关键词: 图像编码, 图像质量评价, 图像压缩, 光场

Abstract: Recent researches propose several new approaches to light field image coding that achieve significant compression rate using the HEVC (high efficiency video coding) encoder, most of which use PSNR (peak signal-to-noise ratio) as the sole objective metric to evaluate different coding schemes. However, PSNR does not have a good correlation with the subjective quality of light field images, as it does not take the heterogeneous optical distortion into consideration, and it only measures discrete pixels rather than continuously rendered views presented to  observers. In this paper, a new objective metric is proposed to address these issues. Optical distortion is modeled by a probabilistic distribution, and coding loss results in shifting of the distribution, which is then measured by the corresponding Kullback-Leibler divergence. Furthermore, an objective evaluation of several coding schemes is conducted using the metric along with PSNR to provide a detailed comparison; and a subjective evaluation is performed which shows that the proposed metric outperforms PSNR in correlation.

Key words: image coding, image quality assessment, image compression, light field