PICTURE QUALITY EVALUATING DEVICE FOR DIGITALLY COMPRESSED AND REPRODUCED IMAGE

摘要

PURPOSE: To provide the picture quality evaluating device for the digitally compressed and reproduced image which can evaluate picture quality at low cost in a short time. CONSTITUTION: A synchronism control part 14 controls the delay quantity of a delay part 15 so that original image data inputted from a video source 1 and reproduced image data compressed and reproduced by a system 2 to be evaluated synchronize with each other. A 1st orthogonal transformation arithmetic part 17 performs the orthogonal transformation of a reproduced image and an orthogonal transformation arithmetic part 21 performs the orthogonal transformation of an original image; and a subtraction part 19 finds an error value of a coefficient of the same degree in the same block. A WSNR calculation part 22 weights the said error with a weighting function which varies with the position of the coefficient of the orthogonally transformed data and whether the AC power in the block after the orthogonal transformation of the said original image is large or small and then finds mean weighted S/Ns for each frame or every plural frames. Lastly, a subjective evaluated value calculation part 2 calculates a subjective evaluated value (deterioration degree) on the basis of the mean weighted S/Ns.