Posterize to show value distribution
 

I was asked to illustrate how I used the posterize feature of Photoshop (most imaging software offers this feature) to simplify the value distribution in Melissa Schatzman's "Sheldon" thread.

Because I originally read how to do this on this forum, I used the search feature but could not come up with the original post. If the original poster reads this, please accept credit and direct me to that post.

Anyway,

Step 1 - convert your image to grayscale. From the menu at the top of your screen, click on Image, then Mode, then Grayscale

Step 2

From the menu at the top of your screen, click on Image, then adjustments, then posterize.

When you click on posterize, a dialog box pops up, and you can select a number to reduce the values to. Depending on the reference photograph, you might find 3, 4 or 5 to be most useful.

This image shows the image when I've selected 4 levels:

This shows the image with 5 levels.

Please note, this feature will not save a poor reference photo, but it might help you to decide not to use a particular reference.