Human Contour Extraction For Gait Recognition

Gait recognition is the process of identifying individuals by the way they walk. Compared with other biometrics, such as fingerprint, face and iris, the identification by gait is unobtrusive and does not require touching the human body. In gait recognition, effective extraction of human contour is a prerequisite of subsequent processing including feature extraction, feature expression, target classification and target recognition. The goal of this thesis is to research human contour extraction algorithm. The main contributions are listed as follows:①A new block-matching motion estimation algorithm based on UCBDS (unrestricted center-biased diamond search) is put forward in this thesis. For the original UCBDS, the motion vector of the current block is assumed to be zero, but this doesn't match with the real condition. Aiming at a better prediction result, the median method is adopted to confirm the starting search position. In addition, according to the matching possibility of candidate blocks, the search region of UCBDS is decreased.②This thesis presents a new motion object segmentation algorithm based on motion information and the watershed algorithm. Firstly, the improved block-matching estimation algorithm is used to estimate the motion fields of the image. Secondly, we apply the watershed algorithm to divide the current image into a number of closed and non-overlapping regions. Finally, we utilize the affine parameter model to merge these regions. The experiments show that this new algorithm can effectively extract human contour and improve the performance of gait recognition.③An improved object contour method based on Snake model is investigated for an accurate object contour. The initial contour of Snake model is extracted automatically by the above algorithm rather than by manual work. In this paper, we use Greedy algorithm to compute the energy function of Snake model. The true points of contour and isolated noise points are distinguished automatically by applying a new external function. In addition, a formula is constructed to automatically adjust the weights of internal energy and external energy. The experiments show that the method can extract accurate contour under complex background.