Patent ID: 9623671
Date: 2017-04-18
CPC Classifications: B41J,H04N

Claim:
1. An image processor for printing an image on a first area of a printing medium by using a first nozzle group including a plurality of nozzles in a first nozzle array ejecting a first ink and a second nozzle group including a plurality of nozzles in a second nozzle array ejecting a second ink, and for printing an image on a second area different from the first area of the printing medium by using a third nozzle group including a plurality of nozzles different from the nozzles included in the first nozzle group in the first nozzle array and a fourth nozzle group including a plurality of nozzles different from the nozzles included in the second nozzle group in the second nozzle array, the image processor comprising: a first conversion unit configured to convert a first input color signal including RGB color components and representing a predetermined color to be printed on the first area into a first output color signal including RGB color components by using a first multi-color shading table corresponding to the first and second nozzle groups which defines a correspondence relationship between a combination of input values of the RGB color components of the first input color signal and a combination of output values of the RGB color components of the first output color signal, and convert a second input color signal including RGB color components and representing the predetermined color to be printed on the second area into a second output color signal including RGB color components by using a second multi-color shading table corresponding to the third and fourth nozzle groups which defines a correspondence relationship between a combination of input values of the RGB color components of the second input color signal and a combination of output values of the RGB color components of the second output color signal, wherein parameters for signal conversion that are defined by the first multi-color shading table and parameters for signal conversion that are defined by the second multi-color shading table, are different, wherein the first multi-color shading table and the second multi-color shading table are determined such that a color difference, which is caused by a variation of the ejecting characteristic among the nozzles of the first nozzle array and a variation of the ejecting characteristic among the nozzles of the second nozzle array, between a color of an image printed onto the first area by using the first nozzle group and the second nozzle group to eject the first ink and the second ink based on the first output color signal and a color of an image printed onto the second area by using the third nozzle group and the fourth nozzle group to eject the first ink and the second ink based on the second output color signal is reduced; a color conversion processing unit configured to convert RGB signal based on the first output color signal into a first multiple ink signal including an ink signal of the first ink representing an ink density of the first ink and an ink signal of the second ink representing an ink density of the second ink to be printed on the first area and convert RGB signal based on the second output color signal into second multiple ink signal ink signal of the first ink representing an ink density of the first ink and representing an ink signal of the second ink representing an ink density of the second ink to be printed on the second area; a second conversion unit configured to convert an input ink signal of the first ink representing an ink density of the first ink to be printed on the first area which is based on the first multiple ink signal into a output ink signal of the first ink using a first head shading table corresponding to the first nozzle group of the first nozzle array which defines correspondence relationship between an input value of the input ink signal of the first ink and an output value of the output ink signal of the first ink, and convert an input signal of the first ink representing an ink density of the first ink to be printed on the second area which is based on the first multiple ink signal into an output ink signal of the first ink using a second head shading table corresponding to the third nozzle group of the first nozzle array which defines correspondence relationship between an input value of the input ink signal of the first ink and an output value of the output ink signal of the first ink, the first head shading table and the second head shading table are determined such that a density difference, which is caused by a variation of the ejecting characteristic among the nozzles of the first nozzle array, between a density of an image printed onto the first area by ejecting the first ink only from the first nozzle group based on the output ink signal of the first ink and a density of an image printed onto the second area by ejecting the first ink only from the third nozzle group based on the output ink signal of the first ink is reduced, and configured to convert an input ink signal of the second ink representing an ink density of the second ink to be printed on the first area which is based on the second multiple ink signal into a output ink signal of the second ink using a third head shading table corresponding to the second nozzle group of the second nozzle array which defines correspondence relationship between an input value of the input ink signal of the second ink and an output value of the output ink signal of the second ink, and convert an input signal of the second ink representing an ink density of the second ink to be printed on the second area which is based on the second multiple ink signal into an output ink signal of the second ink using a fourth head shading table corresponding to the fourth nozzle group of the second nozzle array which defines correspondence relationship between an input value of the input ink signal of the second ink and an output value of the output ink signal of the second ink wherein the third head shading table and the fourth head shading table are determined such that a density difference, which is caused by a variation of the ejecting characteristic among the nozzles of the first nozzle array, between a density of an image printed onto the first area by ejecting the second ink only from the second nozzle group based on the output ink signal of the second ink and a density of an image printed onto the second area by ejecting the second ink only from the fourth nozzle group based on the output ink signal of the second ink is reduced; and a print data generating unit configured to generate print data used for printing on the first area and the second area by the first nozzle array based on the output ink signal of the first ink for the first area and output ink signal of the first ink for the second area converted by the second converting unit and print data used for printing on the first area and the second area by the second nozzle array based on the output ink signal of the second ink for the first area and output ink signal of the second ink for the second area converted by the second converting unit.