Blackmagic Forum

For some reason I keep getting these large black glitches on my highlights in resolve after grading. Any advice/help would be much appreciated!



Specs/Info:

Resolve Version: Davinci Resolve Studio 19.1.3 Build 7
OS: Windows 11 Version 23H2 Build 22631.5039
CPU: Intel i5-13600K
GPU: NVIDIA 4070 Super
SSD: Samsung 990 Pro 2TB
RAM: G.SKILL Ripjaws S5 Series 32GB
Editing Off of Synology 1821+ with 56TB of HDDs via 10Gbe connection.

What GPU driver version are you using?

Charles Bennett wrote:What GPU driver version are you using?

Was on 566.36 updated to 572.70 and still having the same issue.

What's your footage?

Jim Simon wrote:What's your footage?

Happens with RED Log3G10 And BRAW. Haven’t tested it on anything else yet

OK.

What's your grade? Can you show us the node tree? Or maybe share the .dpx for testing?

Quite possibly some inf values somewhere in between.
- Are you using any form of linear gamma at some point? Linear gain? a CST going to linear and back?
- any blurs?
- try the highlight node and select one node after another to spot, where the artifacts appear first.
- try clamping the signal before this node.

Sven H wrote:Quite possibly some inf values somewhere in between.
- Are you using any form of linear gamma at some point? Linear gain? a CST going to linear and back?
- any blurs?
- try the highlight node and select one node after another to spot, where the artifacts appear first.
- try clamping the signal before this node.

Wow yeah it was definitely the blur node, when disabled, the issue goes away. I am also using linear CST nodes. Can you or someone explain why this issue is happening?

Kinda hard to tell from the screenshots. i think you accidentally uploaded one twice, I can't see a difference between the second and third image.
Oh and btw, since you are using the HDR wheels inside of the linear sandwich, I hope you tagged the tool correctly to expect linear valuse?

Are you using the Film Damage OFX just to add blur? If so, ditch it and use a Gaussian Blur OFX or just the normal blur palette instead. The blur in the Film Damage OFX is just a gaussian blur, but if you are not using any of the scratches or dirt overlays anyway it feels unnecessary to use this OFX.

Can you post screenshots with and without the artifacts, so we can see what we are talking about?

Sven H wrote:Oh and btw, since you are using the HDR wheels inside of the linear sandwich, I hope you tagged the tool correctly to expect linear valuse?

What do you mean by this?

dkouba wrote:

Sven H wrote:Oh and btw, since you are using the HDR wheels inside of the linear sandwich, I hope you tagged the tool correctly to expect linear valuse?

What do you mean by this?

HDR wheels need to know the color space they are in to work correctly. They assume it is 'timeline', but i you start coloring outside the lines with CSTs you are going to have to manually tell it what color space you chose.

dkouba wrote:

Sven H wrote:Oh and btw, since you are using the HDR wheels inside of the linear sandwich, I hope you tagged the tool correctly to expect linear valuse?

What do you mean by this?

the HDR wheels are color space aware and respect the incoming timeline color space tag. by default that's "use timeline"
But if you modified the signal with color space transforms (going to linear) and the tool expects a log image, there is a mismatch which can cause problems.

Watch this video (important part starting at 1:35), where I explain the basic concept

If you want to use Exposure/Balance while in linear you can use the Gain wheel. The HDR global wheel if set up correctly does kinda the same but I stopped using HDR wheels because it's a massive slowdown switching between normal and HDR wheels. I've resorted to using Gain instead on a node that by itself converted to linear gamma so the 'wheels' panel never needs to be toggled.

Regarding your issue check what's been said above but I'd like to add, it looks like you're using Film Unlimited film emulation correct? You may want to double check if you set up your project color management settings for that correctly. Depending on how people set up the emulation and their node conversions your project's timeline may have to be set to a specific color space regardless of the kind of footage you're using it on. Check their manual or how to videos if you haven't already.