[Openfx-developer] empty alpha channel

[<ph...@fr...>]

Hi guys,

I'm just starting out porting Filters to OpenFx and encountered an unexpeted problem. I have a filter
plugin which accepts only  RGBA input and output and everything seems to work fine.

Apart from when the image has no Alpha channel (i.e. Jpegs) then Nuke delivers that image in RGBA format but
with all the alpha values set to zero. When I request the premultiplication state for the image it sais unpremultiplied.
So my plugin assumes it really is not and does premultiplication itself resulting in an all black output.

So i wonder if this is defined behaviour and if so how i can find out about it or prevent it.
I went through the docs but did not find any image or clip properties that would explain the missing Alpha
values to me nore did i find anything else. So I'm not sure if this is related to the host I'm trying it in (Nuke)
or if it's a general ofx thing. Any hints would be appreciated.

Thank you,
________________________
philipp  ~  frischluft.com°