| 摘要 |
PROBLEM TO BE SOLVED: To provide a dither mask discriminating device suitable for the character recognition of a dither picture image. SOLUTION: A dot distribution type or dot concentration type dither picture image is stored in an image storing part 12. A change point detection part 18 executes raster scanning for the dither picture image stored in the storing part 12, counts up the sum H of white-to-black change points and black-to-white change points and counts frequency A turning a scanning point to a black picture element. An evaluation value calculating part 20 finds evaluation value = (H.N)/A (N is an optional positive integer) and compares the evaluation value with a threshold THL. It is defined that N=16 and THL=7 for instance. When the evaluation value exceeds the threshold THL, the dither picture image obtaining the evaluation value is judged as a dot distribution type, and when the evaluation value is less than the THL, the image obtaining the evaluation value is judged as a dot concentration type. Since a recognition dictionary to be used for the character recognition of the dither picture image is switched or a filter for correcting the image is switched in accordance with the judged result, the recognition accuracy of the dither picture image can be improved. |
