PURPOSE: To adequately select quantization parameters by an easier method than before by relating a perceptual noise sensitivity(PNS) class, mental visual quality and quantization parameters. CONSTITUTION: Quantization parameters used for encoding an area of an image are determined by three factors, i.e., a classification of the area to one among specific plural PNS classes, a level of mental visual quality which can be achieved for an encoding version of the image and an experientially derived and previously stored model for the relation among the PNS class, mental visual quality level and quantization parameter values. A PNS classification unit 105 determines quantization parameters qp for respective macroblocks as a function of both a PNS classification in which the macroblocks are classified and a specific mental visual quality level Q to be predicted that can be achieved for the encoding version. The metal visual quality level is received by the PNS classification unit 105 as an input from a quality decision unit 130.
METHOD AND APPARATUS FOR GENERATION OF QUANTIZED PARAMETER