In most graphics and video applications you can go to the Opacity setting for an object and adjust it's opacity (or transparency to look at it from the opposite POV).
I typed "Opacity" into the Vuo node library and didn't really get any obvious answers.
In QC (yes that again!) you could apply a colour to an image with white in it and the colour would apply. Same for the opacity setting, from 0 (invisible) to 1 full opaque.
I'm looking for something that simple. Even if I figure out how to generate a texture of greyscale to make a mask, it's a bit of overkill for such an everyday task... what am I missing here?