Gamut

Gamut is a technical Fusion Color node for converting between color-space coordinates and handling transfer/gamma curves. It is not the same as Gamut Limiter or Gamut Mapping: those tools constrain or remap gamut, while Gamut converts source and destination image encodings.

Before using the node, record four properties of the actual arriving RGB signal: primaries, transfer function, the upstream MediaIn/Loader interpretation and any project/OCIO/ACES transforms already applied. The camera name is not sufficient evidence of the current image values.

Source Space identifies the input encoding. The original Inspector dropdown visibly lists No Change, ACES/ACEScg, Adobe RGB, Apple Log 2, ARRI choices and several Blackmagic Film generations. These are only the options visible in a scrolled screenshot, not a claim that the menu is exhausted.

Remove Gamma is used when a known non-linear image must enter a scene-linear compositing chain. Enable it only if the corresponding curve has not already been removed. Double decoding is a common cause of unexpected contrast and brightness in Fusion.

With color spaces aligned, the linear segment of the graph can contain Merge, blur, glow and CGI compositing. Combining values encoded in incompatible gamuts/transfers is not a mathematically controlled mix even if the Viewer looks superficially attractive.

Output Space selects the destination color encoding and Add Gamma can apply the output curve when necessary. This pair is not a complete ACES IDT/ODT, automatic HDR-to-SDR tone mapping, or perceptual gamut compression; do not promise no clipping for wide-to-narrow mappings.

No Change is not automatic profile detection. Output Space often remains No Change during an input linearization step; Source Space can stay No Change when a known linear image is being encoded for output. In both cases the upstream and downstream graph matter.

Use White Point Adaptation addresses a mismatch in reference whites. It is not a creative white-balance, temperature, tint or exposure control. Test it using known source/output spaces and reference neutral patches rather than eyeballing the monitor.

Pre-Divide / Post-Multiply matters for premultiplied RGBA titles, keyed overlays and CGI. Color is temporarily unpremultiplied, transformed and multiplied by alpha again. Do not assume the same checkbox setting is correct for a straight-alpha file without testing.

The manual documents a second Gamut input named Effect Mask. Rectangle.Mask or other mask data can restrict the already-processed operation. A partially masked technical gamut transform can leave a shot containing incompatible RGB encoding regions, so use this for explicit local tests rather than as a default delivery technique.

Viewer LUT, Fusion pixel values and actual Render/Deliver transforms are separate stages. Verify the final result with a grayscale ramp, chart and waveform after all relevant transforms; a pleasing Viewer result does not prove correct output tags or pixel values.

A defensible acceptance test uses an owned known-space sequence containing a gray ramp, color reference patches and soft-alpha edges. Static graph validation proves image/mask wiring only, not exact numeric colorimetry or the rendered behavior of Resolve 21.