P4K red channel clipping looks strange.

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Ryan Payne

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P4K red channel clipping looks strange.

PostFri Oct 19, 2018 6:44 am

Heyo,

People over on the BMCUSER forum noticed that the red highlights are looking extremely blown out with little roll off on the pocket 4k, doesn't look right.

http://www.bmcuser.com/showthread.php?2 ... d-clipping

Looks a bit like the issue with ACES highlights.

V1 colour science doesn't show this artefact but when switching to V4 it does.

resolve version 15.1.0.025

I'll update to the latest and see if the issue remains.
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Ryan Payne

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Re: P4K red channel clipping looks strange.

PostFri Oct 19, 2018 7:24 am

Still there with Resolve 15.1.2.008

On the micro cinema camera at 3:1 raw the artefact is not present in v1 colour but when switched to V4 it appears.

V1
Image

V4
Image
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Jamie LeJeune

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Re: P4K red channel clipping looks strange.

PostFri Oct 19, 2018 9:59 pm

I found an easy way to deal with it in standard Davinci YRGB mode. I tested it with cDNG clips that have raw tab gamma set to "BMD Pocket 4K Film" but it should also work equally well for ProRes clips recorded in film mode.

1. In project settings, set Color Science to "Davinci YRGB" and set Timeline Color Space to "Blackmagic Design Pocket 4K Film"
2. On color page, add Color Space Transform OFX to the first node.
3. Set the inputs and outputs of Color Space Transform to "use timeline", tone mapping to "none" and Gamut Mapping to "Saturation Mapping", then tweak the knee and max settings until the super saturated highlights look the way you like.
4. After that can just grade normally. Or, you can set the CST node output color space and gamma to Rec709, if that's what your monitor is calibrated for and you like the look as a starting point. Or, you could instead add the "Blackmagic Pocket 4K Film to Extended Video" LUT as it provides a very nice starting point for a grade. I personally prefer the latter.

Screen Shot 2018-10-19 at 2.35.25 PM.png
Screen Shot 2018-10-19 at 2.35.25 PM.png (60.33 KiB) Viewed 456 times


Screen Shot 2018-10-19 at 2.37.46 PM.png
Screen Shot 2018-10-19 at 2.37.46 PM.png (71.23 KiB) Viewed 456 times


EDIT: For anyone working in other apps, or for whatever reason you need to use LUTs, I made two to deal with highly saturated lights on the 4K Pocket. They should work in Davinci YRGB no matter how the timeline color space is set.

This LUT linked below does only the saturation mapping:
https://drive.google.com/open?id=1oXRC2UuplLKPSZiH_qPWTwsW72mC5445

This LUT linked below does the saturation mapping and adds the standard Blackmagic Pocket 4K Film to Extended Video v4 transform:
https://drive.google.com/open?id=13Q5lf1nd0L8SEIBHBGnfpe1Dhq3t9_pK
www.cinedocs.com
http://www.imdb.com/name/nm4601572/
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rick.lang

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Re: P4K red channel clipping looks strange.

PostSat Oct 20, 2018 2:44 am

Just to clarify, Jamie, you’re using YRGB, not YRGB Colour Managed?


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Jamie LeJeune

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Re: P4K red channel clipping looks strange.

PostSat Oct 20, 2018 3:28 am

Correct. It’s for anyone working in standard REC709. The LUTs will work in any app that accepts the .cube format.

The CST node method could be adapted to work in Color Managed mode (or in ACES once BMD gets around to including an IDT for the 4K Pocket), or if you’re working in Color Mananged you could instead set the saturation rollof at the project settings level.
www.cinedocs.com
http://www.imdb.com/name/nm4601572/
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rick.lang

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P4K red channel clipping looks strange.

PostSat Oct 20, 2018 5:03 am

Thanks, Jamie. With the ACES support lacking, I’ve switched to Colour Managed. Hope to get back to ACES as soon as possible.


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Jamie LeJeune

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Re: P4K red channel clipping looks strange.

PostSat Oct 20, 2018 6:53 am

For REC709 output, the new "extended video" in v4 color is also a fine place to start a color grade.
www.cinedocs.com
http://www.imdb.com/name/nm4601572/

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