Peer Group Filter for Impulsive Noise Removal in Color Images

In this paper a new approach to the problem of impulsive noise removal in color images is presented. The proposed method is based on the evaluation of the statistical properties of a sorted sequence of the accumulated distances used for the calculation of the vector median of samples belonging to the filtering window. The statistical analysis is performed using the Fisher's linear discriminant, which enables the detection of outliers introduced by the noise process. The described filter output switches between the vector median and the original central pixel. In order to increase the filter's performance, two thresholds are introduced, which enhance the detail preserving abilities of the proposed filtering scheme. The described filtering technique is robust, fast and therefore it can be used in real time denoising applications.