Evaluation of JPEG Blockiness by the Fast Analysis of Information on Local Image Frequency

Abstract

In this paper, we propose a method for estimating the JPEG blockiness in a given image. The most advanced method in this research area is the method that is based on the analysis of gradient information obtained for three types of image regions; the region inside of the block, the region at the boundary of the block, and the region over entire image. The method can be used to detect the blockiness and to calculate the image quality measure accurately. However, the correlation between the calculated measure and the subjective estimation by humans is not very high. Therefore, we propose a method for estimating the blockiness in the image by examining the relationship between the frequency structures of the pixels inside and on the boundary of the JPEG block. For analyzing the frequency, we used the co-occurrence histogram because it provides some useful information on the frequency structure. Experimental results have proved that the coefficient obtained in correlation of our method is greater than that obtained in the conventional method and a subjective evaluation by approximately 0.04.