Abstract: An apparatus and method are provided for processing a digital image to determine whether the image includes a region of differential gloss (which would yield a differential gloss when that digital image is printed into hardcopy). The method includes identifying whether an input digital image has a periodic characteristic which is indicative of a cluster screen halftoned digital image and, if so, determining a correlation between first and second filters and halftone structures of the identified digital image. The second filter has a different polarization from the first filter. The first and second filters are selected to enable a region of differential gloss in the identified digital image to be identified, based on the determined correlations. Where such a region or regions are detected, a representation of the differential gloss image may be displayed and/or another action automatically initiated, such as restricting printing of the image.

Abstract: An efficient method and system for eliminating halftone screens from scanned documents while preserving the quality and sharpness of text and line-art is disclosed. The method and system utilizes one or more independent channels with different sensitivities (e.g., Max, High, and Low) to provide high quality frequency and magnitude estimation. The most sensitive channel (Max) derives the frequency estimate, and the remaining channels (e.g., High and Low) are combined to create the screen magnitude. The Max channel is the most sensitive and will usually report the existence of frequencies even when the screen is very weak. Therefore, the screen frequency must be additionally qualified by the screen magnitude. The screen magnitude can be interpreted as the level of confidence that the local neighborhood represents half-toned data.

Abstract: A highly efficient method and system for eliminating halftone screens from scanned documents while preserving the quality and sharpness of text and line-art is disclosed. The method and system utilizes a single channel screen frequency estimator module, which generates a screen frequency estimate for image data. The module generates a signal based on the highly filtered image signal at low contrast levels, and based on a reliable estimate to the halftone frequency at higher contrast levels. The single channel screen estimate module has adequate performance in resolution ranges from 300 to 600 dpi.

Abstract: An image processing apparatus includes a reduced image generating part generating a reduced image having a lower resolution than that of an original digital image. A first extracting part distinctly extracts a first foreground image and a first background image from the reduced image. A first continuous tone converting part converts, into a continuous tone, a halftone dot pattern of the first background image extracted from the reduced image. A combining part combines the first background image of which halftone dot pattern is converted into the continuous tone and an image based on the first foreground image extracted by the first extracting part.

Abstract: A method of performing a descreening process with high accuracy by separating a first region from which a gradation area is to be derived and a second region from which a monotone area is to be derived from each other in a screened image with high accuracy is provided. Halftone dot positions and halftone cells are specified at an output resolution level based on the angle dependence of a distribution obtained by counting recorder grids constituting each halftone dot in one direction. By extracting edges of halftone dots and counting them in one direction, the position of deformed halftone dots positioned on a boundary between first regions having different gradation levels is detected at the output resolution level, whereby the position of picture-originated pixels is specified with high accuracy.

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 to detect frequency and angle of a binary halftone pattern. The method employs an exclusive-or operation which is applied locally to a region of a binary bit map and its spatially shifted version. The resulting bits from the exclusive-or operation are summed over the region. The exclusive-or operation is repeated for a range of shift values. In a halftone region, the shift at which the minimum sum occurs reflects the angle and the frequency of the halftone.

Abstract: Performing inverse halftoning on a halftoned image includes smoothing the halftoned image using a two-dimensional filter to produce a smoothed image, detecting edge areas in the smoothed image, performing lowpass filtering on non-edge areas of the smoothed image, and generating an enhanced image comprised of the edge areas of the smoothed image and lowpass-filtered non-edge areas of the smoothed image.

Abstract: A method and a system for de-screening an image signal. The system comprises a filter bank, a control module and a blend module. The filter bank filters the image signal and produces a set of filter output signals. The control module generates at least one control signal based on the image signal and some of the filter output signals. The blend module dynamically blends the filter output signals in accordance with the control signal to produce a de-screened output signal.

Abstract: A method provides for determining an optimal sample dimension when descreening high-resolution image data so that a lower resolution image color proof may be created without suffering the problems typical of over sampling image data. The method allows to generate a single set of image data to create on-the-fly either a medium resolution color proof or a high resolution printed image without having to RIP the data twice, once for the proof, and once for the printed image.

