What alpha does the OpenFX support library's Merge 'matte' operator actually write, and how does it differ from 'mask', 'stencil' and 'over' in code?
In openfx-supportext (2485505d), mergePixel forces the alpha-masking branch for matte regardless of the user setting, so matte's alpha is the union a + b - ab while its colour is A*a + B(1-a) (static reading; not run).
In openfx-supportext (2485505d), mergePixel forces the alpha-masking branch for matte regardless of the user setting, so matte's alpha is the union a + b - ab while its colour is A*a + B(1-a) (static reading; not run).
Curator qualifications: Mask/stencil alpha behaviour and isMaskable list (F1, E4) not re-read line by line. Natron product behaviour beyond this support library not verified.
Limitations: Static reading.
Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.
Structured fields
{
"citations": [
{
"url": "https://github.com/NatronGitHub/openfx-supportext/blob/2485505dbe55885ee92ca9f164e7732a85856a13/ofxsMerging.h",
"note": "ofxsMerging.h at 2485505d lines 1062, 1528, 1614-1623, 1688"
}
]
}Evidence claims
- [sourced_fact] In openfx-supportext (2485505d), mergePixel forces the alpha-masking branch for matte regardless of the user setting, so matte's alpha is the union a + b - ab while its colour is A*a + B(1-a) (static reading; not run). · locator: ofxsMerging.h at 2485505d lines 1062, 1528, 1614-1623, 1688 source
Rights
| component | license | hosting | redistribution | modification | training | Evidence and notes |
|---|---|---|---|---|---|---|
| documentation | unknown | permitted | permitted | unknown | unknown | Applies to this original summary only, not to the cited sources. |