Abstract: Method, system and computer-readable medium containing instructions for performing halftone gamma correction in a printing environment to achieve and maintain high print quality. The system includes one or more subsystems, including a tone reproduction subsystem that creates one or more print calibration pages, each having a tone curve defining a relationship between a plurality of input color levels, output color levels and a level of measured darkness. A pixel adjustment subsystem associates each input color level with one of the output color levels based on a desired percentage change in the level of measured darkness. Further, a gamma correction system performs gamma correction on a selected tone curve of one of the print calibration pages by associating each input color level with one of the output color levels based on the desired percentage change in the level of measured darkness in a substantially flat region of the selected tone curve.

Abstract: Image processing apparatus and image processing method for formation of high quality image by high-speed error diffusion processing by execution of more complicated threshold condition processing in a simple manner. When error diffusion processing is performed on multivalued image data having plural density components and the result of processing is outputted, upon execution of error diffusion processing on a first density component among the plural density components, a threshold value used in the error diffusion processing is determined based on a density value of a second density component, then the error diffusion processing is performed on the first density component based on the determined threshold value, and the result of execution of the error diffusion processing is outputted.

Abstract: Defects in an image forming system may give rise to visible streaks, or one-dimensional defects in an image that run parallel to the process direction. One known method for compensating for streaks introduces a separate tone reproduction curve for each pixel column in the process direction. A compensation pattern according to this invention has a plurality of halftone regions that are lead by, trained by, and separated by rows of fiducial marks. The fiducial marks allow the printer pixel grid and a scanning pixel grid to be correlated. The gray level in each pixel column of each gray level portion is measured and analyzed to produce a local tone reproduction curve for each pixel column and associated line width. The local tone reproduction curves are then used to compensate for the streak defect when printing.

Abstract: A halftone dot image HI composed of halftone dots is produced by halftone dot meshing of an object image OI. A smoothed object image SOI and a smoothed halftone dot image SHI are then produced by smoothing the object image and the halftone dot image. An interference moire image IM is produced by obtaining a difference between the smoothed object image SOI and the smoothed halftone dot image SHI.

Abstract: Disclosed is a method, system, and program for managing calibration files in a printing system. Patches are printed using a screening algorithm and incorporating at least one output appearance factor. A calibration file is generated from measured color values of the printed patches mapping a color space for the printed patches to a color space of a printer used to print the patches. Information is associated with the calibration file indicating the printer and at least one output appearance attribute for use in selecting one calibration file to use when printing a print job.

Abstract: An image processing apparatus, which performs color conversion for input tone data in an RGB color space to obtain tone data for a CMY color space, and which performs halftone processing to convert the tone data in the CMY color space to image reproduction data, is characterized in that a gamma characteristic A for an output density for a tone in the RGB color space is identical to a gamma characteristic B for an output density for a tone in the CMY color space in the halftone processing. In accordance with the invention, for the color conversion, even when the tone data for the RGB color space between the grid points of a color conversion table is obtained by interpolating the tone data for the CMY color space, the halftone process is performed for the RGB tone data in accordance with the same gamma characteristic B. Thus, image reproduction data can be obtained that provide the same output density as the output density allocated for the tone data of the RGB color space.

Abstract: An apparatus for printing halftone recipe color images which comprises a printhead (500). The printhead (500) prints a first color (800) at a first intensity. The printhead (500) prints a second color (802) at a second intensity. The first and second colors (800, 802) are superimposed and coextensive.

Abstract: Techniques for recovering an original image from its halftone version using information obtained from the dither matrix used to generate the halftone. The techniques involve determining a bounding region defined by (xmin, xmax) for each pixel location and color value, based on the information obtained from the dither matrix, and applying a low-pass filter to the halftone version as follows. For each pixel color, the post-low-pass-filtered value of that color is used, if the filtered value is greater than or equal to xmin and less than or equal to xmax, the xmin value is used, if the filtered value is less than xmin and the xmax value is used, if the filtered value is greater than xmax. Next, it is determined, for each pixel, whether its value for that color is to be used in an averaging process based on the distance between the bounding region of that pixel and neighborhood pixels' bounding regions.

