I have a document with many layers and each layer contains some transparent pixels. I'm trying to replace the transparent pixels in each layer with the colour black, essentially adding a background to them.
I'm struggling. This doesn't seem like something that should be so tricky.
The only way I can do it is by converting to Smart Object, edit, new layer, fill black, save, then Rasterize. But I need to do this hundreds of times, so I'd like to find a way to do it that I can save as an Action.