This step is optional. If you would like to colorize the final results, follow this step:
Add a new Hue/Saturation adjustment layer (Layer> New Adjustment Layer> Hue/Saturation) as the top layer. Checkmark Colorize and apply your desired color settings. Here are the settings I've used for this step:
Colorize: Checked
Hue: 100
Saturation: 100
Lightness: 0

Rollover the images below to see the before and after effect.

