Fast Zernike moments

Zernike moments are important digital image descriptors used in various applications starting from image watermarking to image recognition. Lots of fast algorithms have been proposed to speedup the computation of Zernike moments. This work provides computational complexity analysis of methods for the computation of Zernike moments, as well as a thorough study and simplification to the methods of finding Zernike moments from geometric moments. A new formula that relates Zernike moments to moments of digital filters is introduced that is very efficient and accurate. Comparisons are performed using Zernike moment via geometric moments method, the Q-recursive method, the coefficient method, and the symmetry method. Using a well defined performance metric, this work finds out that Zernike moments from geometric moments of digital filters is nearly 70 times faster than the best method known as the symmetry method.