Abstract: A method of defining a glyph font character representing an input binary code includes defining a first portion of a matrix using an input binary code including a plurality of input bits. A second portion of the matrix is defined by performing a transformation on the input binary code so that the second portion of the matrix includes a plurality of transformed bits. A glyph character is derived that corresponds to the matrix. The glyph character is defined by a plurality of components corresponding in location to said bits of said matrix, wherein the components of the glyph character comprise a first component (e.g. a forward slash /) that corresponds to and represents a “1” bit of the matrix and second component (e.g., a backslash \) that corresponds to and represents a “0” bit of the matrix. The transformation operation includes a NOT operation or other logic operation, and includes a shift operation.

Abstract: A method of file preparation, ripping and plate making for high end graphics printed on cylindrical products utilizing Dry Offset printing presses. While utilizing two inverse angle techniques and one fixed angle on the Black, with virtually unlimited color pluralities, encompassing a majority of all open areas of the common printing blanket without any ink overlap. The nesting of the halftone dots at even coarse line screen rulings eliminating a dot rosette pattern and creating a continuous tone appearance. Print contrast is increased to that of offset printing quality and ink contamination over the course of the run length is virtually eliminated. This current invention also increases the ability to print white with colors as opposed to needing white coating done in advanced to transparent plastics and metallic surfaces.

Abstract: A method of processing a continuous tone image includes using a halftone screen to generate a bi-level bitmap; partitioning the contone image into an array of image blocks; halftoning the image blocks; using the bi-level bitmap to select some of the halftone image blocks; and modifying the selected halftone image blocks using code words, such that information contained in the code words is embedded in a halftone image. A method of extracting embedded information in a halftone image includes accessing a bi-level bit map; partitioning the halftone image into a plurality of image blocks; using the bitmap to select at least some of the blocks; identifying a code word sequence in the selected blocks; and extracting the information from the code word sequence.

Abstract: Disclosed herein is an image processing apparatus including: a screen processor for determining each pixel value of a screen processing application unit region composed of a plurality of pixels to which a threshold matrix is applied, in an inputted image; and for carrying out a screen processing by applying one threshold matrix among a plurality of threshold matrices in which applied positions of the threshold values are different from each other, to the plurality of pixels in the screen processing application unit region based on each determined pixel value.

Abstract: A halftone screen is modified to reduce harmonic artifacts. Artifacts are modeled from the screen in a frequency domain. Threshold values in the screen are modified to reduce amplitude of at least some of the modeled artifacts.

Abstract: A method and system are provided for characterizing performance of a printer across a plurality of halftone screens. A first non-uniformity profile is generated by measuring printer performance. Cross-position differences between the first non-uniformity profile and selected corresponding cross-positions of a second halftone screen are detected. A scaling factor is computed relating the detected differences. Printer performance with the second halftone screen is predicted by applying the scaling factor associated with the second halftone screen to the non-uniformity profile of the first halftone screen.

Abstract: As set forth herein, computer-implemented methods and systems facilitate halftoning using boundaries and centers of a polygonal tiling with a parameterized spot function that operates within the tiles. Defining the halftone structure includes defining the polygonal tiling with a specification of the polygon boundaries and center, and setting and applying parameters of the spot function, which utilizes center-to-boundary distances. The tiling can be defined explicitly, by defining a tile structure, or providing centers, one per polygon, and vertices for the polygons. The vertices and centers are used to generate the polygon boundaries. The polygonal tiling can be regular (e.g., repetitive) or irregular, and can also be varied in a manner adapted to the image content or to data that is being embedded.

Abstract: Before image data are screened for the subsequent exposure of a printing form, files needed for the screening step are changed in such a way that the values of individual elements in the data fields are changed. The number of elements whose values are changed is determined by evaluating contiguous regions within the data fields. These can be, for example, threshold value matrices in which individual matrix elements are set to a value corresponding to the color white, or which, for the half-tones, are calibrated to a reduced value of the full-tone density. In the latter case, the full-tone image points are screened with a frequency-modulated screen.

Abstract: In a method for trapping of print data with a plurality of objects, transferring the print data together with first trapping instructions and/or parameters in a print data stream for execution of the trapping in a computer or a printing device. With the print data stream referencing resource data that can be repeatedly retrieved and which contain second trapping instructions and/or parameters specific to the printing device.