Abstract: An image processing apparatus processes image data which is obtained by reading an halftone dot image. In the image processing apparatus, the image data is separated into the image data corresponding to halftone dots which form the halftone dot image and other image data. On the image data corresponding the halftone dots, the smoothing process is performed, and on the other image data, the edge enhancement is performed. Both of image data are synthesized and outputted. Since only the separated image data corresponding to halftone dots are smoothed out, it is possible to suppress creation of a moiré due to the halftone dot image which is an aggregation of the halftone dots, without influencing the smoothing processing upon the character portion in the vicinity of the halftone dots. On the other hand, since the other image data are edge-enhanced, the character portion, a line and the like show sharp and legible.

Abstract: A system and method for automatic descreening of a digital image is disclosed. The method comprises automatically detecting, prior to a final scan of the document, the presence of a predefined visual artifact in a sample region of an image of the document being scanned; performing the final scan of the document to obtain the digital image; and automatically descreening the digital image to obtain a final digital image of the document in response to the automatic detection of the predefined visual artifact.

Abstract: This invention is to correct a difference of dot gain between output devices. This invention for converting binary data for a first output device to binary data for a second output device includes the steps of: converting the binary data for the first output device to multi-value data; correcting the multi-value data so that an output density by the second output device becomes equal to an output density by the first output device; and converting the corrected multi-value data to the binary data for the second output device. As stated above, by carrying out the correction so that the output density of the first output device coincides with the output density of the second output device, the user can obtain the same output result without giving consideration to a difference between output devices.

Abstract: Processing of a pixel in a digital image includes performing inverse halftoning on the pixel with respect to a local pixel neighborhood; and performing selective sharpening on the inverse halftoned pixel with respect to the local pixel neighborhood.

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: Method and apparatus for dithering and undithering data words in a data stream. The method comprises the steps of processing a data word in a data stream to obtain an output data word by calculating (14) a first difference, calculating (16) a second difference, comparing (14, 16) the first difference and the second difference with a comparator value S, shifting left (12) the first data word with a first number of bits, the first number being equal to a shift value G minus one, and adding (18) an offset value D to the first data word only when both the first difference and the second difference are equal to the comparator value S. The apparatus comprises elements to perform the steps of the present method. The present method and apparatus allow using common steps, respectively elements to perform both dither and undither operations.

Abstract: A printer is permitted to obtain printed matter of high picture quality from print data transferred in the state changed into 1 bit for the purpose of shortening data transfer time. A multi-value conversion unit (23) converts CMYK respective 1 bit binary data from an expansion unit (22) into multi-valued data. The multi-value conversion unit sets values that a remarked pixel should take, which corresponds to circumstances of surrounding pixels, in a table where two gradation data (0, 1) of the remarked pixel and two gradation data of pixels around the remarked pixel, e.g., upper and lower, left and right and oblique eight pixels are assigned to respective digits of binary number of eight figures are taken as parameter to make reference to this table to thereby convert two gradation data into multi-valued data.

Abstract: A method and a system for controlling de-screening of documents. The control system is included in a de-screening system including a bank of filters. The filter bank receives an image signal and produces a set of filter output signals. The control system comprises a contrast module, a halftone estimate module and a pixel control module. The contrast module receives a filter output signal from a filter having a large filter span and produces a contrast signal. The halftone estimate module receives the image signal and a filter output signal from a filter having a small filter span and produces an estimated frequency signal and a halftone weight signal. Based on the contrast signal, the estimated frequency signal and the halftone weight signal, the pixel control module produces a control signal which includes information regarding which of the filter output signals are to be blended and the proportion of blending.

