Picture Signal Thresholding Patents (Class 358/465)
  • Patent number: 5699454
    Abstract: An image processing apparatus includes a detecting section for detecting a density value as a threshold value for suppressing an effect from a background from image data composed of plural picture element data obtained by digitizing each picture element of the image and a density converting section for outputting the image data after converting density values of the picture element data whose density values are below the threshold value into a predetermined value indicating white when the density value of the picture element data is below the threshold value. The detecting section computes a degree of separation indicating a ratio of a between-class dispersion to a within-class dispersion of two classes divided by the threshold value by sequentially varying the density value. Then, the density value corresponding to a gravitational center of a differential histogram showing the respective differences in degree of separation from a density Tm which maximizes the degree of separation to a highest density Te.
    Type: Grant
    Filed: May 2, 1995
    Date of Patent: December 16, 1997
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Yoshiyuki Nakai, Youichi Yamamoto, Keiji Taniguchi
  • Patent number: 5696611
    Abstract: An achromatic color judging region is determined in a red-green-blue (RGB) color system, and it is judged in an achromatic color judging unit whether or not a color picture at a remarked pixel designated by a R multi-valued digital input signal, a G multi-valued digital input signal and a B multi-valued digital input signal is placed within the achromatic color judging region. Also, the RGB multi-valued digital input signals are converted into pieces of RGB binary data in an error dispersion processing unit while dispersing errors occurring in the RGB binary data. In case where it is judged that the color picture is an achromatic color because the color picture is placed within the achromatic color judging region, a piece of achromatic color data is generated from the RGB binary data in an achromatic color reproducing and color transforming unit and is output to reproduce the color picture at the remarked pixel.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: December 9, 1997
    Assignee: Matsushita Graphic Communication Systems, Inc.
    Inventors: Kazuyuki Nishimura, Shinichi Sato
  • Patent number: 5694224
    Abstract: A method and apparatus for reproducing an original image includes a scanner or other image source for generating a digitized raw image data for each pixel area of an image. For each pixel the raw image data is transformed into a gray level rendering value pixel by comparing the raw image data value with threshold values from threshold mask sets. Tone adjustment means is provided for generating a tone corrected rendering gray level pixel value for each pixel. A printer or display is controlled to print the digitized image signal by rendering the dot regions in accordance with the tone corrected gray level rendering pixel value. Thus after a print is made a tone correction adjustment maybe made and in response to this tone adjustment a new print can be made using rendering image data in buffer memory without the need for rescanning of the image.
    Type: Grant
    Filed: December 8, 1994
    Date of Patent: December 2, 1997
    Assignee: Eastman Kodak Company
    Inventor: Hwai-Tzuu Tai
  • Patent number: 5689582
    Abstract: When a frame marked with a marker pen in a black-and-white image is to be extracted, an intermediate-density portion present on a character edge portion is removed by a frame extracting circuit. The frame extracting circuit removes an intermediate-density pixel adjacent to a high-density pixel corresponding to a character/figure. Accordingly, the extracting precision of the marker portion in the black-and-white image is improved. The extracting precision of the marker portion will not be decreased even when extraction is to be performed from an image enlarged by an input system.
    Type: Grant
    Filed: January 30, 1996
    Date of Patent: November 18, 1997
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Naoya Murakami
  • Patent number: 5689623
    Abstract: A spread spectrum digital screening mask and a method and system for digital screening a continuous tone image with the spread spectrum digital screening mask. The mask is characterized in the frequency domain by a function in magnitude independent of angle within a band of frequencies between a minimum frequency and a maximum frequency. The mask may be further characterized by its thresholded binary planes at each of a plurality of predetermined threshold values. The binary planes are characterized in frequency domain by magnitudes primarily distributed within the band of frequencies. For each binary plane, the number of pixels having one of the binary values divided by the total number of pixels in the binary plane equals a fraction determined by the predetermined threshold value of the binary plane divided by the maximum threshold value.
