RESOLVE FX · EXPLICIT SIGNAL CONVERSION
Color Space Transform.
Describe what the signal is.
Then say exactly what it must become.
CST is the node-level contract between one color-space/gamma state and another. The hard part is not opening dropdowns; it is assigning ownership correctly: source description, working state, display rendering, tone mapping, gamut mapping, OOTF, and white-point adaptation must not be duplicated by project management or neighboring transforms.
Input gamut + gamma
Working / display state
Tone · gamut · OOTF
Turn on “Project Color Management already owns transforms” in the lab while both CST stages remain active. The red warning is the core production failure this guide is designed to prevent.
Teaching model only. It visualizes signal-state ownership, transform order, and mapping responsibilities; it does not reproduce Resolve CST matrices, transfer functions, tone curves, gamut compression, or OOTF math.
Actual Resolve captures + signal-state teaching model; no claim of reproducing CST matrices, curves, or internal DRT math.
17 controls / states · 8 captures · 4 exercises01READ THE PIPELINE BEFORE THE PICTURE
CST is not a Log-to-Rec.709 button. It is an explicit before/after signal contract.
Once the four signal fields are correct, Tone/Gamut Mapping and Advanced controls become understandable. If the contract is wrong, every downstream decision is built on a false premise.
CST starts with a signal contract, not a “nice-looking” preset
The four top fields — Input Color Space, Input Gamma, Output Color Space, and Output Gamma — describe what the signal is before the node and what it should become after it. If the input description is wrong, the math faithfully transforms the wrong premise. Camera gamut/log therefore comes from metadata, camera documentation, or a verified pipeline, not from guessing based on Viewer contrast.
Tone Mapping and Gamut Mapping are separate responsibilities
Tone Mapping Method redistributes luminance and dynamic range; Gamut Mapping Method handles colors that do not fit the destination gamut. They often coexist in an output CST but solve different problems and are verified with different scopes: Waveform/HDR for luminance, Vectorscope/CIE for chroma. Turning both on by habit is not a sound signal-management strategy.
Node placement determines what Output means
An input CST typically converts camera-native material into a working space, the creative grade lives inside that space, and an output CST converts the working state into a display/delivery state. Blackmagic’s Colorist Guide explicitly demonstrates a two-CST workflow and notes that the first CST should map to a working space rather than directly to deliverable output. That keeps the transform visible, bypassable, and debuggable.
Advanced is not a set of look switches — Apply Forward OOTF represents an intentional scene-referred → display-referred relationship; Apply Inverse OOTF does the reverse. Use White Point Adaptation performs chromatic adaptation between differing white points. These controls must follow the actual pipeline. If the image only “looks better” after a random OOTF toggle, audit the signal domain and neighboring transforms first.
02THE REAL RESOLVE 21 PANEL
Seventeen visible or conditional controls, grouped by responsibility rather than screen position.
The screenshots are evidence of the UI. The explanations answer the harder question: what signal decision does each control own, and how do you verify it?
Signal contract
Four fields must describe the real state before and after the node.
- Input Color Space
Describes the input gamut/primaries. Use timeline is safe only if upstream processing has not changed the signal state relative to the timeline.
VERIFY / WATCHAfter an upstream CST, DCTL, or LUT, the signal may no longer match the timeline; Use timeline can then describe it incorrectly.
- Input Gamma
Describes the input transfer function/tonal encoding — camera log, display gamma, PQ/HLG, and other options.
VERIFY / WATCHDo not choose gamma from visual contrast. A wrong value changes the shape of all downstream tonal math.
- Output Color Space
Defines the destination gamut/primaries in which downstream nodes or the display pipeline should receive the signal.
VERIFY / WATCHFor an input CST, output is commonly a working space; for an output CST, a display/delivery space. Node context matters more than the preset name.
- Output Gamma
Defines the destination transfer function and combines with Output Color Space to form the complete output state.
VERIFY / WATCHDisplay gamma, camera log, and scene-linear states are not interchangeable. Validate Color Space + Gamma as one contract.
