A method of single-pass printing uses a printing system having first and second aligned printheads supplied with a same ink. The method includes the steps of: receiving first and second halftone images at the first and second printheads, respectively; printing the first halftone image from the first printhead; and printing the second halftone image from the second printhead. The first halftone image is based on a first dither pattern and the second halftone image is based on a second dither pattern, the first dither pattern being different than the second dither pattern.

A method of processing a contone image for single-pass printing uses a printing system having first and second aligned printheads supplied with a same ink. The method includes the steps of: providing the contone image at a first resolution in a printing direction; dithering the contone image using a combined dither pattern to provide a full halftone image at the first resolution; dividing the full halftone image into first and second halftone images at a second resolution in the printing direction, the second resolution being less than the first resolution; and sending the first and second halftone images to respective first and second printheads for printing. The combined dither pattern is a combination of a first dither pattern for the first printhead and a second dither pattern for the second printhead, the first dither pattern being different than the second dither pattern.

An image processing apparatus generates image data for an image forming apparatus having a recording head with recording elements in a first direction that forms an image on a recording medium by ejecting ink from the elements toward the medium fed in a second direction perpendicular to the first. The apparatus has an acquiring unit that acquires multi-valued input image data having tones, a conversion unit that converts the input image data into halftone image data indicating a dot pattern, by using a dither matrix, and a correction processing unit that executes a density unevenness correction process in accordance with properties of each of the recording elements. The properties of the elements are obtained by reading a chart image formed based on the halftone image data. The dither matrix is a dispersive dither matrix with a size of Sx rows corresponding to the second direction, Sx, a natural number.

An image processing apparatus generates image data for an image forming apparatus having a recording head with recording elements in a first direction that forms an image on a recording medium by ejecting ink from the elements toward the medium fed in a second direction perpendicular to the first. The apparatus has an acquiring unit that acquires multi-valued input image data having a uniform tone, a conversion unit that converts the input image data into halftone image data indicating a dot pattern, by using a dither matrix, and a correction processing unit that executes a density unevenness correction process in accordance with properties of each of the elements. The properties of the elements are obtained by reading a chart image formed based on the halftone image data. The dither matrix is a dispersive dither matrix with a size of Sx rows corresponding to the second direction, Sx, a natural number.

An image processing apparatus includes a processing unit that converts first input image data for a first region and second input image data for a second region to reduce a difference between first region recorded image density and second region recorded image density, and generates dot position data of a dot to be generated in each of the first and second regions based on the dot data after the conversion processing. The acquisition unit acquires edge information indicating a first object pixel edge of an image pixel for the first region and a second object pixel edge of an image pixel for the second region. Based on the acquired edge information, conversion and generation processing are performed in such a manner that a color signal of an edge pixel is increased/reduced to a degree lower than a degree to which a color signal of a non-edge object pixel is increased/reduced.

In an embodiment of the present disclosure, an image processing apparatus for generating dot data, which defines whether or not a dot is arranged in each pixel, includes: a dot number derivation unit configured to derive a number of dots to be arranged in a predetermined region of image data; a determination unit configured to determine an arrangement priority of a pixel in which a dot is arranged, based on the pixel value of each pixel included in the predetermined region and a threshold value group in a threshold value matrix; a correction unit configured to correct the derived number of dots, in a case where the derived number of dots is smaller than a criterial number of dots; and a generation unit configured to generate the dot data, based on the corrected number of dots and the arrangement priority.

When a sum of a first gradation data for a first color and a second gradation data for a second color is greater than the maximum value of thresholds of a first threshold matrix, a generation unit generates a first overlapping gradation data and second overlapping gradation data by dividing a value obtained by subtracting the maximum value from the sum. Further, the generation unit generates a first quantization data based on a result of comparing the first overlapping gradation data with the second threshold or a result of comparing a difference between the first gradation data and the first overlapping gradation data with the first threshold, and generates a second quantization data based on a result of comparing the second overlapping gradation data with the first threshold or a result of comparing a difference between the second gradation data and the second overlapping gradation data with the second threshold.

In an embodiment of the present disclosure, an image processing apparatus for generating dot data, which defines whether or not a dot is arranged in each pixel, includes: a dot number derivation unit configured to derive a number of dots to be arranged in a predetermined region of image data; a determination unit configured to determine an arrangement priority of a pixel in which a dot is arranged, based on the pixel value of each pixel included in the predetermined region and a threshold value group in a threshold value matrix; a correction unit configured to correct the derived number of dots, in a case where the derived number of dots is smaller than a criterial number of dots; and a generation unit configured to generate the dot data, based on the corrected number of dots and the arrangement priority.

An image processing apparatus includes a target value calculation unit configured to calculate a target value to be output in a predetermined region in input image data based on pixel values of pixels included in the region, a distribution order determination unit configured to determine a distribution order of output values for distributing output values corresponding to the target value in the region based on a pixel value of each pixel included in the region and a threshold value in the threshold matrix corresponding to the pixel, and an output value determination unit configured to determine an output value of each pixel included in the region by allocating the target value to at least one pixel included in the region in the distribution order.

When a sum of a first gradation data for a first color and a second gradation data for a second color is greater than the maximum value of thresholds of a first threshold matrix, a generation unit generates a first overlapping gradation data and second overlapping gradation data by dividing a value obtained by subtracting the maximum value from the sum. Further, the generation unit generates a first quantization data based on a result of comparing the first overlapping gradation data with the second threshold or a result of comparing a difference between the first gradation data and the first overlapping gradation data with the first threshold, and generates a second quantization data based on a result of comparing the second overlapping gradation data with the first threshold or a result of comparing a difference between the second gradation data and the second overlapping gradation data with the second threshold.