    Type: Grant
    Filed: March 27, 1995
    Date of Patent: November 18, 1997
    Assignee: Optronics International Corporation
    Inventor: Adam I. Pinard
  • Patent number: 5668643
    Abstract: A reading apparatus and a recording apparatus having the reading apparatus which can reduce storage capacity for storing read data and, because the read data processing modes can be switched according to the type of documents to be processed, perform fast and proper document reading operation. If a document to be processed is an image document, the controller operates in the image processing mode in which M pieces of read data are sampled out of N pieces of read data and a mean value of the M pieces of read data is calculated to be stored in the memory as gradation data of one pixel. If the document is a text document, the controller operates in the text processing mode in which read data of one read unit of the image scanner is digitized by a threshold to be stored in the memory. Switching between these two processing modes is performed by the conversion processing operator section in the controller.
    Type: Grant
    Filed: May 28, 1996
    Date of Patent: September 16, 1997
    Assignee: Alps Electric Co., Ltd.
    Inventors: Masaki Sakamoto, Yuki Oishi, Hideki Yorozu, Kazutaka Suzuki
  • Patent number: 5661570
    Abstract: An apparatus for processing multilevel image data representing a half-tone image, into bilevel image data representing a bilevel image corresponding to the half-tone image, the multilevel image data including sets of multilevel pixel data each set of which represents one of three or more color values as a first color value indicating a color of a corresponding one of pixels of the half-tone image, and is processed into a corresponding one of sets of bilevel pixel data of the bilevel image data so that the corresponding one set of bilevel pixel data represents one of two color values as a second color value indicating a color of a corresponding one of pixels of the bilevel image, the apparatus including a data processing device for processing each set of multilevel pixel data into a corresponding one set of bilevel pixel data, by an error diffusion process wherein an error value occurring in processing each set of multilevel pixel data into a corresponding one set of bilevel pixel data is distributed to one or
    Type: Grant
    Filed: July 25, 1995
    Date of Patent: August 26, 1997
    Assignee: Brother Kogyo Kabushiki Kaisha
    Inventor: Mayumi Nomura
  • Patent number: 5640465
    Abstract: A scanner system comprises an optical line detector for linewise, optical scanning of an original for generating a data signal in response to the grey-level received by the detector from points along a respective line. The points are sorted with associated grey-level values in groups in response to their positional origin on the original. The individual threshold values for the grey-level values are determined statistically for a plurality of zones on the original in response to the frequency of respective grey-level values in the respective zone. The threshold values of respective zones are stored in a store. The original is re-entered by linewise, optical scanning, and the data signal generated by the scanning and representing grey-levels in points along respective, entered lines is compared in a comparator with a threshold value calculated for the point concerned, and in response to this a binary, electric representation of the original is generated.
    Type: Grant
    Filed: December 4, 1995
    Date of Patent: June 17, 1997
    Inventor: Asbjorn Smitt
  • Patent number: 5625756
    Abstract: A printer apparatus and method for operating a digital printer are provided which utilize a super-pixel bit map set containing a plurality of pixel pattern bit maps, each pixel pattern bit map defining the on or off condition for a plurality of individual pixels which make up a super-pixel which forms a part of a printed area, such as for gray or color shading.
    Type: Grant
    Filed: April 23, 1996
    Date of Patent: April 29, 1997
    Assignee: Hewlett-Packard Company
    Inventor: Russell Campbell
  • Patent number: 5617489
    Abstract: An adaptive threshold for converting an analog video signal to a binary video signal. This video system employs two identical array sensors. These sensors are operated synchronously and each has its own lens. The lens of the primary array sensor is focused for a sharp image. The analog output of this primary array sensor is the primary video signal. A secondary array sensor is implemented with its lens intentionally set to some degree of defocus. This degree of defocus defines the adaptive threshold function, independent of the primary video. The analog output of this secondary array sensor is the adaptive threshold signal.
    Type: Grant
    Filed: August 4, 1993
    Date of Patent: April 1, 1997
    Assignee: Richard S. Adachi
    Inventor: Richard S. Adachi
  • Patent number: 5611022
    Abstract: A bi-level printer is controlled to selectively enhance each pel, based on an error diffusion process. However, each channel (e.g., RGB red, green and blue color channels; Lab luminance, red direction and blue direction channels; or other suitable channel division) is processed individually according to a suitable kernel to provide a multi-color image. In addition, an individual "threshold" level (by which the "actual" state of enhancement of a pel is determined) is calculated for each color channel, based on the minimum and maximum enhanced levels of all of the pels in the "desired" image. Also, the order of processing individual pels and the error diffusion matrix are both reversed for each subsequent line of pels. It has been found that each one and various combinations of these features significantly improves image clarity, sharpness and tone continuity.
