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How Do You Grade Your Footage? (LUTs / ACES)

LensMeAHand
Key Contributor

In my quest to figure out how to color grade, I started grading without LUTs (adjusting each clip from scratch), then I tried starting with a base LUT and tweaking from there, and more recently, I've been using the ACES color space with input transforms.

The first method (adjusting color wheels manually for each clip to get the look I want) is the most tedious. I also feel like the LUTs are designed to fix color shifts from the camera sensor and make the image look more lifelike. So without a LUT, I felt like my work looked worse.

Starting with a base LUT speeds things up, but I recently noticed that I'm losing information:marlin LUT.jpg

Take a look at her cheek. All the color information is lost—it's just a sea of red. And there's no amount of finagling the color wheels that will get that information back. Now compare that to the same still, grading in the ACES color spaces with an input transform to SLog3:marlin_aces.jpg

Notice the smooth roll off on her cheek from highlights to shadows. Much better. And much more flexibility in grading as well.

Most of the times, the difference between these two methods isn't noticeable, but the intense red light really brings out the limitations of that specific LUT.

Anyways, I'm curious how others are grading their footage? Any nuggets of knowledge you've gleaned on your color grading journey?

1 REPLY 1

alisterchapman
Top Contributor

When you use LUT's you do not loose any of the original image information, it's all still there. But if you grade your material by adding corrections down stream (after) the LUT then the LUT will have baked in its look and then you are adjusting that look, you are not adjusting the log. So, you need to do your adjustments in a node or layer before the LUT, that way you are adjusting the Log before it gets to the LUT and then you will have access to the full tonal range that was captured. One thing well designed LUT's also do is take care of the colourspace transform that is necessary to bring the S-Log content into the Rec-709 colourspace that most are working in.

ACES and other colour managed workflows do generally simplify the grading process as they take care of the conversion from the shooting colour space (S-Log3/SGamut) to the desired final colour space - Rec-709, HDR10 or whatever it is you need to view and deliver in. Simple direct grading of S-Log3 material in a non colour managed  Rec-709 project does not include any colourspace transforms, so sometimes you will get funky colours or odd behaviours that make getting exactly what you want tricky. Colour management eliminates these issues and generally the footage is handled in a way that makes changing the white balance or exposure much simpler. BUT - ACES in particular is designed to add a film like look. This can work for you very nicely if you want a film style roll off and lower level skin tones etc. But it can also work against you if you are working with content that you want to "pop" and be bright, the ACES roll off that is applied on the output signal will try to stop your content from getting bright. 

So, there is no one fits all workflow. ACES is great for film style projects. LUT's are great for fast turn-around with pre determined looks. A colour managed workflow such as Resolves own may be better for brighter and more vibrant projects.

In the near future when we will need to deliver in multiple standards so that you will have an HDR version for the multitude of HDR devices from phones to TV's that are already out there, as well as Rec-709 for legacy devices. Or use processes such as Dolby to provide a single multi-standard compatible deliverable colour managed workflows will become both necessary and normal.

Alister Chapman
Cinematographer/Producer/Trainer