QUICK PHOTOSHOP CHEAT TO CLEAN UP YOUR MESSY SKETCH
In Photoshop, when you scan an image in RGB, the file has three “channels”: The Red channel, the Green channel, the Blue channel. Now, I don’t know what the fuck “channels” are, but I do know that when you switch to a channel, the colors of that channel gets subtracted from your image: Red channel eliminates red, Green channel eliminates green, Blue channel eliminates blue.
I guess if you want an analogy it’s kinda like color filtering? Imagine a sheet of white paper that has a red line on it. Now imagine taking a red transparent sheet and placing it on top of the white paper. If you look at it, the entire paper is now red (well duh, the red transparency is on top of it), but because the entire paper is red, that red line has now disappeared. It’s blended with the red environment, kinda.
What the channels on PS do, it seems, that it filters out the channel’s color and turns everything else grayscale. So as you can see in the photoset, I scanned in an inked drawing that has really messy sketch done in red, and then I would switch to the red channel (Ctrl+1) and BOOM all that messy sketch disappeared instantly. All I need to do afterwards is to switch the image to Grayscale (Image > Mode > Grayscale), and level it accordingly. I never had to erase my messy red lines.
Similarly, if you use Green, you can get rid of it using Ctrl+2, or Ctrl+3 if you wanna get rid of Blue. To go back to the normal RGB mode, you can hit Ctrl+`, which is the button to the left of 1. However, I found that Green and Blue lines don’t get subtracted as cleanly as Red. Even those non-photo blue pencils.
This is actually the reason I always do all my sketches with red pencil/pen.
EDIT: clarification — Ctrl+1 does not get rid of your sketch permanently, it just makes it not visible. To get rid of it permanently you need to then switch mode to Grayscale. This action is what takes out the sketch. Of course this method won’t work if you’re trying to scan a colored piece, but works fabulously for b/w art, like for comics and/or storyboards.