A printer performs a multi-pass printing including: (a) pass process executed with Ka number of nozzles; (c1) pass process executed with Kc1 number of nozzles; (c2) pass process executed with Kc2 number of nozzles; and (b) pass process executed with Kb number of nozzles. Kc1 and Kc2 are greater than or equal to Kb and smaller than Ka. An upstream gradient of dot recording rates of (c1) pass process is greater than a gradient of (a) pass process. A downstream gradient of (c1) pass process is the same as the gradient of (a) pass process. An upstream gradient of (c2)-pass process is the same as a gradient of (b) pass process. A downstream gradient of (c2)-pass process is greater than the gradient of the (a) pass process. Kc1 is greater than Kc2.

An image forming apparatus includes an image processor, a converter, a light source driver, an identifying unit, and a pattern generator. The image processor generates image data of first resolution and generates tag information indicating whether to perform image processing and associated with pixels of the image data of first resolution. The converter converts the image data of first resolution to image data of a higher second resolution. The light source driver drives a light source using a modulation signal corresponding to the image data of second resolution. The identifying unit identifies a target pixel to be subjected to image processing in the image data of first resolution based on the tag information. The pattern generator generates an image-processed pixel pattern of the second resolution according to the target pixel. The converter converts the target pixel in the image data of first resolution to the generated image-processed pixel pattern.

An image forming apparatus includes an image processor, a converter, a light source driver, an identifying unit, and a pattern generator. The image processor generates image data of first resolution and generates tag information indicating whether to perform image processing and associated with pixels of the image data of first resolution. The converter converts the image data of first resolution to image data of a higher second resolution. The light source driver drives a light source using a modulation signal corresponding to the image data of second resolution. The identifying unit identifies a target pixel to be subjected to image processing in the image data of first resolution based on the tag information. The pattern generator generates an image-processed pixel pattern of the second resolution according to the target pixel. The converter converts the target pixel in the image data of first resolution to the generated image-processed pixel pattern.

Each area in a test pattern for performing color shift correction is recorded by a discharge port at an edge portion in many times of scanning and by a discharge port other than the discharge port at the edge portion in fewer times of scanning.

A printer performs a multi-pass printing including: (a) pass process executed with Ka number of nozzles; (c1) pass process executed with Kc1 number of nozzles; (c2) pass process executed with Kc2 number of nozzles; and (b) pass process executed with Kb number of nozzles. Kc1 and Kc2 are greater than or equal to Kb and smaller than Ka. An upstream gradient of dot recording rates of (c1) pass process is greater than a gradient of (a) pass process. A downstream gradient of (c1) pass process is the same as the gradient of (a) pass process. An upstream gradient of (c2)-pass process is the same as a gradient of (b) pass process. A downstream gradient of (c2)-pass process is greater than the gradient of the (a) pass process. Kc1 is greater than Kc2.

There is provided an ink jet printer including a carriage, and an ink jet head. The ink jet head has two first nozzle groups to jet a first ink, two second nozzle groups to jet a second ink, and two third nozzle groups to jet the second ink. Each of the first, second and third nozzle groups includes a plurality of nozzles arrayed at a pitch P along a second direction. The second nozzle groups accord respectively with the first nozzle groups in terms of nozzle position in the second direction, the third nozzle groups are dislocated respectively from the second nozzle groups in terms of nozzle position in the second direction, and any two groups selected from the first and second nozzle groups are arranged respectively on two opposite sides of each of the third nozzle groups in the first direction.

The methods and apparatuses herein relate to inkjet printing a substrate at a desired print resolution. A substrate advances at a first speed under the first printhead and the second printhead such that a desired print resolution exceeds the maximum print resolutions of a first printhead and a second printhead. When the substrate is advancing at the first speed, the first printhead ejects ink onto the advancing substrate at a first firing frequency to create a first printed zone, and the second printhead ejects ink onto the advancing substrate at a second firing frequency to create a second printed zone. In turn, the first printed zone and the second zone together define a printed region having the desired print resolution.

A method and apparatus for subdividing and printing regions of a substrate with multiple print heads or multiple print head assemblies which substantially decreases printing time is described. The method includes a feathering method which reduces overlap artifacts which is useful in any printing situation where adjacent regions are printed that could be misaligned, offset, or have slightly different colors.

A printing apparatus includes a transport unit configured to transport a medium in a first direction, a carriage configured to move in a second direction intersecting the first direction, a first printing unit held by the carriage, and a second printing unit held by the carriage, the second printing unit being arranged at least one of a position further upstream and a position further downstream than a position of the first printing unit, a length of the second printing unit in the first direction is shorter than a length of the first printing unit in the first direction, and the second printing unit is caused to be available in a multi-pass mode.

A printer includes a printbar having plural dice partially overlap in the direction of rows and a halftoner. The dice receive nozzle firing data which determines when and where the individual print nozzles are to be operated in order to emit the colorant onto the media so as to form the desired printed image on a media. The halftoner is a bidirectional error diffusion halftoner that is structured to generate halftoned data. The halftoned data is mappable into the firing data. The halftoner includes a serpentine direction reverser which is structured to halftone print data image pixels in a first serpentine direction to form halftoned data and then to halftone print data image pixels in an opposite serpentine direction to form the halftoned data.