Method of judging whether or not darkness of foreign matter has been read, method of calculating representative value of darkness of test pattern, and apparatus that judges whether or not darkness of foreign matter has been read

摘要

A method of judging whether or not darkness of a foreign matter on a test pattern printed on a medium with predetermined darkness has been read at the time of reading the darkness of the test pattern using a reading section, includes: detecting a section in the test pattern for which an amount of deviation, from a predetermined reference value, of a readout value on the darkness of that section exceeds a predetermined darkness-deviation threshold which is a threshold adopted for the deviation in darkness; and judging whether or not the darkness of the foreign matter has been read based on a size of the above-mentioned section that has been detected.