Gait recognition refers to automatic identification of an individual based on his/her style of walking

which is a new biometrics recognition technology. This paper attempts to describe gait contour by using the distance between the contour centroid and the pixels on the edge

to make quasi-periodic analysis on height and width ratio of gait image

and to solve the problems resulting from image sequence of different gait cycle by HMM. By utilizing the algorithm in the paper

the experiments with CMU database have achieved comparatively high correction identification ratio.