Abstract: A digital imaging system and method uses a two-stage sigma filter to de-screen color images. This filter does not assume any a priori knowledge about the screening process using to produce the halftone image. The two-stage sigma filter may therefore be used to convert color halftone images into continuous-tone images irrespective of the screening process used. The two-stage sigma filter may be constructed, or emulated in software, using an O (N) algorithm which performs smoothing and preserves edge information simultaneously in the Red/Green/Blue color space. This system and method outperforms conventional approaches which, for example, use a Gaussian blur, because it satisfies the dual criteria of completely eliminating halftone screens while preserving edge information. When combined with halftone segmentation techniques, a complete document processing algorithm for gray-scale and color documents is created.

Abstract: A primary binary image is converted into a weighted multivalued image with pixel values weighted. An upper shift-inverting unit inverts the pixel values, shifts them upward by one dot, and thus converts the primary binary image into an inverted upper-shifted image. A lower shift inverting unit inverts the pixel values, shifts them downward by one dot, and thus converts the primary binary image into an inverted lower-shifted image. A right shift inverting unit inverts the pixel values, shifts them rightward by one dot, and thus converts the primary binary image into an inverted right-shifted image. A left shift inverting unit inverts the pixel values, shifts them leftward by one dot, and thus converts the primary binary image into an inverted left-shifted image. A gradation processing unit subtracts the inverted upper-shifted image, inverted lower-shifted image, inverted right-shifted image and inverted left-shifted image from the weighted multivalued image, thereby synthesizing these pieces of image data.

Abstract: A system and method descreen halftone images into a continuous tone image while preserving edge detail and reducing initial image blur. The descreening can be applied to monochrome or color images. Descreening is achieved by first using a low pass filter to form a blurred image of the original, which is used to guide future image filtering, but which further filtering is applied to the original image. The intelligent filtering is provided by a Sigma filter, which can be performed in a single iteration and sized and shaped according to values of the blurred image. The system and method can take a block-oriented approach that performs analysis for an entire block of pixels rather than on individual pixels. This further improves the implementation speed of the process.

Abstract: An adaptive filtering method and apparatus for descreening a scanned halftoned image representation is disclosed. The apparatus includes an image input subsystem; a processing subsystem for processing halftoned image data provided by the image input subsystem; and software/firmware means operative on the processing subsystem for a) low-pass filtering a halftoned input pixel value provided by the image input subsystem to produce a low-pass filtered pixel value; b) notch-filtering the halftoned input pixel value to produce a notch-filtered pixel value; c) determining a local contrast value for the halftoned input pixel value; and d) producing a descreened output pixel value based on the low-pass filtered pixel value, the notch-filtered pixel value, or a combination of the low-pass filtered pixel value and the notch-filtered pixel value depending on the local contrast value.

Abstract: A digital image processing method for adaptively sub-sampling an image to X % of original pixels, includes the steps of generating an edge map of the image; normalizing the edge map to N-bits; applying a shift to the normalized edge map such that X % of the pixels will be ones when the normalized shifted edge map is halftoned using a blue noise halftoning technique; halftoning the edge map using the blue noise halftoning technique to generate a halftone mask; and sub-sampling the image at the pixel locations represented by ones in the halftone mask.

Abstract: Disclosed is a liquid crystal shutter that uses as a shutter a liquid crystal panel constructed by sandwiching DHF liquid crystal between a pair of substrates provided with one or more pixel electrodes and one or more counter electrodes, wherein a driving waveform for the panel has a write period comprising two subfields. In each of the subfields, a single pulse is applied to a pixel, the single pulse applied in one subfield being opposite in polarity to the single pulse applied in the other subfield. On the other hand, a constant voltage of 0 V or close to 0 V is applied to the pixel during a period in which neither of the single pulses is applied.

Abstract: Methods, systems, and media to enhance image processing for a color reprographic system are disclosed. Embodiments of the invention may calibrate a component like scanner and/or printer in response to user input and/or coupling the component to the reprographic system. More specifically, embodiments may generate correction parameters that describe differences in color values between an image scanned by a scanner or an image printed by the printer by comparing the outputs to known characteristics like color values for the image. Some embodiments comprise a graphical user interface (GUI) to communicate with the user, allowing the user to select user preferences to change, for example, the brightness of an image being copied. Further embodiments incorporate network and phone system interfaces to communicate with remote components as well as to receive input from and/or output to other systems via email, facsimile, etc.

