RESOLVE FX · LIGHT · EMITTER FIRST
Glow.
Do not blur the frame.
Build light from believable emitters.
Glow is most predictable as a staged light pipeline: isolate source regions, shape the primary halo, add a second environmental scale only when needed, introduce atmosphere, then decide frame behavior and recompositing. Every downstream control becomes easier once the emitter map is clean.
Threshold + Alpha
Shape + energy
Secondary + Air
Switch the lab to Source Regions before changing Spread. That one habit separates emitter-selection problems from halo-shape problems—the most important diagnostic distinction in Glow.
Teaching approximation, not Blackmagic OFX: emitter extraction, blur kernels, channel spread, Secondary Glow, Atmosphere and compositing are intentionally simplified. Slider values do not claim Resolve parameter ranges. Use the lab to understand cause and order, then judge the real Glow in Resolve on moving footage.
Seven native Inspector captures + an independent teaching approximation.
Source · Halo · Environment · Mix01SOURCE BEFORE BLOOM
Glow is three decisions: who emits, how the halo spreads, and how it returns to the shot.
Thinking this way prevents the common “soft-focus over everything” failure. Threshold and alpha define causality; Spread and color define the optical-looking response; Secondary Glow, Atmosphere and Advanced Controls define environment and presentation.
Emitter map
Glow does not begin with blur. It begins by deciding which pixels count as light emitters. Source Regions, Input Alpha and Shine Threshold form the upstream gate for the entire effect.
Halo geometry
After selection, the primary glow gets a spatial response: Spread, H vs V Ratio and relative RGB radii define shape; Gain/Gamma/Saturation/Color Filter define energy and color.
Environment + recomposite
Secondary Glow adds a second spill scale, Atmosphere breaks perfect smoothness, and Advanced Controls resolve frame edges, blend mode, source recovery and final mix.
Feature references: Blackmagic · Resolve 20.1 Secondary Glow + Atmosphere ↗ · Resolve 20.2 Glow From Alpha ↗
02THE ACTUAL RESOLVE 21 PANEL
Seven native captures anchor every current control group and menu used here.
Values visible in screenshots are evidence of one Inspector state, not recommendations and not declared parameter ranges. The stable meanings of Secondary Glow, Atmosphere and Glow From Alpha are cross-checked against Blackmagic feature guides.
01 · SOURCE REGIONS
Decide what is allowed to emit Glow before shaping it.
- Source Regions · Glow Alone · Final Result
The three views change diagnostic presentation of the same effect. Source Regions shows emitter selection, Glow Alone isolates the generated glow layer, and Final Result returns the recomposite.
CheckCheck Threshold and Input Alpha in Source Regions, halo shape in Glow Alone, and integration only in Final Result.
- Input Alpha · Masks The Source Regions · Is Used For Compositing · Is The Source Of The Glow
Input Alpha changes embedded-alpha routing. It can constrain automatic source regions, participate only at compositing, or become the emitter map itself.
CheckIs The Source Of The Glow requires a meaningful alpha/matte; arbitrary alpha produces an arbitrary emitter map.
- Shine Threshold
Defines the luminance threshold for source-driven emitters. A low threshold pulls in skin, walls and texture; a high threshold keeps only strong highlights and light sources.
CheckIf the whole shot turns into soft focus, return to Shine Threshold before Spread, Gain or Global Blend.
02 · SHAPE AND SPREAD
Shape the spatial halo only after the emitter map is clean.
- Spread
Sets primary-halo extent: how far light travels from source regions. It is a geometric control, not a brightness control.
CheckFind halo size first, then raise Gain. Excessive brightness can hide the real spread.
- H vs V Ratio
Changes the relationship between horizontal and vertical spread. Neutral placement gives a symmetric halo; offsets create directional or anamorphic character.
CheckJudge it on compact sources; anisotropy is harder to read on large white areas.
- Relative Spread Red · Relative Spread Green · Relative Spread Blue
Lets each RGB channel use its own relative radius. Equal values keep the halo neutral; offsets create chromatic separation.
CheckKeep channels close for naturalistic bloom. Large offsets quickly turn light into a stylized RGB effect.
