| 摘要 |
<p>The invention corrects for rotational misalignment of images having a prominent periodic structure in a preferred direction, particularly imaged text pages (40). It preferably also finds the degree of correlation between different images. First the rotational misalignment of an imaged page is detected and corrected (30), bringing the page into alignment with an axis. The angle of rotation of the page is detected by performing a linear regression analysis (56) on filtered, tow-dimensional power spectral density distribution of the page, to find the angular orientation of the periodic components. In the preferred embodiment, two imaged pages (40) are then cross-correlated (72), preferably by an optical correlator (18), to find the degree of correlation between the pages (40).</p> |