Abstract: Halftone pixels are distinguished from non-halftone pixels in pixels making up an image according to a predetermined algorithm based on a result of edge detection for determining whether the pixels are edge pixels. The pixels which have been determined to be non-halftone pixels according to the predetermined algorithm, are continuous to the pixels determined to be halftone pixels according to the predetermined algorithm including those which have been redetermined to be halftone pixels and are not lower than a predetermined threshold density in density are all redetermined to be halftone pixels.

Abstract: A method for segmenting a compound document initiates with receiving image data, followed by processing the image data at both a first scale and a second scale. Next, region types of the compound document are determined according to a combination of processing output at the first scale and processing output at the second scale. Methods for labeling digital image data and labeling and enhancing documents defined through digital data, as well as associated computer readable medium embodiments are provided. An image replication device and a microprocessor configured to segment and enhance image data associated with a compound document are also provided.

Abstract: Image content may be generated in high resolution by performing raster operations, and half-toning is then performed on the image content. Due to such a sequence, a substantially consistent image may be generated on different printers irrespective of the degree of half-toning. Another aspect of the present invention enables the computation requirements to be reduced by storing in a temporary buffer the image data (paint, destination, source) used multiple times.

Abstract: A method of processing data from a digital image to enhance the neutral tonescale estimates a neutral offset, a neutral gain and a neutral gamma from the input data and uses these estimated values to transform the input image data.

Abstract: We propose methods for generating a halftone image, in which each pixel takes one of two tone values. The generated image contains hidden data, which is present at data storage pixels chosen using a pseudo-random number generator. In a first case, the data is hidden within an existing halftone image by reversing the tone value at certain of the data storage pixels, and at pixels neighboring the data storage pixels. In a second case, the halftone image is generated from a grey-scale image, and data is hidden during this conversion process.

Abstract: A method of printing including replacing each of black dots of a first subset of black dots of a bit map for a predetermined area with a process black dot, adding a non-black dot to each of black dots of a second subset of black dots of the bit-mapped data, and printing the bit map.

Abstract: A method of generating halftone print data for overlapping end portions of a pair of consecutive printhead chips includes the step of generating continuous tone print data for an array of the printhead chips. An initial dither matrix to be applied to the continuous tone print data is generated. Overlap data representing an extent of overlap of the end portions is generated. The overlap data is applied to the initial dither matrix with a summation means to generate an output value. The output value is applied to the continuous tone print data.

Abstract: A method of printing including changing each process black dot and each black plus non-black dot of a halftoned bit map to a black dot, if each of first and second adjacent dots on either side of such process black dot or black plus dot along a predetermined axis comprises a black dot, a black plus non-black dot, a process black dot, or a white dot, and printing the bit map.

Abstract: There is provided a color region extending section that extends a color region with an image processing apparatus. Thereby, even if color pixels existing in a predetermined size of pixel matrix region decreases around a boundary of a color halftone dot region and a black character region and a count value of the color pixel approximates a reference value, the color region can be discriminated as so precisely. As a result, a color halftone dot region can be discriminated as so precisely.

Abstract: To provide high-speed printing with an inexpensive arrangement, a dedicated printer control hardware circuit 5 is provided between a printer driver 1 of a host computer and a printer 9. The printer driver 1 divides an image to be printed into an illustration (a natural image), such as a photograph or a drawing, and characters/graphics. The printer driver outputs full-color RGB raster data for the illustration, while performing color conversion/halftoning for the character/graphic data and outputting binary CMYK raster data. The control circuit 5 performs color conversion/halftoning for the full-color illustration RGB raster data to convert them into binary CMYK raster data. Then, the control circuit 5 superimposes the obtained binary CMYK raster data and the binary CMYK raster data for characters/graphics to form binary CMYK raster data for a complete print image, and transmits the final binary CMYK raster data to the printer 9.

