Abstract: In a system, such as in a digital copier, for classifying image data derived from an original image, the image data is classified by type. An algorithm is applied to the gray levels of pixels surrounding each pixel of interest. The algorithm determines whether a local maximum or minimum is part of an image of closely-spaced lines.

Abstract: A method of screening a continuous tone image into a halftone representation for a flexographic printing operation can compensate for characteristic printing problems in highlight areas by selectively placing non-printing dots or pixels proximate highlight dots. The non-printing dots or pixels raise the printing relief floor in the highlight areas providing additional support for marginally printable image features.

Abstract: An image-processing device includes an image-reading unit that reads image data from a document optically, an image-recording unit that records the image data read onto recording paper, a first-density-correction unit that corrects first density characteristics that depend on the image-reading unit, a second-density-correction unit that corrects second characteristics to reproduce density of the document, a third-density-correction unit that corrects third density characteristics that depend on the image-recording unit, and a control unit that independently controls each of the first, second and third density-correction units to execute density correction. The image-processing device can record a high-quality image by adjusting the above described density characteristics by controlling each of the first, second and third density-correction units independently.

Abstract: Characteristics of text or text components or features are considered when selecting halftoning screens. For example, an italic slant angle of text is recognized and used to select or generate a compatible halftone screen oriented at the same angle. A screen frequency may be selected based on a thickness of a text component. Descriptive tags associated with text or text components facilitate screen selection. Tags are assigned based on font descriptions included in a document during authoring. Alternatively, tags are assigned based on the results of document segmentation and character recognition techniques. An image processing system operative to consider characteristics of text or text components when selecting halftone screens includes a text component characteristic recognizer, a halftone screen selector and a halftoner. Optionally a print engine is also included. In a xerographic environment the print engine includes a xerographic printer.

Abstract: A method of producing a printing plate on a cylindrical printing-plate carrier includes subdividing the printing-plate carrier by computation in terms of its width and axial length into at least two circumferential subareas. Then an actual transfer characteristic curve for each subarea is determined and compared by computation with a predetermined desired printing characteristic curve for each subarea to find a deviation. The method further includes calculating a correction to compensate for each deviation; receiving a digital image data in a first data format using a raster image processor; converting the digital image data into machine-specific image data including the position and the tonal value in the form of a bitmap; applying the correction for a predetermined desired printing characteristic curve for the edition print to the machine-specific image data using the raster image processor; and supplying the corrected machine-specific image data to an imagesetting unit.

Abstract: An image processing method and apparatus for generating a gray level rendered pixel value that has been subjected to a halftoning process. In the method and apparatus a gray level pixel value of the pixel to be rendered by the halftoning process is provided as one input to a lookup table. A coordinate value that is determined from a pixel location in the image of the pixel to be rendered by the halftoning process is also provided as a second input to the lookup table. The first and second inputs represent an address in the lookup table of a rendered halftone value for halftone rendering of the pixel having the input gray value and the pixel location in the image.

Abstract: The present invention overcomes the limitations of the prior art by providing a system and method for halftoning using time-variable halftone patterns. Successive frames that are presented to the output device are individually halftoned. The halftone pattern is changed from frame to frame. The different halftone patterns can be generated in real time, or they can be calculated prior to halftoning and stored in memory. Additionally, the halftone patterns can be generated using any conventional halftoning technique. The same halftoning technique can used to create each halftone pattern, or the halftoning techniques can be varied when creating halftone patterns. The halftoned frames are then viewed in a sequence in time. Because the halftone pattern is changing from frame to frame, the visibility of the pattern is reduced when compared with the patterns produced by prior art halftoning methods.

Abstract: A number of lasers (402) used to image a bitmap file (630) of a halftone screen is comprised of generating a first bitmap file (630) for a first color. A first image (710) is printed with the first bitmap file for the first color with n lasers. A second image (720) is printed with the first bitmap file for the first color with n?1 lasers. An optimum number of lasers is selected for printing the first bitmap file based on the image with the least number of defects (700).

