A recording device includes a head including a first nozzle row that discharges a plurality of drawing inks; and a second nozzle row that discharges an overcoat ink posterior to the drawing inks, and also includes a dot-data generating unit that performs dot-data generating processing including halftone processing using a dither mask. When generating dot data used to perform recording in accordance with a first recording mode in which no nozzle that discharges the overcoat ink is assigned to part of pixels in a recording target region of the recording medium, the first recording mode being a recording mode using the second nozzle row, the dot-data generating unit generates the dot data by using a first overcoat dither mask having a threshold value set so as not to form a dot with the overcoat ink on the part of pixels.

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.

A image processing method includes a shifting step for determining whether to shift an identical color pixel region, in which two to N pixels of an identical color are arranged consecutively in a first direction, in the first direction or a direction opposite to the first direction within the image data, provided that N is an integer of 2 or greater, and shifting the identical color pixel region in the first direction or the direction opposite to the first direction when the shifting is determined to be performed, and an averaging step, in which in the shifting step, the shifting is determined to be performed when the identical color pixel region exists across two of the unit regions, and the identical color pixel region spanning across the two of the unit regions is shifted so as to be included in any one of the unit regions.

An image forming apparatus includes: a hardware processor that quantizes each pixel with a dither pattern divided according to a resolution in a predetermined direction, and sets a recording amount of each pixel by adding up processing results of the quantization.

A method for correcting distortion in image printing, the method includes receiving a digital image (200, 306, 376, 500, 600, 700, 810) acquired from a printed image. Based on the digital image (200, 306, 376, 500, 600, 700, 810), a geometric distortion in the printed image is estimated. One or more pixel locations (228, 504, 506, 514, 610, 620, 630, 640, 712, 716, 722, 724) are calculated, such that, when one or more dummy pixels (232, 234) are implanted therein, compensate for the estimated geometric distortion. The geometric distortion is corrected in a subsequent digital image to be printed, by implanting the one or more dummy pixels (232, 234) at the one or more calculated pixel locations (228, 504, 506, 514, 610, 620, 630, 640, 712, 716, 722, 724) in the subsequent digital image. The subsequent digital image having the corrected geometric distortion is printed.

A recording device includes a head including a first nozzle row that discharges a plurality of drawing inks; and a second nozzle row that discharges an overcoat ink posterior to the drawing inks, and also includes a dot-data generating unit that performs dot-data generating processing including halftone processing using a dither mask. When generating dot data used to perform recording in accordance with a first recording mode in which no nozzle that discharges the overcoat ink is assigned to part of pixels in a recording target region of the recording medium, the first recording mode being a recording mode using the second nozzle row, the dot-data generating unit generates the dot data by using a first overcoat dither mask having a threshold value set so as not to form a dot with the overcoat ink on the part of pixels.

In an image forming device, a controller converts continuous-tone image data to raster image data using a dither matrix. The continuous-tone image data includes pixels each has a tone value. The raster image data is binary image data corresponding to exposure areas. The dither matrix includes threshold values. The dither matrix is configured so that as an exposure area percentage of the raster image data increases, growth of the exposure area progresses according to a growth process including: a stage at which an exposure area extends in a predetermined screen direction from an isolated exposure area to connect with another isolated exposure area; and a stage at which after the isolated exposure area connects with another isolated exposure area, the exposure area extends in a crossing direction crossing the predetermined screen direction. The controller controls the exposure device to expose the photosensitive drum based on the raster image data.

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.

A image processing method includes a shifting step for determining whether to shift an identical color pixel region, in which two to N pixels of an identical color are arranged consecutively in a first direction, in the first direction or a direction opposite to the first direction within the image data, provided that N is an integer of 2 or greater, and shifting the identical color pixel region in the first direction or the direction opposite to the first direction when the shifting is determined to be performed, and an averaging step, in which in the shifting step, the shifting is determined to be performed when the identical color pixel region exists across two of the unit regions, and the identical color pixel region spanning across the two of the unit regions is shifted so as to be included in any one of the unit regions.