Image hashing via hough transform

Given an image as an input, an image hash function should produce a short bit string such that the hash values are similar (if not the same) for “perceptually similar” content and significantly different for “perceptually different” content. Image hash functions find extensive applications in content authentication, database search, and watermarking. There are a lot of approaches reported for image hashing, but many of them do not perform well when the input image undergoes severe linear transformations (for example, big angle rotations or scaling with a very big or very small scaling factor). In this paper we propose a new algorithm for generating image hash values based on Hough transform. Our new approach can do well even for images with big changes. Furthermore, for anti-piracy purposes, a secret key can be added to the hash value calculation process such that the hash function has favorable security properties. Some test results obtained using this method are included and they demonstrate that the new algorithm can achieve desirable results for identifying image content.