Abstract: When input N-bit multi-valued image information having density information is converted into M-bit (N?M) image information and the converted image information is output, information (S signal) indicating whether or not an image conversion process is executed for one line including a pixel of interest of the multi-valued image information is generated on the basis of the multi-valued image information. Only when the S signal indicating that the image conversion process is to be skipped successively appears for a number of times equal to or larger than “the number of lines required for the process”+1, the control is made to forcibly set the processing result of the image conversion process to be a predetermined value, and to inhibit execution of the image conversion process for one line including the pixel of interest of the multi-valued image data.

Abstract: The present invention relates to an image processing method, an image processing apparatus and a recording medium that convert a grey scale image into an area gradation image. The present invention intends to provide an image processing method, an image processing apparatus and a recording medium capable of increasing processing speed in a state where high image quality is maintained. In the image processing method and the image processing apparatus according to the present invention, image data of a C component and image data of an M component in grey scale image data are converted into halftone image data in accordance with an error diffusion method, and image data of a Y component are converted into halftone image data in accordance with a blue noise mask method.

Abstract: A method of automatically selecting screen characteristics value to be used for printing a color image, comprising the steps of: forming a digital representation of the color image, the digital representation comprising a plurality of separations; dividing at least one of the plurality of separations into a plurality of regions; and assigning at least one screen characteristic value to each of the plurality of regions.

Abstract: A method for providing in use estimation of dot gain in digital printing using digital printing plates, the method comprising: applying to a digital printing plate a calibration strip, the strip comprising at least one set of patches, each patch comprising a plurality of dots at a predetermined gray level within said dynamic range, gray levels of said set of patches being distributed over said dynamic range, printing from said calibration strip under a current set of printing conditions, measuring intensities of said printing, and interpolating from said measurements to generate a curve of dot gain over said dynamic range. The curve can then be used to compensate. When moving to a different set of printing conditions, a single test print is then carried out and a new dot gain estimation is available.

Abstract: An image forming method includes the steps of a) multi-level quantizing a multi-tone image by an error diffusion method, and b) representing each pixel of the thus-quantized image having a quantized level higher than 0 using a dot which is larger as the quantized level thereof is higher. Occurrence of dots having a specific size is repressed in a specific shade region relating to the dots.

Abstract: In order to produce a high-quality output of an image which is a mixture of images having different characteristics, there is provided an image processing apparatus having an image memory storing an entered color image and a feature detector, arranged for detecting a feature signal from the entered color image and storing the feature signal in the image memory. The feature signal represents a feature of the entered color image. An outputter is arranged for reading an image signal of the entered color image and the feature signal thereof out of the image memory, and outputting the image and feature signals as a recording signal. Processors are arranged for respectively processing one of a number of color components, which represent color image information, in accordance with the recording signal. The detection and storage in the image memory of feature signals and the readout of the image signal and associated feature signal from the image memory are performed in parallel.

Abstract: An image transformation apparatus for performing a transformation processing for outputting a color image by an image output device such as a color printer. The image transformation apparatus has an image receiving section for receiving an image represented by digital data, an image sort discrimination section for discriminating whether the image received by the image receiving section is a halftone dot image or a multiple gradation image, an image transformation section for applying a conversion processing for the multiple gradation image to the halftone dot image when it is decided by the image sort discrimination section that the image received by the image receiving section is the multiple gradation image, and a driver section for outputting an image discriminated as the halftone dot image by the image sort discrimination section and an image converted into the halftone dot image by the image transformation section to an image output device.

Abstract: A printing method identifies where parts of an image will not be printed correctly due to partial or total device failure and if possible adjusts the size of ink dots in adjacent rows or columns so as to lessen the visual effect of failure to print at the original location.

