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Media Editor
Inspiring
March 13, 2019
Question

Luts

  • March 13, 2019
  • 4 replies
  • 866 views

Should Luts only be used for color grading?

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    4 replies

    R
    rodneyb56060189
    Legend
    March 13, 2019

    Aside: The color page nodes, as opposed to fusion nodes...

    Some nodes used in fusion ( like merging to nodes ) do require (sometimes) creating a 'fusion clip' in cache... so that's a different animal IMO.

    R
    rodneyb56060189
    Legend
    March 13, 2019

    I'm not at all sure about the programming, but it's my understanding that the nodes are database driven info that applies to each node, rather than something that is 'cached' as a sort of rendered addition to the clip, which would keep the overhead on resources down maybe ??  Autodesk Maya used to have similar stuff (database driven stuff ) for dealing with 3D modeling, if I remember correctly. That might be a fundamental difference other than simply 'some visual thing on screen to interact with ' ??

    Maybe I'm misinformed or something. Wouldn't be the first time.

    R Neil Haugen
    R Neil Haugen
    Legend
    March 13, 2019

    Define "color grading" ... and I'm really not joking. There's a recent thread on LiftGammaGain about defining color correction/grading that even got a bit heated.

    A LUT by nature is dumb brute force. Very rarely can they be applied without 'trimming' the media before the LUT, but through the LUT, to avoid clipping or other nasty effects. But ... a lot of times, they can be quite useful to say take a LOG clip to 'normalized' Rec.709/sRGB or other similar technical corrections. Applying one to do so is actually a help in simply editing the darn thing.

    And ... modifying media to seem to sorta be something else, again with trimming adjustments. Giving a quick "look" to a scene or type of scene in a larger project so say your morning-light shots have a similar 'feel' and a different one from your 'afternoon-light' shots. Having a stored LUT for those sorts of things gives you a solid and continuous start-point.

    Neil

    Everyone's mileage always varies ...
    R
    rodneyb56060189
    Legend
    March 13, 2019

    hmmm, interesting question.

    Basically, NO is the answer, because tonal range can also be described by a LUT ( like Rec 709, which is a basic broadcast standard).

    Different editing programs handle this differently. Some allow you to assign a 'color space' to your source, timeline, and export which theoretically get you in the ballpark where what you SEE on your monitor ( after adjustments BEYOND the LUT assignment) is kinda close to what you want, in tonal range.

    Let's say you shoot S Log or Raw, … you'll notice that the stuff looks flat and unsaturated to start (without any assignment ).

    Depending on the program you are using ( PPro, Resolve, Avid ) you can basically try to tell the program what tonal range you want to live in ( broadcast or projection, or web ).  Now, you have to do a quick manual adjustment to each clip ( maybe ) to get your shadows, mid tones and highlights "legal" ( within the IRE or NIT scale you are using ).. That is typically 'luminance' adjustment for lift gamma gain. Lift = blacks and shadows, Gamma= mid tones, Gain = highlights (basically). Pivot adjusts the ranges of each in terms of the 'middle' of each tonal range ( like stretch a rubber band, that's your range for highlights in the example I am describing.. and now take the middle of that rubber band and pull it toward one end or the other ).

    Anyway, this is all just tonal, and has NOTHIN to do with color yet.  So you can do that with a LUT.

    At this point you will have a really pretty tonal range ( image ) with a full range of tones you imagined you'd get with camera.  Before this you would see flat and unsaturated stuff.  Is normal.

    Then, in Resolve for example, you can add a serial node AND use THAT for color adjustments.  I don't know what PPro offers for that... probably adjustment layers ??

    You should have a color calibrated monitor where you view the images ( program or timeline viewer ) in the same color space ( rec 709 in this case ).

    R
    rodneyb56060189
    Legend
    March 13, 2019

    I think most people adjust shadows first, then gain, then mid tone, then bounce back through all three (repeat ) until it is close to the tones you want. You can then edit away and it's pretty fast to do.  Later on you can tweak everything, etc.

    E
    excited_Genie16B8
    Legend
    March 13, 2019

    Depends.

    The LUTS included with PP are designed for a specific use.  Many people use them 'incorrectly'.  You can learn more below.

    Lumetri Color Panel Explained - Premiere Pro CC 2015 - YouTube

    But you can use your own LUTS as well, and they can serve any purpose you need.

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