Utilizing soft information in image decoding

This paper explores the utilization of soft information in image decoding. Error free transmission is not always possible in today´s nor future´s communication networks without retransmissions. Retransmissions, however, introduce delay. To delay sensitive applications the concept of soft information, i.e. lower layer knowledge about the channel conditions, could reduce the number of retransmissions. It is not sufficient to treat the soft information and the image decoder separately. By combining soft information and the knowledge of the image structure in the decoding process image quality can be improved. A modified JPEG2000 image decoder that utilizes soft information has been developed. Experimental results with images transmitted over a simulated wireless channel show that iterative decoding with soft information can give high gains in image quality.