An image forming apparatus includes an image forming section and a controller. The image forming section forms an image on a first sheet or a second sheet. The controller controls the image forming section. The first sheet is a blank sheet. The second sheet is a reused sheet. The controller refers to reference images each belonging to any of a plurality of categories to determine whether or not the image belongs to any of the categories. The controller directs the image forming section to form the image on the second sheet when determining that the image does not belong to any of the categories. The controller directs the image forming section to form the image on the first sheet and stores the image as a reference image when determining that the image belongs to any of the categories.

An image processing apparatus includes (A) a dither processing unit to perform dither processing on first image data to generate second image data, the second image data including a target pixel and an adjacent pixel, each of the pixels having a density value, the density value of the target pixel being greater than that of the adjacent pixel, and the density value of the adjacent pixel being not greater than a predetermined density, (B) a diffusing unit (a) to determine an error value resulting at the target pixel, (b) to diffuse the error value to pixels subsequent to the target pixel, and not to diffuse an error value resulting at the adjacent pixel to pixels subsequent to the adjacent pixel.

A halftone raster image, suitable for rendering a continuous-tone image, which comprises a plurality of regularly tiled spiral dots. Said spiral dots comprise (i) image pixels arranged as a first arc (200) or as a plurality of arcs which together represent a first spiral (100), and (ii) non-image pixels arranged as a second arc (201) or as a plurality of arcs which together represent a second spiral (101), wherein neighbour halftone dots from said plurality of regularly tiled halftone dots represent a double spiral or triple spiral.

Apparatus and methods for printing multi-level and multi-color digital image are disclosed herein. In some embodiments, first and second level AM half-tone screens are respectively applied to first and second multi-level color-components of the multi-level and multi-color input digital image to respectively generate first and second target binary images. The first and second target binary images are printed respectively using first and second inks (e.g. of different colors) onto a common surface. Specific properties of the AM half-tone screens as well as techniques for producing the AM half-tone screens are disclosed herein. In some embodiments, the techniques overcome objectionable textures derived from rounding errors in divisional of conventional AM supercells.

In an image forming apparatus that employs a laser scanning optical system that does not use an f 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.

An image forming apparatus includes an image forming section and a controller. The image forming section forms an image on a first sheet or a second sheet. The controller controls the image forming section. The first sheet is a blank sheet. The second sheet is a reused sheet. The controller refers to reference images each belonging to any of a plurality of categories to determine whether or not the image belongs to any of the categories. The controller directs the image forming section to form the image on the second sheet when determining that the image does not belong to any of the categories. The controller directs the image forming section to form the image on the first sheet and stores the image as a reference image when determining that the image belongs to any of the categories.

An image processing apparatus of the invention, includes: an error value calculation unit configured to calculate an error value in a target pixel from a concentration value in the target pixel of input image data, and a PWM error value calculated on the basis of a light amount of laser light which is actually emitted on the basis of a PWM signal of a pulse width corresponding to the concentration value, and a light amount of ideal laser light corresponding to the pulse width; and a concentration value calculation unit configured to add the error value calculated in peripheral pixels positioned in the vicinity of the target pixel to the concentration value at a predetermined ratio, in which the error value calculation unit sets the error value in the target pixel to 0 according to the concentration value or a pixel position of the target pixel.

An image forming apparatus is provided, which is capable of implementing updating of gamma correction information with a high accuracy while avoiding a wasteful output of a patch image even in the case where environmental fluctuations occur. The image forming apparatus corrects a density tone level of image data by using gamma correction information, forms an image based on the corrected image data, and includes an updating unit configured to update the gamma correction information by using a patch image, and the updating unit updates the gamma correction information by using a patch image the output stability of which is high as first updating and further updates the gamma correction information updated by the first updating by using a patch image the sensitivity of which is high as second updating.

An disclosed image processing apparatus reproduces an input pixel expressed by a gray level through a printing process performed on a plurality of segmented regions of the input pixel, based on an output pattern. The image processing apparatus includes: a duplicator configured to duplicate the input pixel into at least two pixels; a storage configured to store a plurality of tables, each of the plurality of tables associating the gray level and an output pattern of one of the duplicated pixels, such that a plurality of output patterns exist with respect to each gray level; and a controller configured to control a plurality of output regions, based on the output pattern corresponding to the gray level of the input pixel in accordance with a table selected for each of the duplicated pixels, the plurality of output regions corresponding to the plurality of segmented regions of each of the duplicated pixels.

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.