Making an existing layer with transparency fully opaque?

[Teri Pettit]

Is there any way to convert a layer that is partially transparent to fully opaque, when the transparency is not a layer setting nor a layer mask, but rather just the alpha channel of that layer's content pixels?

I have a large complex layer that used to be fully opaque, but is currently only 88% opaque over most of it. I suspect at some point in the very distant edit history I accidentally flattened something I shouldn't have, but since it started as a copy of the (locked) layer below, it took me a long time to notice, as every pixel that hasn't been edited looks the same on both layers. (It just seemed like some of my edits weren't quite "taking".) There have been thousands of adjustments made on the upper layer since the accidental flattening that introduced transparency, though.

I want to reset the layer's alpha channel to 1 for all pixels. Is this accessible through some UI?

[Jeff Arola · Accepted solution]

Try Layer>Layer Mask>From Transparency

then shift click on the layer mask

[Teri Pettit]

Thanks! I'd just figured that out on my own (actually, I just did a Delete Mask after the Layer Mask>From Transparency, rather than shift-clicking it), and came here to say "never mind", then saw your reply.

I figured there must be some way, but since I typically add layer masks by making a selection then clicking the icon at the bottom of the Layers panel, I was not familiar with the "From Transparency" command.