The image processing apparatus of the present invention includes: a first memory configured to store a first threshold value matrix used for halftone processing; a second memory configured to store a second threshold value matrix that is a threshold value matrix used for halftone processing and whose size is larger than the first threshold value matrix; and at least one circuit, the at least one circuit causing processing below: performing halftone processing for image data by using the first threshold value matrix or the second threshold value matrix selected based on attribute information on the image data, and the first threshold value matrix includes threshold values whose maximum number of bits is N and the second threshold value matrix includes threshold values whose maximum number of bits is M (M<N).

An image forming apparatus, for performing image forming by transferring and fixing an image formed on an image carrier to a printing material, that selects a smallest dot size of a halftone dot pattern representing a halftone of a highlight region corresponding to a type of the printing material, and uses a screen representing the selected smallest dot size to perform exposure control of the image carrier.

A secure image for a security document is generated by performing a rasterization process for each of a plurality of mono-color base images using a plurality of different threshold functions. For each base image, the plurality of threshold functions cover different intensity regions and result in a complex rasterization pattern depending on the intensity of the input image. The resulting binary images obtained by the rasterization process are combined using offset printing with fluorescent inks of different colors, to result in a multi-color fluorescent output image including a plurality of different complex rasterization patterns.

An image processing apparatus of the present invention performs halftone processing with respect to first image data to generate second image data. In such a case, based on a threshold and values of a plurality of pixels in a reference area that includes a target pixel of first image data, whether or not the target pixel is included in an edge portion is determined, and a pixel value of second image data corresponding to the target pixel determined to be included in the edge portion is corrected by using correction data generated from the value of the target pixel.

An example embodiment may involve obtaining a digital image containing a pixel block. An AM halftone may be configured to be applied to the digital image by default. The example embodiment may also involve deriving, from the pixel block, a bitmap defining foreground and non-foreground pixels of the pixel block. The example embodiment may also involve sequentially scanning horizontal lines of the bitmap to identify clusters of foreground pixels. Each pixel in a particular cluster of the clusters of foreground pixels may be either (i) the only pixel in the particular cluster, or (ii) vertically or horizontally adjacent to another pixel in the particular cluster. The example embodiment may also involve, possibly based on the clusters of foreground pixels identified in the bitmap, applying an FM halftone to the digital image, and causing the digital image to be printed with the applied FM halftone.

An image processing apparatus includes a storage and processing circuitry. The storage is configured to store a dither table in which a plurality of dither patterns are recorded, each of the dither patterns being formed with a halftone dot screen in which an output area ratio that is a proportion of void halftone dots per unit area corresponds to any one of gradation values of image data. The processing circuitry is configured to read a gradation value for each region in image data input for each toner color, decide a dither pattern to be applied to the read gradation value, read out the decided dither pattern from the dither table, and perform dither processing of applying the read dither pattern to the region in the image data.

A data-bearing image (391) is created from a carrier image (371). The carrier image (371) is scaled to produce a scaled image. A clustered-dot halftone screen is applied to the scaled image to produce a halftone image. A resulting number of cells in the halftone image conforms to a cell count (372) that includes a horizontal cell value and a vertical cell value. Payload data is encoded into the halftone image to produce a data-bearing halftone image, including shifting pixel clusters within cells of the halftone image that include pixel clusters.

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 example method of rapid image registration includes recovering an affine transform of a quasi-periodic object based on peak locations of Discrete Fourier Transform (DFT) in a captured image. The example method also includes filtering a region of the captured image to match a filtered version of a reference image including the quasi periodic object. The example method also includes recovering translation parameters to reduce image differences between the reference image and the captured image for a subset of the image locations of the filtered image and outputting an approximate transform including translation.

In one example, halftone data comprising first data and second data representing a plurality of pixels in a halftone is generated. The first data associates a first subset of the plurality of pixels in the halftone with a first colorant, the first subset defining a first region in the halftone. The second data associates a second subset of the plurality of pixels in the halftone with a second colorant different from the first colorant, the second subset defining a second region in the halftone. The first subset of the plurality of pixels in the halftone and the second subset of the plurality of pixels in the halftone are mutually exclusive, and the first region is at least partially enclosed by the second region.