Abstract: While powerful in diffusion at one resolution to print photos at a finer resolution, the invention is not thus limited. It defines superpixels (“spels”) for each desired colorimetric level, generates/receives image data, renders by finding levels for image positions, and prints an image using selected spels. One invention aspect finds a randomized value at each found level and uses the value to select the spel from plural ones for each level. Another aspect derives/maintains a randomized-value matrix; and maps a matrix location to an image position, to select a random value at that location and spel for that position. Another uses the value in common for all planes to select a spel for each plane at the found level—compatible spels for different planes, to coordinate color placement in planes. Another controls defining/selecting for a blue-noise property of spels in aggregate. In another, spels defined for a level vary in value to yield nonintegral color quanta.

Abstract: Digital watermark embedding is incorporated into processes for generating halftone images. In a halftone process using a halftone screen, the halftone screen is used to determine the geometric distortion of an image. After determining the geometric distortion, a watermark decoder compensates for this distortion and retrieves an embedded digital watermark.

Abstract: An image-forming apparatus processes image signals based on a predetermined gradation-converting curve. The predetermined gradation-converting curve includes at least one of: a first gradation in which a maximum absolute-value of a difference between a lightness gradation curve and its smoothed curve in a range of about 1/10 of its gradation number is not greater than 1; a second gradation in which a maximum absolute-value of first-order differential values of a difference curve between a lightness gradation curve and its smoothed curve in a range of about 1/10 of its gradation number is not greater than 100; and a third gradation, in which a maximum absolute-value of first-order differential values of a difference curve between a first smoothed curve in a range of about 1/100 of a gradation number and a second smoothed curve in a range of about 1/10 of a gradation number, is not greater than 100.

Abstract: A continuously variable screening tool is used to generate a unique texture pattern for every color in a multicolor image. The continuously variable screening tool allows a single colorant version of the image to be generated with less information loss than typically suffered in the multicolor to single color transformation process. The continuously variable screening tool is generated by blending patterns from a set of reference screens. The reference screens are associated with selected reference colors in, for example, a machine independent color space. A calculated screen is generated through a weighted blend of reference screens located near the arbitrary color in the machine independent color space. Typically, the weights depend on the distance the arbitrary color is from each of the reference colors. The screens consist of arrays of threshold values. Each threshold value is associated with a dot position and an image pixel.

Abstract: A printing method and system thereof are described. The locations in a printed image for a plurality of first color (e.g., cyan) dots and the locations in the printed image for a plurality of second color (e.g., magenta) dots are determined. Locations in the printed image for a plurality of third color dots (e.g., yellow) are then determined. The locations for the third color dots are dependent on the locations of the first color dots and the locations of the second color dots. The decision on where to place third color dots is thus made after, and therefore dependent on, the decisions on where to place first color dots and second color dots. Accordingly, color fluctuations in the printed image are minimized, resulting in superior color smoothness and improving the quality of the printed image.

Abstract: A method and system updates individualized calibrated tone-reproduction curves. A plurality of predetermined stored calibrated tone-reproduction curves are used, each predetermined stored calibrated tone-reproduction curve corresponding to a distinct media type and halftone type combination along with a plurality of predetermined relationships between each stored calibrated tone-reproduction curve and a reference media type and reference halftone type combination. A new tone-reproduction curve corresponding to a reference media type and reference halftone type combination calibration operation is generated, and each predetermined stored calibrated tone-reproduction curves based on the newly generated tone-reproduction curve corresponding to the reference media type and reference halftone type combination and the plurality of predetermined relationships between each stored calibrated tone-reproduction curve and the reference media type and reference halftone type combination is updated.

Abstract: A halftoning method and apparatus reduces the occurrence of unaesthetic color print output associated with the different relationships found in the numeric data contained within the color data planes. The calculation, modification and distribution of error values, resulting from the mismatch between color plane values and firing thresholds, are performed in a manner that minimizes unaesthetic conditions. Error values are modified by use of error modification functions, bitmaps and matrixes. Firing decisions are based on a comparison of the modified error.

Abstract: A printhead controller controls printing of a page by at least one printhead. The printhead controller, in use, receives data, in a compressed format relating to the page to be printed, the data including a page description comprising a bi-level black layer and a contone color layer. The printhead controller extracts from the compressed data relating to the bi-level black layer the contone color layer. Memory is provided for temporary storage of the expanded data. A dithering/compositing unit produces a ditherer page from the data temporally stored in the memory and feeds its out put to the printhead.

