Improved DC Estimation for JPEG Compression Via Convex Relaxation

Mass image transmission has undergone an explosion of growth with the development of the internet, DCT-based lossy image compression like JPEG is pervasively conducted to save the transmission bandwidth. Recently, DCT-domain coefficient estimation approaches have been proposed to further improve the compression ratio by discarding DC coefficients at the sender’s end while recovering them at the receiver’s end via DC estimation. However, known DC estimation needs to enumerate all possible DC coefficients. Consequently, they are limited and resource-consuming due to the low delay requirements in real-time transmission. In this paper, we propose an improved DC estimation method via convex relaxation, which achieves state-of-the-art performance in terms of both recovery image quality and time complexity. Extensive experiments across various data sets demonstrate the advantages of our method.