1. An image statistic computation device for computing region-based image statistics of an inputted image, the device comprising: a propagation device that is configured to produce a cumulative image representation by propagating an aggregate function through image data from the inputted image, where each data point in the cumulative image representation includes cumulative image information that is based on a value of previously propagated adjacent points as well as a value of the data point; a target region recognition device that is configured to identify at least one generalized rectangular region from the cumulative image representation; a corner analyzing device that is configured to identify corners of the identified generalized rectangular regions, and characterize each corner as one of predefined corner types, the predefined corner types including at least an interior region of 90° angle formed by two lines, an exterior region of 270° angle formed by two lines, and an intersection region of a pair of 90° angles formed by two crossing lines; and a computation device that is configured to compute statistical information over the identified generalized rectangular regions based on the type of each corner and the cumulative image information at each corner.