Resolve FX · Color · Color Space Transform
Color Space Transform, usually shortened to CST, is the technical Resolve FX for converting an image from one colour-space/gamma description to another. It is the core manual transform tool on the Color page when you need an explicit node-level conversion rather than a broad project-wide colour-management shortcut.
This page documents the effect itself: Input Color Space, Input Gamma, Output Color Space, Output Gamma, Tone Mapping, Gamut Mapping and related advanced switches. Broader project workflow remains on the Color Management page, while ACES Transform and Chromatic Adaptation keep their own focused references.
Controls
The panel looks longer than Color Compressor or Blur FX, but the logic is straightforward: describe the input correctly, describe the output correctly, then decide how Resolve should handle luminance range and out-of-gamut colours.
Input Color Space defines the colour space of the incoming signal. This is where you describe the source honestly: use the timeline settings or choose an explicit option such as ACES, Adobe RGB, Apple Log 2 or ARRI Wide Gamut from the Resolve list. A wrong choice undermines every downstream decision.
Input Gamma describes the tonal encoding of the source. Resolve 21 exposes options such as Use timeline, ACEScc, ACEScct, Apple Log, ARRI LogC3, ARRI LogC4 and Blackmagic Design Film. If gamma does not match the actual signal, CST calculates the transform from the wrong tonal model.
Output Color Space defines the destination space CST should convert into. That can be Use timeline or an explicit destination such as ACES, Adobe RGB, Apple Log 2 or ARRI Wide Gamut. Choose it according to the actual pipeline rather than whatever looks nicer on screen.
Output Gamma completes the description of the destination signal. Resolve exposes Use timeline, ACEScc, ACEScct, Adobe RGB, Apple Log, ARIB STD-B67 HLG, ARRI LogC3, LogC4 and more. Together, Output Colour Space and Output Gamma define what state the image should leave the node in.
Tone Mapping Method controls how Resolve remaps luminance when converting between different gammas and dynamic ranges. Resolve 21 offers None, Clip, Simple, Luminance Mapping, DaVinci and Saturation Preserving. It becomes especially important when translating HDR to SDR or moving between different display contexts.
Gamut Mapping Method defines what happens when colours fall outside the destination gamut. The Resolve panel shows None, Saturation Compression and Clip. This is not about luminance but about how saturated colours are brought into the destination space without harsh failures.
The lower part of the panel contains Gamut Mapping and advanced switches such as Apply Forward OOTF, Apply Inverse OOTF and Use White Point Adaptation. These belong to more exact technical configuration and should be enabled only when you understand the node’s role in the wider project pipeline.
Workflow
Set the real Input Color Space and Input Gamma. If the project context already describes them correctly, Use timeline can be appropriate; otherwise choose explicit values.
Choose the destination Output Color Space and Output Gamma according to the actual downstream workflow: a working space, a display space or a delivery transform.
Use Tone Mapping and Gamut Mapping only when the conversion actually needs them. They are not decorative extras but technical choices about dynamic range and saturated colours.
A dedicated technical node makes CST easier to bypass, compare and debug. That is safer than hiding a transform inside broader creative grading.
Colour science
CST should stay a practical Resolve FX page. The underlying theory now lives in the dedicated Colour Science section, so each control can link to a full explanation instead of repeating the same fundamentals here.
Primaries, gamut, white point and why RGB numbers need a defined coordinate system.
OETF, EOTF, OOTF, gamma, log and why the Gamma menu contains very different transfer functions.
What D50, D60 and D65 mean and why white point is not brightness or gamma.
How luminance is remapped when source and target display ranges do not match.
What happens to out-of-gamut colours and how compression differs from clipping.
How CST fits into input transforms, working spaces and output transforms without double conversion.
CST and neighbouring tools
CST is the general-purpose effect for converting between colour-space and gamma descriptions on a specific node. It is the clean answer when you need an explicit local transform.
The Color Management page explains managed workflows, project-wide ACES ideas and when CST belongs in the larger pipeline. It is broader than this single FX page.
ACES Transform is a dedicated effect built around ACES Version plus Input/Output Transforms. Use it when the pipeline itself is ACES-centric rather than merely requiring a generic colour-space conversion.
Chromatic Adaptation solves a narrower problem: adapting between illuminants or white points. It can sit beside CST, but it is not a replacement for explicit input/output colour conversion.
