Ink jet printing apparatus performing printing with correction of image data at boundary portion of image

An ink jet system using a printing head having a plurality of ink ejection elements arranged in a predetermined direction and performing printing on a printing medium on a basis of image data corresponding to said plurality of ink ejection elements, said system comprising:

• test pattern printing means for printing a test pattern, based on the image data corresponding to the test pattern, on the printing medium to be used for printing by using the ink ejection elements of the printing head;
• reading means for reading density of the test pattern printed by said test pattern printing means so as to obtain density corresponding to each of said plurality of ink ejection elements used for printing said test pattern;
• setting means for setting correction data for correcting the image data corresponding to the ink ejection elements used for printing both end portions of a printing region to be printed, on a basis of differences between the density corresponding to a first group of ink ejection elements including at least ink ejection elements at both end portions of the printing region and an average density value corresponding to a second group of ink ejection elements that excludes the first group of ink ejection elements;
• correction means for correcting the image data corresponding to said ink ejection elements at both end portions on a basis of the correction data set by said setting means;
• and
• controlling means for controlling correction of the image data performed by said correction means, the image data corresponding to the test pattern, when said setting means sets the correction data corresponding to the ink ejection elements, wherein said controlling means controls said correction means based on the correction data respectively corresponding to the first group of ink ejection elements and the second group of ink ejection elements.

A method of correcting a density fluctuation in an image printed in an ink jet printing apparatus using a printing head having a plurality of ink ejection elements arranged in a predetermined direction and performing printing on a printing medium on a basis of image data corresponding to said plurality of ink ejection elements, said method comprising the steps of:

• printing a test pattern, based on the image data corresponding to the test pattern, on the printing medium to be used for printing by using the ink ejection elements of the printing head;
• reading a density of the printed test pattern so as to obtain density corresponding to each of the plurality of ink ejection elements used for printing said test pattern;
• setting correction data for correcting the image data corresponding to the ink ejection elements used for printing portions including at least both end portions of a printing region to be printed, on a basis of differences between the density corresponding to a first group of ink ejection elements including at least ink ejection elements at both end portions of the printing region and an average density value corresponding to a second group of ink ejection elements that excludes the first group of ink ejection elements;
• correcting the image data corresponding to said ink ejection elements at both end portions on a basis of the set correction data;
• and
• controlling correction of the image data performed in said correcting step, the image data corresponding to the test pattern, before said setting step sets the correction data corresponding to the ink ejection elements.

An ink jet printing apparatus using a printing head having a plurality of ink ejection elements arranged in a predetermined direction and performing printing on a printing medium on a basis of image data corresponding to said plurality of ink ejection elements, said apparatus comprising:

• a first correction portion for correcting the image data corresponding to the ink ejection elements of end portions of the arranged ink ejection elements so that density indicated by said image data is decreased;
• a second correction portion for correcting the image data corresponding to said ink ejection elements of said end portions on a basis of the density indicated by the image data corresponding to the plurality of ink ejection elements;
• a print control portion for driving the printing head on a basis of the image data corrected by both said first correction portion and said second correction portion to perform printing;
• and
• a controlling portion for controlling correction respectively performed by said first correction portion and said second correction portion.

A method of correcting a density fluctuation in an image printed in an ink jet printing apparatus using a printing head having a plurality of ink ejection elements arranged in a predetermined direction and performing printing on a printing medium on a basis of image data corresponding to said plurality of ink ejection elements, said method comprising the steps of:

• correcting, in a first correction step, the image data corresponding to the ink ejection elements of end portions of the plurality of ink ejection elements so that density indicated by said image data is decreased;
• correcting, in a second correction step, the image data corresponding to the ink ejection elements of the end portions on a basis of the density indicated by the image data corresponding to the plurality of ink ejection elements;
• driving, in a printing step, the printing head on a basis of the image data corrected in both said first correction step and said second correction step to perform printing;
• and
• controlling correction respectively performed in said first correction step and said second correction step.