Remove the White Background From Line Art in Adobe Photoshop

When you draw the line art digitally, you can use a separate layer for this. But what if you used the Undo command one time too many and photoshop, according to its weird habit, switched you to the background layer, and you didn't notice it until it was too late? Or what if you have drawn your line art traditionally, on a white sheet of paper, and now you need to remove it without redrawing the lines with a tablet?

In this very short tutorial I'll show you two methods of getting the lines back—a popular one, and a professional one. If you don't have any line art to use at the moment, feel free to download the attachment and follow me.

1. Go to Image > Mode > Grayscale (then Don't merge, Discard)
2. Command+A to select the entire artwork, then Command+C to copy
3. Open your Channels panel (under Window > Channels, if you don't see it)
4. Click Create New Channel (A new layer will appear named Alpha 1)
5. Command+V to paste your selection onto this layer, then Command+Dto deselect
6. Click Load Channel as Selection (You'll see the white parts of your artwork are all selected)
7. Shift+Command+I to invert your selection (You'll see all the black parts of your artwork are selected)
8. Select the Gray channel (On the Channels panel)
9. Click Create a New Layer (On the Layers panel)
10. Select your Paint Bucket Tool (G) and fill the selection with black
11. Command+D to deselect
12. Hide your original linework layer
13. Optional: Go to Image > Mode > RGB Color (or CMYK, whichever you want to work in)