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.
The LK project is funded by the European Commission under Project No. 231126