Recovering sketch from Background layer (in PS)

Ever had those moments you created a new file and started sketching something awesome only to discover you made it on the Background layer?
No worries! With these steps you'll be able to recover it.

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Just a little something for those derp moments, sketching on the background layer.
Works best with black sketches (or the opposite, white on black I guess, just don't do the invert then). If it's along those lines the sketch separates almost flawlessly.
Have some little short-cuts along with it as well

This isn't the only way, but it allows for some other stuff as well.
What it does is only showing black because the layer you put the mask on only contains black (or the other colour you chose).
Since layer masks only use greyscales it works best with black on white sketches, but can also at least partially recover anything not white.
If your sketch is already finished and just need to do an under-painting (or something), setting it on Multiply could work fine as well.
The method I've shown however allows you to freely transform, cut, paste, and whatever else you can think of. You can also just take selections of what you want to separate.

Alternative method:
[CTRL+ALT+2] selects your RGB channel (all visible layers, though), which you can then invert [CTRL+SHIFT+I] and 'fill' on a new layer (or layer mask)

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This is a little tip/hint/trick 2 FunBit, because I didn't have a 2 FunBits journal in more than 2 weeks.
Initially this idea I'd just type it out, but heh, lets do something fresh.

PS: My writing, though. haha.

Used Photoshop CS6