    Type: Grant
    Filed: July 7, 1993
    Date of Patent: March 11, 1997
    Assignee: Dataproducts Corporation
    Inventors: James Estrada, Said Zandian
  • Patent number: 5583659
    Abstract: A technique, specifically apparatus and an accompanying method, for accurately thresholding an image based on local image properties, specifically luminance variations, and particularly such a technique that uses multi-windowing for providing enhanced immunity to image noise and lessened boundary artifacts. Specifically, a localized intensity gradient, G(i,j), is determined for a pre-defined window (300) centered about each image pixel (i, j ) . Localized minimum and maximum pixel intensity measures, L.sub.min and L.sub.max, respectively, are also determined for another, though larger, window (330) centered about pixel (i,j). Also, a localized area gradient measure, GS(i,j), is determined as a sum of individual intensity gradients for a matrix of pixel positions (370) centered about pixel position (i,j). Each image pixel (i,j) is then classified as being an object pixel, i.e., black, or a background pixel, i.e., white, based upon its area gradient, GS (i,j), and associated L.sub.min and L.sub.max measures.
    Type: Grant
    Filed: November 10, 1994
    Date of Patent: December 10, 1996
    Assignee: Eastman Kodak Company
    Inventors: Yongchun Lee, Joseph M. Basile, Peter Rudak
  • Patent number: 5583661
    Abstract: An image is processed by using an error diffusion method of propagating density distribution errors in pixels around a pixel to be noted. A method includes the steps of calculating thresholds (Th.sub.1, Th.sub.2) of densities corresponding to the area ratio between the pixels; selecting a pixel to be noted (f) which are different in the area ratio from each other; calculating errors (E) produced in the peripheral pixels according to the distances from the peripheral pixels to the noted pixel and areas of the individual peripheral pixels; adding the propagated errors to a density of the noted pixel so as to make a rearrangement (f') on the density of the noted pixel; comparing the rearranged density of the noted pixel with the thresholds to obtain a corresponding level (G) represented in a binary form, and obtaining density distribution errors (e).
    Type: Grant
    Filed: September 13, 1994
    Date of Patent: December 10, 1996
    Assignee: Riso Kagaku Corporation
    Inventors: Syouji Kurita, Noboru Inamine, Ikuo Noguchi
  • Patent number: 5563721
    Abstract: An improved method for providing a more faithful and pleasing rendition of a pixel pattern is described herein. This method first places the original pixel pattern in a bit mapped memory. A small portion of this bit mapped pattern, called an input tile, acts as an address for a look-up table containing a corrected pixel pattern portion (an output tile) corresponding to the target pixels to be corrected in the input tile. To derive the output tiles stored in the look-up table, a high resolution bit map is created from an input tile by scaling the input tile. A triangular portion of each convex corner in the high resolution bit map is chopped off, and a triangular portion of each concave corner in the high resolution bit map is filled in. The resulting pattern is then smoothed using a low pass filter. The size of these triangular portions and the extent of low pass filtering are determined using a function based on the vulnerability of a pixel to being eliminated during the above smoothing process.
    Type: Grant
    Filed: April 5, 1995
    Date of Patent: October 8, 1996
    Assignee: Hewlett-Packard Company
    Inventor: Mark A. Overton
  • Patent number: 5553165
    Abstract: In order to display continuous tone colour image on a discrete colour level display, methods of halftoning must be used. The high display rate of colour output devices means that serial methods of real time halftoning are difficult to use. A method and apparatus are disclosed for reducing the speed with which a halftoning method must be performed by performing the halftoning of an output image in parallel by simultaneously error diffusing more than one line of input at a time.
    Type: Grant
    Filed: January 4, 1994
    Date of Patent: September 3, 1996
    Assignee: Canon, Inc.
    Inventors: Michael Webb, William C. Naylor, Jr.
