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Old 18th June 2021, 17:16   #1  |  Link
SquallMX
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Join Date: Nov 2002
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Fixing wrong brightness levels?

Unfortunately, the Blu-ray release of NOBODY has wrong brightness levels, the blackest black is actually 8,8,8 this is pretty evident during the credits, which probably is not a stylistic choice because the UHD Disc has proper blacks.

"Tweak(0.0,1.0,-7.0,1.05)" seems to fix it, but I don't know if that is the best way to handle it.
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Old 20th June 2021, 03:12   #2  |  Link
hello_hello
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Assuming 8,8,8 refers to full range levels (after saving a screenshot or something?), try Levels(24, 1.0, 235, 16, 235, coring=false), where 16 is black for limited range video and 235 is white. It'll stretch the whole range "down" a bit, although that's generally a good thing when the levels are wrong.
If the color appears a little more saturated as a result (or will it be a little less, I can't remember), you can adjust the saturation with Tweak.

There's also YLevels. http://avisynth.nl/index.php/Ylevels
The Levels() page says it only gamma corrects luma, and the YLevels page says that unlike Levels() it only processes luma.
I'm not sure that means they shouldn't produce the same result, but they don't as they have a different effect on the color saturation. I usually try them both and use the one that floats my boat at the time.

Last edited by hello_hello; 20th June 2021 at 14:38.
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Old 20th June 2021, 09:29   #3  |  Link
Sharc
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As far as I understand it:
Levels() affects all three Y, U and V and clips the levels.
YLevels() changes Y only and leaves U and V untouched. It does not clip.

One may use 'chroma copyback' with Levels() in order to leave U and V untouched, like
Code:
mergechroma(Levels(24,1.0,235,16,235,coring=false),last)

Last edited by Sharc; 20th June 2021 at 12:10. Reason: typos
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Old 20th June 2021, 17:56   #4  |  Link
SquallMX
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Thank you guys, I will play with Levels and YLevels.
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