Settings / Blend
Sets how strongly the processed result is mixed into the image.
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Color & ChannelsIntermediate
AlphaDivide
Unpremultiply RGB from alpha
Divides RGB by alpha to convert premultiplied imagery into straight alpha before color or filtering operations.
AlphaDivide
DaVinci Resolve · Fusion
AlphaDivide is a technical alpha-management node used before operations that need the true color of semi-transparent pixels rather than RGB already multiplied by alpha.
Overview
What AlphaDivide does
AlphaDivide is a technical alpha-management node used before operations that need the true color of semi-transparent pixels rather than RGB already multiplied by alpha.
Mental model
Temporarily unpack the transparent image: restore the real RGB values at soft edges, process them, then repremultiply with AlphaMultiply.
Common uses
Prepare keyed footage for color correction
Avoid dark halos before Blur or Glow
Process semi-transparent graphics cleanly
Diagnose premultiplied-versus-straight alpha problems
Flow anatomy
Inputs & outputs
The port structure shows how this node fits into a Fusion graph.
Input
Source image for the operation.
Effect Mask
Optional mask limiting where the operation is applied.
AlphaDivide
Fusion node
Output
The processed result from this node.
Inspector
Important parameters
Start with these controls before reaching for more complicated workarounds.
Settings / Process when Blend is 0.0
Sets how strongly the processed result is mixed into the image.
Settings / Process R G B A
Selects which RGBA channels are processed by the node.
Settings / Apply Mask Inverted
Inverts the connected Effect Mask before it is applied.
Settings / Multiply by Mask
Multiplies the AlphaDivide result by the connected effect mask.
Settings / Use Object
Uses Object as part of this operation.
Settings / Use Material
Uses Material as part of this operation.
Settings / Use GPU
Uses GPU acceleration for this operation when supported.
Settings / Hide Incoming Connections
Hides incoming connection lines in the node interface.
This is a display preference; it does not change the processed result.
Layers / Process Layers
Chooses which image layers or channels the operation processes.
Layers / Input Layer
Selects the source layer or channel set read by the operation.
Layers / Effect Mask Layer
Limits the effect to the connected mask.
Comments
Stores a note with the node.
Comments are for documentation only; they do not change the image, scene or simulation.
Practical setup
A reliable workflow
- 1
Place AlphaDivide before the color or filtering operation that is producing edge artifacts.
- 2
Inspect semi-transparent edges in the viewer.
- 3
Perform the intended correction, blur, glow or transform.
- 4
Add AlphaMultiply after the processing stage.
- 5
Compare the result against the original premultiplied chain for halos or bright fringes.
Typical node chain
Premultiplied RGBA→
AlphaDivide→
Processing→
AlphaMultiply
Examples
Where this node fits in real work
Clean color correction on a keyed subject
Unpremultiply the keyed subject before grading the edge pixels, then restore premultiplication.
KeyerAlphaDivideColorCorrectorAlphaMultiplyMerge
Glow on transparent graphics
Avoid muddy semi-transparent glow edges by processing straight RGB.
Text+AlphaDivideGlowAlphaMultiplyMerge
Troubleshooting
Common mistakes
Using AlphaDivide without restoring premultiplication later
Applying it to opaque footage where it provides no benefit
Judging only the center of the image instead of soft alpha edges
Production notes
Practical tips
Use AlphaDivide and AlphaMultiply as a clearly named pair in larger comps.
If edge colors look wrong after grading, inspect premultiplication before changing the key itself.
Related nodes