Photoshop
Use the polygonal lassoo tool, use it to draw around the bocker to select them, then copy and paste them as a new layer. Cut out all the bits you don't want (holes in the frames, gap between the footplate and hoof, etc), and then right click the layer, choose "blending options" and pick "colour overlay". Set the colour to black, and BAM, you've got yourself a Silhouette