Low bit rate image/video coding is essential for many visual communication applications. When bit rates become low, most compression algorithms yield visually annoying artifacts that highly degrade the perceptual quality of image and video data. To achieve high bit rate reduction while maintaining the best possible perceptual quality, postprocessing techniques provide one attractive solution. In this paper, we provide a review and analysis of recent developments in postprocessing techniques. Various types of compression artifacts are discussed first. Then, two types of postprocessing algorithms based on image enhancement and restoration principles are reviewed. Finally, current bottlenecks and future research directions in this field are addressed.