that, personnaly, i would follow the R-REC-BT.2087, so with XYZ method, which should, theoricaly, be the proper way.

Unfortunately, this is not helping the mess.
Quote:
Originally Posted by poisondeathray View Post
In practice, only matrix is usually accounted for, not primaries. You see this in professional HD to SD conversions, broadcast NLE's too . Technically you should adjust for the primaries too, but it's rarely done.
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Last edited by jpsdr; 19th August 2019 at 15:49.
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