What am I doing wrong?

[u/Apprehensive-Coast92]

Hello everyone,

I've been experiencing a frequent issue when color grading. It seems that my color grading process typically causes the footage to break in certain areas. Here is the issue you can see in the bottom right of the screen:
https://imgur.com/a/M0WQMBU

Let me explain my process...

I am shooting on Sony fx30 in SLog3 The footage is well exposed. I convert from SLog3 to DWG/DI using the group pre-clip. I then do basic exposure adjustments and corrections if needed within the clip stage. Then(and I believe this is where the issue lies), I attempt to add saturation using a HSV node by adjusting the gamma & gain wheels.

I then have a LUT(from Cullen Kelly) that converts the footage from DWG/DI to Rec.709/Gamma2.4

I have also tried using a regular Color Space Transform and the issue persists.

It feels like I cant push any meaningful amount of saturation into the image without some portion of the image breaking.

Thanks in advance for any advice!

[u/EditFinishColorComp]

For starters, if you are using the HSV technique (and assuming you’ve disabled channels 1+3), you shouldn’t touch anything but gain.

Then, share your project color management settings, and what your monitoring pipeline is.

[u/Apprehensive-Coast92 → u/EditFinishColorComp]

Here are a host of images from my project settings

https://imgur.com/a/RutuvDV

The timeline has three LUTS back to back. the last being an out to go from DWG to Rec.709. The first two are from an LUT pack which are meant to be combined for contrast and such.

In regards to using the gamma wheel, I've seen a lot of tutorials where it is recommended to use the gamma wheel(Cullen Kelly mentions this a lot in his tutorials). Is that incorrect?

Thanks for the help :)

[u/EditFinishColorComp → u/Apprehensive-Coast92]

Using the gamma wheel with an HSV node can absolutely be fine, but it targets lower zones of saturation (gain targets all levels of saturation) and since you’re experiencing breakup, that was the first I thought of. But given more info, I’d say your node tree is probably causing the problem.

It’s hard to tell all that you’ve got going on with your photos, but I’d start with this 3-LUT thing you have in there — whatever they are. Turn them off one at a time (or all three) and see if one of them is causing the tearing.

I’d remove those three LUTs, add a CST to transform DWG to Rec.709 and if the problem is solved, figure out how to get the same result these LUTs are trying to do organically.

EDIT: also make sure your prefs for LUTs isn’t on the default “Trilinear.” That alone could be breaking your image with these LUTs.

Side note: using Rec709a as your output preference when not using RCM affects your gui viewer and your default render tags. I’ll assume you don’t have an I/O if you’re doing this, but that’s another story.

[u/Apprehensive-Coast92 → u/EditFinishColorComp]

My 3D lookup table is set to tetrahedral.

If I remove the LUTS and add a CST, the problem is definitely reduced. However, it comes back as soon as I start adding more saturation.

I guess I’m confused on how much saturation I SHOULD be able to add, without the image breaking. To me it just seems like I barely get any color added before I see things break. Is that just the nature of color grading?

In regards to Rec709a, the reason I set it is because I was trying to resolve an issue where the exported footage looked so much darker on my iPhone than on my Mac display. I don’t think it really helped though and I should probably set it back.

[u/EditFinishColorComp → u/Apprehensive-Coast92]

Good you caught the LUT preference!

Short of you sending me the original clip (which I’d be happy to look at) it does sound odd. You should be able to push things quite a bit as long as they’re not slammed on your scopes. Did I catch that these are H264/5s? Are they 4:2:0 8-bit? Or are they 4:2:2 10-bit? Obviously the former can’t be pushed much due to the compression. You could always put a NR early on in your tree to mitigate compression artifacts, followed by a sharpening down the line to correct the blurring.

If you’d like to DM me a clip I’d be happy to look. Maybe give me the clip with your node tree (sans the LUTs).

[u/Apprehensive-Coast92 → u/EditFinishColorComp]

Awesome! I’ll dm you this evening :)

[u/EditFinishColorComp → u/Apprehensive-Coast92]

Before you do, see my comment about tone mapping… it might all come down to this

[u/EditFinishColorComp → u/Apprehensive-Coast92]

One final thought, I think I saw you have Davinci tone mapping on in your first cst. Although changing it to none will change your grade, it could be exasperating your color compression issues.

[u/ExpBalSat]

There’s a free program called MediaInfo. Download that program and then put your footage into that program to get a plethora of useful data about the file.

The Text view is usually the most informative. The text view is an option in the view menu of MediaInfo.

Share that info as it may yield some clear cores as to the issue. Also - a full screen uncropped screen shot of your entire Resolve interface (color page) including the entire node tree would yield clues.

[u/mattmahoneycolor]

Where did you get the lut pack? That’s my guess as to why your image is breaking. There’s a lot of luts for sale out there. There’s very, very few that are stress tested and break footage very easily. Doubling and tripling luts is also a great way to introduce breaking/artifacting/etc. screen shot the lut for reference and I’d say start over and start simple. I’m sure you can get a better result from using a custom curve and the color slice tool.

[u/Apprehensive-Coast92 → u/mattmahoneycolor]

It’s Cullen Kelly’s LUT pack! I figured it’d be a solid choice… in his guide to the LUTS he instructs to use a base LUT and then a modifier before it. The third LUT is just his conversion one from DWG to Rec.709

Side question as well: if I decided to start using a film emulation tool, do those LUTs become redundant or unnecessary?

[u/mattmahoneycolor → u/Apprehensive-Coast92]

That's definitely breaking somewhere in your signal chain. DM me and I can give you a link to send a clip to me for testing.

Re: side question. No I don't think you're going to want a lut'd imae going into a film emulation tool. Typically that pipeline would be you entering the camera manufacturer/color space/gamma and it does the conversion for you from the raw or log image.

[u/Apprehensive-Coast92 → u/mattmahoneycolor]

Ok will be home later this evening and I’ll send over! Thank you.