Spatial prefiltering scheme based on anisotropic diffusion in low‐bitrate video coding
Hiroyuki Tsuji, Shinji Tokumasu, Hiroki Takahashi, Masayuki Nakajima · Systems and Computers in Japan · 2007
Abstract It is desirable for a prefilter used for low‐bitrate video coding to have a nonlinear characteristic achieving reduction in the amount of data by smoothing, as well as preserving as much as possible of edges that are visually important. Thus, we conducted a basic study for formulating an edge‐preserving smoothing filter using anisotropic diffusion. It is known that if the conventional anisotropic diffusion Perona–Malik (PMD) diffusion is used as a smoothing filter, there will be problems such as noise with large gradients remaining and excessive edge enhancement. In this paper, we determine the conditions that the edge‐stopping function must satisfy to solve these problems and derive a concrete function according to those conditions. Also, we verify by numerical experiments that the above problems are solved by anisotropic diffusion with our proposed edge‐stopping functions. Further, targeting application to a prefilter for low‐bitrate video coding, bit count reduction effect of our proposed filter was tested to verify its effectiveness. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(10): 34–45, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/scj.20566