| 摘要 |
PROBLEM TO BE SOLVED: To enable a user to easily look at the address, zip code, etc., of a mail and to improve the mail recognition rate by converting the density data of a matrix form which are divided into plural steps for every pixel into the black and white pixels according to the 2nd threshold that is different from the 1st threshold in response to the changing instruction of threshold. SOLUTION: An input part 34 has a dark key 34a which is inputted when the displayed characters of an image display part 33 are too light to be recognized and a light key 34b which is inputted when the displayed characters are too dark. A gradation processing circuit 36 performs the gradation processing (binarization processing) of the density data on every pixel expanded by an expansion processing circuit 35, e.g. 256 steps by means of the standard threshold '192' serving as a prescribed screen display parameter. Then the circuit 36 changes the threshold serving as the screen display parameter into '224' with input of the key 34a and also into '160' with input of the key 34b respectively.
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