Wednesday, June 25, 2014

Quick Levels Adjustment for Scanned Sketches

I like to do a quick Levels adjustment to my sketches right after scanning them. The process is even quicker if I set up an Action to perform on multiple scans, but that's for another blog post.

  1. To get started, open the scanned sketch in Photoshop. Then go to Window > Info to view the Info panel (A in the image below). 
  2. Now, open Levels (cmd-L, or Image > Adjustments > Levels).
  3. I usually just slide the Black Point (labeled B in the image) toward the middle to make the scanned pencil line darker. (If there is something in the image that you want to be solid black, then you can click the Black Point Eyedropper on it.)
  4. For the White Point (C), I like to scroll around inside the image to get Info readings for the paper white. My scanner tends to scan white paper at 5 to 6% gray, which I reset to 0 by clicking the White Point Eyedropper on a representative area inside the scan (like the top-right corner of the illustration below). Click OK. Using the White Point Eyedropper is the same as just sliding the White Point Slider toward the middle, but it gives you more control.
  5. You can use a Levels Adjustment Layer if you want to be non-destructive: On the Layers panel, click on the black-and-white circle (at the bottom), scroll down to Levels.
A. (Info Panel) Grayscale value of the point in the image that the cursor hovers over.
B. The Black Point, which I slide in toward the middle in the Histogram of Levels.
C. The White Point, which I set by clicking on the paper white inside the image.
Click to enlarge.


June said...

Thanks for the clear instructions Dave.
I'm glad to discover I do things just the same way :) I learnt through trial and error!

Moira Munro said...

Nice and clear. I tend to forget how to do this if I don't do it often enough.
One thing I wonder if you can help with is how to create the adjustment layer to adjust JUST the pencil sketch layer and none of the layers beneath. I used to do it with one click, but have forgotten how. I have to create the adjustment layer and then click on the adjustment layer's menu to select "Create clipping mask".

David Opie said...

Moira, on the Adjustment Layer panel, click on the first icon along the bottom (arrow pointing down/square) to "clip" that Adjustment Layer to the Layer directly beneath (and not affect the other Layers). I'll do a blog post about Layer Adjustments soon.

Moira Munro said...

Thanks Dave, that's less annoying than clicking on a menu. For me, with WIndows, it's 3rd from the left and looks like an oval switch. I had never looked at those little icons.