Blackmagic Forum

I've made the background of an OpenEXR clip transparent. In the preview it has a checker board pattern but in the edit tab the background is still there and when I have it above another clip it's transparent but the clip underneath is almost completely white (I'm guessing it gets the affect that the alpha channel is supposed to get).

Here are some pictures to better explain:

These are the nodes for the clip


How the clip looks in fusion:


How the clip looks in the edit preview with a clip underneath it:


I would add more pictures but unfortunately I could only attach 3 and I can't post any links.

bump

Looks like you haven’t premultiplied your RGB with your newly produced alpha values. AlphaMultiply node should do the trick.

Can you post screenshots of your settings for your ChannelBooleans and BrightnessContrast nodes?

Hendrik Proosa wrote:Looks like you haven’t premultiplied your RGB with your newly produced alpha values. AlphaMultiply node should do the trick.

I added an AlphaMultiply node before the output and now it looks like this:
I'm quite new to fusion so I'm not sure what I'm doing wrong.

Looks better, but what I’d check next is values in alpha channel outside 0.0-1.0 range. You must clamp alpha to this range before AlphaMultiply. Currently it seems that premulting changes areas where alpha should be solid. Reason for out of range values probably lies in your brightnesscontrast node.

Hendrik Proosa wrote:Looks better, but what I’d check next is values in alpha channel outside 0.0-1.0 range. You must clamp alpha to this range before AlphaMultiply. Currently it seems that premulting changes areas where alpha should be solid. Reason for out of range values probably lies in your brightnesscontrast node.

Thanks a lot, it works now!