Abstract: A method is disclosed for screening color separations of a lenticular image with a lenticular frequency of the lenticular lenses needed for viewing the lenticular image. An amplitude-modulated halftone image is calculated for each of the color separations at a screen angle and at a screen frequency, the tangent of the screen angle being a rational number. For a specific color separation, a screen angle relating to the direction perpendicular to the image strips of the lenticular image is defined, a pair of whole numbers whose ratio is equal to the tangent of the screen angle is determined, and the screen frequency of the color separation is calculated as the product of the lenticular frequency and the square root of the sum of the squares of the two whole numbers.

Abstract: A print apparatus includes an edge detector using attribute information, a screen processor which binarizes each pixel included in image data with a screen processing, a pulse width converter which converts each pixel included in the image data to pulse width data in accordance with an input gradation value, and an output unit which outputs pulse width data from either of the screen processor or the pulse width converter for each pixel. The output unit outputs the pulse width data from the pulse width converter for an edge pixel and outputs the pulse width data from the screen processor for a non-edge pixel.

Abstract: A print defect management device that supports job-specific print defect management automatically assesses print job pages to determine the severity of image quality defects likely to occur on one or more selected printers. Views of identified troubled pages may be rendered to include approximations of color and image quality defects based on the original page image data, and each printer's color rendition data and defect data, thereby allowing troubled pages for one or more selected printers to be viewed prior to printing. Suggested changes may be automatically or manually applied. Once satisfied with the image quality of print job pages rendered for a specific printer, a user may submit the print job to the same printer, thereby assuring that the user's image quality expectations are met in the printed product. The device may support job-specific print defect management with both local and/or remote printers via LAN, WAN and/or Internet based connectivity.

Abstract: A method for creating a differential gloss image includes providing first and second anisotropic halftone structures. The first and second anisotropic structures have different orientations. One of the first and second anisotropic structures is applied to image data in a first region of an image to be halftoned. The other of the first and second anisotropic structures may be applied to image data in a second region of an image to be halftoned. A mixture of the first and second anisotropic structures is applied to image data in a third region of the image to be halftoned, whereby when printed, the three regions each have a gloss characteristic which differs from that of the other two regions.

Abstract: Disclosed is a method for generating a basic template utilized to form a screening mask. The method includes adjusting lines per inch or minimum pattern (such as cluster size or density) of a testing template, printing the adjusted testing template by an outputting device, determining if the gray level of the printing result matches a specific gray level, and continuously adjusting the setting of the lines per inch or the minimum pattern when it does not match the specific gray level, otherwise selecting the adjusted testing template as a basic template. The basic template is optimized according to the printing ability of the outputting device, so the printing performance of the outputting device when using the screening mask formed from the basic template can also be optimized, and the minimum color points can be printed faithfully thereby avoiding dropping of the carbon powder.

Abstract: An image processing device, which includes: an original reception unit that receives an original image; a dot image generation unit that generates, on the basis of additive information to be added to the original image, a dot image in which a plurality of dots each formed by one or more pixels are arranged; a state alteration unit that, when any of the dots in the dot image is determined to be not extractable, alters a state of the non-extractable dot on the basis of a relationship between a position on the dot image generated by the dot image generation unit and a corresponding position on the original image; and a composite image generation unit that generates a composite image by superimposing, on the original image, the dot image having the state of the non-extractable dot altered by the state alteration unit.

Abstract: An image forming apparatus includes a resolution conversion unit that integrates n pixels that are contiguous in the sub-scanning direction, and that determines an average value of pixel values of the n pixels as a pixel value of integrated pixels, a quantization unit that quantizes the pixel value of the integrated pixels to N levels, an image analysis unit that performs first determination processing for determining whether the difference between the pixel values of the n input pixels exceeds a threshold value set in advance, and second determination processing for determining whether a direction in which the pixel values of the n input pixels becomes greater is a forward direction of the sub-scanning direction or an opposite direction, and a pixel selection unit that determines n output pixels, based on the results, from a quantization result of the integrated pixels.

Abstract: A method for improving printing quality of a digital image using error diffusion screening including the steps for each pixel in a digital image: a) initialize weighted error diffusion value; b) translate first value (220) of each pixel of the digital image to a second value (916); c) translate the second value of each pixel of the digital image to create a third value (920); d) translate the third value of each pixel of the digital image by adding the error diffusion value (216) to create a fourth value (224); e) generate a quantization value for each pixel in the digital image by using at least one threshold value; f) perform geometrical distribution in space of the first quantization (924) utilizing a first pixel mask (1604) and possibly a second pixel mask for setting pixels in designated areas defined by the pixel masks; and g) update said error diffusion value and go to step (b) till all the pixels of the digital image are treated.

