| 摘要 |
<p>PROBLEM TO BE SOLVED: To more properly detect image quality degradation such as mosquito distortion. SOLUTION: A block processing circuit 12 of this image signal processor receives an image signal obtained as a result of coding/decoding in compliance with the MPEG1 via an A/D converter 11. The block processing circuit 12 separates a supplied signal into two-dimensional image blocks. An output from the block processing circuit 12 is fed to a DCT circuit 13 and an ADRC circuit 14. The DCT circuit 13 applies discrete cosine transform to the received data and a low frequency component latch circuit 15, a horizontal high frequency component latch circuit 16 and a vertical high frequency component latch circuit 17 latch coefficients of low, horizontal high frequency and vertical high frequency components in DC coefficients respectively and absolute value variance calculation circuits 18, 19, 20 of the post-stage calculate absolute value variance of each coefficient. A 1st flag denoting high possibility of occurrence of image quality deterioration such as mosquito distortion is outputted as a result of arithmetic processing such as threshold value processing on the basis of an output of each absolute value variance calculation circuit is outputted.</p> |
