Distance blurring for space-variant image coding
We present a novel selective blurring algorithm that mimics the optical distance blur effects that occur naturally in cameras and eyes. The proposed algorithm provides a realistic simulation of distance blurring, with the desirable properties of aiming to mimic occlusion effects as occur in natural blurring, and of being able to handle any number of blurring and occlusion levels with the same order of computational complexity. We have performed subjective experiments to compare the perceived quality of distance blurred images with that of foveation-filtered images under equivalent conditions, when both are used as space-variant prefiltering stages prior to a JPEG encoder. The results show that the distance-based blurring was significantly preferable to the foveation blurring for four out of nine test images, whereas a significant converse preference was found for only one test image.