Abstract: A method of generating a printable image from a base image includes identifying parameters of a printer on which the printable image is to be printed, and creating a bit map image from a plurality of sub-cells, the identified parameters, and the base image.

Abstract: Provided is a 3-colorant DOD (dot-off-dot) periodic halftone geometry used to render an image. The DOD 3-colorant halftone geometry includes a base colorant halftone screen with hexagonally tiled halftone dots arranged in a hexagonal pattern, the hexagonally tiled halftone dots having a first fundamental frequency vector Vh1, a second fundamental frequency vector Vh2, and a third fundamental frequency vector Vh3, where Vh3 is substantially equivalent to Vh1+Vh2.

Abstract: What is disclosed is a system and method for efficiently and accurately estimating the complete TRC for a color marking device equipped with a multi-center cluster halftone screen which has a similar halftone tiling geometry and a similar growth specified by a corresponding single-center cluster halftone screen. The present method introduces a cluster-based printer model which establishes a relationship between a color output of a single-center cluster halftone screen and a color output of a multi-center cluster halftone screen. The present cluster-based printer model determines the complete TRC for the multi-center cluster halftone screen using the measurements for the single-center cluster halftone screen. Results of halftone dot linearization with different printing devices demonstrates that high accuracy can be achieved using the reduced measurements from the single-center cluster halftone screen.

Abstract: An image forming apparatus that includes: a laser beam source; plural photoconductive members corresponding to plural colors; a modulation drive unit for performing pulse width modulation for each of colors by an image clock having a cycle of a pixel length,; a single piece of polygon mirror whose reflection surfaces are disposed in a rotation direction thereof with a plurality of different inclination angles with colors; a beam detector that is disposed adjacent to the photoconductive member; and an image clock/data switching unit configured to generate the image clock of a frequency varying with the colors for making the same a color-based image magnification, and switch the image clocks generated for each of the colors in synchronization with a detection signal coming from the beam detector.

Abstract: An image forming apparatus performs dither processing on image data to form an image subjected to pseudo-halftone processing. The image forming apparatus includes a dither processing unit that performs dither processing on image data, and a dither pattern generation unit that generates a dither matrix for use in the dither processing, in accordance with an output gradation level. The dither matrix has a size of M×N pixels, and has a plurality of halftone dots arranged in a predetermined pattern in accordance with the output gradation level in order to represent a gradation of each color. The plurality of halftone dots are arranged in the dither matrix such that the halftone dots corresponding to at least two colors are substantially identical in color area ratio to each other in the dither matrix irrespective of a relative position with respective to the colors.

Abstract: A new method of creating fluorescent color images visible under UV light is proposed, which relies on fluorescent colorants obtained by superposing fluorescent ink dots, on juxtaposed halftoning, and on mapping the gamut of the image to be reproduced into the gamut of the fluorescent colorants. The resulting color images are invisible under daylight and have, under UV light, a high resemblance with the original images. Applications comprises the protection of security documents and valuable articles, as well as publicity, fashion and night life, where fluorescent images viewed in the dark under UV illumination have a strongly appealing effect.

Abstract: The appearance of a color print viewed under UV illumination is predicted using a target comprising color patches each printed using a known coverage of printer colorant(s). In one case, the target is illuminated using a UV light source and an electronic image of the target is captured using a digital camera or the like. In another case, a spectrophotometer is used both with and without a UV cutoff filter to measure the target. The captured image data or the spectrophotometric measurements are used to derive a UV printer characterization model that relates any arbitrary combination of printer colorants to a predicted UV color appearance value. Metameric colorant mixture pairs for visible light and UV light viewing can be determined using the UV model together with a conventional visible light printer characterization model. A visual matching task is used to determine a correction factor for the UV printer characterization model.

Abstract: An aspect of the present disclosure provides a halftoning method for annular rasters comprising: using annular rasters with uniformly spaced raster lines and uniformly spaced pixels within the raster lines; angularly tiling wedge shaped halftone cells around at least a partial circumferential print medium wherein an integer number of wedge tiles fills a disc space; wherein the annular rasters are considered in arcs and wherein pixel thresholds in the wedge shaped halftone cells are considered in arcs so as to conform to the annular rasters upon tiling the wedge shaped halftone cells; and, setting the number of pixel thresholds in each arc raster of the cell to an integer value near a desired writing resolution to enable seamless tiling wherein the number of thresholds increase as a function of a wedge cell radius.