  • Patent number: 5535019
    Abstract: A method and apparatus for quantizing pixels in an image formed by a plurality of pixels, each pixel constituting an image signal representing optical density of the image at a location therein, and having an original optical density value selected from one of a set of `c` original optical density values that has a number of members larger than a desired output set of `d` optical density values, through a process of error diffusion. For an input image so comprised, initially, an image signal is initially modified in accordance with previously determined error. Thereafter, during the quantization step of the process, the threshold signal for quantization determination is dynamically adjusted in accordance with previous output quantization determinations to selectively control likelihood of whether the next pixel will exceed the threshold.
    Type: Grant
    Filed: September 15, 1994
    Date of Patent: July 9, 1996
    Assignee: Xerox Corporation
    Inventor: Reiner Eschbach
  • Patent number: 5534945
    Abstract: In a system for the reproduction of natural images on a display or printer, unviewable negative brightness caused by noise or grain in individual shadow pixels, into adjacent pixels is diffused into adjacent pixels made excessively bright by the same noise or grain process. The visual effect of this diffusion produces truer, deeper blacks in shadow areas, enhances shadow contrast and detail, and reduces perceived noise in shadow areas.
    Type: Grant
    Filed: December 16, 1994
    Date of Patent: July 9, 1996
    Assignee: International Business Machines Corporation
    Inventor: Albert D. Edgar
  • Patent number: 5532827
    Abstract: Partial images each constituting a predetermined matrix are sequentially taken out, and density data corresponding to pixels constituting the matrix are subjected to correction. The correction of the density data is so made as to respectively add density correcting values predetermined to correspond to pixel positions in the matrix to the density data. Consequently, the density data corresponding to the pixels constituting the matrix are considerably varied. Therefore, in a binary image obtained by subjecting the partial image constituting the matrix to halftone processing, the density of a document image is sufficiently reproduced.
    Type: Grant
    Filed: July 12, 1993
    Date of Patent: July 2, 1996
    Assignee: Mita Industrial Co., Ltd.
    Inventors: Tetsuji Kajitani, Ariyoshi Hikosaka, Hideo Azumai, Satoshi Iwatsubo
  • Patent number: 5530559
    Abstract: An image data processing apparatus binary-codes an image signal obtained from an image sensor of the CCD type or the like so as to output a binary-coded image signal. The image signal obtained from the image sensor A/D-converted into digital image data. Based upon the digital image data, average values of luminance values of the digital image data are calculated for an array of pixels in a preselected area of the CCD. This average value is used as a threshold level for binary coding the image data for these pixels at the center portion of this preselected area. Furthermore, to detect coutours this data processing apparatus calculates a gradient in the luminance values of the pixels in a portion of the preselected area of the CCD in an X direction and a Y direction, and the gradient value is used to obtain binary-coded data in accordance with the above-described method.
    Type: Grant
    Filed: April 24, 1995
    Date of Patent: June 25, 1996
    Assignee: Casio Computer Co., Ltd.
    Inventor: Takashi Sato
  • Patent number: 5530561
    Abstract: To obtain a binary gradation image from a continuous gradation image, a multi-valued image signal I(x,y) is compared with a threshold signal TH by a comparator to produce a binary image signal P(x,y), an error signal E(x,y) is determined from the binary image signal P(x,y) and the multi-valued image signal I(x,y), and the error signal E(x,y) is multiplied by an error diffusion coefficient W(k,l) to produce a diffusion error signals .DELTA.E(x,y). A random number R(x,y) generated by a random number generator and a weighting coefficient f(I(x,y)) generated as a function of an image signal by a weighting coefficient generator are multiplied, and the product is added to the diffusion error signals .DELTA.E(x,y). The sum is added to the multi-valued image signal I(x,y) thereby to produce a corrected multi-valued image signal I(x,y), which is then compared with the threshold signal TH by the comparator thereby generating a binary image signal P(x,y).
    Type: Grant
    Filed: March 24, 1995
    Date of Patent: June 25, 1996
    Assignee: Fuji Photo Film Co., Ltd.
    Inventor: Osamu Shimazaki
  • Patent number: 5528384
    Abstract: A method and system implements a high addressability characteristic into an error diffusion process. A grey level value representing a pixel is received. The grey level value is interpolated to generate subpixel grey level values which correspond to a second resolution. A threshold circuit thresholds the interpolated grey level value. In parallel to the interpolation circuit and threshold circuit is an error circuit which generates a plurality of possible error values. One of the plurality of possible error values is selected based on the number of subpixels exceeding a threshold value. A portion of the selected error value is then diffused to adjacent pixels on a next scanline.
