This was a drawing with a number two pencil that I pressed a little too hard on the paper and could not get a good photograph. Couldn't fix it with levels or curves so I decided to make four duplicate layers and run them through threshold at four graduated spots on the slider.The Layer on the bottom will have the most paint /color - the lightest value. The fourth layer being the least area to receive color will be the darkest value. I think of organizing printing plates or silk screening; any color is game as long as they keep getting darker as you add layers.See example below of image next to Layers palette in Photoshop 7. (click to enlarge)
I'm not sure if you can do this in Photoshop elements. I would have to check with Linda R. Ollis. She is teaching Basic photoshop on her blog here.