Abstract: What is disclosed is a novel system and method for encoding/decoding data in a cover contone image via halftone dot orientation modulation. Arrays of halftone threshold values are used to determine a desired orientation, e.g. 0/90°+/?45° for a given single data value of the original message to be embedded. Message data is embedded as a function of halftone dot orientation. Detection modeling of the print-scan process enables the determination of dot orientation from the image scan via statistically motivated image moments. A probabilistic model of the print-scan channel conditions received moments on input orientation. Density values of the received moments are used to determine dot orientation for each halftone cell. The embedded data is retrieved based on the determined orientations. The present method is applicable to areas of data embedding, document security, and the like.

Abstract: A form of stochastic random distribution is used to print an invisible watermark using a typical, e.g., 600 dpi, printer. The watermark contains such information as “Do Not Copy,” or other such information. Although the watermark is not visible on a first generation version of a document that is printed, various techniques are used to print the watermark in such a way that it becomes readily apparent when the first generation document is photocopied. The preferred embodiment of the invention is concerned with a technique for improving such techniques, for example so that gray levels are improved to address variations from printer to printer. Another preferred embodiment of the invention is also concerned with a technique for performing error diffusion watermarking without the need for performing a calibration step.

Abstract: What is disclosed is a novel system and method for encoding/decoding data in a cover contone image via halftone dot orientation modulation. Arrays of halftone threshold values are used to determine a desired orientation, e.g. 0/90°+/?45° for a given single data value of the original message to be embedded. Message data is embedded as a function of halftone dot orientation. Detection modeling of the print-scan process enables the determination of dot orientation from the image scan via statistically motivated image moments. A probabilistic model of the print-scan channel conditions received moments on input orientation. Density values of the received moments are used to determine dot orientation for each halftone cell. The embedded data is retrieved based on the determined orientations. The present method is applicable to areas of data embedding, document security, and the like.

Abstract: An image processing apparatus for converting a multiple gradation image into a binary or multivalue image by use of an area gradation method according to a screen cell is provided. The apparatus includes a receiving unit that receives an input pixel value of each pixel of the multiple gradation image and position information on the screen cell, an output unit that has a lookup table storing an output pixel value corresponding to the input pixel value in such a manner that an image is formed in which the output pixel value is increased or decreased with an increase in the input pixel value, and a screen line number is kept at a prescribed level with the increase in the input pixel value but a dot position is different, and that outputs the output pixel value at a pixel position on the screen cell corresponding to the position information by referring to the lookup table, according to the input pixel value and the position information received by the receiving unit.

Abstract: An image processing method generates a halftone image by forming a halftone dot represented by a set of one or plural output dots corresponding to an intensity of an input image signal while making a part of the dots constituting the halftone dot to be an actual non-output dot so as to reduce an amount of a coloring material of a halftone-dot portion. The image processing method includes holding in a predetermined storage medium halftone-dot profile data for forming the halftone dot corresponding to the intensity of the image signal and gap-size profile data representing a size of a set of the non-output dot; and generating the halftone dot comprising a gap having a size based on the gap-size profile data, a size of the halftone dot being based on the halftone-dot profile data.

Abstract: Methods and apparatuses for halftoning an image are provided using a parametrically controlled hexagonal halftone dot shape threshold function that reduces tone reproduction irregularities in the halftoned image which can occur at darker gray levels. The halftoning transforms image data representing contone image pixels into halftoned image data in the form of clustered-dot hexagonal halftone screens for representing halftone dots of a halftoned image. Weight parameters can be used to control the rate at which a respective vertex of a halftone dot approaches a vertex of a neighboring halftone dot in relation to gray level. The hexagonal halftone dot shape threshold function can also control the shape of the sides of the halftone dots.

Abstract: An isolated point detection portion detects an isolated point in image data input from an image data adjustment portion. An isolated point removal portion makes a replacement of image data at a point of an isolated point detected by the isolated point detection portion. An edge identification portion performs edge identification for identifying a character region for the image data from which the isolated point has been removed by the isolated point removal portion. In this technique, edge identification is performed after the isolated point is erased by performing isolated point identification as a preliminary step of edge identification, so that isolated point noise can be removed with high accuracy.

