I still see deviants asking how to separate their lineart from the background, while there's a very simple way to do it cleanly. I made this action for myself, so that it literally takes one click of the mouse to obtain clean black lines on a transparent background. I decided it was simpler to post it than to keep explaining how to do it!

Requirements: You must scan your inked piece (not pencil!) using the "black and white" (or "bitmapped") setting on your scanner _{[I recommend scanning bigger than your final size, then reducing it to the desired size after applying the action]}. Scanning in this mode ensures only your inked lines get picked up – anything light grey on the paper such as smudges, unerased pencil, or even lines will be ignored _{[although if you work on lined paper you probably deserve the punishment of having to clean them up manually]}.

The action will work on greyscale documents but the result will depend on what you're scanning (any lineart will work out fine). I created this for lineart such as I use in my comic, so I leave you to experiment and take no responsibility for other uses.

How to use this:
Click Download.
Decompress the file in the location of your choice.
In Photoshop, open the Actions palette and select Load Actions, then this file [Clean Lineart.atn]
Open your scanned file, select the action in the palette and press the Play button. You're done. Your lineart is now a layer floating above a transparent background.
(Note that the line quality in the preview looks blurry because it's a screenshot, not because of the action)

If you want to color the lineart alone, just lock the layer and use any coloring tool – only the lines will get colored.

I hope this helps. No credit necessary or anything. Just don't claim you made it – I'd never find out, but you'd still be a prat.

This action was made in CS3, but it works in CS2, so it's worth trying on whatever PS version you have!