Abstract: In order to carry out gradation drawing processing without causing deterioration of printing processing throughput, i.e., deterioration of printer engine performance, in the event that a received drawing command is a gradation drawing command, the degree of change of color within the gradation drawing area is obtained, and a thinning-out level within the gradation drawing area is determined, based on the obtained degree of change of color. An enlargement value is determined based on the thinning-out level decided upon, and instructions are given to an image processing unit to draw the gradation drawing area in a manner enlarged with the enlarging value decided upon. Next, the color values of the pixel values within the gradation drawing area are calculated at pixel intervals determined by the thinning-out level, and this is used as gradation data.

Abstract: An image forming apparatus can apply a smoothing process to multiple value image data without generation of errors due to an unnecessary smoothing process. A template matching process unit determines whether or not the original image data is to be subjected to a smoothing process, and outputs the original image data together with a selection signal indicative of a result of the determination. A smoothing process unit selectively applies a smoothing process to the original image data based on the determination of the template matching process unit so as to output smoothed image data. A first control signal source outputs a first control signal representing whether or not application of the smoothing process is permitted on an individual image basis. A second control signal source outputs a second control signal representing whether or not application of the smoothing process is permitted on an individual pixel basis.

Abstract: An image forming apparatus comprises an edge detection means for detecting an edge in image data, a thinning judgment unit (11) for judging whether or not a thinning process in the image data should be performed, and an edge density conversion unit (12) for receiving a discrimination signal from said thinning judgment unit (11) to perform density conversion of a pixel which is judged to be subject to the thinning process.

Abstract: In general, it is difficult for the end user to implement a simulate illustration process for an image, since manual setups of the process are complicated and require skills. Also, there is room for improvement in terms of image quality. In this invention, the luminance histogram of an original image is generated, the brightness of that image is detected based on the histogram, and the image undergoes a filter process corresponding to the detected brightness, thus easily performing the simulate illustration process using bright tone for the image. Especially, since a filter is set for rasterized image data in correspondence with the number of lines of the data to be processed, an effective simulate illustration process can be implemented.

Abstract: The present invention is related to a method for processing a digital image, wherein the digital image comprises at least a gray-scale component. The method may comprise: morphologically filtering the grayscale component to produce a segmentation result; low-pass filtering the gray-scale component under control of at least the segmentation result to produce an image mask; and enhancing tone reproduction of the digital image utilizing at least the image mask.

Abstract: An image forming apparatus capable of solving problems experienced in the error diffusion method operates in the following manner. An input pixel value is thresholded by a corrected threshold value, and a binarized pixel value is output. From the output value, the corrected threshold value is subtracted, the result is multiplied by a feedback coefficient ?, and the result is diffused to the threshold values of surrounding pixels. As the threshold value and a scale of the pixel value are changed by the processing unit before thresholding, degree of edge enhancement is controlled.

Abstract: An adaptive image tone mapping curve based on perceptual preference guidelines is generated as a sigmoidal function, in which the sigmoidal function parameters (slope and shift) are determined by original image statistics. Tone curves generated for different images each have a smooth sigmoidal shape, so that the tone mapping process does not change the image histogram shape drastically. The sigmoidal function has the form: t ? ( x ) = 100 1 + exp ? ( - ? ? ( x / 100 - ? ) ) , where ? is the slope parameter and ? is the shift parameter. The input value x in the sigmoidal function varies in the range [0, 100], because the tone curve is generated on an L* scale, which has values from 0 to 100.

Abstract: This invention is a method of multilevel dither screening in a printer. Plural pixel values are packed into equal sections of a first data word. Corresponding dither values are packed into the equal sections of a second data word. These first and second data words are added in an arithmetic logic unit selectively spilt into the equal sections. Each section of the sum data word is saturated to all 1's. A predetermined number of least significant bits of the saturated sections are truncated. The resulting normalized pixel values are quantized into a limited set of threshold ranges. This dithering process serves to introduce an amount of scattering to the input pixel values to reduce quantization and pixelation artifacts in the final printed product.