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: Processing of a pixel in a digital image includes performing inverse halftoning on the pixel with respect to a local pixel neighborhood; and performing selective sharpening on the inverse halftoned pixel with respect to the local pixel neighborhood.

Abstract: Blind inverse halftoning on a digital image is performed by applying a robust convolution filter to the digital image.

Abstract: A method of performing a descreening process with high accuracy by separating a first region from which a gradation area is to be derived and a second region from which a monotone area is to be derived from each other in a screened image with high accuracy is provided. Halftone dot positions and halftone cells are specified at an output resolution level based on the angle dependence of a distribution obtained by counting recorder grids constituting each halftone dot in one direction. By extracting edges of halftone dots and counting them in one direction, the position of deformed halftone dots positioned on a boundary between first regions having different gradation levels is detected at the output resolution level, whereby the position of picture-originated pixels is specified with high accuracy.

Abstract: Techniques for converting images defined by halftone bitmaps to continuous tone (CT) representations can better preserve geometric information from the original halftone bitmaps, enhancing the accuracy of CT proofs produced by lower resolution proofers such as inkjet and electrophotographic devices. The conversion techniques may involve the application of different conversion processes to text/linework and image regions of the bitmaps. For example, the conversion process for image regions may involve application of bandwidth limitation to remove halftone dot structures prior to downsampling. On the contrary, the conversion process for text/linework regions may exclude bandwidth limitation in order to preserve sharpness of text and linework.

Abstract: A method and system for de-screening an image signal utilizing a bank of filters to provide several increasingly blurred versions of the original image signal is disclosed. At any given time, only two of these blurred versions are created, on a pixel-by-pixel basis. The outputs from the selected pair of blurred signals are then blended together to create a variable blending output that can vary smoothly from no blurring to maximum blurring in a smooth and continuous manner. In addition, the method provides the capability to enhance text and line art by using a variable un-sharp masking mechanism with independent post-blur sharpening control, and the capability to detect and enhance neutral (no-color) output pixels.

Abstract: An efficient method and system for eliminating halftone screens from scanned documents while preserving the quality and sharpness of text and line-art is disclosed. The method and system utilizes one or more independent channels with different sensitivities (e.g., Max, High, and Low) to provide high quality frequency and magnitude estimation. The most sensitive channel (Max) derives the frequency estimate, and the remaining channels (e.g., High and Low) are combined to create the screen magnitude. The Max channel is the most sensitive and will usually report the existence of frequencies even when the screen is very weak. Therefore, the screen frequency must be additionally qualified by the screen magnitude. The screen magnitude can be interpreted as the level of confidence that the local neighborhood represents half-toned data.

Abstract: A method and a system for de-screening an image signal. The system comprises a filter bank, a control module and a blend module. The filter bank filters the image signal and produces a set of filter output signals. The control module generates at least one control signal based on the image signal and some of the filter output signals. The blend module dynamically blends the filter output signals in accordance with the control signal to produce a de-screened output signal.

Abstract: Methods and apparatus for reconstructing digitized images are provided that include an image reconstruction path that receives a digitized image and provides a processed RGB or CMYK image that may be printed or stored in memory. The image reconstruction path is configured to operate in either a multiple scan or single scan environment if the source of the digitized image is a scanner. A plurality of optional functional units in the reconstruction path can be controlled by user or internal controls. These functional units perform preliminary color adjustment, automatic deskew, background and dust removal, descreen, text detection and enhancement, color conversion, scaling, and color manipulation.

Abstract: A method, computer program product, and a program storage device readable by machine, for repurposing images includes classifying the pixels of a binary image as being either halftone image pixels or non-halftone image pixels, further processing the halftoned image pixels with halftone image pixel processing and combining the outputs of the halftone image pixel processing and non-halftone image pixel processing to prepare the images for a second purpose such as a second printer. The processing that classifies the binary pixels as being either halftone image pixels or non-halftone image pixels segments the image into regions of halftone image pixels and regions of non-halftone image pixels. The processing of regions of halftone image pixels first constructs an intermediate gray scale representation of the regions of halftone image pixels.

