I asked this before but I forgot it...

[ChrisHerself]

How would I remove the bluelines from a penciled sketch in Photoshop? Something involving channels, I know, but I was only sniffing around. I managed to half-ass it but I've totally forgotten how to do it right. Anyone?

[Ilaekae]

If the blue lines are close to cyan, and assuming you scanned in color, just make sure your drawing is in CMYK, then go to cyan in channels, select all and hit delete. If your color blue is a little hinky (not pure cyan), you may have to fiddle with the ADJUST BRIGHTNESS/CONTRAST in the magenta and yellow channels, and maybe even touch up a little in Black with the eraser. then convert the entire mess back to grayscale or RGB.

This is how I do it. Somebody else may have a different way that's more convenient.

[Kwiix]

Here's a similar method to what Ilaekae posted (check out step 1-3):

http://members.jcom.home.ne.jp/jun1f/archive_how2/recent01e-1.html

Hope this helps.