Colorful printing using more colors based on data for printing with a single color or few colors is enabled.

A printer control unit 15 includes a print data acquisition unit 15c, print data processing unit 15d, and print control unit 15e. The print data acquisition unit 15c acquires data for a print object and a command specifying the print position of the print object. Based on the print position specified by the command acquired by the print data acquisition unit 15c, the print data processing unit 15d applies a process setting an attribute of the print object, or a process replacing the print object with another print object.

A method of processing a document for printing includes receiving a document; for at least one of the plurality of regions, determining a drop size for that region and determining whether the drop size for printing the region meets a threshold criterion and, if so, processing the region using a tile-based screen for halftoning and, if not, processing the region using an error diffusion screen for halftoning; and printing the processed regions. Another method includes additionally considering coverage level to determine whether to use a tile-based screen or error diffusion screen. Yet another method includes determining whether the region is within a threshold range of a drop step change.

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.

When a corrected pixel value of a target pixel is within a first range and the target pixel is not a prohibited pixel, a first value indicating formation of a dot of a first type having a minimum size is determined as a pixel value of a print pixel corresponding to the target pixel. When the corrected pixel value is within a second range different from the first range and the target pixel is not the prohibited pixel, a second value indicating formation of a dot of a second type having a size greater than the dot of the first type is determined as the pixel value of the print pixel. When the corrected pixel value is within the first range and the target pixel is the prohibited pixel, a non-formation value indicating formation of no dots is determined as the pixel value of the print pixel.

The present invention provides an image processing apparatus which employs a dither method capable of printing a thin line of desired density without any break irrespective of printing conditions. The first threshold changing unit changes part of threshold values in a threshold matrix to generate a first threshold matrix so as to increase the number of dots to be printed in a specific pixel area. The second threshold changing unit changes part of threshold values in the threshold matrix to generate a second threshold matrix such that the number of dots to be printed in a specific pixel area is smaller than the case of changing a threshold value by the first threshold changing unit. A determining unit determines whether a threshold value in the threshold matrix is to be changed by the first threshold changing unit or by the second threshold changing unit.

The color of object data that indicates the shape and the color of an object is reproduced faithfully when modeling an object. A model is formed by discharging droplets having the same color from droplet discharging units onto a medium, based on the same reference signal. Colorimetry is performed on the model, and a first-portion and a second-portion having a color with a higher density are specified. The liquid amount of droplets per unit area to be discharged from droplets discharging units that formed the first-portion and the liquid amount of droplets per unit area to be discharged from droplets discharging units that formed the second-portion are adjusted such that a difference in density of colors to be reproduced decreases. The object is modeled by repeating processing for discharging droplets from the droplet discharging units based on the object data.

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.

An image forming apparatus in which a lighting position of a dot to be firstly generated by screen processing is changed, in a vertical direction, between a first sub-matrix and a second sub-matrix that are included in a dithering matrix and that are adjacent to each other in a lateral direction, in order not to generate a region where no dot exists in a main scanning direction.

An image processing apparatus configured to generate, based on image data corresponding to a printing image, print data for causing a printer to execute printing includes an input unit (input device, display device) configured to receive, for each of the first ink and the second ink, an ink discharge correction volume for correcting an ink volume discharged from predetermined nozzles among a plurality of first nozzles and a plurality of second nozzles, and a print data generating unit (printer driver) configured to generate the print data based on the image data and the ink discharge correction volume input.

A halftone comprises a first halftone screen and a second halftone screen. The first halftone screen comprises a first plurality of amplitude modulated dots arranged according to a first plurality of rows, the first plurality of rows being orientated according to a first direction and comprising a first dot spacing. The second halftone screen comprises a second plurality of amplitude modulated dots arranged according to a second plurality of rows, the second plurality of row being orientated in a second direction and comprising a second dot spacing. The first direction and the second direction define an angle of 45 degrees or less and a ratio of the second dot spacing to the first dot spacing is less than one.