| 摘要 |
A method and apparatus are provided to measure spatial distortion. Measure and remove borders; and rescale the active test image, the active reference image, or both, such that they are the same size. A representative line is obtained, or selected, from each image providing a reference representative line (ReferenceRL) and a test representative line (TestRL). A local Pearson' cross-correlation coefficient (LPCCC) image is created from both the ReferenceRL and the TestRL at different horizontal shifts. The highest average intensity line across the LPCCC image is found as the coordinates of the corresponding Hough Transform image pixel with maximum intensity is determined. The Hough Transform Theta and R are converted to spatial scale and offset. The crude and refined offsets and scale values are combined to produce total horizontal and vertical scale offset values. These spatial measurements can then be provided.
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