03 · COLOR AND COMPOSITE
Keep primary-glow energy separate from its shape.
- Gain
Controls glow-layer energy/brightness after source selection and spatial spread. Raising Gain should not be used to enlarge the halo.
CheckIf the halo size is right but too weak, change Gain; if the size is wrong, return to Spread.
- Gamma
Changes intensity distribution inside the glow response and the perceived falloff from the bright core toward the outer halo.
CheckInspect Glow Alone; Gamma can be mistaken for overall brightness when judged only in Final Result.
- Saturation
Controls primary-glow color intensity. Source-emitter color and Color Filter interact, so high Saturation is not always necessary.
CheckOn skin and white emitters, watch for unwanted color contamination of surrounding tones.
- Color Filter
Tints the primary halo through the swatch/eyedropper. Useful for art-directing neon, displays and reflected light.
CheckBuild a correct neutral glow first, then tint it. Color Filter should not hide incorrect source selection.
04 · SECONDARY GLOW + ATMOSPHERE
Separate the second light scale from environmental variation.
- Add Secondary Glow · Gain · Spread · Color Filter
Secondary Glow is a second halo over the primary with independent Gain, Spread and Color Filter. Blackmagic added this toolset in Resolve 20.1 specifically to separate inner and outer glow.
CheckOuter glow is usually broader and weaker than inner glow. Equal strength often reads as a doubled blur.
- Add Atmosphere · Strength · Detail · Scale · H vs V Ratio · Evolution · Seethe
Atmosphere adds spatial and temporal variation to an already-formed glow: Strength controls modulation amount, Detail/Scale its structure, H vs V Ratio anisotropy, and Evolution/Seethe change over time.
CheckFirst build a convincing static Glow with Atmosphere off. Add variation afterward and inspect several seconds of motion.
05 · ADVANCED + FINAL MIX
Frame behavior, recompositing and final amount belong last.
- Glow Framing · Reflect In Camera · Vignette
Glow Framing defines how generated glow behaves near frame boundaries. The supplied menu confirms Reflect In Camera and Vignette.
CheckCompare on an emitter close to leaving the frame; the image center may show little difference.
- Composite Type · Normal · Add · Subtract · Difference · Multiply · Screen · Overlay · Hard Light · Softlight · Darken
Composite Type chooses how generated glow is blended. The capture shows the listed visible portion of the menu, with more items continuing below. Add and Screen are useful starting points, but this is a creative decision, not a single correct mode.
CheckDo not compensate for an unsuitable composite mode with random Gain changes. Choose blend behavior first, then amount.
- Opacity
Attenuates the glow layer at recompositing while preserving the internal geometry of the halo.
CheckIf Glow is correctly shaped but too strong, Opacity is often safer than rebuilding Threshold/Spread.
- Invert Effect
Inverts effect behavior for unusual dark-to-light treatments. This is a creative branch, not a repair for normal bright-source glow.
CheckFor normal optical bloom, leave it off and repair source selection upstream.
- Source Recovery
Restores readable source-core detail after strong bloom without removing the outer halo itself.
CheckUse it on lamps, white text and speculars when Glow has erased source structure.
- Global Blend · Blend
Final mix of the entire Resolve FX instance with the source frame. It is the last amount control after source, halo, atmosphere and recompositing.
CheckBlend should not hide a bad Threshold, clipped framing or unsuitable composite mode.
03ALPHA ROUTING + DIAGNOSTIC VIEWS
Input Alpha changes the signal path; Source Regions and Glow Alone change what you inspect.
Resolve 20.2 added explicit “Is The Source Of The Glow” behavior to Glow and related Light FX. That makes alpha routing a real source-design decision rather than a finishing detail.
| Input Alpha | Role | Best view |
|---|---|---|
| Masks The Source Regions | Alpha gates where brightness-selected emitters are allowed to exist. | Source Regions |
| Is Used For Compositing | Source detection remains image-driven; alpha is applied when the generated result is recomposited. | Final Result |
| Is The Source Of The Glow | Embedded alpha itself becomes the emitter map—useful for custom VFX/Fusion mattes. | Source Regions → Glow Alone |
Source Regions
WHO EMITS?Judge Input Alpha and Shine Threshold without being distracted by halo beauty.
