Context-based adaptive zigzag scanning for image coding

Coefficient scanning plays an important role in block-based image and video coding standards, such as JPEG, MPEG, and the latest H.264/AVC. In these coding standards, the zigzag scanning method is used for image / frame coding and the field scanning method is used for field coding. Although these scanning methods can achieve acceptable coding efficiency, they do not take the statistical properties of the quantized coefficients of each block into consideration. Therefore, coding redundancy still exists. In this paper, we propose a novel adaptive zigzag scanning scheme, which is called the context-based adaptive coefficient scanning method, and apply it in the lossy JPEG baseline algorithm. Simulation results show that our proposed method achieves better coding efficiency than both the conventional zigzag scanning method and the two-stage zigzag scanning (TSZS) method adopted in JPEG.