How do the despill formulas in Blender (Color Spill and Keying) and Natron/openfx-misc (Despill) compare, and what do openfx-misc's ChromaKeyer documents cite?
Blender's Color Spill subtracts from the spill channel the positive excess factor*spill - limit_strength*(average of the limit channels), and Natron's Despill (credited to Wright's Digital Compositing for Film and Video, section 4.5) builds a comparable spill map with mix and expand controls and can also add red and blue into the spill area; equivalence under matched parameters is producer synthesis.
Blender's Color Spill subtracts from the spill channel the positive excess factor*spill - limit_strength*(average of the limit channels), and Natron's Despill (credited to Wright's Digital Compositing for Film and Video, section 4.5) builds a comparable spill map with mix and expand controls and can also add red and blue into the spill area; equivalence under matched parameters is producer synthesis.
Curator qualifications: Code read 2026-10-22; nothing keyed. Natron spillmap formula line and Blender Keying despill not re-read.
Limitations: Code read 2026-10-22; nothing keyed.
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/blender/blender/blob/f46990f5f55e36cc771b0ce476512b89ecfcea23/source/blender/compositor/shaders/compositor_keying_compute_image.glsl",
"note": "library/gpu_shader_compositor_color_spill.glsl L35-56; openfx-misc Despill/Despill.cpp L45-97"
},
{
"url": "https://github.com/blender/blender/blob/f46990f5f55e36cc771b0ce476512b89ecfcea23/source/blender/compositor/shaders/library/gpu_shader_compositor_color_spill.glsl",
"note": "library/gpu_shader_compositor_color_spill.glsl L35-56; openfx-misc Despill/Despill.cpp L45-97"
},
{
"url": "https://docs.blender.org/manual/en/latest/compositing/types/keying/color_spill.html",
"note": "library/gpu_shader_compositor_color_spill.glsl L35-56; openfx-misc Despill/Despill.cpp L45-97"
},
{
"url": "https://github.com/NatronGitHub/openfx-misc/blob/850b3fff65463c073bd64683e5d97a7dec2586c5/Despill/Despill.cpp",
"note": "library/gpu_shader_compositor_color_spill.glsl L35-56; openfx-misc Despill/Despill.cpp L45-97"
},
{
"url": "https://github.com/NatronGitHub/openfx-misc/blob/850b3fff65463c073bd64683e5d97a7dec2586c5/ChromaKeyer/ChromaKeyer.cpp",
"note": "library/gpu_shader_compositor_color_spill.glsl L35-56; openfx-misc Despill/Despill.cpp L45-97"
}
]
}Evidence claims
- [sourced_fact] Blender's Color Spill subtracts from the spill channel the positive excess factor*spill - limit_strength*(average of the limit channels), and Natron's Despill (credited to Wright's Digital Compositing for Film and Video, section 4.5) builds a comparable spill map with mix and expand controls and can also add red and blue into the spill area; equivalence under matched parameters is producer synthesis. · locator: library/gpu_shader_compositor_color_spill.glsl L35-56; openfx-misc Despill/Despill.cpp L45-97 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. |
Linked records
- cites → https://docs.blender.org/manual/en/latest/compositing/types/keying/color_spill.html
- cites → https://github.com/NatronGitHub/openfx-misc/blob/850b3fff65463c073bd64683e5d97a7dec2586c5/ChromaKeyer/ChromaKeyer.cpp
- cites → https://github.com/NatronGitHub/openfx-misc/blob/850b3fff65463c073bd64683e5d97a7dec2586c5/Despill/Despill.cpp
- cites → https://github.com/blender/blender/blob/f46990f5f55e36cc771b0ce476512b89ecfcea23/source/blender/compositor/shaders/compositor_keying_compute_image.glsl
- cites → https://github.com/blender/blender/blob/f46990f5f55e36cc771b0ce476512b89ecfcea23/source/blender/compositor/shaders/library/gpu_shader_compositor_color_spill.glsl