Issues when converting from CLog3 to Rec709

[anour.esa]

I'm editing a video I shot for a client. I shot on a Canon R5 in CLog3. I'm currently trying to color correct and color grade. In color correction, I am applying a clog3 to rec709 LUT. First thing I noticed is that the footage has a lot of pink happening. All the reds look pretty pink, and people look extra pink. And just random stuff looks pinkish. The second thing is I’ve noticed a lot of what I think is banding? More noticeable on some clips than others, but essentially it’ll go from green to pink and there will be a TON of noise revealed. Not noticeable on the flat footage. I've tried a different CLog3 to Rec. 709 LUT, I've tried reducing the intensity of the LUT, but nothing really makes a strong difference. I've attached before and after screenshots of a clip with and without the LUT applied, at 100% intensity. I've also attached a video of the weird green and pink flickering happening. 

Anyone have any ideas for these two issues? I am very new to color grading shooting in log, so fully accept the possibility that there is user error happening here. 

[Sumeet Kumar Choubey]

Hi anour.esa,

We're sorry to hear about this. We would need more info to diagnose the issue properly.

• What is the source of the LUT (is it official LUT from Canon)? Is it also happening if you color correct the media without using the LUT?
• Which version of Premiere Pro are you using & what is the color space of the sequence?
• Let us know the specifications of the media & the system.

Thanks,

Sumeet

[anour.esa]

Regarding the exaggerated pinks overall -- I switched to the official canon LUT and it was much better. 

The green/pink flickering is still happening in all the shots it was happening in before. I am using Premiere Pro v22.2.0 (Build 128), and the color space of the sequence is Rec 709. It is in a 23.976 fps timebase and display format as my interviews are in 23.976.

Here are the properties of one of the clips that is flickering: 

Type: MPEG Movie File Size: 475.08 MB Image Size: 1920 x 1080 Frame Rate: 59.94 Source Audio Format: 48000 Hz - Compressed - Stereo Project Audio Format: 48000 Hz - 32 bit floating point - Stereo Total Duration: 00;00;17;16 Pixel Aspect Ratio: 1.0 Alpha: None Color Space: Rec. 709 Color Space Override: Off Input LUT: None Video Codec Type: HEVC 10 bit 4:2:2

Could it be something with frame rates? The clip is slowed down to 50% so it's at 29.97, but I have almost all of my b-roll in that same exact format and slowed down and the flickering isn't happening. 

[anour.esa]

Here are screenshots of one frame where the tint looks pink, and the next where it flickers to green. The effect is most prominent in the shadows, particularly the barrel rings on the right side. 

[R Neil Haugen]

First bit of advice about grading log ... colorists call LUTs "the dumbest math out there". They are nothing but a matrix table ... this pixel on input changes to that pixel on output. No "brains" there at all.

So LUTs are built under a specific lighting color/intensity-exposure/contrast ... and as long as you feed the LUT a clip with the exact same exposure/contrast/lighting color, it's cool. Change any of those factors, well ... not so cool.

So any transform LUT should be applied with the capability to trim the exposure, black/white points, contrast, and saturation prior to the LUT. To get your clip to fit what the LUT expects to see.

In Premiere, that means using the Creative tab dropdown for any normalization/transform LUTs. Then use the Basic tab controls to trim or fit the clip into the LUT. I've argued this for year with their chief color scientist. NO OTHER app does the process the way their Basic tab does, with the LUT applied first ... should be at the bottom of the tab. Lars is ... thinking about this.

Next ... I had to check your scopes for that flicker, as I couldn't see it in the image. And thanks for including the scopes, you can see it in the upper left waveform quite clearly.

What I think this may well be is the light source of the image itself. I've seen this sort of thing with a number of different "modern" lights. Having a flicker of one direction with an LED bulb, while a supposedly clean daylight flourescent gives a different color. And like this, they flicker in/out on a regular basis due to the nature of the electrical current (frequency) and the nature of the bulb.

There's a plugin that can help with this by RE:Vision Effects ... that's the only solution I've got. And yes, this is maddening. Frustrating.

DEFlicker Plugin

Neil

[gerbensteyaert]

I've been having the same issue with this 'chroma' noise, and can't find any solution. My collegues with the same camera don't have this issue. After weeks of research, I'm becoming a little desperate for any help or information... Did you ever solve the problem? You're one of the first persons I've come across with the same issue...

[R Neil Haugen]

I would suggest making a new thread, with a detailed post with multple screengrab examples of 1) what you're doing and 2) what happens.

Neil

[A3user]

I'm also having the same problem with my canon r6. Where you able to solve it?

[R Neil Haugen]

Please create a new thread on the forum.

List your computer specs in detail, which specific *number* version of Premiere, and whether you are using auto detect log/auto tonemapping, or using a LUT based normalization routine, or manually doing so.