Research And Realization Of Image Preprocessing And Registration In Electronic Reading-pen

Image Preprocessing and Frame-to-frame Registration is the core technique of electronic reading pen based on shift-scanning OCR. This paper builds up a complete front-end processing algorithm system for images acquired by Shift-scanning, then studies and implements the algorithms of every stage in this system.The actual work of this paper is as follows:1. Analyses the format of the AVI video-files and BMP files; realize the extraction of single-frames image from an AVI file, the conversion of RGB images to gray images and the saving of mosaic images after registration in BMP format; provide good experimental media to the further research.2. In image binarization, implements Otsu global-threshold algorithm and Bersen local-threshold algorithm, and then realizes the step-binarization method based on these two algorithms mentioned above, which has good experimental effects.3. Realize the letter skew detection algorithm based on Hough-transform, analyzes the complexity and defects on skew detection of Hough-transform; adopts the projection-value-checking algorithm in slop degrees checking, introduces the Bresenham algorithm to calculate the projection values to lower the complexity of calculation. Furthermore, through the comparison on performance of max-projection-value method and max-blank-length method of this algorithm, selects the max-projection-value method in final experiment, which was proved to be more effective.4. Carries out text-row extracting using horizontal-projection algorithm, and normalizes the image size using bicubic-interpolation method.5. In image Frame-to-frame Registration and mosaic, creates the SIFT algorithm, registration algorithm based on letter figure and on projection. The paper improves the projection registration and the experiments result show that the improved method is robust to image distortions.In a word, this paper creates a complete front-end processing algorithm system for electronic reading pen based on shift-scanning OCR, and the final experiment shows that this algorithm system works well, and build up the foundation for the character recognize in back-end of Electronic Reading Pens.