Certain examples described herein relate to a three-dimensional threshold matrix. The three-dimensional threshold matrix may be used for three-dimensional halftoning. In one example, values for a predefined two-dimensional threshold matrix are shifted with respect to a third dimension to provide the three-dimensional threshold matrix. In one example, the three-dimensional threshold matrix may then be processed in association with a digital representation of a three-dimensional object to output discrete material arrangement instructions for at least one production material. The instructions may be used to control an additive manufacturing system to produce the three-dimensional object.

A method of color image processing for quantizing output includes obtaining an input for an object pixel which is represented by a vector in a first color space. A modified input equal to the input plus a sum of errors from other pixels in a neighborhood of the object pixel is generated. For each color component in the first color space, where corresponding color components of the modified input are located with respect to a preset range is determined. If the modified input's color component is greater than the preset range, then that color component for an output is determined to be on; if less than the preset range, then that color component for the output is determine to be off; and, if within the preset range, then that color component for the output is determined to be unknown. A transformed modified input is mapped to a perceptual color space when any color component of the output is unknown. Colors consistent with color components of the output that have already been determined are also mapped to the perceptual color space. The color in the perceptual color space that lies closest to the transformed modified input is chosen. An output in the first color space having color components on and off is generated consistent with the determinations and/or choices made. Error for the object pixel is then calculated as the difference between the output and the modified input.

An image processing apparatus includes an input unit configured to receive first material appearance data representing a material appearance of an image, a material appearance mapping unit configured to convert the first material appearance data into second material appearance data corresponding to a material appearance reproducible by a material appearance reproducing apparatus, and a conversion unit configured to convert the second material appearance data into control data for reproducing the material appearance of the image using the material appearance reproducing apparatus. The first material appearance data includes a gloss signal corresponding to a specular gloss and a gloss signal corresponding to an image clarity.

In an image forming apparatus that employs a laser scanning optical system that does not use an fθ lens, in the case where magnification correction by insertion/removal of an auxiliary pixel is performed based on the premise of digital PWM, an insertion/removal position of an auxiliary pixel is controlled in accordance with a purpose of each piece of image processing.

Mask entries for each of a plurality of passes over which print fluid drops are to be dispensed for printing an image are generated based on different types of masks and based on image data for the image. Print fluid drop dispensation for a pixel for which the mask entries for a given pass specify repeated print fluid drop dispensation is moved to a mask entry for an adjacent pass that does not specify print fluid drop dispensation for the pixel. Ejection of print fluid to print the image is caused based on the generated mask entries.

Mask entries for each of a plurality of passes over which print fluid drops are to be dispensed for printing an image are generated based on different types of masks and based on image data for the image. Print fluid drop dispensation for a pixel for which the mask entries for a given pass specify repeated print fluid drop dispensation is moved to a mask entry for an adjacent pass that does not specify print fluid drop dispensation for the pixel. Ejection of print fluid to print the image is caused based on the generated mask entries.

An image is rendered on a display having a limited number of primary colors by (104) combining input data representing the color of a pixel to be rendered with error data to form modified input data, determining in a color space the simplex (208—typically a tetrahedron) enclosing the modified input data and the primary colors associated with the simplex, converting (210) the modified image data to barycentric coordinates based upon the primary colors associated with the simplex and (212) setting output data to the primary having the largest barycentric coordinate, calculating (214) the difference between the modified input data and the output data for the pixel, thus generating error data, applying (106) this error data to at least one later-rendered pixel, and applying the output data to the display and thus rendering the image on the display. Apparatus and computer-storage media for carrying out this process are also provided.

An image is rendered on a display having a limited number of primary colors by (104) combining input data representing the color of a pixel to be rendered with error data to form modified input data, determining in a color space the simplex (208—typically a tetrahedron) enclosing the modified input data and the primary colors associated with the simplex, converting (210) the modified image data to barycentric coordinates based upon the primary colors associated with the simplex and (212) setting output data to the primary having the largest barycentric coordinate, calculating (214) the difference between the modified input data and the output data for the pixel, thus generating error data, applying (106) this error data to at least one later-rendered pixel, and applying the output data to the display and thus rendering the image on the display. Apparatus and computer-storage media for carrying out this process are also provided.

An image forming apparatus includes: a correction unit configured to correct a tone of each pixel in first image data in accordance with an image height on a photosensitive member, and output second image data; a halftone processing unit configured to determine exposed regions of pixels in an image by applying halftone processing to the second image data; and a scanning unit configured to form a latent image by scanning the photosensitive member with light that changes in scanning speed in accordance with an image height based on the exposed regions of the pixels. The scanning unit is further configured to perform partial exposure with respect to the pixels based on the exposed regions of the pixels, the partial exposure exposing partial regions of the pixels to light unlike entire exposure that exposes entire regions of the pixels to light.

An image forming apparatus includes: a correction unit configured to correct a tone of each pixel in first image data in accordance with an image height on a photosensitive member, and output second image data; a halftone processing unit configured to determine exposed regions of pixels in an image by applying halftone processing to the second image data; and a scanning unit configured to form a latent image by scanning the photosensitive member with light that changes in scanning speed in accordance with an image height based on the exposed regions of the pixels. The scanning unit is further configured to perform partial exposure with respect to the pixels based on the exposed regions of the pixels, the partial exposure exposing partial regions of the pixels to light unlike entire exposure that exposes entire regions of the pixels to light.