Abstract: The system and method reduces aliasing which is formed by the patterns that are introduced by the halftone screens used in the printer. The system and method provides halftone-specific anti-alias filters for obtaining optimal effective resolution in printed images. A method of reducing aliasing in a digital image includes providing a digital image; selecting a halftone screen for halftoning the digital image, wherein the halftone screen has a directional component associated with it; filtering the digital image with an antialiasing filter, the antialiasing filter having been designed to have a directional frequency response that is optimized for the directional component of the selected halftone screen; and halftoning the filtered digital image.

Abstract: The tincture of an input image is analyzed, and stable, smooth screen angles are assigned in descending order from the most dominant color. When the input image has dot information, like a print, the two-dimensional frequency components of the input image for C, M, Y, and K are analyzed, screen angles and frequencies which do not interfere with these components are analyzed, and various textures are assigned to the respective colors on the basis of the analysis result. Accordingly, an image which is stable and smooth in tone and excellent in color reproducibility can be output.

Abstract: An image-writing device writes a dot image onto an image-receiving body in such a way that the dots align at a certain screen angle. The dots are written by an array of writing elements such as light-emitting diodes. The image-writing device has a memory that stores compensation parameters that compensate for non-uniformity of the writing elements. The compensation parameters are also calculated to produce dots with approximately uniform widths as viewed in the screen-angle direction. When driven according to the compensation parameters, the writing elements produce a dot image that is comparatively free of dot-width irregularities aligned in the screen-angle direction, which is the direction in which such irregularities are most noticeable.

Abstract: A method and an apparatus are provided in which a color of an input image can be reproduced with high accuracy by a small number of colors, and an image quality except the color reproducibility can be optimized. A color of each pixel of the input image is converted into one color selected from a plurality of reproducible colors, and an error due to the conversion is diffused into pixels surrounding the target pixel. In this conversion of the number of colors, a plurality of rules to be selected for a plurality of reproducible colors is prepared. One of the plural rules is selected to be applied for the whole or each part of the input image.

Abstract: A method of compensating for image quality of an inkjet printer includes selecting one of combinations of a plurality of shingling modes controlling shingling characteristics of image data and a plurality of printed data generating modes, which are set separately from the shingling modes, controlling other characteristics of image data except the shingling characteristics. Therefore, deterioration of the image quality due to a defective nozzle can be compensated without replacing an ink cartridge.

Abstract: A technique for selective enhancement of black including printing a non-black color at pixel locations identified by a candidate pixel array and which correspond to marked pixels in a predetermined pixel pattern, wherein the candidate pixel array comprises a plurality of N-pixel candidate tiles respectively associated with N-pixel image tiles of a black half-toned bit map, wherein an N-pixel candidate tile includes marked pixels only if the associated N-pixel image tile comprises a portion of a half-toned uniform region and the number of marked pixels in the associated N-pixel image tile is at least a predetermined percentage of N, and wherein the number of marked pixels in some of the N-pixel candidate tiles is less than the number of marked pixels of the associated N-pixel image tile.

Abstract: Tone dependent plane dependent error diffusion halftoning takes into account multiple color planes, such as cyan and magenta, when determining the placement of a dot in any of the color planes. The combined tones of the correlated color planes is used to determine the threshold levels against which the combined tones and the accumulated errors for the correlated color planes is compared. Further, tone dependent error weightings are determined based on the combined tones of the correlated color planes. The tone dependent error weightings are used to diffuse the final accumulated errors for each color plane. A prerendered mid-tone bitmap may be used to break up any structured patterns that occur in the mid-tones. Using this technique, printed dots of two or more colors are dispersed so as to avoid noticeable clumping of dots of two or more colors to provide a more uniform pattern and to avoid the unintentional overlapping of colors. This technique can be used to augment any existing error diffusion method.

Abstract: A method (and system) for producing a halftoned image, includes calculating errors corresponding to a plurality of different viewing conditions of a halftone image, and minimizing a function of the errors, such that the halftoned image appears as a different image under different viewing conditions. Alternatively, in another embodiment, the halftoned image appears as the same image under different viewing conditions.

