JPS6475273A - Method for detecting printing line - Google Patents

Abstract

PURPOSE:To correctly judge the presence of printing if a stain exists in a passbook printing line direction and in a passbook line feed direction, by a method wherein, white/black judgement is performed at every scanning, and the judgement of the presence of printing by the black scanning number in one line is ANDed with the judgement of presence of printing by the black level data number in one line. CONSTITUTION:By optically scanning on the printing of a passbook surface, a detection signal of white/black level is obtained. This signal is binarized, and white/black data is stored in a memory. By counting black data at every scanning, a histogram is obtained. If the number of scannings with the black data number more than a predetermined value alpha is more than a predetermined value beta and the total black data number is more than a predetermined value gamma, the presence of printing is judged. If a stain exists in the printing line direction of a passbook, memory storage data is obtained, the number of black data is counted, and a histogram is obtained. In this case, the number of scannings above alpha is beta or below; thus, the absence of printing is judged. If a stain exists in the line feed direction of the passbook, memory storage data is obtained, and a histogram is obtained. In this case, the number of scannings above, alphais beta or more, but the total black data number is gamma or less; thus, the absence of printing is judged.