Image processing method, image processing apparatus, inkjet image forming apparatus and correction coefficient data generating method

An image processing apparatus for creating image data for forming an image on a recording medium by ejecting liquid droplets from a plurality of nozzles of a recording head onto the recording medium while causing relative movement of the recording medium and the recording head, the image processing apparatus comprising:

• a correction coefficient storage device which stores correction coefficients for ejection failure correction based on difference of landing interference patterns of a plurality of types, the correction coefficients being determined according to correspondence information indicating correspondence relationship between the respective nozzles and the landing interference patterns based on a landing interference inducing factor including a deposition sequence of the liquid droplets on the recording medium that is defined by an arrangement configuration of the plurality of nozzles and a direction of the relative movement, the correction coefficients for ejection failure correction being stored according to the landing interference patterns;
• an ejection failure nozzle position information acquisition device which acquires ejection failure nozzle position information indicating a position of an ejection failure nozzle which cannot be used for forming the image, of the plurality of nozzles;
• and
• a correction processing device which performs a correction calculation on input image data using a corresponding correction coefficient obtained by referring to the correction coefficients for ejection failure correction according to the ejection failure nozzle position information, so as to generate image data corrected in such a manner that output of the ejection failure nozzle is compensated by a nozzle other than the ejection failure nozzle.

An inkjet image forming apparatus comprising:

• a recording head having a plurality of nozzles for ejecting liquid droplets;
• a conveyance device which conveys at least one of the recording head and a recording medium so as to cause relative movement of the recording head and the recording medium;
• a correction coefficient storage device which stores correction coefficients for ejection failure correction based on difference of landing interference patterns of a plurality of types, the correction coefficients being determined according to correspondence information indicating correspondence relationship between the respective nozzles and the landing interference patterns based on a landing interference inducing factor including a deposition sequence of the liquid droplets on the recording medium that is defined by an arrangement configuration of the plurality of nozzles and a direction of the relative movement, the correction coefficients for ejection failure correction being stored according to the landing interference patterns;
• an ejection failure nozzle position information acquisition device which acquires ejection failure nozzle position information indicating a position of an ejection failure nozzle which cannot be used for forming the image, of the plurality of nozzles;
• a correction processing device which performs a correction calculation on input image data using a corresponding correction coefficient obtained by referring to the correction coefficients for ejection failure correction according to the ejection failure nozzle position information, so as to generate image data corrected in such a manner that output of the ejection failure nozzle is compensated by a nozzle other than the ejection failure nozzle;
• and
• a droplet ejection controller which controls droplet ejection of the recording head according to the image data generated by the correction processing device.

A correction coefficient data generating method of generating correction coefficient data for ejection failure correction to be used in correction processing for compensating for output of an ejection failure nozzle which cannot be used for image formation, by a nozzle other than the ejection failure nozzle, when the ejection failure nozzle is present in an inkjet image forming apparatus which includes a recording head having a plurality of nozzles for ejecting liquid droplets and deposits the liquid droplets ejected from the plurality of nozzles onto a recording medium while causing relative movement of the recording medium and the recording head so as to form an image on the recording medium,

• the correction coefficient data generating method comprising:
• a test chart forming step of forming test charts of a plurality of types corresponding to landing interference patterns of a plurality of types, by performing an ejection disabling process of artificially disabling liquid ejection in different nozzles corresponding to difference of the landing interference patterns, according to correspondence information indicating correspondence relationship between the respective nozzles and the landing interference patterns based on a landing interference inducing factor which includes a deposition sequence of the liquid droplets on the recording medium that is defined by an arrangement configuration of the plurality of nozzles and a direction of the relative movement;
• a correction coefficient determination step of determining correction coefficients for ejection failure correction respectively for the landing interference patterns, from output results of the test charts of the plurality of types created respectively for the landing interference patterns;
• and
• a storage step of storing the landing interference patterns and the correction coefficients determined respectively for the landing interference patterns in association with each other in a storage device.