- Swap
Swaps the input and output pairs. It is useful when building the inverse CST, for example when a second node should reverse the direction of the first transform.
VERIFY / WATCHSwap does not prove the whole pipeline is mathematically invertible: tone/gamut mapping, LUTs, and creative grading can make a round trip asymmetric.
Dynamic range
Tone Mapping controls the luminance transition; custom nits define its actual operating points.
- Tone Mapping Method
Chooses the luminance-remapping policy: None, Clip, Simple, Luminance Mapping, DaVinci, or Saturation Preserving.
VERIFY / WATCHNone and Clip do not provide a soft roll-off. DaVinci/Luminance Mapping/Saturation Preserving serve different rendering goals — compare highlight detail, reference white, and color at the extremes.
- Use Custom Max. Input · Max. Input (nits)
Lets you explicitly define the assumed peak of the input signal instead of relying on an automatic/contextual tone-mapper value.
VERIFY / WATCHThe nit value should come from mastering/source context. It is not another Exposure control.
- Use Custom Max. Output · Max. Output (nits)
Sets the target peak for tone mapping. Blackmagic demonstrates a practical case where a 1000-nit PQ signal is mapped by CST to 250 nits using Custom Max. Output.
VERIFY / WATCHDo not pick target peak by eye from one Viewer. Cross-check the display/master target and HDR scopes.
- Adaptation
A tone-mapping-model parameter related to adaptation to scene/image brightness. The shown Inspector uses the typical 9.00 default.
VERIFY / WATCHThis is not a generic brightness/exposure slider. Very bright images may retain more highlight detail at higher values; adjust it only after the nit endpoints are correct.
Color volume
Gamut Mapping manages saturation/chroma, not luminance.
- Gamut Mapping Method
The current Resolve capture exposes None, Saturation Compression, and Clip. None applies no extra remap, Saturation Compression smoothly compresses extreme chroma, and Clip creates a hard boundary.
VERIFY / WATCHFor LED/neon and wide-gamut material, compare Vectorscope/CIE and smooth gradients. Hard Clip can collapse differences among nearby saturated colors.
Signal-domain switches
Advanced controls change domain/white-point behavior and require an explicit reason.
- Use HDR Standard Conversion
A conditional HDR control shown disabled in the current screenshot. Availability depends on the chosen input/output combination and HDR transition.
VERIFY / WATCHDo not infer behavior from a grayed checkbox: if the control is unavailable for the current pair, do not treat it as mandatory for every CST.
- Use HDR 203 Nits Diffuse White
A conditional option for SDR↔HDR contexts tied to BT.2100-style 203-nit diffuse white. It is also disabled in this capture.
VERIFY / WATCHUse it only when the selected signal conversion actually requires that reference-white mapping; it is not a generic HDR enhancement.
- Apply Forward OOTF
Enables a scene-referred → display-referred relationship. This is a display-rendering decision, not creative contrast.
VERIFY / WATCHIf project Color Management or a neighboring output transform already performs scene→display rendering, another Forward OOTF may duplicate it.
- Apply Inverse OOTF
Performs the reverse display-referred → scene-referred relationship.
VERIFY / WATCHDo not enable Forward and Inverse as a balancing pair. Each toggle must correspond to a real domain transition.
- Use White Point Adaptation
Applies chromatic adaptation to reconcile differing white points between input and output spaces. The manual gives P3-D60 → P3-D65 as an example.
VERIFY / WATCHDisable it only deliberately, for example when you need to view the input white point unaltered in the output space. It is not a brightness or temperature control.
03NODE OWNERSHIP
Two-CST manual management is clean only when project management is not doing the same job.
Blackmagic’s Colorist Guide demonstrates an input CST into a working space and a later output CST. In a managed project, the same conceptual stages may already belong to RCM/ACES.
Convert into the working space
Describe the camera input exactly, then output to the chosen working color space/gamma. Keep display rendering out of this input stage unless the pipeline specifically requires it.
