This tutorial works with images that have a good range of hightlights/midtones/shadows but lack of shadows obscuring any parts of the face if you are using this effect on an image of a person. Other images may need a lot of color correcting before they could be made suitable for use in this tutorial, especially as regards shadows on the face. Choose your images wisely before starting the tutorial. 

1.) Open your image. Duplicate the background layer and give it a useful name. Save to PSD to get your working file established.

2.) Make sure your new layer (not the background) is highlighted and run menu option Image > Adjustments > Threshold… The default value in the Threshold dialog box is 128 and then increase or decrease the threshold until you are satisfied with how it looks then press OK. 

3.) Highlight the threshold layer and go to Filter > Stylize > Diffuse then Select Anisotropic mode and press OK.

4.) Run menu option Select > Color Range and use the eyedropper to sample the black portion of the image, then run the Fuzziness slider in the Color Range dialog box up to 200. Press OK. The black portion of the image should now be surrounded by marching ants.

5.) Run menu option Select > Save Selection and give the selection a name and press OK. Press CTRL-D to deselect. You will reload the selection later.

6.) Make a new layer on top of the others. Select the Paint Bucket tool. Set the tool to fill with a pattern rather than a color and fill the new layer. You can use one of Photoshop’s built-in patterns. 

7.) Make another new layer on top of the others and fill it with white. Add a layer mask to this layer by pressing the Add Layer Mask button on the Layers palette.

8.) Run menu option Select > Load Selection and choose the selection you saved earlier from the dropdown menu in the Load Selection dialog box and press OK.

9.) Go to Edit > Fill and fill the selection with black (which should correspond to your current background color if the mask layer is highlighted). Though you’ve filled the selection with black, you won’t see black in the image. What you should see is the pattern fill from the layer below showing through where the selected mask was filled. Press CTRL-D to deselect. 

10.) With the mask layer still highlighted, select the Brush tool and choose a large, hard-edged brush – around size 19. Painting on the mask with white as the foreground color, paint over those parts of the image you might not need, assuming you see extra stuff that doesn’t need to be there.