Pedestrian segmentation is a problem of considerable practical interest. In this work we present an extended version of our shape-based model for pedestrian segmentation, which can also be used to give an initial guess of the 2D pedestrians pose/orientation. The proposed model is initialized by a bounding-box of the person under analysis, which can be estimated by a person detector. The basic idea of the proposed model is to create a graph around the detected person, based on a scale invariant shape model and the estimated contour is given by a path in the graph that maximizes certain boundary energy. In practice, such energy should be large in the boundary between the foreground/background. To cope with pose/shape variations, the¯nal estimate is given by a selection scheme, which takes into consideration the individual estimate given by di®erent generated graphs. Experimental results indicated that the proposed technique works well in non trivial images, with comparable accuracy to the state-of-the-art. Int. J. Semantic Computing 2016.10:53-71. Downloaded from www.worldscientific.com by MONASH UNIVERSITY on 06/11/16. For personal use only.The pedestrian segmentation task can be considered a special case of person/ human segmentation. As related in the work of Dollar et al.[2], people analysis, by computer vision techniques, makes the use of datasets containing people in unconstrained pose in a wide range of domains whilst the area of pedestrian analysis uses datasets containing upright people (standing or walking), typically viewed from more restricted viewpoints.Pedestrian segmentation can be used in several applications, including robotics, surveillance systems, driver assistance models, among others. Farenzena and his group [3], for example, assume the presence of the silhouette of an individual, obtained for each person by inferring over the STEL generative model [4], to extract appearance features applied in a person re-identi¯cation problem. Similarly, Ma et al.[5] adopted a pedestrian parsing (partitioning the human body into semantic regions, such as head, torso, arms, etc, which may include clothes and accessories) model [6] to extract appearance features of speci¯c pedestrian's body parts for the same purpose (person re-identi¯cation). This trend seems to be very useful in human analysis (speci¯cally in person re-identi¯cation tasks), as the background usually include several noise, making even more di±cult to obtain a good solution for such task.In this work we extend our shape-based model for pedestrian segmentation in still images [7] to estimate the main orientation of pedestrian¯gures. In addition, other features of the model were evaluated, as considering grayscale images (instead of color¯gures) as well as the inclusion of a post-processing operation, which takes into consideration color cues. This journal version also includes new experimental results and a more detailed discussion of some technical points.As in the original work [7], we focus on the case where an external pedestrian detector i...