Disclosed are a system and method for encoding and decoding an image. The image compression system includes an image segmentation unit (110) for segmenting a first image into a plurality of sub-images; a first encoding unit (120) for encoding the sub-images to output sub-image bitstreams; a BMAP construction unit (130) for calculating the quantity of information of each sub-image bitstream and generating BMAP information using the calculated quantity of information and information on construction of each sub-image; and a bitstream combining unit (150) for combining the sub-image bitstreams and BMAP information.