Image thresholding for optical character recognition

摘要

The thresholding involves processing the image qualities of the sheet. The image is scanned with a preselected threshold value or a black/white or gray scale image is formed. The image characteristics are analysed, the image data, image content and image distortions, selective for specific areas of the image or for the entire image. The spatial and local spread of the image characteristics are analysed. A threshold value from the results of the analysis is transmitted. The threshold value is selected on the basis that the required image has a more pronounced amplitude and distribution characteristic. The area scanned yield signals ABC that relate to the required signature signal A, background B and image distortion effects C.