No accidental walls, skin or textures.
Glow Alone
WHAT LIGHT WAS BUILT?Judge Spread, RGB separation, Gain/Gamma, Secondary Glow and Atmosphere outside the source image context.
The halo should make sense on black.
Final Result
DOES IT BELONG?Only here judge Composite Type, Opacity, Source Recovery and Global Blend in context.
Integration is a final-stage question.
04ONE EMITTER, MULTIPLE SCALES
Primary Glow, Secondary Glow and Atmosphere should solve different visual problems.
Resolve 20.1 made this separation explicit: Secondary Glow creates a second halo scale, while Atmosphere modulates the light to simulate imperfect air. Neither is a replacement for the primary source/shape stage.
Primary
Threshold → Spread → GainTight response physically tied to the emitter. This layer establishes the identity of the light.
Fix this layer before enabling the others.
Secondary
Gain · Spread · Color FilterBroader environmental spill with independent color—especially useful when the surrounding surface changes the apparent outer glow.
Usually broader and weaker than primary.
Atmosphere
Strength · Detail · Scale · SeetheVariation in the medium through which the generated light appears to travel.
Validate in motion, not on a still.
Recompose
Framing · Type · Recovery · BlendPresentation stage: frame edges, blend behavior, source-core readability and final amount.
Do not use it to hide upstream mistakes.
The hero lab approximates this causal structure with simple deterministic blur and modulation kernels. It deliberately does not claim to reproduce Blackmagic’s private OFX kernels, parameter scales, framing math or exact compositing internals.
05FROM EMITTER MAP TO FINAL MIX
Build upstream decisions first; diagnose the stage that actually failed.
The graph separates construction from repair. It stops a common mistake: lowering the whole effect when the real issue is a dirty emitter map, wrong halo geometry or unstable Atmosphere.
Isolate believable emitters
Use Source Regions, Input Alpha and Shine Threshold. Do not move downstream until walls, skin and unrelated highlights are excluded.
Teaching signal flow, not a literal Blackmagic OFX graph. The durable rule is emitter selection first, primary geometry/energy second, Secondary Glow and Atmosphere third, framing/recompositing last.
Related workflows: Color node pipeline ↗ · Fusion Glow ↗
06BUILD REPEATABLE GLOW
Four exercises with acceptance conditions—not magic values.
Glow depends on exposure, resolution, emitter size and delivery transform. The transferable skill is the order of decisions and a visible acceptance condition.
Neon: tight core + coloured wall spill
Separate the emitter light from the broader reflected halo.
PrepareA shot with a bright colored sign or LED near a colored wall.
- 01
In Source Regions, raise Shine Threshold until the sign remains the emitter rather than the entire wall.
- 02
Build a compact primary halo with Spread/Gain in the emitter color.
- 03
Enable Secondary Glow, make it broader and weaker, and sample/tint it toward the wall color when useful.
- 04
Return to Final Result and reduce Opacity/Global Blend only after the two-scale light structure is correct.
The core stays readable; outer spill is broader, softer and reads as environmental illumination rather than a duplicate blur.
Specular bloom without mush
Give highlights optical breathing room without making midtones glow.
PrepareA product or beauty shot with controlled specular highlights.
- 01
Open Source Regions and raise Shine Threshold to a clean map of strong highlights.
- 02
Keep Spread moderate and H vs V Ratio neutral.
- 03
Tune Gain/Gamma in Glow Alone, then compare Add and Screen in Final Result.
- 04
If the core loses structure, use Source Recovery rather than lowering Threshold further.
Glow is visible around speculars while skin/material texture and midtone local contrast remain intact.
Use a VFX matte as the emitter map
Generate light from a prepared object even when its RGB is not the brightest region in the shot.
PrepareRGBA/Fusion output with a meaningful alpha for a sign, interface or VFX object.
- 01
Choose Input Alpha → Is The Source Of The Glow.
- 02
Inspect Source Regions: the emitter map should follow alpha rather than unrelated RGB highlights.
- 03
Shape Spread/Gain, then add Secondary Glow if the shot needs a broader spill.
