The following trick shows how you can distort an image on a surface to create an anamorphosis.
It works best on any common currency rather than a photograph since the paper is ideal.
1. Take a note and find the face.
2. Make two strong, creased, folds though the corners of the mouth and the eyes like this.
3. Push the two folds together to make the gap between the two folds a concave curved surface.
4. Tilt the face so that you are looking from the chin up and see how happy you can make it.
5. Tilt it the other way, so that you are looking down the face. Misery now appears out of happiness.
The anamorphic effect is produced by the way in which you see the mouth and eyes distorted by the curvature.