A storage device stores dither patterns composed of three-dimensional block consisting of the number H of dots in a horizontal directionthe number V of lines in a vertical directionthe number F of frame directions. Each value from a minimum value to a maximum value of dither values of n bits is written in each address of the storage device corresponding to each dot. When each value is written into the storage device, processing of obtaining a spatiotemporal density value indicating a degree of density of an address in which a dither value has already been written in a predetermined three-dimensional area centered on each of the addresses in which a new dither value is writable, and processing of selecting an address having the smallest spatiotemporal density value among the addresses in which a new dither value is writable and writing a dither value are repeated.

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.

A computer-implemented method for generating an amplitude modulated multi-cluster halftone dot for use in an amplitude modulated screen includes determining an arrangement of clusters within the dot; determining a cluster function for each cluster, the cluster function defining a pixel sequence indicating a sequence of turning on device pixels within an area of a particular cluster; determining a dot function for the dot, the dot function defining a cluster sequence indicating a sequence of the clusters; and generating a set of data representative of the dot for a particular tonal value, by determining the device pixels within the dot turned on for that particular tonal value according to the cluster functions and the dot function. A computer program, a printing device and a printed product are also provided.

An image forming system that classifies a block formed by Nb pixels included in image data into Nt groups including a group including a pixel of a highest gradation value and a group including a pixel of a lowest gradation value, generates, for at least one of the Nt groups, positional information that is information indicating positions of pixels that form the corresponding group, determines a block gradation value in accordance with a data amount that is smaller than a data amount that is used for expressing gradation values of the Nb pixels for each of the Nt groups as a target, based on a gradation value for each of pixels that form each group, tentatively determines, determines, for the block as a target, the dot arrangement using the tentatively determined dot arrangement and the positional information, and forms an image using the determined dot arrangement.

Provided are an image recording apparatus, a dither mask, and an image recording method capable of reducing occurrence of concentration unevenness without decrease in productivity. In an image recording apparatus that repeats a main scan operation of relatively moving a recording head having a nozzle row with respect to a recording medium in a main scan direction to perform recording and a sub scan operation of relatively moving the recording medium with respect to the recording head in a sub scan direction, a nozzle jetting rate of each nozzle is controlled by a dither mask. The dither mask is subjected to threshold setting so that a sum of a sum of nozzle jetting rates of corresponding nozzles of respective nozzle groups used in recording a first half scan for recording each scan band and a sum of nozzle jetting rates of corresponding nozzles of respective nozzle groups used in recording a second half scan becomes a specific value that is in a defined allowable range, with respect to at least a part of a recording duty range.

For a dither matrix used when converting multivalued data into image data for an output apparatus, thresholds are set such that: a first dot and a second dot alternately become larger until both of the first dot and the second dot reach a first dot size; after both of the first dot and the second dot reach the first dot size, the first dot becomes larger until the first dot reaches a second dot size while the second dot does not become larger, and thereafter, the second dot becomes larger until the second dot reaches the second dot size while the first dot does not become larger; and after both of the first dot and the second dot reach the second dot size, the first dot and the second dot alternately become larger.

An image processing apparatus includes a multi-gradation-level dither processing unit and a screen processing unit. The multi-gradation-level dither processing unit performs a multi-gradation-level dither process for a target image. The screen processing unit performs an FM screen process for the target image for which the multi-gradation-level dither process has been performed. Further, in the multi-gradation-level dither process, the multi-gradation-level dither processing unit selects each pixel in the target image as a target pixel in turn; using a conversion characteristic corresponding to each local pixel position group in a unit matrix, converts a pixel value of the target pixel to one of: a minimum gradation level, a maximum gradation level and an intermediate gradation level corresponding to the pixel value of the target pixel; and sets a pixel value of each pixel in the unit matrix as a pixel value obtained with the conversion characteristic.

An image forming apparatus includes: a nozzle head in which nozzles that form dots on a recording medium by ejecting ink onto the recording medium are arranged in a row in a first direction; a moving mechanism that moves at least one of the recording medium or the nozzle head relative to another in a second direction intersecting the first direction; an image acquirer that acquires image data for forming an image of dots on the recording medium; and a halftone processor that determines whether to form a dot at each pixel position of the image on the basis of the image data, wherein the halftone processor includes: an n-value processor; a grouping processor; a total value calculator; and a rearrangement processor.

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.

Provided is quantization processing that can reduce color development defect due to dot overlapping and can output an image with reduced granularity when the image is printed by using multiple kinds of colorants. To this end, dot arrangement information for a colorant for which dot arrangement is already determined among multiple kinds of colorants is acquired for a predetermined region of the image, and an evaluation value of each pixel included in the predetermined region is derived based on the arrangement information. In addition, for the predetermined region, a target value for a predetermined colorant for which dot arrangement is yet to be determined is derived based on the image. Then, whether or not to arrange a dot of the predetermined colorant in the predetermined region is determined based on the target value and the evaluation value.