Confounded by YUV<->RGB Conversaion

wswartzendruber · 17th January 2021, 21:20

What the devil is going on here...

I took that from Wikipedia. The article it's from specifically states that Y is linear light and that Y' is gamma-corrected, perceptual light. It also states specifically that RGB is linear light.

So how in blue blazes do you get a gamma-corrected Y' value for output when taking linear-light values in as input...using nothing but multiplication?

Sharc · 17th January 2021, 22:23

I would follow the original ITU-R BT.601-7 and ITU-R BT.709-6 specification rather than one of its many interpretations. Perhaps it helps to clarify your questions.
There are some doubts and questions about this article in its 'talk' page by the way .....

wswartzendruber · 17th January 2021, 23:28

I would like to convert from linear, full-range YCbCr to linear, full-range RGB....and back.

Sharc · 17th January 2021, 23:50

You may find the answer here:
http://poynton.ca/notes/colour_and_g....html#RTFToC18
see also para. 7. .... 12.

https://web.archive.org/web/20120403...onversion.html
http://poynton.ca/notes/colour_and_gamma/GammaFAQ.html

jpsdr · 18th January 2021, 16:42

Have you checked if you can use my avs plugin here for doing what you want ? (Maybe also check zimg).
I've also added a pdf document to try to explain the linear/non-linear part in my plugin.

17th January 2021, 21:20	#1 \| Link
wswartzendruber Registered User Join Date: Feb 2008 Posts: 103	Confounded by YUV<->RGB Conversaion What the devil is going on here... I took that from Wikipedia. The article it's from specifically states that Y is linear light and that Y' is gamma-corrected, perceptual light. It also states specifically that RGB is linear light. So how in blue blazes do you get a gamma-corrected Y' value for output when taking linear-light values in as input...using nothing but multiplication?

17th January 2021, 22:23	#2 \| Link
Sharc Registered User Join Date: May 2006 Posts: 3,796	I would follow the original ITU-R BT.601-7 and ITU-R BT.709-6 specification rather than one of its many interpretations. Perhaps it helps to clarify your questions. There are some doubts and questions about this article in its 'talk' page by the way ..... Last edited by Sharc; 18th January 2021 at 16:13.

17th January 2021, 23:50	#4 \| Link
Sharc Registered User Join Date: May 2006 Posts: 3,796	You may find the answer here: http://poynton.ca/notes/colour_and_g....html#RTFToC18 see also para. 7. .... 12. https://web.archive.org/web/20120403...onversion.html http://poynton.ca/notes/colour_and_gamma/GammaFAQ.html Last edited by Sharc; 18th January 2021 at 15:41.

18th January 2021, 16:42	#5 \| Link
jpsdr Registered User Join Date: Oct 2002 Location: France Posts: 1,871	Have you checked if you can use my avs plugin here for doing what you want ? (Maybe also check zimg). I've also added a pdf document to try to explain the linear/non-linear part in my plugin. __________________ My github.

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17th January 2021, 23:28	#3 \| Link
wswartzendruber Registered User Join Date: Feb 2008 Posts: 103	I would like to convert from linear, full-range YCbCr to linear, full-range RGB....and back.