Simple Garbage Mask on Keyed Still Frame

We are trying out Resolve 15 coming from Flame and have a real basic question... I need to apply and animate a garbage mask on a keyable still frame from photoshop over a background. Timeline effect that I am not seeing? Fusion or color? I tried a simple mask in Fusion but it does not apply to the keyable still frame from the timeline. I am assuming paint on alpha or something along those lines.

Thanks.

It seems that masks are not connecting in fusion on any media inputs (unless we are doing something incorrectly).

It kind of depends how you do it, with the way the processing pipeline works, masks and keys do not transfer between the fusion and color pages. So when keying a shot and adding a garbage matte, both operations will have to be done on the same page. If you can post screenshots of how you're trying to do it, it will be easier to point you in the right direction.

I'll post a screen grab tomorrow, but taking a simple keyable element such as a .psd file and keying it over a background in edit... bring both layers into fusion with a merge and try to add any mask to the keyable .psd. The mask node will not connect. I am sure I am doing something wrong or it is a limitation.

Thanks.

If you want to mask a mediaIn node the easiest way I have found is to connect it to a merge as the foreground. Then add a transparent background node as the background of the merge. Then you can select the merge and add a mask. This will mask your footage from the mediaIn node.

With the merge selected click on the polygon mask button, then draw your garbage mask. Right click on the area suggested in the inspector for the tool to set the first keyframe and therefore animate the shape.

Thank you - that did it.

A simpler method: The Matte Control node can be used to garbage mask an image. The mask goes into the grey input. If necessary, you can invert the mask in the Matte Control—I've indicated the control in my screenshot. Or you can invert it in your mask tool.