Settings / Blend
Sets how strongly the processed result is mixed into the image.
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Color & ChannelsIntermediate
AlphaMultiply
Repremultiply RGB by alpha
Multiplies RGB by alpha again after straight-alpha processing so transparent imagery composites correctly through Merge.
AlphaMultiply
DaVinci Resolve · Fusion
AlphaMultiply is the counterpart to AlphaDivide. It restores premultiplied alpha after color, blur or other processing has been performed in straight-alpha space.
Overview
What AlphaMultiply does
AlphaMultiply is the counterpart to AlphaDivide. It restores premultiplied alpha after color, blur or other processing has been performed in straight-alpha space.
Mental model
Pack the transparent image back up: after processing true RGB values, multiply them by alpha so normal compositing math works again.
Common uses
Finish an AlphaDivide processing chain
Prepare keyed footage for Merge
Restore proper transparent edges after Glow or Blur
Correct straight-alpha graphics before final compositing
Flow anatomy
Inputs & outputs
The port structure shows how this node fits into a Fusion graph.
Input
Straight-alpha RGBA image, typically coming from AlphaDivide and a processing chain.
Effect Mask
Optional mask limiting where repremultiplication occurs.
AlphaMultiply
Fusion node
Output
Premultiplied RGBA image ready for conventional Fusion compositing.
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 AlphaMultiply result by the connected effect mask.
Settings / Use GPU
Uses GPU acceleration for this operation when supported.
Layers / Process Layers
Chooses which image layers or channels the operation processes.
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
Keep AlphaMultiply after any operation that was intentionally performed after AlphaDivide.
- 2
Verify that the alpha channel itself is still correct.
- 3
Check semi-transparent contours against a contrasting background.
- 4
Merge the result over the target background.
- 5
If fringes remain, inspect the order of AlphaDivide, processing and AlphaMultiply.
Typical node chain
Straight RGBA→
AlphaMultiply→
Premultiplied RGBA→
Merge
Examples
Where this node fits in real work
Straight-alpha grading pair
Restore premultiplication after grading a keyed element.
AlphaDivideColorCorrectorAlphaMultiplyMerge
Transparent title finishing
Repremultiply a title after optical effects.
Text+AlphaDivideBlurGlowAlphaMultiplyMerge
Troubleshooting
Common mistakes
Leaving a straight-alpha result unpremultiplied before Merge
Placing AlphaMultiply before the processing that required straight alpha
Trying to fix a bad matte by changing premultiplication alone
Production notes
Practical tips
View the result over both black and white backgrounds to expose edge problems.
Treat AlphaMultiply as a technical boundary between straight-alpha processing and normal compositing.
Related nodes