1. A method for determining an orientation of a local line segment in a contour in a local area of a binary contour image implemented by a processing unit accessing a storage memory unit, comprising: a first step for obtaining the numbers of pixels each having a first predetermined value and located in a plurality of orientations around one of pixels, located in the local area and having said first predetermined value, wherein the pixels are stored in the storage memory unit; and a second step for determining that a local line segment exists in an orientation in which the number of pixels located in the orientation is greater than a second predetermined value using the processing unit.