Rolling Your Own LUTs

The Case For Completely Avoiding LUTs (And Going DIY)

June 13, 2013

You shouldn't be a slave to LUTs... learn how to quickly decide if they're working. And if not, learn to throw away those LUTs and just 'Do It Yourself'.


Series

In ML0022 I demonstrated how typical camera LUTs (used for expanding the contrast of ‘flat’ log-recorded images), when applied in the middle of color grading operations, break the 32-bit Float operations of color grading apps.In this Insights Article I’ll spend some time showing you the creative nature of LUTs, using ARRI LUTs as an example. And once we understand that camera LUTs are creative tools—not technical tools—then we can feel more comfortable ignoring those LUTs and learning to grade ‘flat’ footage without their assistance.

Don’t be a slave to LUTs

The main point of this article is to teach you not to be a slave to LUTs… but rather, learn to use them when they work for you, throw them away when they don’t, make the decision quickly if you’re going to use a LUT on a job or not and if you do throw away the LUT—it’s okay!

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Homepage Forums The Case For Completely Avoiding LUTs (And Going DIY)

Viewing 9 reply threads

    • Remco Hekker
      Participant

      Hi Patrick, Thank you for the clear explanation and the vote of confidence to “step away from the LUT’s”. 😉
      I
      find myself often using the kodak emulation LUT’s, that Juan Melara was
      kind enough to share with everyone
      http://juanmelara.com.au/print-film-emulation-luts-for-download/

      I
      find that these LUT’s constrict me in some situation and would love to
      grade these shots completely manual. Could you maybe show me a way to
      analyse the LUT’s so I know in what direction to grade?

      Kind regards,

      Remco


    • Patrick Inhofer
      Guest

      Remco,

      I remember that post when it first appeared on the intertubes.

      I’ve been thinking about how best to handle your request… and I think I’ll do a video exactly as you ask – how to figure out what this LUT wants your image to look like and how to properly prepare an image for the LUT to do its job.

      Just to warn you, there’s a large amount of variability when working with LUTs – especially technical LUTs that are being pressed into doing duty as a ‘creative’ LUT. But I think I can give you some ideas for deciding if the LUT will do what you want it to do.


    • Remco Hekker
      Participant

      Hi Patrick,

      Thank you so much. I’am looking forward to the video. You’ve already been able to explain some pretty complex material very well, so I have all confidence that this video will be great aswell.

      Kind regards,


    • George
      Guest

      Dear Patrick,

      Great video once again!

      Quick question after watching it – whatever you say is 100% right IF we are talking about gamma/contrast.

      However, in case of a film print emulation LUT (which most people are using), wouldn’t it be much harder (if not impossible) to roll your own LUT? I understand that film emulation LUTs map colors differently, apart from the contrast/gamma.

      What do you think?


    • Patrick Inhofer
      Guest

      Hi George,

      I would consider a film print emulation LUT to fall in the class of ‘techincal LUT’. So yes, if you know the properties of a particular film stock and can discern if what you’re seeing is right or wrong, then ‘rolling your own’ isn’t appropriate.

      But I’d guess that 80% of the people using film emulation LUTs couldn’t give a hoot about the precise properties of a precise film stock and are just looking for something more ‘filmic’ and hoping the LUT gets them there. In that case… try a film emulation LUT – if it works, great. If not – if you like what your rolled yourself – then go for it.

      Or better yet, a combination… start with a film emulation LUT and then modify to achieve the creative goals and tastes of everyone on the project. As you can see, I treat 90% of the LUTs in existence as ‘optional’. They’re simply tools which we can choose to use. Or not.


    • George
      Guest

      I completely agree Patrick.
      In fact, you can probably safely up that percentage to 95%. Since almost nobody does film-outs anymore, basically all film emulation LUTs are now used as “creative” LUTs, even though their main goal was “technical”. So it becomes a matter of preference and – in the end – personal taste.

      One quick question after watching the entire series on LUTs (great series!)

      Is there any advantage – in your opinion – of dedicating a node in Resolve to a LUT? Why not keep the look-up-table as an “output” LUT and do all your corrections “under” the LUT? Contrast and color balance, qualifiers, windows etc. Do you find any advantages in doing some of your corrections (after the balance) after the LUT? Assuming you don’t change LUTs from one shot to the other.

      Thanks!
      George


    • Patrick Inhofer
      Guest

      My only problem with an output LUT… I sometimes like working after the LUT. You get a different feel (depending on the LUT and how the footage was shot). Grading after the LUT feels more like grading traditional video sources… which isn’t good or bad – just a different feel / look when doing the same correction.

      But if you were to tell me you always apply your LUTs as an Output LUT – I’d have no problem with that. Although if you do legalization at the Track level, I can see where that would complicate matters—which would get solved by putting the LUT as the last node at the clip level (and serve the same purpose as an Output LUT).


    • George
      Guest

      Dear Patrick,

      You hit the nail on its head.

      In fact, that’s EXACTLY why I opened an account on the site – because indeed, I also like the “traditional” feel of grading a video source. I love how different film emulation look, but I often feel that I am “fighting” the lut when I operate the controls in Resolve (when “under” the LUT). Balancing, contrast, color adjustments, even keys.

      Are there any articles on the site specifically dealing with grading “under” the LUTs? Or about balancing contrast/color using the log controls, as opposed to the 3-way color traditional approach?

      In fact, in order to balance log material “under” the LUT – do you use the log controls, or the 3-way wheels? I’d love to learn more about it. As I mentioned, this is the reason I came on this site 🙂

      Thanks Patrick!
      George


    • Lucas W
      Guest

      Aspiring colorist here! This flight path on luts has helped me tremendously. Self-learning from Hurkman’s Color Correction Handbook taught me to normalize with luts and then I ran into issues that you discussed with varying exposure, etc. I thought I was losing my mind.

      Question: On the making your own lut, is using curves your preference? How would that look without curves, could I just adjust contrast/pivot, lift/gamma/gain, and pump up the saturation? That’s how I had been troubleshooting the occasional “off” shot.

      And do you ever touch the log wheels?


    • Pat Inhofer
      Guest

      Lucas, I missed this question when first asked… You can certainly set up a node that processes the image the way you want using Lift/Gamma/Gain/Sat tools.

      RE: Log Wheels – I use them but sparingly. Mostly to work the shadows or highlights without effecting the rest of the image.

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