Abstract: What is provided are a novel system, method, and computer program product for hierarchical (telescopic) color error diffusion which effectively controls the dot distribution for both primary and secondary dot formation which covers the class of error diffusion that follow telescopic dot firing constraint principles. In one example embodiment, an input CMYK ink coverage is received. The input CMYK ink coverage is transformed into a CMYKRGB domain using a CMYK to CMYKRGB conversion. A weighted error value can be added to each color component of the CMYKRGB domain. The color components of the CMYKRGB domain are hierarchically grouped into a plurality of subgroups based on relative dot visibility. More visible subgroups are half-toned earlier to achieve maximum uniform dot distribution. Dots of specific color channels within subgroups are fired based on thresholding and a set of decision rules provided herein.

Abstract: In a method for designing a halftone screen configured to reduce artifacts in a printed image, artifacts due to a process variation resulting from printing of the image through use of a halftone screen design are modeled and the halftone screen is designed to have threshold values that substantially reduce the artifacts due to the process variation.

Abstract: A printing system, printing method, and host apparatus is capable of analyzing the degree of ink blur in consideration of print conditions and the properties of an image typified by a photograph or the like, and prompting a user to change the print conditions depending on the analysis result. The system sets print conditions upon printing an image on a printing medium via a man-machine interactive operation by the user. If the system determines that ink blurs upon printing on the printing medium on the basis of the generated print data in accordance with the set print conditions, it warns the user about the print conditions.

Abstract: An image forming apparatus prints a first image data rendered at a first number of halftone levels based on a second image data rendered at a second number of halftone levels larger than the first number of halftone levels. A dot forming section forms lines of pixels on a print medium, the lines including a number of groups of sub lines of sub dots. The groups are aligned such that the sub lines of sub dots extend in traverse directions substantially perpendicular to an advance direction. A controller controls the dot forming section such that a selected number of sub dots in the advance direction are combined to form a pixel. Sub dots on the same sub line have the same exposure energy and sub dots on different sub lines in the same pixel have different exposure energies.

Abstract: A preferred embodiment reproduces an image by receiving an input contone array of M contone data values. The contone data values may lie within a range from 1 to N. The embodiment includes comparing each contone data value to an array of M sets of pattern look-up tables to generate an array of M pattern values. M may be a number of one or more. Each pattern value in the array of M pattern values may be decoded to a corresponding K by L multi-pixel pattern of binary data. The binary data is rendered by a reprographic device.

Abstract: An image processing circuit includes: a plurality of counters that extract image blocks each of which includes a predetermined number of pixels from input image data, count a number of pixels having a predetermined value for each of the image blocks, calculate a pixel value for each of the extracted image blocks, and output a plurality of bit streams each of which represents the counted number for a respective image block, the number of the plurality of counters being larger than a bit length defined for a single writing process with the memory divided by the bit length of a value calculated for an image block; a converter that converts the bit streams output from the plurality of counters, by adjusting a bit length of the bit streams for writing in the memory, and outputs the converted bit streams; and a synthesizer that synthesizes the plurality of bit streams output from the converter to generate a bit stream having the bit length defined for a single writing process with the memory, and outputs the genera

Abstract: To improve the rendering of a printing, a halftone rendering method is applied. This method optimally comprises a step for the adaptive tiling of the image. This tiling is based on a subdivision of the image by self-similar structures. These subdivisions are locally limited by the local intensity of the image. These local limitations make the tiling adaptive. The result of this tiling is a cloud of sampling structures, each of these structures being associated with a pixel of the image and a label produced during the tiling. The intensity of the pixel, and the label, enable the reading, in a table of correction vectors, of a correction vector corresponding to a shift to be applied to the pixel before it is printed. The table of the correction vectors is pre-computed in using a relaxation algorithm.

Abstract: Method and apparatus for font/line art rendering via multi-level halftoning including the selecting or generating of halftone cell patterns related to the minimal stable pixel of a rendering electrography (EP) engine and image processors including EP engines.

Abstract: Systems and method for digitally reproducing a moiré-free color halftone output image having an embedded correlation-based digital watermark are provided using an enhanced halftone screen set consisting of a halftone screen for each of N colorants forming N color separations (where N?3). The N different uniform rosette halftone screen configurations are generated such that each meets uniform rosette halftone screen conditions. A corresponding three-dimensional threshold array is generated for each halftone screen configuration having a phase shift value as an input. The color input image is halftoned, halftoning each one of the N different color separations using a corresponding halftone screen configuration and three-dimensional threshold array to form a moiré-free color output image having the correlation-based digital watermark embedded therein. A single key can be used to produce a full color image of the output image having the watermark image visible therein.