Abstract: An image processing apparatus for a laser printer, wherein a halftone control through laser pulse modulation (PWM) is used in combination with distributed clustered-dot halftone processing which distributes a tone level over four clustered-dots, and the value represented by higher bits of a threshold are used to switch a PWM pulse pattern in a highlight area to a discontinuous pattern, thereby implementing the high density halftone processing, which provides a high highlight tone density and stability, only with a small scale memory and circuit.

Abstract: A method for producing halftone dot patterns involves generation of a halftone dot pattern one color channel as a function of the halftone dot pattern generated for another color channel. Placement of dots for one color channel in view of dot placement of one or more other color channels can enhance image quality, promoting improved spacing of dots among the halftone dot patterns generated for the overprinted color channels. Dot placement for a color channel may depend on the number of dots placed for color channels that precede it in the halftoning process. With improved dot spacing in view of inter-channel effects, an inter-channel dot placement method can reduce the incidence of mottle and other image artifacts, improving the visual appearance of the integrated image. A master threshold array may be used to produce halftone dot patterns for all color channels, but applied, in effect, on a shifted basis to promote improved inter-channel dot spacing.

Abstract: This invention relates to a color image dithering method and apparatus for producing an output point in an output color space corresponding to a selected vertex in a tetrahedron of a three-dimensional cubic subinterval of a pixel point in a source color space.

Abstract: A technique is described to greatly reduce or avoid the quantization errors that occur when mapping a relatively linear RGB color space into a greatly non-linear printer CMY color space of equal precision, avoiding the contouring or banding that occurs when printing color gradients in a non-linear printing system. The technique performs a dither-like process on the original RGB continuous tone data. The RGB values are dithered to create a range of values that, when mapped to the non-linear printer continuous tone CMY values, creates a range of CMY values that, on average, represent the correct average tone of the input RGB values. The generated CMY continuous tone values are then halftoned and printed.

Abstract: When black regions are adjacent to color regions, the adjacent black regions are encoded (rendered) at the resolution of the color regions (e.g., 300 dpi) even though the printer has the capability of printing black at a higher resolution (e.g., 600 dpi). To make full use of the 600 dpi resolution of the printer, the black pixels are separated from the color pixels. The 300 dpi resolution black pixel field is converted to a 600 dpi black image field. A window surrounding a selected group of (600 dpi) black/white target pixels is chosen. The pixels in the window are applied to a logic circuit having a plurality of logical conditions. As a result of the logic processing, values of each of the target pixels can be changed to a different pixel value to avoid jagged edges in the printed images, thereby providing a pseudo-600 dpi resolution for the target pixels. The logical operations are performed until all of the pixels have values determined by the logic circuit.

Abstract: A method of and apparatus for printing color images by the superimposition of a number of separations, using a first half-tone technique optimized for surface reproduction, such as dithering, and a second half-tone technique, differing from the first and optimized for edge reproduction, such as thresholding with error diffusion, is disclosed. The second half-tone technique is used in edge transitions for pixels of a separation which substantially influences the edge transition, and the first half-tone technique is used outside the edge transition. And the first half-tone technique is used throughout in the case of pixels of a separation which provide no or minimal contribution to the edge transition.

Abstract: A system and method of processing an image including black text data and non-black text data are described. The system and method use a parametric analysis for discrimination of halftones, texts, and photographs. The parametric analysis provides results that track measurable image metrics without the inherent risk of errant decision making during classification. The creation of symbolic representations is intrinsically a classification process that is subject to error. It represents a fundamental departure from fuzzy logic image segmentation. In the parametric analysis, no pattern matching, no auto-correlation, no screening parameter calculation, and no conventional edge detector (such as a high pass filter) are used.

Abstract: A facsimile apparatus, a computer-readable program, and a storage medium are disclosed. The facsimile apparatus is equipped with a reader for reading original image data, a communication interface for transmitting the read image data to a predetermined network and receiving image data from the network, and a printer engine for forming an image on a medium based on the received image data. The facsimile apparatus further includes storing means for storing the image data in a first data format; receiving means for receiving a request that the image data be sent to a predetermined transmission destination; data format conversion means for converting the stored image data from the first data format into a second data format; and transmitting means for transmitting the converted image data to the requested transmission destination.