    Type: Grant
    Filed: August 3, 1994
    Date of Patent: June 18, 1996
    Assignee: Xerox Corporation
    Inventors: David J. Metcalfe, Jeng-Nan Shiau, Leon C. Williams
  • Patent number: 5521710
    Abstract: There is provided a method of labeling a job in a printing system. The method includes the steps of storing, in memory, a list of electronic labels and displaying, on a display screen, both the list of electronic labels and a print outline with a selected identifiable area. The selected identifiable area is positionable on the print outline for representing a relative size, location and orientation of an area on a print upon which a selected one of the electronic labels is to be printed, and the displaying step includes applying a grid to the list so that a series of cells is superposed relative to the the electronic labels. In operation, a first location at which a copy of the selected electronic label is to be printed on a selected one of a plurality of prints is indicated and a plurality of prints, with the selected electronic label printed on the selected print at the first location, is produced when all of the selected electronic label is disposed in a selected one of the series of cells.
    Type: Grant
    Filed: April 12, 1994
    Date of Patent: May 28, 1996
    Assignee: Xerox Corporation
    Inventors: James C. Strossman, Linda D. King, Hollise G. Mitter-Brown, Michael W. Barrett
  • Patent number: 5519791
    Abstract: In order to display a continuous tone colour image on a discrete colour level display, methods of halftoning must be used. The high display rate of colour output devices means that serial methods of real time halftoning are difficult to use. A method and apparatus is disclosed for reducing the speed with which a halftoning method must be performed by performing the halftoning of an output image by simultaneously dividing the input image into a number of areas and simultaneously halftoning the areas individually making special provisions for pixels located in the boarder regions of a given area.
    Type: Grant
    Filed: January 4, 1994
    Date of Patent: May 21, 1996
    Assignee: Canon, Inc.
    Inventors: Michael Webb, David R. Brown, William C. Naylor, Jr.
  • Patent number: 5519509
    Abstract: The present invention provides a half-tone image processing method utilizing an error diffusion technique which allows for the density adjustment of a half-tone image to be reproduced. When the density of an object pixel is converted into binary-coded data, a binary-coding object value is first calculated by adding a density value of the object pixel to an error sum of binary-coding errors distributed to the object pixel from peripheral pixels around the object pixel. Then, the binary-coding object value is compared with a threshold value TH for judging whether the object pixel is a black pixel or a white pixel. The binary-coding object value is also compared with a reference value GSLVB or GSLVW which can be variably set for the calculation of a binary-coding error HG of the object pixel. The level of the binary-coding error HG can be adjusted by variably setting the reference values GSLVB and GSLVW. Thus, the density adjustment of a half-tone image can be realized.
    Type: Grant
    Filed: January 3, 1995
    Date of Patent: May 21, 1996
    Assignee: Mita Industrial Co., Ltd.
    Inventors: Ariyoshi Hikosaka, Tetsuji Kajitani, Hideo Azumai, Satoshi Iwatsubo
  • Patent number: 5515180
    Abstract: The present invention is made to reduce the effect of variation of pulses for driving a printer when recording image data and to improve the gray level representation of picture images to be printed. Data incoming through an image reading device are quantized and processed two pixels at a time by a gray level image processing circuit. The two-pixels' data are first discriminated by an edge discriminator to determine whether they represent an edge portion within the image or not. An object image, on which an operation for inter-pixel spacing shall be conducted, is selected according to the discrimination result. The arithmetic and logic portion performs the above-mentioned operation by two pixels at a time if the data correspond to a non-edge portion and performs correction for enhancement if the data correspond to an edge. This may eliminate the effect of dot displacement due to variation of drive pulses of a printer and improve the quality, in particular, of a gray level image portion.
    Type: Grant
    Filed: November 16, 1993
    Date of Patent: May 7, 1996
    Assignee: Sharp Kabushiki Kaisha
    Inventors: Hiroshi Maeda, Toshio Yamagishi, Norihide Kunikawa, Toshihiro Okahashi, Tatsuya Itoh, Masatsugu Nakamura
  • Patent number: 5506698
    Abstract: Apparatus and process for reproducing apparatus capable of reproducing a source image, wherein an original intensity value determined on the basis of an intensity at each picture element under consideration of the source image is quantized to one of two levels by comparison of the original intensity value with a threshold value, using a minimized average error technique, and wherein the original intensity value at each picture element under consideration is divided into a plurality of fractions, and each of the is quantized to one of two levels, with the minimized average error technique being practiced for each fraction.
