An adaptive joint source channel coding (JSCC) for image transmission over an additive white Gaussian noise (AWGN) channel is studied in a particular context, that to use the bandwidth effectively, which leads to a robust communication. Such that, the source symbol and the channel symbol possibly have different dimensions, the basic idea is to map efficiently the source space symbols into channel space symbols. The case of decreasing dimension is denoted bandwidth reduction, while the dimension is increased is called bandwidth expansion. We introduce several operators, being based on the channel optimized vector quantization (COVQ) algorithm and the Han mapping. We will also give a background of the theoretical limits for Gaussian sources and channels, expressed by OPTA (optimal performance theoretically attainable), and we compare the performances of these operators with these limits.