Abstract: The current invention discloses methods and devices of storing an additional piece of information along with compressed image data without increasing the compressed data size and without substantially affecting the reproduced image. To accomplish the above objectives, an additional piece of the information such as a data block image characteristic signal is inserted in certain compressed data at or near the least significant bit position. Because of the position, the compressed data does not substantially affect the de-compression process. However, the additional information is used to improve the reproduced image.