Despill

Resolve 21 places Despill in Resolve FX Color. Unlike neighboring DCTL, Dehaze and False Color entries, its manual heading is not marked Studio Version Only. On the DaVinci Resolve Fusion page, Resolve FX appear as normal 2D processing plugins; native Resolve FX are not available in standalone Fusion Studio.

Spill is not leftover green/blue background geometry in the alpha. It is physical screen light reflected onto the foreground. A key can remove the background perfectly while green or blue cast remains on hair, skin, white fabric, glass or metallic reflections. Despill addresses that RGB contamination.

Despill is therefore not a keyer and should not be used to repair silhouette shape, holes, chatter or missing hair detail. Stabilize the key/matte first and judge edge color second. Lowering green or blue cannot repair incorrect alpha geometry.

Key Color is a discrete Red, Green or Blue choice rather than an arbitrary color eyedropper. Green is the conventional green-screen case, Blue handles blue-screen spill, and Red is for genuine red contamination. Selecting the wrong channel can damage legitimate scene color while barely touching the actual spill.

Strength controls the amount of despill. Resolve 21 states that 1.000 equals the full despill behavior of the former 3D Keyer checkbox. Treat that as a reference endpoint rather than a universal goal: variable Strength exists specifically so more original color information can be retained when the context permits it.

The manual gives an important production example: less despill can be appropriate when the new composited background is also green. The same principle applies to legitimate green/blue props, practical lights, fabric, eyes, reflections and environmental color that should not be neutralized merely because they overlap the selected channel.

On the Fusion page, the optional Effect Mask is the normal spatial gate for the Resolve FX result. It answers where calculated Despill may contribute; it does not choose the spill channel and it does not replace the subject's alpha/key. This is useful when contamination is local but other parts of the foreground contain legitimate matching color.

Output remains a normal 2D image stream. The documented job is color cleanup, so inspect RGB and alpha separately: bypassing Despill should reveal a color problem, not magically fix matte geometry. Any alpha cleanup belongs in the keyer/MatteControl stage before or independently of Despill.

Despill exposes only two effect-specific Controls in the captured Fusion Inspector: Key Color and Strength. Do not confuse these with common host/Settings controls. Establish the technically correct Key Color and Strength first; use any host Blend/bypass only as a final perceptual A/B rather than a substitute for correct spill selection.

A reliable order is key/matte → realistic final/test background → Key Color → moderate Strength → skin/hair/transparency playback check → optional local Effect Mask → final grade. Spill is much easier to judge over the environment the foreground will actually inhabit than over transparency or the original chroma screen.

If skin becomes gray, magenta or unnaturally warm, suspect over-despill or an overly broad spatial region before adding more correction. Back Strength down first, isolate the truly contaminated edge if necessary, and only then use a separate color correction for creative integration.

Despill is especially useful after ChromaKeyer/DeltaKeyer/3D Keyer, with externally generated keys/masks, or after roto when alpha already exists but foreground RGB still carries screen-light contamination. Its strength is deliberately narrow: remove reflected screen color without turning color cleanup into another keying stage.

Judge Despill only after the foreground has actually been separated from the screen; otherwise the screen itself dominates RGB and hides the distinction between reflected spill and background color.

Despill repairs foreground color rather than matte geometry. Holes, chatter, clipped hair and motion-blur silhouette errors remain keyer/MatteControl/roto problems.

Key Color chooses the primary screen channel to neutralize. There is no arbitrary hue picker or semantic detector, so the node cannot know whether a given green pixel is contamination or a legitimate subject color.

Green-screen spill can appear cyan-green on skin, cold on white fabric, or strong on metal; the selected Key Color still follows the physical screen-light source.

Blue-screen spill can push warm skin and translucent edges noticeably; excessive Strength can overcompensate toward yellow/orange.

Red is for real red-screen/reflection contamination and should not be used as a generic red-skin reducer.

Strength 1.0 is the documented full-despill reference, useful as an A/B endpoint rather than a mandatory production value.

The correct Strength is defined by whether spill stops reading as screen contamination in the final composite, not by reducing the selected channel to zero.

A replacement background with similar color can justify some residual spill because it helps environmental integration.

On an oppositely colored replacement background, even weak residual spill can become more obvious, so Strength cannot be judged without composite context.

Hair, translucent fabric, glass and motion-blurred edges mix foreground, background and screen light; over-despill can make these areas gray or lifeless.

White/gray clothing is a useful QC reference because screen cast is visible there and over-correction becomes obvious quickly.

Skin is another mandatory QC reference: a technically clean edge does not justify unhealthy skin hue.

Metallic/glossy props reflect the real environment and may contain legitimate green/blue information that Despill cannot identify semantically.

Effect Mask is the appropriate tool when spill is local, allowing stronger cleanup at contaminated edges without damaging legitimate color elsewhere.

Effect Mask is not the subject alpha and does not replace the key/matte.

A soft Effect Mask feather is important because a hard boundary in color neutralization can be more visible than the original spill.

If environmental color matching is needed after cleanup, use a separate ColorCorrector/grade rather than forcing Strength to perform both technical and creative jobs.

Despill before Merge keeps the operation scoped to the foreground; applying it after Merge can unintentionally change the replacement background.

Common Resolve FX Blend is a final host-level mix, not a substitute for Strength.

If an upstream keyer already performs despill, adding standalone Despill can create over-correction; verify what changed RGB upstream.

An externally generated matte can be perfect while RGB still contains heavy screen contamination, which is a strong use case for standalone Despill.

Despill is a compositing correction rather than a mathematically exact recovery of the object's pre-shoot color.

Strong neutralization can expose chroma/compression artifacts on heavily compressed material, so inspect at 100%.

Downstream saturation/contrast can make weak residual spill visible again; final QC should happen after major color decisions.

For automation, Key Color enum and Strength serialization should be confirmed from a target-build .setting/.comp.

Static documentation captures the documented behavior while exact host Blend/alpha preservation and runtime behavior remain live-certification items.