Image output apparatus and image formation system for correcting density unevenness
AssigneeCanon Kabushiki Kaisha
InventorsKazuyoshi Takahashi, Takashi Watanabe, Toshiyuki Yanaka
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Abstract
A test image is formed by performing overlap printing using a plurality of printing heads provided for a printing agent of one color. Density data attained by reading this test image is averaged. On the basis of this average value, a common correction is performed for drive signals for the printing heads. This makes it possible to perform head density unevenness correction at a high efficiency in performing overlap printing by using the plurality of printing heads.
Claims21
An image forming apparatus which forms an image on a printing medium by using a first printing head having a plurality of printing elements, comprising:
- scanning means for scanning the first printing head relative to the printing medium;
- image formation control means for causing said scanning means to scan the first printing head to form an image on the basis of image data corresponding to the plurality of printing elements respectively, said image formation control means causing said scanning means to scan the first printing head a plurality of times to a predetermined area on the printing medium to form an image, wherein said image formation control means is adapted to form an image so that image areas formed by the plurality of elements of the first printing head may be at least partially overlapped in each of the plurality of scans of the first printing head;
- test image forming means for causing said first printing head to form a test image, wherein the test image is formed by using said image formation control means;
- obtaining means for obtaining correction amounts for respective image data corresponding to the plurality of printing elements on the basis of a result of reading of an image density of the test image, the correction amounts for equalizing an image density of an image formed by said first printing head;
- and
- correcting means for correcting image data in accordance with the correction amounts obtained by said obtaining means, for the respective image data corresponding to the plurality of printing elements, wherein the correction amounts obtained by said obtaining means are common for the printing elements scanned to a given place during the plurality of scans.
An image forming method which forms an image on a printing medium by using a printing head having a plurality of printing elements, comprising:
- a step of forming a test image, including a first image forming step of scanning the printing head to form an image on an area of the printing medium corresponding to the plurality of printing elements, and a second image forming step of scanning the printing head to form an image on an area which partially overlaps the area on which the image is formed in said first image forming step;
- a step of obtaining correction amounts for respective image data corresponding to the plurality of printing elements on the basis of a result of reading of an image density of the test image, wherein the correction amounts obtained in said obtaining step are common for the printing elements scanned to a given place in the first and second image forming steps, and wherein the correction amounts are for equalizing an image density of an image formed by said printing head;
- a step of correcting image data in accordance with the correction amounts obtained in said obtaining step, for the respective image data corresponding to the plurality of printing elements;
- and
- a step of forming an image with said printing head based on the corrected image data.
Dependencies are inferred from the claim text.