| 摘要 |
This invention provides methods, apparatus and article of manufacture used as a countermeasure to image distorting. The present invention involves automatically detecting the presence of distortion in a presumed distorted image, measuring the magnitude and type of distortion, and finally creating a realigned image. Once image distortion is removed, conventional invisible watermark extraction methods are employed to extract the watermark from the realigned image. The automatic method does not depend on a process of visually examining a composite image and recording the coordinates of pixel locations closest to common image features in a distorted image and reference image. Generally, the presumed distorted image is resized to the same size as the reference image. Reference centers at at least three distinct points that do not form a straight line are selected. At each reference center, a sub-image is excised. Pairs of sub-images, one excised from the reference image and the other excised from the distorted image, having the same reference center are used in the process of removal of the distortion.
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