Comparison of the performance of correlation filters on images with real-world non-overlapping noise: influence of the target size, illumination and in-plane rotation distortion

We present in this paper a study of the influence of the target resolution and contrast on correlation filter performance. Classical filters and the Optimum filter designed by Javidi et al. for non-overlapping noise were considered and tested on a set of realistic images based on real-world non-overlapping noise realizations. We show that for the images that we have tested, there is a limit of the resolution after which classical linear filters fail to detect properly targets, while the Optimum filter still performs well. Furthermore, it was observed that for some background images and fairly low target resolutions, there are values for the target illumination that prevent the classical filter to detect the target, while again it is possible to tune the Optimum filter to make it tolerant to varying target illumination. Eventually, we propose a new composite filter for in-plane rotation tolerance based on individual optimum filters and built according to the equal correlation principle perform best for our test images.