An image forming method being configured to execute halftone processing using a dithering matrix on input image, output a halftone image, perform correction on the halftone image to shift a pixel at a correction position, and generate an image with a converted lower resolution based on the corrected image, wherein the matrix includes a plural sub-matrices, wherein an arrangement of a threshold in a first sub-matrix is configured to form a first halftone dot having a first line shape for an input image with a predetermined density, wherein an arrangement of a threshold in a second sub-matrix is configured to form a second halftone dot with the same angle as the first line shape and having a center position different from the first halftone dot for the input image with the predetermined density, and wherein the first and second halftone dot form a line shape with a predetermined screen angle.

In order to implement preferred sharpness recovery processing for an image, an image processing apparatus which generates, based on input image data, halftone image data used for an image forming process of forming an image on a print medium. The apparatus converts the input image data into color material amount data used for the image forming process; performs, on the color material amount data, gamma correction to compensate for non-linearity of an input/output density in the image forming process; performs, on the color material amount data after the gamma correction, recovery processing to compensate for sharpness degradation of an image formed by the image forming process; and performs halftone processing on the color material amount data after the recovery processing to generate halftone image data.

A temporary dot pattern at a dot pattern determining target gradation is determined by adding or removing dots as much as the number of dots corresponding to a gradation difference to or from a dot pattern at a gradation at which a dot pattern is already determined, and a dot pattern at a dot pattern determining target gradation is determined by performing a replacement process of replacing dots including some of dots at a dot pattern determined gradation among the dots in the temporary dot pattern with non-dot arrangements. A halftone mask may be constituted by a group of dot patterns at each gradation, or the halftone mask may be constituted by setting a dot pattern for each gradation as a threshold value.

An image forming device includes: a hardware processor that performs halftone processing on input image data using a threshold matrix of a dither method, and that, when dot missing exists in a formed image by the image forming part, performs interpolation by rearranging a missing dot to peripheral pixel position; and an image forming part that forms an image on a recording medium on the basis of image data after halftone processing by the halftone processing part, wherein the hardware processor, using the threshold matrix, sets a blank pixel having a high probability of being generated next when gradation is increased, as a rearrangement destination of the missing dot.

In an example, an apparatus is described that includes a color conversion module an a visual noise module. The color conversion module converts page description language describing an image into rasterized image data. The visual noise module then recalculates pixel values in an area of flat tint detected in the rasterized image data to introduce visual noise in the area of flat tint.

This disclosure describes examples for generating image content based on both a color value and a dither value that is to be applied. When a color value for the current pixel is the same as the color value for a previous pixel, and a dither value that is to be applied to the current pixel is the same as the dither value that was added to the previous pixel, a display processor may output the output color value for the previous pixel as the output color value for the current pixel.

A copy-evident document and a method of printing a copy-evident document wherein a void pantograph is created including a first set of halftone elements and a second set of halftone elements different in modulation from the first set of halftone elements. An overlay including a white image with a plurality of halftone hole locations is preferably formed, wherein the halftone elements of the void pantograph are converted to the plurality of halftone hole locations. The overlay is then preferably merged with a background image, such that portions of the background image are visible at the halftone hole locations of the overlay when printed. The merged image is then printed on print media, wherein the portions of the background image that are printed are printed at locations where the holes locations are present in the overlay creating a copy-evident feature.

An image processing apparatus for forming an image by superimposing n (n2) records on a same region in a recording medium includes: a holding unit configured to hold a threshold matrix characteristic representing a dispersity of a dot pattern of each tone obtained when dithering is performed using a threshold matrix; a setting unit configured to set recording data for n recording scans by dividing image data for the n recording scans based on the threshold matrix characteristic; and a halftoning unit configured to perform dithering using the threshold matrix on the recording data for each of the n records.

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.

Quantization is performed on multi-valued data corresponding to a non-overlap recording area and one of recording heads on the basis of a dither pattern and multi-valued data corresponding to the non-overlap recording area and the other one of the recording heads, and also arrangements of thresholds for the dither patterns used between the scanning operations are varied.