Abstract: A system for compensating for a calibration drift in an image output device includes a user input means for specifying an output medium. An image output device controller converts original image data to final image data used by the image output device. The image output device produces a calibration image, as a function of an output medium, for a plurality of halftone screens capable of being produced by the image output device. A processor communicates with the controller. The processor calculates a plurality of candidate tone reproduction curve sets for the specified output medium. Each of the sets corresponds to one of the plurality of halftone screens. The candidate tone reproduction curve sets are accepted for compensating for a calibration drift in the image output device.

Abstract: Although almost the same color reproducibility as with a reference print head has been attained in single-color printing, inconsistency in color reproducibility has occurred in mixed-color printing. Where ejection of color ink or any other recording material for forming dots on such a printer as an ink-jet printer (31) varies due to an instrumental error, it is burdensome to set up a degree of adjustment for correcting inconsistency in each color.

Abstract: An image-processing device includes an image-reading unit that reads image data from a document optically, an image-recording unit that records the image data read onto recording paper, a first-density-correction unit that corrects first density characteristics that depend on the image-reading unit, a second-density-correction unit that corrects second characteristics to reproduce density of the document, a third-density-correction unit that corrects third density characteristics that depend on the image-recording unit, and a control unit that independently controls each of the first, second and third density-correction units to execute density correction. The image-processing device can record a high-quality image by adjusting the above described density characteristics by controlling each of the first, second and third density-correction units independently.

Abstract: A method for providing in use estimation of dot gain in digital printing using digital printing plates, the method comprising: applying to a digital printing plate a calibration strip, the strip comprising at least one set of patches, each patch comprising a plurality of dots at a predetermined gray level within said dynamic range, gray levels of said set of patches being distributed over said dynamic range, printing from said calibration strip under a current set of printing conditions, measuring intensities of said printing, and interpolating from said measurements to generate a curve of dot gain over said dynamic range. The curve can then be used to compensate. When moving to a different set of printing conditions, a single test print is then carried out and a new dot gain estimation is available.

Abstract: Disclosed is a method, system, and program for halftoning data for an output device capable of rendering multiple intensities. Input values are received. For each received input value, the input value is used as an output value if the input value is a predetermined value. Otherwise, if the input value is not the predetermined value, then the input value is halftoned to produce an output value used to render one of multiple intensities. This allows the use of data intended for bi-level printers that may have already been halftoned.

Abstract: This invention involves approximating a gray scale tone with a more limited range image producer, a process known as screening. This invention reduces the time needed for such screening by discriminating when screening is not needed. In a first embodiment, the rendering process produces a minimally enclosing bounding box surrounding all rendered objects. In an alternative embodiment, scan lines including any part of a rendered object are noted. The screening makes better use of memory by dividing each row of a preference matrix into segments. The lookup tables associated with these segments are sequentially loaded into a memory cache. Input pixels mapping into the loaded segment lookup tables are screened. Then the lookup table associated with the next segment of the preference matrix are loaded into the memory cache and used to screen input pixels mapping into that segment.

Abstract: An image processing system receives image input terminal information and image output terminal information. Based on the content of the image input terminal information and the image output terminal information a new system tone reproduction curve is determined. This device independent methodology allows system tone reproduction curves to be generated as needed, and allows the additional flexibility for changes in the image input terminal or the image output terminal.

Abstract: Even if there may exist a difference in reading density between reading positions, there will be provided an image reader capable of accurately detecting and removing streaks-shaped noise caused by the adhesion of dust particles to the reading unit. A CCD reads an original at each reading position, and image data A and B in each reading position are obtained from an output delay circuit and a shading correction circuit. A streak detection circuit judges a difference A?B between each image data through the use of a threshold corrected on the basis of an average density difference between each image data A and B, and outputs black streak detection data in accordance with the judgment result. A streak removal circuit always outputs the image data A, but if black streak detection data is outputted, image data B corrected on the basis of the average density difference is outputted in place of the image data A.

Abstract: A raster image path architecture having the capacity for supporting the rendering and output of a device-independent grayscale raster image, while also offering the capacity for supporting the rendering and output of a device-dependent grayscale raster image, thus offering the advantages of outputting a device-independent grayscale raster image while preserving the performance and image quality advantages of a conventional binary raster image path architecture.

