Image smoothing, or denoising, is a very important pre-processing operation in almost all applications of digital Image processing ranging from enhancement of space-probe pictures to automatic finger print identification. In this paper we present the results of a comparative analysis study of four different smoothing techniques for digitized binary images.
The techniques considered are: Majority smoothing, Directional logic smoothing, Majority smoothing with contour checking, and a simple l-D median filter-type smoothing. The first three are two dimensional. Three criteria for judging the performance of the examined techniques are selected, which are: The qualitative effect on the image quality, the processing time, and the effect on the image compression efficiency. The four techniques are implemented and tested on a wide range of test images. A sample of the test images, original and smooth ed, will be presented to illustrate quantitatively the effect of the different methods. The l-D smoothing was found to require the least processing time , while the majority smoothing method was found to have the best effect on the compression efficiency (average increase of 20% ). The study was done using the Wang Professional Image Computer (PIC), which is a microcomputer-based imaging system.