METHOD FOR DETECTING MARKER SIGNAL DETERIORATION FOR IMAGE QUALITY EVALUATION, AND IMAGE QUALITY EVALUATING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a marker signal deterioration detecting method and an image quality evaluating device that can evaluate image quality with accuracy higher than that by the conventional device. SOLUTION: A comparison section 44 detects an amplitude Adet of a marker imbedded object frequency component in a spread spectral of a decoded image of a coded image, the amplitude Adet is divided by a predetermined quantized size M and whether the amplitude Adet is correctly or wrongly detected is discriminated depending on whether the integer part of the quotient is an even number or an odd number. A marker deterioration estimate section 46 estimates an amplitude Aset of a marker imbedded image before coding depending on the discrimination result of the correct or wrong detection and detects a deterioration ERRblk of the amplitude of the marker signal on the basis of the amplitude values Aest and Adet. An image quality evaluation estimate section 47 obtains a square mean valueσe2 of the amplitude deterioration ERRblk on the basis of the square mean valueσe2 to obtain an image quality evaluation scale PSNR.