Abstract: On the basis of a standard one-dimensional LUT 412, a plurality of one-dimensional LUTs 413 having mutually different tones are generated. Next, a plurality of monochrome sample images are generated using this one-dimensional LUTs 413, and a catalog print in which these monochrome sample images are arranged is printed out. Once the user has selected from the catalog print a sample image having the desired tone, a monochrome image is printed out using the one-dimensional LUT 413 that corresponds to the sample image.

Abstract: An image processing method is provided for reproducing multi-gradation image data in the form of a bi-gradation image as used particularly in a printer, a scanner, a copier, a facsimile, etc. The method comprises acknowledging a pixel arrangement around a target pixel through examining an on/off-state of each pixel of a binary form, calculating error correction data from the pixel arrangement, and carrying out a binary coding of multi-gradation image data. Accordingly, as the error data for a binary form of the multi-gradation image data is corrected depending on the density of its actual printed form, unstable artifacts generated in the reproduction of pixels can be suppressed during the binary coding.

Abstract: The present invention comprises an image reading unit for reading an image recorded on a medium, a gradation histogram generation unit for generating the gradation histogram distribution of the image data read by the image reading unit, a threshold value generation unit for calculating an appearance frequency ratio between the lowest gradation value and the highest gradation value from the image data read by the image reading unit, determining a threshold value level based on the calculated appearance frequency ratio and further determining the threshold value level based on the gradation histogram distribution generated by the gradation histogram generation unit, and a binarization unit for binarizing the read image data based on the determined threshold value level. Therefore, a threshold value can be generated based on the features of an image to be read, an optimal threshold value can be obtained depending on a medium and, as a result, a correct binarization process is available.

Abstract: Disclosed are two novel techniques for digital color halftoning with green-noise stochastic dither patterns generated by homogeneously distributing minority pixel clusters. The first technique employs error diffusion with output-dependent feedback such that the overlapping of pixels of different colors can be regulated for increased color control. The second technique uses a green-noise mask which is a dither array designed to create green-noise halftone patterns. The green-noise mask is constructed to also regulate the overlapping of different colored pixels. As is the case with monochrome image halftoning, both techniques are tunable, allowing for large clusters in printers with high dot-gain characteristics, and small clusters in printers with low dot-gain characteristics.

Abstract: To simplify the management of unique information on printing apparatuses, the printing apparatus sends the HS data unique to a particular print head to the computer terminal equipment which, based on the HS data, corrects the print data and sends the corrected print data to the printing apparatus.

Abstract: An image processing apparatus comprising an edge detection circuit which detects an edge from pixel data, a pseudo-halftone processing circuit which performs pseudo-halftone processing of the pixel data and outputs pseudo-halftone data, and a data synthesis circuit which synthesizes pixel data based on the pseudo-halftone data with the pseudo-halftone data at positions corresponding to the edge which the edge detection circuit detects to output the pseudo-halftone data having pixel data at the edge positions. With the apparatus applied, a print effected with the pseudo-halftone data has a high quality outline with no jaggedness.

Abstract: In one embodiment, a print system includes an anticipated ambient lighting selector to allow selection of an anticipated ambient lighting. A rendering module is configured to map a print job into raster data configured to reduce color cast in gray output when displayed under the anticipated ambient lighting.

Abstract: There are disclosed a halftone dot conversion apparatus capable of creating a halftone dot image that is small in an interference between periodical noises occurred at the time of output and a periodical structure of halftone dots, and contributing to avoiding the graininess and prevention of the disorder in geometry on halftone dots; a halftone dot conversion program storage medium storing a halftone dot conversion program; and a dot matrix capable of readily creating the halftone dot image. A halftone dot conversion section forms the halftone dots by sets of drawing pixels number of which is associated with the tone values obtained by the tone value obtaining section, and scatters blanks of the drawing pixels about the halftone dots, on at least a predetermined range of tone values.

