Frequency domain blockiness measurement for image quality assessment

Block-based digital image and video compression could lead to visible distortions in the coded image or video, with dominant artifacts like blockiness. Subjective quality assessments [1] are reliable but they are too costly and not possible to be computerized. The objective quality meter is designed for evaluating the image quality. The blockiness is measured in frequency domain in which the ratio of harmonics to other AC components is calculated and used to estimate the blockiness artifact. Before blockiness estimation in frequency domain, the property of Human Visual System is applied in the form of edge cancellation and spatial masking in spatial domain. After the spatial masking of coded image according to the spatial activity of the reference image, the blockiness is calculated locally in frequency domain and accumulated in the end for a single quality metric. The results in the end show that this approach is very simple to implement and has easy calculations. The work is tested on 233 images from LIVE image database and the Pearson´s Correlation Coefficient of 94% is obtained even without training on any image.