Post & the DI

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Hi Matthew Tomlinson,

Thanks so much for replying to my post, it is much appreciated. This whole LUT creation and image science field has been occupying my mind for some time. I am not naturally technical, but i would like to create a LUT that brings out a pleasingly natural 'cinematic' image. I am not happy with Arri's standard REC709. I have previously tweaked the REC709 through Arri's software, but it was really just to the extent of desaturating and adjusting the contrast rather than moving the values of different hues in their saturation or colour balance. I agree that lighting is critically important, but i also strongly feel that being able to start with a pleasing 'look' from the camera in terms of its contrast and colour reproduction is very important. I find a good LUT inspiring much like the way that film stock or a great grading 'look' is inspiring in comparison to an unpleasant digital colour space that some cameras out there will initially give you. I also feel that understanding a good LUT, much like a film stock, is important in the sense that it might effect decisions down the line. How saturated to make the paint on a wall, how much to warm up that light, how strong to go with the colours of costume and so on. I say this on the basis of trying to shoot as much in camera as possible rather than adjusting costume, paint or whatever it is in post.

Thank you for your invitation for further questions, i have some i would love to follow up with...

1. Isn't any LUT, whether created through option one or two as outlined in my previous post, subject to the monitor it was created/viewed on? I assume that even a LUT created from code would have to be viewed on a monitor and that monitor would have to be calibrated to a particular colour space? You specified that the monitor was important with option 2 in particular so i'm curious why this is not also equivalently the case when using option 1?

2. What are the restrictions of creating a LUT through something like Da Vinci Resolve? Can Da Vinci be just as accurate as a LUT created in code or with the proprietary software/process i presume you used to create Roger's LUT? Is a LUT created through coding perhaps more accurately able to move around and control the different elements of a colour? I thought perhaps Da Vinci could create broad strokes but perhaps not get into clinical detail? Did you see Steve Yedlin's (DoP of next Star Wars) display prep demo (») where he showed a test of film next to Alexa RAW engineered to look nearly identical? He used math and proprietary software that has taken years of research to formulate, so i assumed doing something like this in Da Vinci is not straight forward. Can a LUT created through code and one created through Da Vinci ultimately produce the same thing however complex?

3. Does Roger's LUT move colour hue's and saturation far from Arri's REC709 LUT base look? The colours of Roger's LUT feel natural so i'm curious how much the colours, broadly speaking, are being mapped to different values or saturation levels. Was the intention in the LUT creation process to look like film? I wouldn't ask you to break down the DNA of Roger's LUT, i understand that is proprietary and could actually hinder someone from finding their own 'look' but i'm interested in the process, however much you feel able to illuminate. For example did you start by just adding contrast and saturation to Arri's RAW file and then manipulate from that point? Do you find that adding contrast and saturation to Arri Raw is a good starting point?

4. You spoke about testing a LUT created through Da Vinci to see if it would clamp or clip colours. If a person is creating a 'natural' looking LUT is this problem much less likely to happen?

5. In general, how does a LUT respond to Arri ProRes XQ in comparison to Arri RAW in your experience?

6. What is the difference between XYZ and P3? As far as i understood XYZ replicates the eye and has to be conformed to P3 because that is the colour space of a cinema projector. Do you either essentially work in P3 (Cinema) or REC709 (TV) or are there further colour spaces that need to be considered?

7. There was mention that working via ICC colour management is a problem. Why is this? I have a monitor running directly out of my mac (i.e. via ICC) rather than a hardware device. I calibrated the monitor using a light measuring puck in conjunction with software to REC709 2.4. Is this not sufficient if the end display is also a REC709 2.4 TV or equivalent? I assumed that as long as my monitor is displaying the correct colour values and contrast for REC709 all should be ok.

Thank you so much for your time.

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