Abstract: An image processing apparatus includes a reduced image generating part generating a reduced image having a lower resolution than that of an original digital image. A first extracting part distinctly extracts a first foreground image and a first background image from the reduced image. A first continuous tone converting part converts, into a continuous tone, a halftone dot pattern of the first background image extracted from the reduced image. A combining part combines the first background image of which halftone dot pattern is converted into the continuous tone and an image based on the first foreground image extracted by the first extracting part.

Abstract: A method is provided for substantially matching a first output produced by a first marking device with a second output produced by a second marking device. A first set of sample tone levels is produced using the first marking device. A second set of sample tone levels is then produced using the second marking device. The first and second sets of sample tone levels are then compared and one or more calibration set points are determined. A custom tone transfer function associated with the first marking device is generated in accordance with the calibration set points. The first output is then produced from the first marking device using the custom tone transfer function.

Abstract: In an image processor, multi-level image data are divided into blocks, and compressed in the unit of block. The compressed multi-level image data of a block are converted to compressed bi-level image data without expanding the multi-level image data. For example, the compressed multi-level image data on an image of uniform density are converted to compressed bi-level image data expressed with area gradation. In another image processor, the compressed multi-level image data of a block are converted to compressed multi-level image data, without expanding the multi-level image data. For example, the compressed multi-level image data on an image of bi-level image expressed with area gradation are converted to compressed multi-level image data of a half-tone image.

Abstract: When color converting image data of a first color coordinate system to image data of a second color coordinate system using a color conversion module, the tone values of said second image data are proportionally increased for conversion in a tone value range in which small dots or light dots are formed. Next, second image data is converted to dot volume data relating to the dot forming density for various dots with different tone values expressed per single dot. At this time, the proportional increase part of the tone values of the second image data is corrected, and suitable dot volume data is obtained. If this is done, even in an area where small dots or light dots are formed, it is possible to supplement insufficient resolution of image data during color conversion, and to display images of high image quality.

Abstract: A digital imaging system and method uses a two-stage sigma filter to de-screen color images. This filter does not assume any a priori knowledge about the screening process using to produce the halftone image. The two-stage sigma filter may therefore be used to convert color halftone images into continuous-tone images irrespective of the screening process used. The two-stage sigma filter may be constructed, or emulated in software, using an O (N) algorithm which performs smoothing and preserves edge information simultaneously in the Red/Green/Blue color space. This system and method outperforms conventional approaches which, for example, use a Gaussian blur, because it satisfies the dual criteria of completely eliminating halftone screens while preserving edge information. When combined with halftone segmentation techniques, a complete document processing algorithm for gray-scale and color documents is created.

Abstract: A method of detecting halftones in the wavelet domain includes determining an energy value for the sub-bands in a wavelet decomposition. The calculated energy values are compared to a model of energy values that are expected when halftone data are not present. If the actual energy values do not conform to the model, halftone data are deemed to be present. In one embodiment, the model defines a pattern of decaying sub-band energy for each sub-band moving from a highest level of the wavelet decomposition to the lowest level of the decomposition. In another embodiment, the expected energy values in the model vary depending upon the bit-rate of compression of the wavelet-domain data.

Abstract: An adaptive filtering method and apparatus for descreening a scanned halftoned image representation is disclosed. The apparatus includes an image input subsystem; a processing subsystem for processing halftoned image data provided by the image input subsystem; and software/firmware means operative on the processing subsystem for a) low-pass filtering a halftoned input pixel value provided by the image input subsystem to produce a low-pass filtered pixel value; b) notch-filtering the halftoned input pixel value to produce a notch-filtered pixel value; c) determining a local contrast value for the halftoned input pixel value; and d) producing a descreened output pixel value based on the low-pass filtered pixel value, the notch-filtered pixel value, or a combination of the low-pass filtered pixel value and the notch-filtered pixel value depending on the local contrast value.