    Type: Grant
    Filed: September 22, 1994
    Date of Patent: April 9, 1996
    Assignee: Brother Kogyo Kabushiki Kaisha
    Inventor: Masahiro Nishihara
  • Patent number: 5502495
    Abstract: This disclosure relates to an image processing method and apparatus for applying binarizing processing to multivalue image data so as to produce binary image data, reproducing an image having shades of light and dark based upon the binary image data, and outputting the image. On the basis of the value of the inputted multivalue image data, a search is performed to determine whether there is a pixel whose value is "1" at the periphery of each pixel of the binarized image data with regard to the image where the value of the image data is small, i.e., a highlighted portion of the image. A pixel defining an isolated point is detected through this search. Next, with regard to a pixel defining an isolated point of the binarized image, if a pixel whose value is "1" exists comparatively near this pixel, the value of this pixel of interest is diffused near the pixel. If a pixel whose value is "1" exists comparatively far from this pixel, the value of this pixel of interest is diffused far from the pixel.
    Type: Grant
    Filed: July 7, 1994
    Date of Patent: March 26, 1996
    Assignee: Canon Kabushiki Kaisha
    Inventors: Yuichi Bannai, Toshihiko Sato, Kunihiro Yamamoto
  • Patent number: 5493416
    Abstract: A block-based error diffusion technique allows for the printing of colored images having arbitrary screen orientations. The technique improves reproducibility by only compensating for errors arising from quantization in selected "critical blocks".
    Type: Grant
    Filed: October 31, 1994
    Date of Patent: February 20, 1996
    Assignee: Xerox Corporation
    Inventor: Zhigang Fan
  • Patent number: 5488673
    Abstract: An image processing apparatus is arranged such that corrected data for an input objective pixel is obtained by adding the input data for that pixel and data distributed to the position of that pixel, the corrected data is then quantized (e.g., binarized), and, based on the error occurring in quantization, calculating values to be distributed to respective non-quantized neighboring pixels, based on predetermined weighting factors corresponding to the respective positions of those neighboring pixels. The values so calculated are then distributed to the appropriate neighboring pixel positions, and total sum of those values is subtracted from the value of the error, and this difference is in turn distributed to the position of one neighboring pixel located differently with respect to the objective pixel position, at least each time the position of the objective pixel is updated.
    Type: Grant
    Filed: July 19, 1994
    Date of Patent: January 30, 1996
    Assignee: Canon Kabushiki Kaisha
    Inventors: Akihiro Katayama, Hidefumi Oosawa
  • Patent number: 5471319
    Abstract: The invention provides an image processing method and an image processing apparatus suitably applied to an image reading apparatus such as an OCR or a facsimile, by which a drop or a break of a thin line which is caused by a little inclination of an original can be prevented with certainty by a simple processing procedure without emphasizing noise and besides sharp binary digitization processing which does not cause blurring or distortion can be performed even where color characters are present discretely in the original. When a density value of a noticed picture element upon binary processing is lower than a predetermined threshold level, a binary value error of a picture element on the opposite side to the noticed picture element in a main scanning direction or a sub scanning direction is added to the density value of the noticed picture element to obtain a sum value, and the sum value is compared with the predetermined threshold level.
    Type: Grant
    Filed: February 1, 1995
    Date of Patent: November 28, 1995
    Assignee: Fujitsu Limited
    Inventor: Nobuo Ogawa
  • Patent number: 5469515
    Abstract: A method of generating a halftone image on a printer from a grey scale image using a dither matrix. The halftone image is represented by symbols when it is printed out by the printer. The matrix includes many patterns. Each pattern has many elements having values with a different number of ones and zeros. The values of the elements in each pattern depend on a model of the symbols. The model is incorporated into the patterns as each pattern is generated.
