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Blend Multiply vs Multiply?? Bug??

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Skybase
2D/3D Generalist

Posts: 4025
Filters: 76
I can't tell if this is a bug or by design.

I have a threshold feeding a fully black image with alpha, which I blur using the blur node. Now, just to test out something, I added a multiply node to multiply the blur layer on itself. Logically, the multiply should result in a darker image. But the image that's fed out has little or probably no difference between the blur node. So I try the multiply blend mode and it results in what's supposed to happen.

Is this a bug? Screenshot attached of the filter.
Posted: December 26, 2012 2:52 am   Details E-Mail
Indigo Ray
Adam

Posts: 1442
Filters: 82
Multiply component multiplies RGB values (outputs the alpha channel of source A without modification), hence the category title "RGB Math".

Blend set to multiply multiplies RGB but appears to "screen" alpha values (as if you were realistically layering transparent objects). In fact, every single blend mode screens the alpha, no exception.
Posted: December 26, 2012 11:03 am   Details E-Mail
Skybase
2D/3D Generalist

Posts: 4025
Filters: 76
Thanks smile;) Makes sense. Seems like I just freaked out over it. Was going "umm...????!"
Posted: December 26, 2012 8:42 pm   Details E-Mail

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