On the importance of error resilience in visual communications over noisy channels

This paper presents the importance of error resilience tools in visual communications. Error resilience tools provide a mechanism enabling transmission of visual information over channels with residual random bit errors in the received bit stream. The benefits of using error resilience tools are proven by devising the analytic relationship between the time delay in a transparent channel using automatic repeat request (ARQ) and the equivalent residual bit error rate in a nontransparent channel. The error resilience tools make it possible to achieve an acceptable visual quality even in the presence of these residual errors. Our work is related and compared to the standardization work of the next-generation still image compression system JPEG2000.The results show that partial and complete substitution of the quantization and symbol encoding in visual compression systems by robust error resilience tools provides a significant increase in robustness. Three error resilience tools are discussed: (1) substitution of the quantization and symbol encoding by a fixed length coding scheme, (2) substitution by a mixed fixed length coding and variable length coding scheme, and (3) substitution of the variable length coding by reversible variable length coding.