<title>Real Time Television Image Bandwidth Reduction Using Charge Transfer Devices</title>

Abstract

Recent advances in analog semiconductor technology have made possible the direct sensing and processing of television images. By combining a charge transfer device (CTD) imager and a CTD transversal filter, real time image sensing and encoding have been achieved with low power integrated circuits so that digital transmission and bit rate reduction are made possible using differential pulse code modulation (DPCM). Good mean square error performance and freedom from DPCM artifacts are possible in a hybrid intraframe image encoder. The hybrid transform encoder performs a discrete cosine transform (DCT) on each line of the television image as it is scanned. This compacts the variance into low frequency coefficients and the DPCM encodes the corresponding DCT coefficients between successive lines. Computer simulation of this hybrid coding technique has shown good performance on 256 x 256 pixel images at 0.5 bits/pixel and channel bit error rates of 10-2. An experimental system using a low resolution General Electric 100 x 100 charge injection device camera and a Texas Instruments bucket brigade transversal filter as part of the DCT processor has been constructed and provides good low resolution image quality at 1 bit/pixel and bit error rates of 10-3. A high resolution vidicon compatible system is also being constructed.