This is a signal-ownership diagram, not a mandatory node template. The exact node count can vary; the invariant is one clearly documented owner for each input, working, display, tone, gamut, OOTF, and white-point conversion.
04FOUR PRODUCTION EXERCISES
Practice the transform as a pipeline decision, not as a preset recipe.
Camera log → DaVinci Wide Gamut / Intermediate
Build a clean input CST that moves camera-native material into a wide working space without display rendering.
SETUPUse a clip with verified camera gamut/log metadata. The creative grade will happen after this node.
- 01
Set the actual camera Input Color Space and Input Gamma.
- 02
Set Output Color Space to DaVinci Wide Gamut and Output Gamma to DaVinci Intermediate.
- 03
For a clean input transform, start with Tone Mapping = None and Gamut Mapping = None; do not enable OOTF without a scene→display reason.
- 04
Check node bypass and scopes: the result should be a working scene-referred state, not a finished Rec.709 look.
Camera-native material enters a predictable working space, making creative operations between input/output transforms reproducible.
Working space → Rec.709 / Gamma 2.4
Build a transparent output CST for SDR delivery.
SETUPBefore this node, the signal is already in DaVinci Wide Gamut / Intermediate and the creative grade is complete.
- 01
Input must exactly match the output of the working pipeline.
- 02
Set Output Color Space to Rec.709 and Output Gamma to Gamma 2.4 for the relevant delivery context.
- 03
Choose Tone/Gamut Mapping only when the wide dynamic/color volume actually requires roll-off/compression.
- 04
Check Waveform, Vectorscope, and saturated stress colors; the output transform should not hide clipping with another creative correction.
The output node has a clear technical role and can be bypassed/replaced independently for another master.
HDR monitor mapping with Custom Max. Output
Limit peak for a particular HDR monitor while preserving an otherwise identity gamut/gamma transform.
SETUPThe logic mirrors Blackmagic’s Immersive Workflow Guide: PQ input/output remain the same while tone mapping lowers the peak.
- 01
Set identical Input/Output Color Space and Gamma matching the real PQ signal.
- 02
Use DaVinci Tone Mapping and enable Use Custom Max. Output.
- 03
Enter the target monitor peak, for example 250 nits in the relevant monitoring workflow.
- 04
Verify with HDR scopes and an external reference display; do not use the Viewer as the only validation.
One CST performs monitor mapping specifically, rather than replacing the creative grade or the wider color-management pipeline.
Diagnose a double transform in RCM/ACES
Find a case where project-level management already performs the transform repeated by a node-level CST.
SETUPUse a correctly tagged clip in a Color Managed or ACES project that looks suspiciously contrasty or oversaturated.
- 01
Bypass the CST and compare scopes/Viewer.
- 02
Trace ownership of every conversion: input transform, working space, output transform.
- 03
Remove the duplicated stage instead of compensating with Lift/Gamma/Gain.
- 04
Restore the creative grade only after one clear transform path has been recovered.
The pipeline again has one owner for each technical conversion, so the image no longer needs creative repairs on top of duplicated math.
05TOOL BOUNDARIES
CST overlaps several color-management systems. The safe choice depends on who should own the conversion.
| Tool | Use it when | Do not confuse it with |
|---|---|---|
| Color Space Transform | Explicit node-level Color Space/Gamma → Color Space/Gamma conversion with optional tone/gamut mapping. | Do not use it as a random look selector or a second project-level transform. |
| Resolve Color Management | Project/timeline-level ownership of input, working, and output transforms across many clips. | Do not add a redundant CST when RCM already performs the same conversion. |
| ACES Transform | Actual ACES workflow using Academy-defined transforms. | The manual warns that ACES options inside CST are colorimetric conversions and do not replace ACES Transform for a real ACES pipeline. |
| Chromatic Adaptation | A focused white-point/illuminant adaptation task. | It does not replace a full gamut + gamma conversion CST. |
| Gamut Mapping | A dedicated remapping stage when full input/output conversion is not needed. | Do not confuse remapping with explicit signal-state conversion. |
06DIAGNOSE SIGNAL STATE FIRST
When CST creates a problem, adding another correction is usually the wrong first move.
