Glittering color artifacts on export from Resolve

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Jesse Widener

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Glittering color artifacts on export from Resolve

PostTue Jun 13, 2017 3:01 am

I have multiple clips from an interview with the same subject as in the attached image, which are generating some sort of weird random colored artifacts (cyan blocks in this case) around his head (see image) on export from Resolve as ProRes (original footage is RAW 4:1). They randomly bounce around, looking like glitter. What's equally odd is if you look closely, they seem to be within some sort of localized band of large compression blocks. None of the rest of the image displays the large compression blocks. Some notes:

1. Flavor of ProRes does not seem to matter.
2. They are not present in the original footage, though they do appear in the viewer window in Resolve during render.
3. I shot a couple other subjects on the same day, in the same building, which do not exhibit these artifacts.

What's going on? How do I fix it?


Many thanks.
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rick.lang

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Glittering color artifacts on export from Resolve

PostWed Jun 14, 2017 5:27 pm

Never seen that and I shoot a lot of raw 4:1. Think I'll switch to raw 3:1. To prevent that happening, I'd try to pull down your shadows, just enough to begin to crush the green/blue channels (bring up the parade scope) for that stage right dark area over the subject's head; using primary adjustments may work so possibly try that easy fix before doing a window on the area.


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Jesse Widener

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Re: Glittering color artifacts on export from Resolve

PostThu Jun 15, 2017 2:24 am

Hello Rick,


Thank you for the reply. I took the suggestion and crushed the blacks, and the artifacts still appear after conversion to ProRes. In fact, I did a second trial, brutally crushing the blacks so there is no question about the levels there, and the colored artifacts persist.

Again, this is odd because none of my other 4:1 RAW footage shot the same day at the same facility, exhibits this behavior. And again, the odd area of larger compression blocks within which the artifacts appear, is not present in the original 4:1 footage, nor do any areas of larger compression blocks such as those seen here, appear in any of the ProRes conversions of any other footage shot.

This clearly seems to be a Resolve issue. I am trying to run it in the v14 beta. I will try v12.5.x instead.


Many thanks.
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John Brawley

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Re: Glittering color artifacts on export from Resolve

PostThu Jun 15, 2017 6:09 pm

Jesse Widener wrote:I have multiple clips from an interview with the same subject as in the attached image, which are generating some sort of weird random colored artifacts (cyan blocks in this case) around his head (see image) on export from Resolve


Hi Jesse.

Which camera are you using ?

JB
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rick.lang

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Re: Glittering color artifacts on export from Resolve

PostThu Jun 15, 2017 11:59 pm

Jesse, didn't realize this was a 14beta Resolve. If you can still use Resolve 12.5.x, will be interesting to know if that makes a difference. Do you also want to try another codec for delivery? Would be good to isolate the problem to ProRes if other delivery codecs are fine.


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Tristan Pemberton

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Re: Glittering color artifacts on export from Resolve

PostFri Jun 16, 2017 12:28 am

I've seen that problem before on Resolve exports. For me, it randomly seems to occur on some exports. Usually re-exporting solves the problem.

If you're using 14 (beta), as Rick suggested, go back to 12.5 as 14 (beta) is not production ready yet.
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Jesse Widener

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Re: Glittering color artifacts on export from Resolve

PostFri Jun 16, 2017 8:56 am

Hello All,


John, I am using an Ursa Mini Pro, but I am strongly inclined to think this is a Resolve issue rather than the camera.

I did try again in Resolve 12.5.x this time, and the colored artifacts are gone. However, the odd band of larger compression blocks remains, and again it was not in the original RAW footage, nor does it show up in any of the other ProRes files from other interviews from the same day in the same building: different backgrounds for each interview, but similar lighting/exposure. Also...and this is my subjective observation...I have had horrendous system freezing/crashing issues the last couple days while trying to process these files. I am now processing another interviewee from the day, and things seem back to stable. I don't know what to make of it, but there definitely seems to be some bad mojo surrounding the files of the one problematic interviewee.

Rick, what other codec would you suggest I try exporting as?
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rick.lang

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Re: Glittering color artifacts on export from Resolve

PostFri Jun 16, 2017 3:39 pm

Jesse, the codec you use for exporting is normally determined by the needs of your client. I'm glad the cyan artifacts are not present under 12.5.x. This weekend I'll be updating to 12.5.6 after I finish my current project. Hope you can do the same. And the cyan gremlins shouldn't be there anymore.

Since I'm delivering only for the web for this client, I use H.264. Looking forward to using H.265 when that is broadly supported. I suspect you would not have seen cyan artifacts with an H.264. Why are you exporting ProRes? There is a thought that ProRes is the best way to export going to Vimeo for example even though the site will render it to their own codec for web presentation. I have tried that and it worked but still reverted back to doing H.264 in Resolve in the interests of time!


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Jesse Widener

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Re: Glittering color artifacts on export from Resolve

PostFri Jun 16, 2017 9:36 pm

Hello Rick,


This project is a documentary on our Art Deco theater/cultural arts center. It will be pushed to a film festival we run, and we'll see where it goes from there, so it isn't intended for online viewing out of the gate.

I also prefer to edit in Final Cut, so I am exporting to work further in FCP. My situation is a bit too constrained right now to hold all the RAW files for long, so doing a basic grade and converting to ProRes for edit and dropping the original RAW files is a necessity right now.


Many thanks!
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rick.lang

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Re: Glittering color artifacts on export from Resolve

PostFri Jun 16, 2017 11:48 pm

Jesse, thanks. Then definitely use the best quality ProRes that FCP X supports or the best you can retain for archival purposes.


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