Apparatus and method for adaptively encoding pictures in accordance with information quantity of respective pictures and inter-picture correlation

摘要

A method and apparatus for encoding a picture with improved prediction accuracy in predicting the basic quantization step. The apparatus for encoding a picture includes a picture data storage unit, a picture information evaluating unit, an inter-picture correlation detection unit, an orthogonal transform unit for orthogonally transforming the picture data for generating orthogonal transform coefficients, a quantization unit for quantizing the orthogonal transform coefficients produced by the orthogonal transform unit at a pre-set quantization step, an adaptive compression method selection unit and a quantization step control unit. The information quantity is evaluated from stored picture data of plural pictures, and the inter-picture correlation is detected. A picture data compression method is adaptively selected based upon the evaluated value of the information quantity and the inter-picture correlation information. The basic quantization step is predicted from the evaluated value and a pre-set compressed data quantity obtained on compressing one-picture picture data by the selected compression method and the evaluated value.