Joint Utilization of Fixed and Variable-Length Codes for Improving Synchronization Immunity for Image Transmission

Robust transmission of images is achieved by using xed and variable-length coding together without much loss in compression e ciency. The probability distribution function of a DCT coe cient can be divided into two regions using a threshold, so that one portion contains roughly equiprobable transform coefcients. While xed-length coding, which is a powerful solution to the synchronization problem, is used in this inner equiprobable region without sacri cing compression, the outer saturating region is reserved for variable-length codes. The proposed image coder rst encodes the bit allocated DCT coe cients using a xed-rate quantizer bank, then the saturated values for these coe cients are encoded using an entropy constrained scalar quantizer, followed by an arithmetic encoder. Our simulationsshow that the proposed encoder is appropriate for applications in which an acceptable quality must always be maintained in any channel condition.

• Type: Conference
• Year: 1998
• Where: ICIP
• Authors: A. Aydin Alatan, John W. Woods
• Keywords: Constrained Scalar Quantizer, DCT Coe Cient, DCT Coe Cients, ICIP 1998, Image Processing