## Intelligent source coding

Where the error characteristics of the communications channel are known, it is possible to bias the source encoding/decoding process deliberately to be tolerant of a certain type of error.

#### The images shown here are good examples of how intelligent source coding can pay off. The first image uses conventional image coding techniques designed for data channels that exhibit a random distribution of bit errors with time. When subject to a channel that produces short, focused bursts of errors, the decoded image is severely degraded. The second image has been passed through an encoder/decoder designed to be resilient to burst errors, and clearly demonstrates the marked improvement that can be achieved if the source coding is tailored to the channel error conditions - where known. (Images kindly provided by Professor David Bull, Centre for Communications Research, University of Bristol.)