Abstract: What is disclosed is an image path that advantageously uses halftone classification to select appropriate mappings in gray-scale management and color management operations. The tags generated in the scanner help identify different classes of halftones. One is selected from several pixel-value mappings to provide proper compensation. That is, the one-dimensional and multi-dimensional pixel-value mappings within the color management module are selected based on halftone classification tags from the scanner. The tagging is either one bit that indicates “Low Frequency Halftone” and “Not LFHT”, or, more preferably, the tag is multi-bit indicating a frequency bin that contains the frequency of the input halftone. Additionally, the multi-bit tag can indicate particular halftone screen types, such as dot screens, line screens, stochastic screens or error diffusion.

Abstract: A data processing method for a color management module (CMM), applying to image processing, including dividing an object data respectively into a meta file data, a CMM profile data and a screening/half-toning table. The meta file data is processed by a firmware of a printer, while the CMM profile data and the screening/half-toning table are processed by an application specification integrated circuit in the printer, thereby shortening the total time of data processing and thus improving the printing speed.

Abstract: A method and system for jointly designing at least two sets of dither matrices. First, a mosaic color tile is generated for a first concentration level according to a design tile map. The mosaic color tile includes at least a first color tile and a second color tile where each color tile has a color tile concentration level (CTCL) and a color tile number (CTN). Second, a color fluctuation metric is performed on the mosaic color tile. Next, the pixels in the first color tile are modified by an operation (e.g., a swap operation) while maintaining the first concentration level. Then, a color fluctuation metric is re-calculated on the mosaic color tile with all first color tiles being replaced with the modified first color tile (i.e., everywhere the first color tile appears in the mosaic color tile as specified by the design tile map).

Abstract: A method of the present invention first stores color image data for an area corresponding to a height of entire nozzles in the sub scanning direction that are used during color printing into a line selection process buffer BF12. Then, the method selects color image data for printing-subject lines subject to recording of ink dots during a single main scan from the buffer BF12. In addition, the method performs on the color image data the color conversion process and the dither process in the printing resolution to create dot data representing recording states of ink dots in print pixels on the printing-subject lines, and then stores the dot data into a buffer BF14.

Abstract: Corrected values C1, M1, and Y1 corrected in a quasi-grayscale processing section of an image forming device by an error diffusion technique performed for each channel are evaluated in threshold value sections provided for individual channels, so as to determine whether or not they are greater than threshold values. If an overlapping CMY dot formation detector section detects that the density is higher than the threshold value in all of the three channels, a minimum density channel identifying section instructs a first quantized value substitution section and varies the outputs from the threshold value sections, so that the output in the channel with the lowest density has a value that does not represent dot formation. As a result, overlapping dot formation for the three channels is interrupted.

Abstract: A stochastic halftone pattern has been invented which has a narrow band power spectrum due to the incorporation of a dot growth process. The narrow band power spectrum may be matched to the resolution characteristics of specific printers, resulting in smoother printed halftone textures. The spectrum of a halftone pattern may be made anisotropic (angularly dependent), helping to de-couple sets of patterns for color printing with reduced color noise or mottle.

Abstract: A method for reducing or eliminating residual error when “blank” pixels are found in the input image data is provided, such as one that can be used in printers of the type which use error diffusion as part of the halftoning process. When a blank pixel is found, the residual error may be immediately reduced in magnitude in one embodiment. In another embodiment, a “hop count” value is increased (or incremented) when a blank pixel is found, and if sufficient consecutive blank pixels exist in the input data, the hop count achieves a threshold and then either decimates or eliminates the residual error, thus limiting the migration of residual error. If a non-blank pixel is found in the input data before the threshold is achieved, the hop count is reset to zero.

Abstract: A method of providing an image for printing at a predetermined bi-level dot resolution which corresponds to a predetermined continuous tone resolution, the method including the steps of: receiving a first data set indicative of the image, the data set being in a Bayer format of a first resolution; converting the first data set into a second data set of the predetermined continuous tone resolution; converting the second data set into a third data set of the predetermined bi-level dot resolution; and making the third data set available to a printer at the predetermined bi-level dot resolution.