This is where the 3D LUT comes in. The 3D LUT specifies an output for the full set of three inputs—Red, Green and Blue. That means that for any one RGB input color, I can get a specific RGB output color. Going back to our Bingo analogy, each square on your Bingo card would now have three values in it. The caller would say, for instance, "B7", "I3", "N11", and you would have to have that exact combination in one box to mark it off. A 10-bit 3D LUT (with 1,023 possible variations per color channel) would have over 1 billion possible color combinations. Now that’s a complex game of Bingo; senior citizens, watch out.
In reality, a 3D LUT file doesn’t list that many combinations; instead, it skips values and interpolates in between. We refer to the number of actual values as points in the 3D cube file. Most commonly, you’ll find 3D LUTs with 17 or 33 points (the more points, the better, of course). With 3D LUTs, we can specify an output for any combination of inputs, meaning that we can completely change the color of the image. Pretty cool. Now let’s talk about how they work in these new cameras.
SONY F5/F55 3D LUT SUPPORTIn Version 4.0 of the Sony F5/F55 firmware, there’s support for loading in 3D LUTs. The LUTs are loaded in via an SD card and can be applied on top of the Sony S-Gamut3/S-Log3 color space. The 3D LUTs need to be in a .CUBE format, which is the same format used by Blackmagic Design’s DaVinci Resolve color-grading application. That means that you can create 3D LUTs for the camera in either Sony’s RAW Viewer application or directly in DaVinci Resolve.
Once on an SD card, you can load them directly into the camera and apply the 3D LUT to either a monitor or EVF output, or choose to burn the 3D LUT into the internal XAVC recording.
By default, Sony won’t burn 3D LUTs into the recorded image. Instead, your 3D LUT is written into the metadata of the recorded RAW or Log clips. So when you open the RAW or Log clips in Sony’s RAW viewer, it will be able to show you the LUT used on set. Your recorded data stays clean, but you can easily reapply the 3D LUT used on set. This is a very important and impressive functionality of the camera, and one that we’re seeing in other cameras, as well.
ARRI AMIRA 3D LUT SUPPORT
The ARRI ALEXA could load in Look files, which had the same basic adjustments as found in an ASC CDL. A great feature, for sure, but now in the AMIRA, full 3D LUT support has been added. To create 3D LUTs compatible with the AMIRA, ARRI created a new tool, the AMIRA Color Tool, which allows you to color-grade a recording from the AMIRA or import a variety of 3D LUT formats to apply to the image.
Here’s the AMIRA Color Tool with the window for importing a 3D LUT [page 26]. The tool will convert an imported 3D LUT or any manual adjustments that you made into a .AML file (AMIRA Look File). Load this .AML file onto an SD card, and then you can load it into the camera for viewing on a monitor/EVF. You also can choose to burn it into the internal recording if looking for a straight-to-edit workflow.