| 摘要 |
PURPOSE:To identify printing by a microscopic difference in pattern by including a direction comparison means for comparing a network point arrangement direction on respective primary color components from an output of an arrangement direction detection means and identifying a color printing method according to the comparison result. CONSTITUTION:The direction comparison means 9 examines the presence and the absence of the directional characteristic according to that the difference between a maximum value and a minimum value in the frequency is larger than a preset threshold or not from the result with respect to the respective primary color components. When the difference is larger, if the direction of the maximum in the frequency to the two primary color components is different, it is decided to be an offset printing and if the direction is equal, it is decided to be gravure printing. According to a picture pattern, when the directional characteristic is not present in all the three primary color components, if the direction of the maximum in the frequency in the primary color component having the directional characteristic is that except 45 deg., it is decided to be the offset printing and if all the directions are 45 deg., they are decided to be the gravure printing. When the difference between the maximum value and the minimum value in the frequency is smaller than the threshold, it is decided to perform other printing on the printed matter. Thereby, the periodicity and the direction of the microscopic pattern structure in the color printing can be identified by a digital picture processing. |
