A Study Of Bilateral Filter For Removing Salt And Pepper Noise

For digital image processing, in order to obtain a satisfactory digital image, filtering is one of the most common but the most critical means. The basic principle of the so-called image filtering is to make possible the useful characteristics such as texture and detail in the original image remain unchanged under the premise down to filter noise in the image. Filtering is the requisite step in the pre-processing of the image. When computing the weighted average of the brightness value of the nearby pixels in the neighborhood of the image, the Gauss filter method will make some of the edges and contours blurred. Bilateral filter is precisely proposed in order to overcome the disadvantage that the Gaussian filter can make the edge of image blurred. But the common bilateral filter is invalid for filtering out salt and pepper noise, and therefore it needs to be improved.It is for this defect in the past pure bilateral filtering method, this paper is to refer to two improving approaches.(1) The first is called pseudo median bilateral filtering method. This method is to introduce median filtering view into the pure bilateral filtering method so as to combine the advantages of pure bilateral filtering and median filtering to form a pseudo median bilateral filtering method.(2) The second is called scaled bilateral filtering method. This method is to introduce Gaussian convolution view into the pure bilateral filtering method so as to form a scaled bilateral filtering method. Finally, this paper compares pseudo median bilateral filtering method with scaling bilateral filtering method to find whose filtering effect of these two methods is better or worse. In addition, this paper also applies scaled bilateral filtering method to color image processing.This paper adopts several gray images and color images, for gaussian noise and salt and pepper noise in the images, and uses the pseudo median bilateral filtering method and scaling bilateral filtering method to do filtering experiments. Experimental results show that the pseudo median bilateral filtering method and scaled bilateral filtering method proposed in this paper is valid for filtering out salt and pepper noise.