Compositing technique that removes unwanted color contamination from greenscreen or bluescreen footage – neutralizes the reflected screen color that bleeds onto subjects' skin, hair, and clothing to create clean, natural-looking composites.
What is Despill?
Despill is a compositing technique that removes unwanted color contamination (color spill) from greenscreen or bluescreen footage. The reflected hue of the screen, which bleeds onto skin, hair, and clothing, is neutralized.
Why Does Spill Occur?
| Cause | Description |
|---|---|
| Reflection | Light reflects off the screen |
| Proximity | Closer proximity, more spill |
| Screen Brightness | Overexposure amplifies |
| Material | Reflective surfaces |
| Hair/Fringes | Translucent |
Despill Methods
| Method | How it Works |
|---|---|
| Subtractive | Subtracts green/blue |
| Average | Replaces with average R/B |
| Replace | Swaps with neutral color |
| Luminance-Based | Preserves brightness |
| Edge-Only | Only on edges |
Software Tools
| Software | Despill Tool |
|---|---|
| Nuke | IBKGizmo, Despill, KeyLight |
| After Effects | Keylight, Primatte |
| DaVinci Resolve | Qualifier, Color Page |
| Fusion | Spill Suppression |
| Silhouette | Advanced Despill |
Typical Problems
| Problem | Solution |
|---|---|
| Skin Goes Gray | Subtle despill |
| Halos | Matte refinement |
| Uneven Spill | Multiple despill passes |
| Blonde Hair | Treat specifically |
| Transparency | Edge-despill |
Workflow
| Step | Description |
|---|---|
| 1. Key | Clean key first |
| 2. Analyze | Identify spill areas |
| 3. Despill | Choose technique |
| 4. Finesse | Problem areas |
| 5. Grade | Color correction |
Best Practices
| Practice | Reason |
|---|---|
| Non-Destructive | Remain adjustable |
| Masks | Limit despill |
| Separate Passes | Hair, skin, clothing |
| Reference | Neutral plate for comparison |
Green vs. Blue Spill
| Aspect | Green | Blue |
|---|---|---|
| Visibility | More noticeable on skin | |
| Despill | Often needs to be more aggressive | |
| Skin Tones | Less overlap | |
| Blonde Hair | More problematic |
Reduce On Set
| Measure | Effect |
|---|---|
| Distance | More = less spill |
| Backlight | Separates from screen |
| Negative Fill | Black surfaces |
| Screen Exposure | Do not overexpose |
IBK Workflow (Nuke)
| Step | Function |
|---|---|
| IBKColour | Analyzes clean plate |
| IBKGizmo | Generates key |
| Despill | Integrated |
| Advantage | Very clean results |
Edge Spill
| Technique | Application |
|---|---|
| Edge Blur | Soft edges |
| Light Wrap | Background integration |
| Edge Despill | Only the edge area |
| Erode/Dilate | Matte adjustment |
Despill vs. Keying
| Aspect | Keying | Despill |
|---|---|---|
| Purpose | Create matte | Correct color |
| What | Alpha channel | RGB values |
| Order | First | After |
Quality Control
| Check | Method |
|---|---|
| Composite Test | Over various backgrounds |
| Skin Tones | Natural? |
| Edges | Clean? |
| Movement | Stable during motion? |
Today
Despill is a fundamental component of any greenscreen composite. Modern tools offer sophisticated algorithms that can effectively handle even difficult situations – blonde hair, reflective materials, strong spill.
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