Image noise reduction by low complexity hardware median filter

Median filters are commonly used in image processing applications for removal of the salt and pepper noise. Denoising is a preliminary step in online processing of images, thus hardware implementation of median filters is of great interest. Hence, many methods, mostly based on sorting the pixels, have been developed to implement median filters. Utilizing vast amount of hardware resources and not being fast are the two main disadvantages of these methods. In this paper a method for filtering images is proposed to reduce the needed hardware elements. A modular pipelined median filter unit is first modeled and then the designed module is used in a parallel structure. Since the image is applied in rows and in a parallel manner, the amount of necessary hardware elements is reduced in comparison with other hardware implementation methods. Image filtering speed has increased in comparison with other methods. Implementation results show that the proposed method has advantageous speed and efficiency.