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LUTs are a great tool as a base for colour grading, and I often use them. But since I also got into movie editing a bit, one thing worries me in the Lightroom imposed order of operations. (Fixed order of transformations done to the base RAW image)

(correct me if I'm wrong - the profile is applied at the very beginning,and all other adjustments are built on top of that?)

So, many movie colour grading guides strongly advise against applying LUT first, but rather recommend doing colour correction first (all exposure related things, white balance.. ) and only after that start to creatively meddle with colours. It's because LUTs, especially 'creative' ones transform colours in a ways which can cause clipping a lot of information, which cannot be recovered later. And it seems there's no way to force Lightroom to process a profile afterwards (like you can do in Photoshop by the order of layers).

I started to think if it would be a good idea to do colour correction first, export to TIFF, and only start to do 'creative' colour grading and retouching on this re-imported image. But I wonder if it's worth the hassle, I would appreciate sharing some experiences related to work with LUT/Profiles. (Also apart from losing time I can lose some information from original RAW when exporting to TIFF, but again, is it important anyhow, after appropriate colour correction?)

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  • \$\begingroup\$ Things can be done in different ways, and applying a series of color transformations does not mean that the intermediate results are computed, then the next result. In many situations the operations can be combined, and then the operation is applied to the image one. This also improves the performance. Similar to transformation matrices. \$\endgroup\$
    – U. Windl
    Commented Apr 28, 2023 at 20:18
  • \$\begingroup\$ "correct me if I'm wrong - the profile is applied at the very beginning, and all other adjustments are built on top of that?" Correction: when you make an adjustment the effect on the output is to use the modified instructions to go back and reprocess the original raw data again from the very beginning when you actually export the image. What you see on your screen immediately after you make an adjustment depends upon what performance (speed) vs. accuracy choices you've made in LR's settings. You may see a re-render (slower), or you may see an estimated difference from the previous version. \$\endgroup\$
    – Michael C
    Commented May 1, 2023 at 12:25
  • \$\begingroup\$ You seem to be confusing the way video gets processed in color grading with the way raw information in a still image files gets processed. "Raw" video isn't really raw in the same way that most still image raw files are. The same black point, white point, etc. are applied to each frame of a video. But in practical terms, LUTs have an effect that could be compared to putting a color filter on your display screen. You can't see accurate colors even when they're being put out by your screen with an orange (or red, or blue, or green or magenta) filter between your screen and your eyes. \$\endgroup\$
    – Michael C
    Commented May 1, 2023 at 12:31
  • \$\begingroup\$ @U.Windl - do you know it works like that in LR, or it's a speculation? BTW maybe I'll do some experiments and come back with results. \$\endgroup\$ Commented May 1, 2023 at 19:02
  • \$\begingroup\$ @MichaelC yes I know, 'RAW' video is different, as there's codec on top of that and so on, but what I meant is that if LR works in terms of math functions composition (like f(g(x)) then, for instance if the order would be color_curves(color_profile(RAW_pixel_vals))then if colour profile (LUT based or any other) 'cuts off' some information(let's say it zeroes everything below 20% luminosity of green colour)-then you won't recover that information by bringing green curve up again. But if order was reverse then bringing greens up first could make them not being cut off yielding different result. \$\endgroup\$ Commented May 1, 2023 at 19:13

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