I have a question about how the resulting alpha is computed for different blend modes in gimp.
The manual [1] describes the color channels, but not how the opacity is processed (I am also sort of interested in a rationale).
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Sign up to join this communityI have a question about how the resulting alpha is computed for different blend modes in gimp.
The manual [1] describes the color channels, but not how the opacity is processed (I am also sort of interested in a rationale).
For all but specific modes (Normal, Dissolve...), the alpha of the result is the alpha of the bottom layer(*). And when it comes to the alpha of the top layer, these two methods produce the same result:
Method #1: Apply Top (blend) layer at x% opacity
Method #2: Apply Top (blend) layer at 100% opacity, get the result (Layer>New from visible
), hide the "blend" layer and set the result layer to x% opacity.
(*) Within a layer group... because layer groups act like parentheses in an equation, the blend mode of a layer only applies to the layers below it in the same group.