A method for automatically determining the region of interest from an image comprises the three steps of (a) analyzing content of the transformed coefficients of an image after a discrete signal transformation and partitioning an image into the interested region and background region that are based on p.times.p-pixel sub-blocks for performing classification; (b) locating the central point of the interested sub-blocks; and (c) integrating a plurality of the interested sub-blocks from said central point to the boundary of an image to generate a closed and continued region of interest by using a image processing technique with considering the bit-rate requirement.