Adaptive quantization apparatus

摘要

There is a signal representing an original image. A device generates a signal representing a predicted image for the original image. A subtracter derives a difference between the original-image signal and the predicted-image signal, and outputs the derived difference as a prediction error signal. The prediction error signal is transformed into a transform-resultant signal. The transform-resultant signal is quantized with variable quantization characteristics. An activity of the original image is derived from the original-image signal. An activity is derived from the prediction error signal. The quantization characteristics are controlled in response to both the original-image activity and the prediction-error activity. <IMAGE>