Image processing method and image forming device

An image processing method used in an image forming in which ink drops are discharged from a plurality of recording elements of a recording head toward a recording medium as the recording head and the recording medium are moved relative to each other to convert an input image having an M number of tones into an image having an N number of tones (N<M) on the recording medium, the method comprising:

• a characteristic information acquiring step of acquiring recording characteristic information of the recording elements;
• an inconsistent density correction information calculating step of obtaining inconsistent density correction information from the recording characteristic information acquired in the characteristic information acquiring step;
• a density correction processing step of obtaining inconsistency corrected image data from the inconsistent density correction information and data of the input image;
• an unfit image detection step of generating inconsistency correction unfit image position information by detecting an inconsistency correction unfit image from data of the input image;
• an N-value conversion processing step of obtaining image data having an N number of tones from the inconsistency corrected image data;
• an image anomaly judgment processing step of judging whether non-correctable conditions arise according to the inconsistent density correction information and the inconsistency correction unfit image position information;
• and
• an image anomaly alerting step of alerting a user to an image anomaly according to judgment results given in the image anomaly judgment processing step.