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.

Certain examples described herein relate to generating a Neugebauer Primary area coverage (NPac) vector. In certain cases, a first plurality of Neugebauer Primaries (NPs) defined by a first NPac vector is determined, the first plurality of NPs defining a set of characteristics of a printing process. A second NPac vector, defining a second plurality of NPs, is generated based on the set of characteristics and a criterion relating to the printing process.

An example embodiment may involve causing a page of a document to be printed on a printing device, wherein the printing device is in an AM halftoning mode and prints the page using an AM halftone; displaying, on the display unit, a graphical user interface, wherein the graphical user interface includes a selectable option to switch the printing device from the AM halftoning mode to an FM halftoning mode; receiving an indication that the selectable option has been selected; possibly in response to receiving the indication that the selectable option has been selected, causing the printing device to switch from the AM halftoning mode to the FM halftoning mode; and causing the page of the document to be printed again on the printing device, wherein the printing device is in the FM halftoning mode and prints the page using an FM halftone.

To set a shading relationship between the plurality of shading inks having the same system color and different densities included in a plurality of kinds of inks, to perform provisional color separation processing to decide a color space value in a virtual color space in the second color system for every lattice point that defines a correspondence relationship between the first and second color spaces, to perform first processing of setting a position of the lattice point where a generation amount of the first ink at the lattice point can be maximized and an ink amount at the lattice point for a first ink which is one of light inks from a result of the provisional color separation processing, and then to perform second processing of setting an ink amount of the first ink and an ink amount of a second ink having a higher density by giving priority to a use of the first ink while maintaining a virtual color space value of the provisional color separation processing result for the first ink.

A document reading device includes red, green, and blue photoelectric transducers; a reader that reads a color image of a document with the photoelectric transducers; and a converter that converts the read color image into a grayscale image. The converter determines the maximum tone value MAX(RGB) among the red, green, and blue tone values of the RGB signal (RGB) of the pixel of the red, green, and blue colors to be a grayscale value of the pixel.

An image processing apparatus includes: a storage unit to store therein, for each of a plurality of colors, correction information in which a correction value for obtaining a target output value is associated with each of combinations of one of a plurality of density values of image data corresponding to the color and one of a plurality of positions in a main scanning direction of image data; and a corrector to correct, when a pixel in input image data indicating image data received from a host device includes two or more colors, for each of the two or more colors, a density value of the color using a value smaller than a correction value corresponding to a combination of the density value of the color and a position of the pixel in the main scanning direction.

In an example, a halftone screen is generated. A plurality of amplitude-modulated dot clusters is arranged in correspondence with a grid. Each of the amplitude-modulated dot clusters comprises a plurality of frequency-modulated dots.

An image processing apparatus that is capable of converting an original color image into a monochrome image to which color scheme intention of the original color image is reflected appropriately. An extraction unit extracts colors used for characters and figures in color data. A first determination unit determines one of the colors as a base color. A second determination unit determines another of the colors as an accent color. An application unit converts the color data into monochrome data by applying a predetermined gray to the base color determined and applying a gray that is distinguishable from the predetermined gray and has a density higher than the predetermined gray to the accent color.

Threshold values in a dither matrix are arranged such that, in a case when screen processing is executed on a multi-tone image that has a first density, halftone dots are formed at a first screen angle, and, in a case when screen processing is executed on a multi-tone image that has a density being higher than a second density that is higher than the first density, halftone dots are formed at a second screen angle that is different from the first screen angle.

From among a plurality of elements included in a printing head and arrayed in a predetermined direction, a faulty element that is unable to form dots properly on a printing medium is identified. At least one of correction processing for increasing a value of multi-valued input image data corresponding to the faulty element and correction processing for decreasing a threshold in a quantization process for the faulty element is performed. Complementary dot data is generated for the faulty element by taking the dot data generated for the identified faulty element as dot data corresponding to an element near the identified faulty element in the predetermined direction.