Quick Tip: OCIO in Blackmagic Fusion (Patreon)

Blackmagic Fusion is a great alternative to Nuke and After Effects. It offers powerful node-based compositing and motion graphics tools and comes in a free version bundled with DaVinci Resolve or a very fairly-priced perpetual license.

Fusion is fairly easy to use, but one part that’s a little confusing at first is its implementation of OpenColorIO (OCIO).

Most other apps divide their OCIO workflow into three steps: input transforms, working space and output transforms. This usually takes the form of:

1. Picking input transforms for all incoming media.2. Setting a global working space.3. Picking a display transform for viewing and output transforms for saving media to disk.

Working space refers to the colorspace which all input media is converted to, all calculations (compositing, color correction, etc.) are done in, and all output media is converted from.

Generally speaking, in ACES there are three main working spaces: ACEScg, ACEScc and ACEScct. They’re all fairly similar. Since we’re working with computer graphics, ACEScg is a fine choice, while experienced colorists might prefer ACEScc or ACEScct.

Here's the working space selection parameter in Nuke’s Preferences:

Set this once in Nuke, then either use rules or manually pick input and output transforms for all your media. Most other CG apps handle this in a similar way.

But Fusion does not! When you import an image there are no obvious display transform settings in the viewer as there are in Nuke, there are no Fusion-specific color management settings, and these are the only OCIO nodes available:

The trick with Fusion is that there is no global working space. Instead, what we have to do is set up a display transform that uses a specific source colorspace, then convert all our input media to that same colorspace.

First, right click on the viewer and select LUT > OCIO Display.

Then right click again and click LUT > Edit.

In the window that pops up, choose your OCIO config and set the Source Space the same as you would your working space in other apps.

In this case we’re telling Fusion to convert everything in the node graph from an ACEScg “working space” to view on an sRGB display.

Next, we have to make sure our input media is converted to our “working space.”

Add an OCIO ColorSpace node, choose your OCIO config again and set the Output Space to ACEScg. Then set the Source Space as appropriate for the media in question.

This render was made in ACEScg, so for correct colors we’ll just be “converting” from ACEScg to ACEScg. For other media you might choose sRGB texture to ACEScg, sRGB linear to ACEScg, etc.

The end result is that we converted our input media to ACEScg, all operations in the node graph will be done in ACEScg, then we’ll view the results using a conversion from ACEScg to sRGB.

And that's all there is to it! Our colors in Fusion will now exactly match Nuke and any other OCIO-enabled app. In this clip we switch between the dark, oversaturated look of the default non-OCIO Fusion View LUT and the correct colors with OCIO enabled. Looks great!