Onezumi Studios Tutorial 8 (c) 2004
Many people have asked me if there is a way to remove lined paper from their sketches. Unfortunately this is difficult. My advice would be to throw away that pesky math notebook or steno pad and bring a fierce sketchbook to class/work. This will save you a bit of a headache.
This is one answer if it's too late to take the above advice. Nothing is more annoying that finding that you have done a drawing you'd like to keep on crappy lined paper. This is only one method of removing the lined paper. This only works if the lines are blue and your sketch is NOT blue.
1. Scan the picture in RGB mode. 300 DPI.
2. Go to Image > Adjust > Hue/Saturation. There will be a dropdown menu that says "Edit: Master". Click that little menu and change it from "Master" to "Cyan". You have just told it to only adjust the hue/saturation of the Cyan colors.
3. There is a slider on the bottom of the Hue/Saturation menu called "Lightness". Slide that all the way to the right.
4. Select "Blue" from the dropdown menu and repeat step 3.
5. Go to Image > Adjust > Levels. Adjust these a bit lighter until the lines drop out a bit. You might have to play with the sliders a bit.
That's really the best advice I can give right now aside from digitally redrawing the sketch. Obviously if your lines are a different color than blue you can experiment with the other colors in the dropdown menu. Good luck!