When doing this sort of art, the hardest subject to work with is a person. This is because we need to keep enough of the person’s features to still recognize him, but yet we have to do it all in just two colors.
It is important to first get rid of any extraneous details, such as distracting backgrounds. Don’t get too compulsive in cleaning up the background, because much of the edge detail will be lost, anyway. For more on getting rid of a background, see this tutorial.
I would call this an intermediate tutorial. If you’re a beginner, though, go on and try it! The hardest part is removing the background.
We will be working with several Photoshop tools and techniques in this tutorial:
- Using an Adjustment Layer
- Using an Adjustment Layer Mask
- Making selective adjustments
In this project, we use a Threshold Adjustment Layer. This Adjustment Layer takes pixels which are lighter than the specified value and makes them appear white. It takes any pixels darker than the specified value and makes them black. Your results will vary, depending upon your own image, but these instructions will give you ideas to use for some different problems you may encounter.
- Open your photo.
- At the bottom of the Layers Palette, click the Add Adjustment Layer button and choose Threshold.
- Move the slider till your subject’s face looks pretty good. His shirt still lacks detail, and the dark shadow under his chin is distracting, but we will fix these in a moment.
4. Now let’s handle those touch-ups. Duplicate the photo layer, by dragging it to the New Layer icon at the bottom of the Layers Palette.
You will now be working on this duplicate layer. You’ll use the Dodge 
and Burn 
tools to make the photo have darker or lighter sections, which will translate into more black or more white, as you view the image through the Threshold Adjustment.
Use the Dodge tool with a soft brush and low exposure to lighten under his chin. This will reduce the black appearing in your image.
Similarly, use the Burn tool to bring out more facial detail and detail in his shirt. I also used a bit of Dodge to bring out more detail in his hair.
Now let’s bring it to Living Color. If you want your image to be in a single color, as I did with Collin here, you can do that with another Adjustment Layer:
- Make a Color/Fill Adjustment Layer.
- Put that Adjustment Layer into Screen Blending Mode at the top of your Layers palette.
I hope you enjoyed this bit of 2-color poster-making!
If you want a more Andy Warhol-like image, make a new layer and and put it into Lighten Blending Mode. Now paint whatever colors you want.
If you want the white parts to be colored, too, a new layer with Darken Blending Mode will serve.