Digital Image Processing
Computer processing on the identification of a Chinese seal image
ICDAR '95 Proceedings of the Third International Conference on Document Analysis and Recognition (Volume 1) - Volume 1
Registration of seal images using contour analysis
SCIA'03 Proceedings of the 13th Scandinavian conference on Image analysis
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As important premises of automatic seal verification system, candidate seal must be detected from processed image and done registration with the template seal. The paper gives such a robust method. After the candidate seal is detected from the processed image by contour skeleton analysis, FFT is performed for template and candidate seals. FFT Magnitude feature matrix describing global and invariant properties of the seal image is constructed by integrating the Fourier transformation over each of the regions of a wedge-ring-detector. Robust rotation angle is evaluated by minimizing the difference between two feature matrixes for the two seals. Then, relative translation can be evaluated by limited position enumerating in the space domain. Experiment results show that our method can deal with noise-corrupted images and complicate-background images. Seal detection and registration are fast and accurate, and the methods have been used in a real seal identification system successfully.