A new content based median filter

In this paper the hardware implementation of a content based median filter suitable for real-time impulse noise suppression is presented. The function of the proposed circuitry is adaptive; it detects the existence of impulse noise in an image neighborhood and applies the median filter operator only when necessary. In this way, the blurring of the image in process is avoided and the integrity of edge and detail information is preserved. The proposed digital hardware structure is capable of processing gray-scale images of 8-bit resolution and is fully pipelined, whereas parallel processing is used to minimize computational time. The architecture presented was implemented in FPGA and it can be used in industrial imaging applications, where fast processing is of the utmost importance. The typical system clock frequency is 55 MHz.