Hope you all are overflowing with ideas and beaming with imagination. This week we will guide you on how to apply a LUT appropriately using Da Vinci Resolve software so that you don’t lose your artistic expression for technical accuracy.
You might have noticed that in order to achieve cinematic color space, a LUT that you usually apply, creates banding and distortions that sacrifice your picture quality. This not only compromises your creative expression but also makes your video output look amateurish.
In today’s blog, we’ll learn how to appropriately apply a LUT to get rid of Banding and achieve a smoother gradient on your footage.
You will be happy to know that DaVinci Resolve’s LUT decoding algorithm holds the key to solving your problem. Using a superior interpolation approach in Resolve, we’ll teach you how to properly apply a LUT for smoother gradients and less banding.
So, let’s begin then!
In Da Vinci Resolve there are typically two interpolation methods for processing a LUT, ‘Trilinear Interpolation’ and ‘Tetrahedral Interpolation’.
Firstly, let’s use DaVinci Resolve’s Trilinear LUT Interpolation feature.
After importing your footage on the software, click on the settings icon at the bottom right corner, then in Color management, we’ll make sure that under the Lookup table section “3-D Lookup table interpolation” is set to Trilinear.
Import the footage in the timeline and then make a harsh adjustment to the footage by using the curves tool. In the tool, select the blue color range and play around with its hue curve till it breaks the footage.
After that right click on the footage and in add a node clicks on add serial. This will create a duplicate node and then on this duplicate node apply the Invert effect.
Note that it is not required for you to invert the picture colors before using the interpolation approach. We have done it so, in order to show you how the math underlying the software’s program is being implemented.
Let’s go ahead, and disable the duplicate “Invert” node and create and export a 17-point LUT from this footage.
Now, let’s reset our adjustment node, and copy-paste the test LUT into Davinci’s LUT folder. We’ll come back to the software and hit refresh inside the LUT gallery, to view our Test LUT.
We’ll go ahead and apply the test LUT on the node where we made our last adjustments. Then we’ll enable the Invert node for better visibility and grab a still and name it “Trilinear”.
Moving on, we’ll now use tetrahedral Interpolation to apply the LUT. Reset the LUT node and disable the “invert” node.
Then click on color management settings and change the Interpolation method from “Trilinear” to “Tetrahedral”.
Click on “Update lists”, hit save, and apply the same LUT from the LUT gallery. Let’s go ahead and enable the “invert” node for better visibility.
You will notice that the tetrahedral interpolation side has a smoother gradient and lesser banding as compared to trilinear interpolation which generates unpleasant and distracting color fringes on the footage.
Why is this?
Quoting the research paper “A survey on 3D-LUT performance in 10-bit and 12-bit HDR BT.2100 PQ” by Jd Vandenberg and Stefano Andriani
“Tetrahedral interpolation outperformed all other interpolations for both SDR and HDR applications. It can achieve the same quality of the Trilinear interpolation using a 3D-LUT 20% to 25% smaller on average. The widely used Trilinear interpolation generated the largest errors among the tested images.”
We can conclude that Tetrahedral interpolation produces a more pleasant hue shift, than Trilinear interpolation, as Tetrahedral engages in a more accurate method of interpolating values between the data points so that it can perform 3-D LUT interpolation with a way higher accuracy.
Not only this, on Adobe’s side setting the Interpolation method to “Tetrahedral” in Adobe Media Encoder gains much better results. To read about it, check out this link. And if you want to understand how tetrahedral interpolation outperforms trilinear interpolation and its underlying mechanics, check out this blog:
Tetrahedral interpolation for colorspace conversion » Steve on Image Processing with MATLAB – MATLAB & Simulink (mathworks.com)
That’s it for this blog! We hope our blog helps you discover creative inspiration. So, until the next blog, find inspiration, make something great, contribute to the world’s beauty, and don’t forget to subscribe to and follow Colorist Factory’s YouTube and Instagram page.
Well done guys. I love your articles. No water, just important information that helps you get better. I read all your articles. Very informative. Thank you for your work. The only thing I would like to ask, if there is such an opportunity, to post at least one cinematic stylized LUT per month. Very stylish: in blue, green, yellow and muted colors.