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Adrian Ramirez

LUT creation workflow

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Can anyone point me to specific resources on a good workflow for LUT creation? Is there a standard to follow or does everyone have their own way of going about it? There's quite a mess to sift through on YouTube and Google so I'm hoping for something a little more pointed. This is out of personal interest and not for a job by the way - I want to be able to develop the skill and have a bit of fun with it at home. Thanks! 

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This may be helpful: https://blog.frame.io/2019/08/12/luts-101/

If you use Davinci Resolve, it’s pretty simple to make one. If you right-click on a graded clip in the Color Page, it will give you the option to create a LUT. Only use primary adjustments (affecting the whole frame, no power windows) for color and contrast.

To test the LUT, It’s best to gather a wide variety of camera footage to see if it will break the footage - exteriors, interiors, gradients, bright highlights, deep saturated colors like reds and blues (both in focus and out of focus), skin tones, dark shadows, skin tones, different ISOs and exposures.

If you regularly grade your own footage, you’ll probably have a good idea of what changes you always need to make for a particular camera. A good way to start is to take the official manufacturer Rec.709 LUT and make small basic adjustments to taste like lowering the highlights a bit or adding a tint to the shadows. You’ll be less likely to mess things up that way. 

Concepts to study:

- Legal (Resolve calls it Video) vs Full range IRE video levels

- Color Gamut of Rec.709 vs whatever your camera outputs (Sony S-Gamut.cine, REDWideGamut RGB, ARRI wide gamut, Canon Cinema Gamut, etc.) 

- 1D vs 3D LUTs

- LUT Size (17x17x17 or 33x33x33 for in-camera and monitor preview, 65x65x65 for post)

- LUT formats (.cube, .vlt, etc.)

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There's a very useful app called LUTCalc, which creates LUTs. You specify the input side (Camera, ISO, Gamma, Gamut) and then the output side (Gamma & Gamut) and it will create a 3D LUT for you.

It has most of the manufacturer's LUTs built into it, so you can mix and match between cameras. It also allows some basic customization of things like white balance, color, black levels etc

The online version is free to use, or you can download it for a small fee.

http://cameramanben.github.io/LUTCalc/

I've used it a lot of the last few years, particularly when shooting with Sony cameras

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22 hours ago, Satsuki Murashige said:

To test the LUT, It’s best to gather a wide variety of camera footage to see if it will break the footage - exteriors, interiors, gradients, bright highlights, deep saturated colors like reds and blues (both in focus and out of focus), skin tones, dark shadows, skin tones, different ISOs and exposures.

This bears repeating for its accuracy; I just wrote a couple of pieces on the subject.

Do not just grab one still, tickle the trackballs then assume you're done. You aren't. Test it with very bad footage.

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12 minutes ago, Phil Rhodes said:

This bears repeating for its accuracy; I just wrote a couple of pieces on the subject.

Do not just grab one still, tickle the trackballs then assume you're done. You aren't. Test it with very bad footage.

The out of focus oversaturated colors was a particular surprise to me in my testing - while small areas of slightly out of gamut colors may look ok when in focus, as you rack out of focus the hard clip edge will become very obvious.

Another surprising area of fail was in out of focus repeating patterns like in flatly lit wallpaper underexposed a few stops. This can be an issue with low bitrate codecs as well. You would think that out of focus areas should compress easily, but I had this issue with early versions of the Sony F5 when shooting in XAVC HD. I haven’t had this issue in 4K and XAVC Class 480.

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55 minutes ago, Stuart Brereton said:

There's a very useful app called LUTCalc, which creates LUTs. You specify the input side (Camera, ISO, Gamma, Gamut) and then the output side (Gamma & Gamut) and it will create a 3D LUT for you.

It has most of the manufacturer's LUTs built into it, so you can mix and match between cameras. It also allows some basic customization of things like white balance, color, black levels etc

The online version is free to use, or you can download it for a small fee.

http://cameramanben.github.io/LUTCalc/

I've used it a lot of the last few years, particularly when shooting with Sony cameras

I use LUTCalc as well, but mostly to convert an existing LUT from 32x32x32 to 33x33x33, or Legal to Full range. For example, you can only output 32x32x32 when making a LUT in Resolve from the Filmconvert OFX plug-in, and you need 33x33x33 to use in-camera in a lot of cameras.

If you need to judge before/after images, I’d rather use Resolve. 

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12 minutes ago, Satsuki Murashige said:

If you need to judge before/after images, I’d rather use Resolve. 

For sure, it's nowhere near as flexible as Resolve, but I don't think that's the intent behind it anyway. I use it mostly for quickly creating LUTs when I'm shooting away from home, staying in a hotel or something, and just need an approximation, knowing that I'll finesse the look in post.

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3 hours ago, Stuart Brereton said:

For sure, it's nowhere near as flexible as Resolve, but I don't think that's the intent behind it anyway. I use it mostly for quickly creating LUTs when I'm shooting away from home, staying in a hotel or something, and just need an approximation, knowing that I'll finesse the look in post.

Agreed, it works well for that use.

Another (free) tool that I think could be better is ARRI Look Creator. It’s rather clunky for creating look files, I kinda wish ARRI cameras would just accept .cube LUTs instead, but I’m sure they have their own reasons for doing it that way. 

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