Abstract: A luminance signal Ya and a color-difference signal Ua/Va constituting an input image signal is transferred to a frame memory (first memory) in the unit of line synchronously with its horizontal synchronous signal and written therein. A memory TG211 reads out a read-out request RRQ. The cycle of this request RRQ is a time computed based on a single vertical effective period of an output image signal Sc and the number of lines objective for rate conversion of an input image signal Sa. The luminance signal Ya and color-difference signal Ua/Va are transferred in the unit of line from the frame memory to rate conversion units (second memory) through buffers. There occurs no deflection in this transfer cycle and in each transfer cycle, the stable data transmission band can be secured.

Abstract: A system or method of removing whitespace between tiled or repeated patterns generated during a printing operation. The system takes an initial image and determines if there exist extraneous bits of whitespace around the edge of actual image. Once this information is established, the printer application program uses that information to alter the tiled output accordingly to produce a seamless image with repeated or tiled patterns of the actual image.

Abstract: A method and apparatus for processing image data representing a color separation or mono-color image includes processing the color separation image data or mono-color image data in accordance with first and second or more halftone screen processings at different screen angles and obtaining results of the processings and combining the results of the processings to generate composite image data of the first and second or more halftone screen processings. The resulting print of the composite image data forms relatively pleasing rosettes or diamond structures in the particular color.

Abstract: The present invention relates to expanding the range of image densities over which the manipulation of differential gloss as may be inherent in halftoned images may be achieved. By selectively applying halftones with anisotropic structure characteristics which are significantly different in orientation while remaining identical in density, a gloss image may be superimposed within an image without the need for special toners or paper. This technique may be enhanced across low and high density areas by application of clear toner to expand the range of image densities over which a desired glossmark image will bear an effect.

Abstract: The teachings as provided herein relate to a watermark embedded in an image, and methodology for same, that has the property of being relatively indecipherable under normal light, and yet decipherable under UV light. This fluorescent mark comprises a substrate containing optical brightening agents, and a first dot design printed as an image upon the substrate. The first dot design has as a characteristic, the property of strongly suppressing substrate fluorescence. A second dot design having a property of providing a differing level of substrate fluorescence suppression from that of the first dot design such that when rendered in close spatial proximity with the first dot design image print, the resultant image rendered substrate suitably exposed to an ultra-violet light source, will yield a discernable image evident as a fluorescent mark.

Abstract: A method and system is provided for providing a variable data guilloché shaped pattern comprised of variable data differential line pattern fonts comprising decodable template symbols which are capable of being selectively assembled into a predetermined variable data code. The code representations are embedded in the guilloché pattern amongst a plurality of unvaried standard base patterns. The representation can be decoded with a digital scan capable of identifying the embedded patterns and communicated it to a user for verifying a document containing the code.

Abstract: To generate a threshold matrix which is compared with an original image in creating a halftone dot image for each color component, in a matrix area for one color component, dot centers are arranged almost uniformly in a random fashion at a predetermined density and in a matrix area for another color component, dot centers are arranged almost uniformly in a random fashion at a density about 0.7 times the predetermined density. Then, threshold values are set so that dots should grow around the dot centers in accordance with an increase in gray level of the original image, to generate the threshold matrix for each color component. In creating the halftone dot images by using these threshold matrixes, characteristics of spatial frequency of the halftone dot images of these color components can be represented in a frequency space as areas (75K, 75C) in a shape of concentric rings.

Abstract: Disclosed is a print apparatus including a rotating unit rotating a printed object, a print head printing visible information by ejecting ink droplets onto the printed object being rotated by the rotating unit, and a control unit generating ink ejection data based on the visible information and controlling the print head based on the ink ejection data. In the print apparatus, the control unit converts the visible information, which is expressed using biaxial perpendicular coordinate data, to polar coordinate data and carries out dot density correction that applies a correction weighting calculated in accordance with the number of dots per unit area for each dot in the polar coordinate data to a luminance value of each dot to generate the ink ejection data.

Abstract: The patterns can be used to reduce one or more undesirable effects such as moire or colour shift in coloured halftone images. Colour screens in the images are based on a combination of non-orthogonal mesh structures with parcels of printing dots which have common shape and size. Preferably the dots grow in mid tones by extending first towards their second, third or fourth nearest neighbours.