Cross-Space Distortion Directed Color Image Compression
Shuyuan Zhu, Mingyu Li, Chen Chen, Shuaicheng Liu, Bing Zeng · IEEE Transactions on Multimedia · 2017
Traditional color image compression is usually conducted in the YCbCr space but many color displayers only accept RGB signals as inputs. Due to the use of a non-unitary matrix in the YCbCr-RGB conversion, low distortion achieved in the YCbCr space cannot guarantee low distortion for the RGB signals. To solve this problem, we propose a novel compression scheme for color images through defining a cross-space distortion so as to reduce as much as possible the distortion in the RGB space. To this end, we first derive the relationship between the distortions in the YCbCr space and RGB space. Then, we develop two solutions to implement color image compression for the most popular 4:2:0 chroma format. The first solution focuses on the design of a new spatial downsampling method to generate the 4:2:0 YCbCr image for a high-efficiency compression. The second one provides a novel way to reduce the distortion of the compressed color image by controlling the quantization error of the 4:2:0 YCbCr image, especially the one generated by using the traditional spatial downsampling. Experimental results show that both proposed solutions offer a remarkable quality gain over some state-of-the-art approaches when tested on various textured color images.