Abstract: A laser print apparatus includes a memory for storing a multi-bit image including a plurality of pixels. Each pixel is represented by an N-bit value, wherein N is greater than one. A modulation code generator analyzes three adjacent pixels. The three adjacent pixels include a left pixel, a center pixel, and a right pixel. The modulation code generator is configured to generate a pulse width value based on the value of the center pixel, and a justification value based on the values of the left pixel and the right pixel. A laser print engine forms an output pixel on media based on the pulse width value and the justification value.

Abstract: A halftone gradation processing method reduces or eliminates the discontinuous gradation reproduction in comparison with conventional error diffusion. A halftone gradation processing method includes obtaining a position and a pixel value of a target pixel in an input image, correcting the pixel value, selecting the closest threshold to the corrected pixel value from among usable thresholds assignable to the pixel value, calculating an error between the corrected pixel value and the selected threshold, and diffusing the error around the target pixel, the pixel value correcting being corrected by the diffused error, and the selected threshold being output to an output device which may handle the assigned thresholds.

Abstract: Color processing architecture and algorithms (CPAA) for color laser printers process and handle incoming RGB image data effectively to achieve high performance, high quality image printing with low memory requirements. CPAA supports a new data structure for faster raster operation processing (ROP) for color laser printers. The CPAA architecture advantageously improves the flow of data through the processing pipeline to provide high speed at higher resolutions, e.g., at 600 and 1200 dpi. An advance quantizer using multilevel dithering flexibly reduces bits to support fast ROP and to enable fast conversion to CMYK data with only a simple look-up table (LUT) operation by a color matching module, while an adaptive filter maintains high image quality.

Abstract: A method for selecting a halftoning mode to be applied to regions within an image. The method operates on received image data to identify low-level regions within the received image data. The low-level regions are defined and separated by edges. Pixels that are not separated by edges are considered to belong to the same region. After the regions have been identified, low-level image attributes for the image data within each region are compiled. A halftoning method suited for the image data within the region can be selected based upon low-level image attributes.

Abstract: A system for simulating grayscales in a digital printer, such as an ink-jet printer, exploits a modified error diffusion technique. When a datum for a particular pixel in an image is 0, the datum is substituted with a low-level artificial datum such as 4 on a scale from 0 to 255. The addition of the artificial datum in the error diffusion algorithm avoids artifacts caused by the presence of large number of zeros in the error diffusion algorithm.

Abstract: An image processing system and method are provided for judging whether a pixelised image or a part thereof is a monochrome or a colour image. To increase the reliability of the judgement, instead of making the judgement on the level of an individual pixel, the judgement is made for substantially all the pixels of the image or image part at the same time by analyzing the cumulative histogram, wherein the distance of each pixel to the gray axis versus the logarithm of the cumulative pixel count is plotted. An advantage of the present system and the method of operating this system is their high sensitivity for detecting small colour objects in monochrome images.

Abstract: An input image is transformed to produce an output image. First pixels occurring at edges within the input image are detected. Second pixels that are part of text within the input image are also detected. The first pixels and the second pixels are combined to produce the output image.

Abstract: From a photosensitive material F, image data S1 is obtained together with the density Ds of the unexposed portion of the photosensitive material F. On the basis of this density Ds, the optimum characteristic curve for the photosensitive material F stored in the storing means 3 is modified by modifying means 4 to obtain a modified characteristic curve. In the storing means 3, a plurality of characteristic curves after the time lapse may be stored, and from these characteristic curves, a modified characteristic curve may be obtained. The modified characteristic curve is inputted to the transforming means 5, and on the basis of this, the image data S1 is transformed to provide processed image data S2. The processed image data S2 is reproduced as a print image K by the printing means 6.

Abstract: Gray scale data converted from color data is enhanced prior to being rendered on a monochrome device. Different enhancements are applied to different image types based on selected monochrome output options. The enhancements to the gray scale data make close shades of gray more easy to distinguish. Advantages of the disclosed system and methods include improved gray scale documents that better convey visual information present in an original color document.