Colour histogram content-based image retrieval and hardware implementation

With the ongoing development of multimedia technology, the number of information systems containing image retrieval functions is increasing rapidly. Techniques of colour histogram content-based image retrieval are compared in terms of speed and efficiency, and a modified approach based on a composite colour image histogram processing is introduced. The proposed approach is fast and provides results comparable to those of much slower algorithms. Furthermore, a novel pipelined hardware structure has been designed and implemented on an FPGA, to increase the operation speed and make the technique suitable for real-time applications. The typical clock frequency of this device is 35 MHz and it can perform over 50 comparisons of 640 x 480-pixel images per second.