HYBRID OPTICAL/DIGITAL PROCESSING APPROACH FOR INTERFRAME IMAGE DATA COMPRESSION

Abstract

Image data compression is an active topic of research in image processing. Traditionally, most image data compression schemes have been dominated by digital processing due to the fact that digital systems are inherently flexible and reliable. However, it has been demonstrated that optical processing can be used for spatial image data compression, using a method called interpolated differential pulse code modulation (IDPCM). This is a compression scheme which functions analogously with conventional digital DPCH compression, except that the specific compression steps are implemented by incoherent optical processing. The main objective of this research is to extend IDPCM to interframe compression, design such systems, and evaluate the compression performance limitation under no channel errors, given the subjectively acceptable image quality by means of digital simulation. We start with a review of digital spatial and interframe compression techniques and their implications for optical implementation. Then, the technological background of electro-optical devices which has made possible hybrid optical/digital processing for image data compression will be briefly discussed. Also, a detailed description of IDPCM coding is given, along with the ways that IDPCM can be extended to interframe compression. Finally, two architectures of hybrid and optical/digital interframe compression are proposed, simulated, and evaluated in order to discover potential performances of optically implemented interframe compression systems. Excellent reconstructed image quality is obtained by the proposed adaptive hybrid (O/D) IDPCM/frame replenishment technique at an overall transmission rate of 3 Mbits/sec, average bit rate of 1.5 bits/pixel, and the average compression ratio of 5.2:1.