GIMP

Steps I think of:

• Id create a square canvas (1024*1024?)
• Id create two background layers.
• Id split each layer in 4 parts with rulers, use the square rectnagle select tool (with magnet on), slect each area and pain it with color backet.
• Id paint the bottom background with the color of the faces and the front background with the background color (hope this makes sense)
• Id use the arrangement tool and arrange each image to the center of each quarter
• Id set each image to grayscale
• Id use them as a layer mask. Black->transparent. White->opaque. This step has some substeps:
  1. Right-click on the layer with the front background
  2. Add layer mask (full opacity)
  3. Click on the layer with the face and ctrl+c (copy the layer)
  4. Click on the mask of the front layer and press ctrl+v (paste the layer).
  5. It will show the pasted layer as a floatijg layer mask. Press the anchor at the bottom of the layer widget to apply the pasted layer as the layer mask of your front background layer. (Source.)
• Id use the threshold tool to retain only the most prominent features of the faces by clicking on the layer mask of the front background layer, clicking on the canvas and dragging the two outer sliders towards the middle (maybe Id use a paint brush and an eraser to bring/remove any details). If you cant see the tool either enable it by edit/preferences/toolbox or type "/" and type "threshold".
• For the text you gotta play with the gimp fonts and text editor, not the most fun thing, but it may work.

Tada:)