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How Lookup Tables Work in Fusion
A Lookup Table (LUT) is a table of values used to transform the color and luminance of an image. A 1D LUT uses a two-column table for input color and output color, while a 3D LUT uses more of a matrix. A LUT is used primarily to correct for variances in the monitor or the source color space of the image. You can choose to apply a LUT to all the viewers or apply different LUTs to each viewer.
Image LUTs
Image LUTs can be applied to each viewer. In fact, you can even apply separate Image LUTs for the A and B buffers of a single viewer. These LUTs can only be applied to 2D images and not to 3D scenes. Image LUTs are routinely used to get from one scene-referred color space to another. For example, if you’re working with log-encoded media but want to see how the image will look in the final color space, you can choose a LUT to make the image transform as a preview.
Buffer LUTs
The Buffer LUT is applied to the viewers regardless of contents, including 3D scenes, 3D materials, and subview types. Only one Buffer LUT can be applied. If a 2D image is being displayed with an Image LUT applied, then the Buffer LUT is applied to the result of the image LUT. Buffer LUTs are typically used to simulate another output color space that’s unique to the display you’re using—for instance, making a DCI-P3 projector show the image as it would look on an sRGB monitor.
1 Disable the LUT button above the viewer.
2 Right-click in the viewer and choose Global Options > Buffer LUT > Enable.
3 Right-click in the viewer and choose Global Options > Buffer LUT > Type of LUT you want to apply.
When dealing with nonlinear files from many of today’s digital cinema cameras, a modern workflow would be to convert everything to linear at the beginning of the node tree, then create your composite, and then apply an Image LUT or Buffer LUT that matches the color space you want it to be in for either grading in the Color page or for final output.
However, in more elaborate production pipelines, you may need to apply multiple LUTs consecutively.
Types of Viewer LUTs
Aside from the industry standard 1D and 3D LUTs, other types of LUTs are supported, including script- based Fuse node LUTs and macros assembled from standard nodes. Generally, LUT processing is performed on the graphics card’s GPU in real time, although the performance of macro-based LUTs is based on the nodes they contain.
Fusion View LUT
The Fusion View LUT is the default and is a frequently used LUT type. It provides an RGBA curve that can be used to assign IN/OUT value pairs. This control is identical to that provided by the Color Curve node.
Since the purpose of the View LUT is to provide an unchanging correction for the monitor or the file’s color space, however, these splines cannot be animated.
Log-Lin View LUT
The Log-Lin LUT converts logarithmic data to linear, and vice versa. This can be particularly useful when used in conjunction with supplied LUT files that expect logarithmic data. It is similar to the Cineon Log node.
Gamut View LUT
The Gamut LUT converts a source color space to an output color space, with options to deal with gamma settings, alpha channels, and premultiplication. The Gamut LUT is a frequently used LUT type to correct the viewer when working with Linear Gamma in the Node editor.
Macro LUTs
Any macro node can also be used as a viewer LUT simply by saving the macro’s .setting file to the correct Fusion directory.
— On macOS: Macintosh HD/Users/username/Library/Application Support/Blackmagic Design/ Fusion/LUTs/
— On Windows: C:\Program Files\Blackmagic Design\Fusion\LUTs
— On Linux: home/username/.local/share/DaVinciResolve/Fusion/LUTs
— On macOS: Macintosh HD/Users/username/Library/Application Support/Blackmagic Design/ Fusion/LUTs/
— On Windows: C:\Users\username\AppData\Roaming\Blackmagic Design\Fusion\LUTs
— On Linux: home/username/.fusion/BlackmagicDesign/Fusion/LUTs
For this to work, the macro must have one image input and one image output. Any controls exposed on the macro will be available when the Edit option is selected for the LUT. For more information about creating macros, see Chapter 68, “Node Groups, Macros, and Fusion Templates.” in the DaVinci Resolve Reference Manual or Chapter 6 in the Fusion Reference Manual.
LUT Presets
All LUTs available to DaVinci Resolve are also accessible to the Fusion page, which includes custom LUTs you’ve installed, as well as preset LUTs that come installed with DaVinci Resolve, such as the highly useful VFX IO category that includes a wide variety of miscellaneous to Linear and Linear to miscellaneous transforms. All of these LUTs appear by category in the viewer LUT menu.
Fuse LUTs
Fuses are scriptable plugins that are installed with the application or that you create in Fusion. A fuse named CT_ViewLUTPlugin can be applied as a LUT to a viewer. You can also script fuses that use graphics hardware shaders embedded into the LUT for real-time processing. Since fuse LUTs require shader-capable graphics hardware, they cannot be applied in software. For more information about Fuses, see the Fusion Scripting Guide located on the Blackmagic Design website.