01The image is too contrasty or appears normalized twice+
First check whether RCM/ACES or an input LUT already performs the same input/output transform. A double transform is usually fixed by removing a redundant technical stage, not by applying an opposing creative correction.
02Log still looks wrong even with the “right” Input Color Space+
Color Space and Gamma form a pair. A correct camera gamut with the wrong log transfer function is as wrong as the correct log with wrong primaries. Verify both against metadata/documentation.
03HDR→SDR clips highlights+
Check Tone Mapping Method and the actual Max Input/Output nit values. Clip/None do not create a soft roll-off. With DaVinci/Luminance Mapping, evaluate Adaptation and scopes after the endpoints are correct.
04Saturated LED/neon colors collapse into similar patches+
This is a gamut problem. Compare None / Saturation Compression / Clip on Vectorscope or CIE Chromaticity. Hard Clip can destroy separation that smoother compression preserves.
05White point shifts between P3-D60 and P3-D65+
Check Use White Point Adaptation. Enabled, it adapts the input white to the output white; disabled, it intentionally preserves the input white point inside the output space.
06Forward/Inverse OOTF only “fixes” the image by eye+
That indicates unclear domain ownership. Forward should correspond to scene→display and Inverse to display→scene. Trace neighboring transforms and project color management instead of tuning toggles by taste.
Waveform / HDR scopes
Verify tone mapping, reference white, Max Input/Output behavior, and highlight roll-off. A prettier Viewer is not proof of a correct luminance transform.
Vectorscope / CIE
Use saturated LEDs, neon, and known brand colors as stress tests for gamut compression or hard clipping.
Node bypass / ownership audit
Bypass CST and inspect project CM, adjacent LUT/DCTL stages, and clip tags. Double transforms reveal themselves faster through ownership than through knob-tuning.
07BEFORE DELIVERY
A correct CST should be explainable in one sentence: “this signal becomes that signal here.”
08FAQ
Practical Color Space Transform questions
What exactly does Color Space Transform do?+
CST explicitly converts a signal from one Color Space/Gamma pair to another and can optionally apply tone mapping, gamut mapping, OOTF, and white-point adaptation. It is a technical transform, not a creative look.
When is Use timeline safe?+
Only when the actual signal state at that point matches the corresponding Timeline Color Space/Gamma. After an upstream CST, LUT, or DCTL, that assumption may no longer be true.
What is Swap for?+
Swap quickly reverses the input and output pairs and is useful for building an inverse CST. Tone/gamut mapping and other nonlinear stages can still make the full round trip non-identical.
How do I choose Tone Mapping Method?+
First decide whether dynamic-range remapping is needed at all. Then compare methods against the target display, highlight/shadow roll-off, reference white, and color at the extremes rather than overall “nicer contrast.”
Are Saturation Compression and Clip the same?+
No. Saturation Compression smoothly redistributes extreme chroma and aims to preserve relationships among colors; Clip creates a hard boundary and can collapse differences.
Should Forward OOTF always be enabled?+
No. It is appropriate only for an intentional scene-referred → display-referred transition in that node. If display rendering is already handled by RCM/ACES or another transform, an extra OOTF can duplicate the processing.
Can I use ACES options inside CST instead of ACES Transform?+
For an actual ACES workflow, the manual recommends ACES Transform: CST performs ACES conversion colorimetrically rather than using the Academy-defined transform set in the same way.
Sources and verification boundaries
Control names and behavior were cross-checked against the current Resolve 21 manual mirror, Blackmagic’s Colorist Guide, Blackmagic’s Immersive Workflow Guide, and the real Resolve screenshots already stored in this project. The teaching lab intentionally stops at signal-state logic and does not claim to emulate Resolve’s internal transform math.