研究压缩图像在显示器上质量主观评价方法,为实现Internet上图像质量主观评价奠定基础。研究包括显示器设置问题;在彩色电视图像质量主观评价ITU—BT.500—11标准的基础上,提出静态压缩图像评价指标;收集了标准彩色测试图像并建立图像库。最后使用JPEG与JPEG2000两种压缩标准对具有不同性质的20景彩色图像进行了7种压缩比的有损压缩,并选取10人采用成对比较的视觉心理物理学方法,对压缩图像进行主观评价实验。得出了JPEG标准下彩色图像最佳压缩比范围为20:1~25:1,JPEG2000范围为25:1—30:1,同时实验结果表明,可以通过视觉的方法对不同LCD显示器进行设置,并达到一个大致相同的设置效果。
Subjective evaluation of compressed image quality on computer displays was studied, in order to realize quality evaluation of compressed images on the Internet. The relative studies include : to set-up displays, to put forward assessment scales for static compressed images based on the standard of subjective assessment of quality for color TV pictures, and to collect color images and establish a database for subjective evaluation. As an example for testing above studies, by using a psyehophysical method of pairwise comparison, subjective evaluation experiments on optimal compression ratio of JPEG and JPEG2000 were conducted on displays for the images, which were from JPEG and lossy JPEG2000 with seven compression ratios. Ten subjects took part in the experiments, and 280 color images for 20 scenes with different contents were used. The experimental results showed that optimal compression ratio range of JPEG is from 20:1 to 25: 1, and optimal compression ratio range of JPEG2000 is from 25 : 1 to 30: 1. The experiments indicated that the display set-up by human eyes can achieve consistency for subjective evaluation of image quality on displays.