Robust Frame Extraction and Removal for Processing Form Documents
A new frame extraction and a removal method for processing form documents is proposed. The method robustly extracts scanned preprintings such as frames and lines. It consists of a frame detection process and a frame removal process. In the frame detection process, the center coordinates are extracted using a Generalized Hough Transformation-based method. Then, using those coordinates, an inscribed rectangular image for each frame is produced. In the frame removal process, the detected frame image is removed along the outside of the rectangular edge. These processes are repeated to remove the target frames successfully by changing some pre-processings such as reducing and enhancing. The method was applied to some types of images. They are postal codes on mail and forms received by facsimiles. In both cases, there often can be seen low quailty pre-printings. For those low quality images, convetional approach such as model pattern maching was not well worked because of local distortion. Through experiments in frame detection and removal of the images, we demonstrated that all of the frames could be successfully removed.
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