requesting help with a LUT for NTSC green Fringe

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farknl

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requesting help with a LUT for NTSC green Fringe

PostThu Feb 14, 2019 5:07 am

I am editing in Davinci Resolve 15.2.3 some old footage that was shot 30 years ago on a Panasonic domestic VHS portable camera (newvicon tube)...Its for a DVD additional content.The footage is "behind the scenes" making a feature film in 1988 in Australia.. Unfortunatley ,during low light ( most of the film was in dark places like ..a recording studio) , black seems to have a green fringe that I cant compensate for correctly .( Im a music, producer )
I ve messed with Luts and downloaded a heap but this is different ... I cant attach a screenshot showing the green fringe in this board but will send separately .Could any please help ? I de be enormously grateful.. cheers Rod
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JPOwens

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Re: requesting help with a LUT for NTSC green Fringe

PostThu Feb 14, 2019 11:28 pm

By "green fringe" do you mean that black values are out of balance towards green or there is a camera registration problem -- or -- the analog recording has a group delay problem -- the color channels have a horizontal timing problem... ?? Picture worth a thousand posts.

jPo, CSI
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farknl

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Re: requesting help with a LUT for NTSC green Fringe

PostFri Feb 15, 2019 3:53 am

Hi JP

Thanks for your response ,. Ive attached it ...
You can see the green in the bottom left and top left and right but to a lesser extent. the centre is normal .
Its ok in the centre but the left is the worse , Its across all my footage most noticable in night footage ...
I just dont know how to attack it to make a suitable LUT .
From reading about early video cameras the newvicon tubes did this when the camera wasnt warmed up ... something like that ... thanks for your help if you can see a way I could correct this Ide be stoked !
Attachments
green tinge_1.38.1.jpg
the green tinge
green tinge_1.38.1.jpg (101.48 KiB) Viewed 106 times
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Marc Wielage

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Re: requesting help with a LUT for NTSC green Fringe

PostFri Feb 15, 2019 7:45 am

farknl wrote:Hi JP Thanks for your response ,. Ive attached it ...
You can see the green in the bottom left and top left and right but to a lesser extent. the centre is normal .
Its ok in the centre but the left is the worse , Its across all my footage most noticable in night footage ...

A LUT will not solve this problem. I see shading issues like this with old film projects (which I do all the time), and I just create one node with a power window, watch the waveform, correct it to create a "flat" field (without color or black contamination on one side), and then correct every shot as normal. In some cases, the effect is greater or worse depending on the exposure and conditions.

But this is not something solvable with a LUT solution -- this is a color-correction problem. Very fixable with the controls available in Resolve.
marc wielage, csi • VP/color & workflow • chroma | hollywood
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Micha Clazing

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Re: requesting help with a LUT for NTSC green Fringe

PostSat Feb 16, 2019 12:33 pm

If the effect is constant across footage you can use that black frame you posted to make a matte in Photoshop that might be more accurate than trying to match it with power windows.

Something like this:
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greenmask.png
greenmask.png (262.94 KiB) Viewed 76 times
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peterjackson

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Re: requesting help with a LUT for NTSC green Fringe

PostSat Feb 16, 2019 3:55 pm

I was about to suggest the same thing. Doesn't Resolve have a native way of doing it? Can't you just "subtract" that reference frame from the others?
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Gary Hango

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Re: requesting help with a LUT for NTSC green Fringe

PostSat Feb 16, 2019 7:28 pm

Going the matte route I would create a color matte using the average of as many black frames that are available because of the chroma noise. You might even want to blur it a bit. Then try subtracting the matte from the video at various strengths for best results.
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