Adaptive image coding with robust channel-optimized trellis-coded quantization

Abstract

We present an error-robust channel-optimized image coder for the transmission of imagery over noisy channels. The proposed coder uses a robust channel-optimized trellis-coded quantization (COTCQ) stage that is designed to optimized the image coding based on the channel characteristics. The resilience to channel errors is obtained only at the level of the source encoder, with no explicit use of channel coding. The robust nature of the coder increases the security level of the encoded bit stream, and eliminates impulsive artifacts induced by channel errors. A novel adaptive classification scheme is employed to increase coding efficiency by exploiting image nonstationarities. Consequently, the proposed channel-optimized image coder is especially suitable for wireless transmission due to its reduced complexity, its robustness to nonstationary signals and channels, and its increased security level. Simulation results show that our coder provides outstanding quantitative and subjective coding performance for a wide variety of channel conditions.