Common mistakes
The most common problem is choosing Input Color Space or Input Gamma by eye instead of using real source information.
If the clip, timeline or LUT chain already transforms the image, another CST can produce double-conversion artefacts.
Tone Mapping is about technical range handling, not about making the picture simply more pleasing.
Very saturated colours can break badly when Gamut Mapping is left unresolved for the chosen destination.
The most useful mental model for CST is a contract: the node expects one specific Colour Space + Gamma pair at its input and promises another pair at its output. If either side is described incorrectly, a mathematically valid transform will still produce the wrong-looking image.
| Layer | What it means | How to verify |
|---|---|---|
| Input Colour Space + Gamma | Defines the RGB coordinate system and transfer function of the input. This is one signal-state description, not two independent creative controls. | Verify against camera metadata/documentation, not the viewer alone. |
| Output Colour Space + Gamma | Defines the signal state leaving the node: working, interchange or display/output. | The next node/stage must expect exactly this pair. |
| Tone Mapping | Redistributes luminance when source and target dynamic ranges differ. None keeps the base transform without additional display-range mapping. | Inspect highlight roll-off, reference white and unwanted contrast changes. |
| Gamut Mapping | Determines what happens to colours outside the target gamut: compression and clipping behave fundamentally differently. | Inspect saturated LEDs/neon/skin edges on CIE scope and RGB Parade. |
| OOTF / White Point Adaptation | Advanced switches alter the more exact scene↔display and white-point behaviour. They are not universal recipe switches. | Document why the switch is enabled and which neighbouring transform expects it. |
Likely cause: Input/Output Gamma is wrong or the transform is being applied twice.
Fix: Check clip tags, RCM/ACES and neighbouring CST/LUT nodes; bypass technical transforms one at a time.
Likely cause: The target gamut is smaller than the source gamut and mapping is disabled or set to Clip.
Fix: Compare None / Saturation Compression on the problem colours and inspect the CIE scope.
Likely cause: Their pre-node decode/tag state differs: RAW settings, clip colour space or camera mode.
Fix: Verify Camera Raw / clip attributes before the grade, then compare CST.
In a manual scene-referred workflow, a common architecture is Input CST before the creative grade, grading in a wide working space, and Output CST after creative nodes. But in an RCM/ACES-managed project, the same CST can become a double transform.
Waveform/Parade reveal unexpected contrast/channel behaviour; CIE Chromaticity helps expose target-gamut excursions; HDR scopes matter when CST participates in HDR↔SDR conversion.
The key question before adding CST is: ‘who already performs the input transform and who performs the output transform?’ If the answer is RCM, ACES project settings, clip tagging or another node, rule out duplication first.
Input → Working → Output and double transforms.
Why Gamma in CST is signal encoding, not a contrast knob.
When luminance mapping is actually needed.
Compression versus clipping for out-of-gamut colours.
Panel names are cross-checked against the Resolve 21 screenshots already shown on each page. Where Blackmagic does not publish proprietary implementation math, the article describes documented signal semantics and observable behaviour rather than inventing an algorithm.
FAQ
Color Space Transform converts an image from one colour space/gamma description to another. It gives explicit node-level control over input, output, tone mapping and gamut mapping.
Project Color Management defines the broader colour pipeline for the whole timeline or project. CST is a local Resolve FX on a specific node, used when a manual technical transform is needed in one place.
Because they tell Resolve what the incoming signal really is. If either one is wrong, the transform starts from incorrect assumptions and the result cannot be trusted.
Use Tone Mapping when the conversion has to reconcile different luminance ranges or display expectations, for example HDR-to-SDR style situations. The right method depends on the destination and the behaviour you need.
It controls how colours that exceed the destination gamut are handled. Resolve 21 exposes None, Saturation Compression and Clip, which represent different strategies for containing saturated colours.
CST is the general-purpose colour-space/gamma conversion effect. ACES Transform is centred specifically on ACES transforms, while Chromatic Adaptation focuses on illuminant or white-point adaptation inside a colour pipeline.
Related Color pages
The canonical page for project-wide colour workflows, managed setups and where CST belongs in the bigger chain.
ACES-specific transform controls: ACES Version, Input/Output Transform and Gamut Compress.
A narrower white-point adaptation tool for source and target illuminants inside the colour pipeline.
Previous FX
The previous ordered Color FX page: Target Color with separate Hue, Saturation and Luminance compression controls.
