JP2825600B

PURPOSE:To enable an omission of printing, running out of printing, and scumming of ink near and inside a printing part to be detected by a method wherein whether a number of total dots corresponding to pixels of the printing part is within a number of reference total dots or not is discriminated and besides, whether a number of bonded components is within a number of reference bonded components or not is discriminated. CONSTITUTION:After establishing a rectangular window W1 enclosing a printing part, an image digital signal in the window W1 is binarily coded and further a number of total dots corresponding to pixels in the printing part and a number of binded components are obtained from this binary coded signal. Then, whether the number of total dots corresponding to pixels of the printing part is within a range of a number of reference total dots established preliminarily based on good products or not is discriminated. When it is outside the range, a product is judged to be an inferior product having defects in printing. Further, when it is within the range of the number of reference total dots, whether the number of bonded components is within a number of reference bonded components or not is discriminated. When running out of printing like the figure '1' MG 2, an omission of printing like the figure '9' MG 3, or scumming of printing MG 1, etc., exist, since the number of bonded components varies, the product is judged to be the inferior product.