Investigation Of Video Compression based Upon Optical Flow

• Main Authors: Ga-U Young, 楊佳遇
• Other Authors: Ben-Shung Chow
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/10486692278729866232

碩士 === 國立中山大學 === 電機工程學系研究所 === 90 === Displacement information is important in dynamic image analysis. The method of optical flow has been well applied to compute the displacement in the field of computer vision. We apply the method of optical flow to compute the displacement information for video compression. We can predict the optical flow between picture 2 and picture 3 by the optical flow between picture 1 and picture 2 by using the principle of inertia. Using the predicted optical flow between picture 2 and picture 3, we can recover a rough version of picture 3. This version can be taken as a reference picture for encoding picture 3. This reference will decrease the compensation information in the following stage, and then improve the compression ratio of MPEG . We modified the traditional optical flow of Horn & Schunck to a regional optical flow by segmentation. Then, the displacement information could be reduced. The picture is recovered by the optical flow in a modified way because some objects couldn’t move in the same direction and velocity. We propose two methods in optical flow prediction. One is the complete information: shape and value. The other is shape only with value recomputed and extra encoded. Experiments demonstrate a better compression ratio of 1% for our motion compensation than the regular motion compensation.