i have a photo on my computer that i took with a digital camera, of a pencil drawing on posterboard. is it possible for photoshop to find the pencil lines, ignoring all the lighting oddities and stuff, and replace all the various shades of dark grey with black, on either a transparent or new plain black background? the only way i know of to do this is to spend a couple hours using the various erasing tools and then the pen tool, tracing sloppily with a mouse, and ending up with a less than perfect result.
this is the pic in question:
