HSL
Keyer.

The primary eyedropper creates the initial HSL range. A click samples one value; a drag gathers a range. A short representative stroke is usually safer than a large sweep across a heterogeneous subject.

CheckCover variation in the target area first; avoid similar foreground colors unless required.

Expands the fully selected core with additional sampled colors. Use it for target regions that genuinely belong inside the key.

CheckAfter each addition, check skin, clothing and reflections: the range expands by color similarity, not only at the click location.

Removes mistakenly captured colors from the core selection. Useful when background and foreground partially overlap in HSL.

CheckIf many similar regions need subtraction, first reconsider the active H/S/L dimensions or rebuild the sample.

Expands the soft outer falloff around the selected range without turning the entire extension into a fully selected core. Useful for variation, motion blur and semi-transparent color transitions.

CheckSelection softness is not matte Blur Radius. Refine color falloff first, then blur the matte only if needed.

Tightens the transition zone when the soft outer range starts touching similar foreground colors.

CheckAn overly tight transition turns hair and motion blur into a stepped alpha.

Flips the polarity of the existing key so selected and unselected sides exchange roles without resampling.

CheckInvert does not fix holes, chatter or spill; it only changes the meaning of the same matte.

Clears the sampled range so the selection can be rebuilt without removing the entire FX instance.

CheckUse it after a strategy change instead of accumulating contradictory Add/Subtract strokes.

Includes hue in the key criteria. Hue-only is useful when the target maintains a recognizable hue despite large changes in brightness and saturation.

CheckIf subject and background share a similar hue, Hue alone is usually insufficient.

Includes color intensity. A saturation-only workflow can isolate strongly colored regions from gray or white areas regardless of hue and luminance.

CheckCheck skin and saturated practical lights; they may fall into the same saturation range.

Adds brightness as the third criterion. H+S+L is the most constrained combination; L-only turns the task into a luminance key.

CheckDo not enable Luminance by habit: uneven lighting can split a good chroma range into multiple brightness bands.

Pre-smooths problematic source structure before key evaluation. It can help with macroblocking or noise, but excessive filtering removes fine detail.

CheckKeep it minimal on clean footage; raise only until the matte stabilizes.

Pushes gray contamination in the transparent/background side of the matte toward pure black.

CheckWatch semi-transparent hair and motion blur: Clean Black can erode them quickly.

Densifies the bright foreground side of the matte toward pure white and closes small dark holes.

CheckToo much can thicken the opaque edge and destroy transparency.

More aggressively forces dark gray alpha toward black. The documented Resolve FX Key model uses a 0–100 range with a default of 0.

CheckUse after Clean Black; heavy clipping quickly turns a soft edge into a hard step.

More aggressively forces light gray alpha toward white. The documented range is 0–100 with a default of 100; lowering it makes more values fully opaque.

CheckDo not compensate for an overly narrow sample with White Clip; fix the selection first.

Softens the finished matte and can reduce fine chatter. It is a post-selection edge control, not sampling softness.

CheckUse the minimum sufficient value; heavy Blur creates halos and detached edges.

Biases edge processing inward or outward and can reposition the edge after blur.

CheckAlways check on bright and dark backgrounds; the bias may be subtle in a B/W matte.

Chooses Shrink, Grow, Opening or Closing. These are geometric operations on an existing alpha, not a new color selection.

CheckOpening helps against white specks; Closing helps against black holes. Heavy morphology destroys thin detail.

Circle, Square or Diamond define the morphology kernel and differ most around corners and diagonals.

CheckShape is not a quality selector; change it only when edge geometry genuinely benefits.

Sets the spatial scale of the morphology operation. Increase only until the specific defect is fixed.

CheckHair, straps, finger gaps and motion blur are the first places to check for collateral damage.

Repeats the morphology operation, increasing its effect without changing the operator type.

CheckRepeated passes accelerate topology loss; if large Iterations are required, the upstream key often needs repair.

None, Rectangle or Ellipse coarsely restrict the region the keyer needs to solve. Enabling a shape exposes geometry/softness controls and Open FX Overlay.

CheckUse for screen edges, stands, booms and set areas; do not trace a complex subject with it like roto.

Softens the Garbage Matte boundary; the official Resolve FX Key description specifies a default of 50 and a 0–100 range.

CheckA hard garbage edge can become visible when the subject or camera moves.

Inverts the coarse geometric matte while keeping the HSL selection logic inside the opposite frame region.

CheckRecheck the overlay after inversion; it is easy to leave the subject on the wrong side of the mask.

Numerically position and size the Rectangle/Ellipse and can be keyframed.

CheckIf the subject moves substantially, the coarse matte must follow or be wide enough to remain safe.

Alpha Highlight shows transparent regions as gray, Alpha Highlight B/W displays the black/white matte itself, and Final Composite shows the keyed result over the lower video track.

CheckTune in the order B/W → Alpha Highlight → Final Composite. A believable composite over a similar background does not prove the alpha is clean.

Determines whether alpha participates in output compositing. It is a common OpenFX control in the Resolve FX Key family.

CheckIf Final Composite unexpectedly resembles the source, check routing/output and Use Alpha before rebuilding the key.