In an ink jet printing method, a recording medium is moved relative to a print head having a plurality of nozzles, and ink droplets are ejected from the nozzles onto the recording medium in a single pass in accordance with print data supplied to the print head. Spit pattern data is included in the print data A location of an expected ink dot ejected according to the spit pattern data is scanned, providing a scanned image, and such ink dot is searched for in the scanned image in order to determine an actual presence of the ink dot.