Detecting photo manipulation on signs and billboards

The manipulation of text on a sign or billboard is relatively easy to do in a way that is perceptually convincing. When text is on a planar surface and imaged under perspective projection, the text undergoes a specific distortion. When text is manipulated, it is unlikely to precisely satisfy this geometric mapping. We describe a technique for detecting if text in an image obeys the expected perspective projection, deviations from which are used as evidence of tampering.

• Type: Journal
• Year: 2010
• Where: ICIP
• Authors: Valentina Conotter, Giulia Boato, Hany Farid
• Keywords: ICIP 2010, Image Processing, Perspective Projection, Planar Surface, Specific Distortion