- 04
In Final Result, compare the alpha-driven setup with Masks The Source Regions to understand the routing difference.
Glow remains tied to the prepared matte and controllable independently of nearby RGB brightness.
Atmosphere without temporal boiling
Add living air around light without turning the noise pattern into the subject.
PrepareAn already-correct static Glow on a shot with camera or source motion.
- 01
Disable Add Atmosphere and confirm the base Glow works on its own.
- 02
Enable Atmosphere at low Strength, then match Detail/Scale to the shot scale.
- 03
Introduce Evolution/Seethe one at a time and judge several seconds rather than a still.
- 04
If variation steals attention from the emitter, reduce Atmosphere rather than Global Blend for the entire FX.
The halo breathes subtly and non-uniformly, but the viewer perceives light rather than procedural noise.
07CHOOSE THE LIGHT MODEL
Glow is the general bloom tool—not the answer to every highlight problem.
Choose the simplest physical/visual model that matches the shot. Stacking specialized Light FX without a reason usually reduces clarity rather than increasing realism.
| Tool | Visual model | Use when |
|---|---|---|
| Glow | Emitter map → soft bloom / halo | You need general highlight bloom, neon spill, alpha-driven glow or atmospheric variation. |
| Halation ↗ | Film-style light scatter and dye-layer reflection | The look should read as film emulsion behavior rather than generic digital bloom. |
| Aperture Diffraction ↗ | Virtual aperture → structured starburst | Aperture shape and diffraction structure are visible parts of the optical signature. |
| AI Cinematic Haze ↗ | Depth-aware atmosphere, halos and rays | The light/air relationship must change with scene depth rather than remain a flat image-space halo. |
08DIAGNOSE THE STAGE, NOT THE AMOUNT
A bad Glow usually points to a specific stage.
Source Regions and Glow Alone are diagnostic instruments. Use them to remove context before deciding whether the source, halo, atmosphere or recomposite is wrong.
01Glow appears across almost the entire frame.
Likely cause: Shine Threshold is too low or Input Alpha routing admits unwanted areas.
Repair: Open Source Regions. Repair Input Alpha and Threshold before reducing Spread, Gain or Global Blend.
02An emitter near the frame edge produces odd clipped or reflected halo behavior.
Likely cause: Glow Framing does not match the intended edge behavior.
Repair: Compare Reflect In Camera and Vignette on the same edge source; judge the boundary rather than the image center.
03The halo looks good, but the bright core has become a featureless white blob.
Likely cause: Gain/Composite Type/Opacity is too aggressive with insufficient Source Recovery.
Repair: Check Glow Alone, restore Source Recovery and reduce Opacity if needed. Do not rebuild the source matte when it is already correct.
04Atmosphere looks attractive on a still but boils in motion.
Likely cause: Strength/Detail/Evolution/Seethe are too visible for the scale of the shot.
Repair: Review several seconds. Reduce Atmosphere spatial/temporal modulation independently and keep Global Blend as the final control.
09FAQ
Practical Resolve FX Glow questions.
How is Glow different from Halation?
Glow is a general source-driven light bloom. Halation models more specific film-style scatter and dye-layer reflection, so its color and structure follow a different model.
Why use Secondary Glow when Spread already exists?
One Spread defines one spatial scale. Secondary Glow creates a second independent scale with its own Gain, Spread and Color Filter—for example a bright red inner halo plus a broad blue wall spill.
When should I choose Is The Source Of The Glow?
When embedded alpha or a Fusion/VFX matte describes the emitter map better than RGB brightness. Resolve 20.2 added this alpha-source behavior to Resolve FX Light.
Why not simply reduce Global Blend when Glow looks wrong?
Because Blend attenuates the finished FX and can hide the cause. A bad emitter map, oversized Spread, unsuitable Composite Type or boiling Atmosphere should be repaired at the stage that created it.
10SOURCES & BOUNDARIES
Current UI labels come from native captures; new Secondary Glow, Atmosphere and alpha-source behavior are cross-checked against Blackmagic documentation.
The interactive lab is intentionally separate from those sources: it is a deterministic educational approximation for cause/effect, not a reverse-engineered implementation of Resolve FX Glow.