We disclose a method for printing by rotogravure, flexography, offset, inkjet or electrophotography invisible images that are viewable under UV light. The method generates juxtaposed dispersed dot halftones by first creating juxtaposed clustered dot halftones and by applying to them dispersed dot halftoning according to a blackness reduction factor. Dispersed dot halftoning is embodied by random threshold error diffusion. The resulting dispersed dot halftones comprise pixel segments located within the areas defined by the clustered dots. These pixel segments specify the areas of the cells to be engraved onto the rotogravure cylinder. For offset, they can be imaged onto an offset plate or for electrophotography, onto a photoconductor. The disclosed juxtaposed dispersed dot halftoning method can be embedded into a framework for the reproduction of fluorescent full color images with three or more invisible fluorescent inks. These invisible fluorescent color images offer a strong protection against counterfeits.

An example system in accordance with an aspect of the present disclosure includes a halftone engine and a gray value engine. The halftone engine is to apply halftoning to an image recursively across a plurality of levels of image scales and spatial resolutions, to generate a pattern that is at least quasi-periodic across the plurality of levels. The gray value engine is to substitute gray values recursively for at least a portion of the halftoning.

An information processing apparatus, in accordance with rising density in an extreme density range, determines a threshold for setting each pixel of a threshold matrix so as to consecutively grow an isolated dot corresponding to a halftone dot in a low density range to a first dot size for each submatrix, sets, when the size of isolated dots in a predetermined number of submatrices is grown to the first dot size, an intermediate position between the isolated dots in the predetermined number of submatrices; and determines, for each of one or more submatrices including a set intermediate position, a threshold to set for each pixel of the threshold matrix so that an isolated dot is consecutively grown until a second dot size smaller than the first dot size.

A method for manufacturing a security document including a security pattern generation method includes the steps of selecting a bounding region, an image object, and a raster image or a function; cutting the image object into image object partitions; and repeating the image object as a pattern, preferably a lattice pattern, in the bounding region wherein each of the image object partitions of an image object is transformed depending on the position area of the image object in the lattice pattern and the rank of the image object partition.

An image processing apparatus includes a multi-gradation-level dither processing unit and a screen processing unit. The multi-gradation-level dither processing unit performs a multi-gradation-level dither process for a target image. The screen processing unit performs an FM screen process for the target image for which the multi-gradation-level dither process has been performed. Further, in the multi-gradation-level dither process, the multi-gradation-level dither processing unit selects each pixel in the target image as a target pixel in turn; using a conversion characteristic corresponding to each local pixel position group in a unit matrix, converts a pixel value of the target pixel to one of: a minimum gradation level, a maximum gradation level and an intermediate gradation level corresponding to the pixel value of the target pixel; and sets a pixel value of each pixel in the unit matrix as a pixel value obtained with the conversion characteristic.

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.

An information processing apparatus and an image processing method are provided. The image processing apparatus detects character data from image data, executes edge enhancement processing, using a first filter, on an edge portion of a region, out of the detected character data, that includes a region whose frequency of points or lines is greater than a predetermined frequency, and executes edge enhancement processing, using a second filter, on an edge portion of a region, out of the detected character data, that does not include a region of a spatial frequency higher than the predetermined frequency. The first filter has, in comparison to the second filter, a larger degree for edge enhancement with respect to a region having a frequency higher than the predetermined frequency.

An image processing apparatus includes a scanner that acquires an image, and a processor that changes areas of a plurality of dot patterns in accordance with gradation values in the image using a plurality of dither matrices, and generates a binary image based on the plurality of dot patterns. A change rate of each of the areas differs from each other. The plurality of dither matrices include a first dither matrix and a second dither matrix. A first change rate of a first area of a plurality of first dot patterns formed based on the first dither matrix and a second change rate of a second area of a plurality of second dot patterns formed based on the second dither matrix differ.

An image processing apparatus that converts image data of a first resolution into image data of a second resolution lower than the first resolution. The image processing apparatus determines a small dot that is included in the image data of the first resolution and matches a first small dot pattern and performs conversion from the first resolution to the second resolution by switching a method of generating resolution-converted image data based on a result of the determination.

An image processing apparatus which performs image processing for print processing, including: a pseudo halftone processing unit configured to perform pseudo halftone processing by dithering with respect to an input image, and generate a halftone image constituted by plural dots, and a threshold matrix holding unit configured to hold a threshold matrix used for the pseudo halftone processing, wherein in the threshold matrix, thresholds are arranged such that the halftone image has a density region in which dots to be formed depending on a density of the input image are not rotational symmetric on a 90 basis, and orientations of the dots differ from each other in the density region.