Joint utilization of fixed and variable-length codes for improving synchronization immunity for image transmission


Alatan A. A. , Woods J.

IEEE International Conference on Image Processing, Illinois, United States Of America, 4 - 07 October 1998, pp.319-323 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • City: Illinois
  • Country: United States Of America
  • Page Numbers: pp.319-323

Abstract

Robust transmission of images is achieved by using fixed and variable-length coding together without much loss in compression efficiency. The probability distribution function of a DCT coefficient can be divided into two regions using a threshold; so that one portion contains roughly equiprobable transform coefficients. While fixed-length coding, which is a powerful solution to the synchronization problem, is used in this inner equiprobable region without sacrificing compression, the outer (saturating) region is reserved for variable-length codes. The proposed-image coder first encodes the bit allocated DCT coefficients using a fixed-rate quantizer bank, then the saturated values for these coefficients are encoded using an entropy constrained scaler quantizer, followed by an arithmetic encoder. Our simulations show that the proposed encoder is appropriate for applications in which an acceptable quality must always be maintained in any channel condition.