I have an image I'm projecting onto a piece of geometry as a texture using a UV project node.

In copernicus, I'm trying to extract the edges of the wording in the sign and add a glow effect to just the outline of the words.

However, I can't figure out how to create a mask from my edge detected letters. I have a greyscale image coming out of the edge detect in the red channel.

Am using a channel swap to move the red channel to the alpha, which I can see is working. Then I am trying to turn alpha channel into a mono signal using the channel extract, but that node doesn't seem to do what I expect it to. I just end up with a blank alpha channel using that node.

Can anyone point me in the right direction?

Thank you

It's unclear from the text what you're doing or why.
Channel Split will give you all the channels separately. Then you route the Red channel's wire wherever you want—use it as a mask or as an alpha channel. To make it an alpha channel, you need to use channel join to assemble the channels: connect the RGB channels themselves, and then connect the Red channel to the alpha channel. This will give you RGBA with an alpha channel from Red. But what do you need RGBA for? Most likely, you just need a monolayer that you can paste somewhere, export, or multiply as a mask.