Quaternion based switching filter for impulse noise removal in color images

A novel color pixel distance based on the quaternion unit transform was proposed to quantify the intensity and chromaticity differences between two color pixels simultaneously. A quaternion switching filter was presented to suppress the impulse noise in color images based on the aforementioned distance and the property of image edge in both structure and direction. Each pixel in the color image was detected along four directions to determine whether it was noisy and only the noisy one was removed by the filter. The experimental result indicates that the proposed filter can suppress both correlated and uncorrelated impulse noise in color image while preserve image detail and has a faster execution speed than the traditional filters.