User Manual

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.
Buer 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.
To use a Buffer LUT:
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.
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