Screen image sequence compression method utilizing adaptive block size coding and hierarchical GOP structure

Abstract

To compress screen image sequence in real-time remote and interactive applications, a novel compression method is proposed. The proposed method is named as CABHG. CABHG employs hybrid coding schemes that consist of intra-frame and inter-frame coding modes. The intra-frame coding is a rate-distortion optimized adaptive block size that can be also used for the compression of a single screen image. The inter-frame coding utilizes hierarchical group of pictures (GOP) structure to improve system performance during random accesses and fast-backward scans. Experimental results demonstrate that the proposed CABHG method has approximately 47%–48% higher compression ratio and 46%–53% lower CPU utilization than professional screen image sequence codecs such as TechSmith Ensharpen codec and Sorenson 3 codec. Compared with general video codecs such as H.264 codec, XviD MPEG-4 codec and Apple’s Animation codec, CABHG also shows 87%–88% higher compression ratio and 64%–81% lower CPU utilization than these general video codecs.

Keywords

screen image sequence / compression / adaptive block size / hierarchical GOP structure / intra-frame coding / inter-frame coding