    Type: Grant
    Filed: May 3, 1993
    Date of Patent: November 21, 1995
    Inventor: Qian Lin
  • Patent number: 5463478
    Abstract: An image processing apparatus prevents an increase in random noise and the like produced by distributing a transformation error, which is produced at the time of a level-number transformation, to unprocessed pixel data. Error data X.sub.n is added to pixel data, which has entered via an input unit, by an adder. Thereafter, the resulting data is subjected to a level-number transformation by a binarizing circuit. Transformation error produced at the time of the level-number transformation is calculated by an error arithmetic unit. The transformation error thus calculated is distributed to unprocessed pixel data by an error-diffusion unit, and the error is accumulated in a line buffer memory as error data. When processing of a prescribed number of lines has ended, a line-number discriminating circuit clears the error data that has been accumulated in the line buffer memory. As a result, an increase in random noise is prevented.
    Type: Grant
    Filed: May 17, 1994
    Date of Patent: October 31, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Takeshi Makita, Susumu Sugiura, Osamu Yamada
  • Patent number: 5461490
    Abstract: Sample areas are designated in a plurality of original images. Histograms representing density distribution for each color component are generated on the basis of the density signals for respective sample areas. Representative average density values in highlight-side and shadow-side in respective sample areas are determined from the histograms. A weighted average of respective representative average density values for the sample areas is calculated to obtain representative density values commonly applicable to the plurality of originals. The difference between the representative density values and the respective representative average density values are calculated, and, if the differences are within a predetermined range, reference density values for each color component are obtained on the basis of the common representative density values. The reference density values are used to define color separation rules common to all of the originals.
    Type: Grant
    Filed: December 21, 1993
    Date of Patent: October 24, 1995
    Assignee: Dainippon Screen Mfg. Co., Ltd.
    Inventor: Yasuharu Yonezawa
  • Patent number: 5452107
    Abstract: An image processing apparatus includes a matrix register part for reading an original image for each area containing a predetermined number of pixels of the original image, and for extracting multilevel image data corresponding to the pixels of the read area, the pixels including a target pixel and neighboring pixels surrounding the target pixel, an averaging part for providing the average of multilevel image data based on the data of the pixels extracted by the matrix register part, and a binarization part for providing a bilevel image signal corresponding to the multilevel image data of the target pixel by using the average of the multilevel image data from the averaging part as a threshold value of binarization.
    Type: Grant
    Filed: March 17, 1994
    Date of Patent: September 19, 1995
    Assignee: Ricoh Company, Ltd.
    Inventor: Kazumasa Koike
  • Patent number: 5450214
    Abstract: A video signal processing device is designed to input selectively a first video signal or a sub-sampled second video signal. These inputs are input to a common filter. The output of the filter is output after being sub-sampled, when the first video signal is being input, and without being sub-sampled, when the second video signal is being input. The output level of the filter is changed over between when the first video signal is being output and when the second video signal is being output.
    Type: Grant
    Filed: December 10, 1992
    Date of Patent: September 12, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventor: Kousuke Nobuoka
  • Patent number: 5446561
    Abstract: A method and apparatus for modifying a digitized image in which the digitized image is received as input pixel values for a plurality of pixels, first selects an unprocessed one of the pixels to be a current pixel. The current pixel is modified by adding a total error value and a screen frequency component to the input pixel value of the current pixel to produce a modified current pixel value. The modified current pixel value is thresholded to produce an output pixel value for the current pixel, which becomes a processed pixel. The output pixel value is then mapped into an image range, and a total error incurred for the processed pixel caused by the mapping is determined. The total error incurred is distributed to at least one of the other of the plurality of pixels that is an unprocessed pixel. The procedure is repeated for each pixel in the plurality of pixels to provide a modified digitized image.
    Type: Grant
    Filed: March 8, 1994
    Date of Patent: August 29, 1995
    Assignee: Eastman Kodak Company
    Inventors: Hwai-Tzuu Tai, Issac I. Ajewole
  • Patent number: 5444552
    Abstract: A method for image processing includes the steps of scanning an image within a first grid of pixels, determining a grayscale value for each pixel scanned in the first grid of pixels, and, for each pixel scanned, activating a number of pixels of a second grid of pixels corresponding to the grayscale value determined. Data representing the second grid of pixels can be compressed, and stored for use in facsimile transmission or photoreprographic image production.
    Type: Grant
    Filed: September 28, 1992
    Date of Patent: August 22, 1995
    Assignee: Xerox Corporation
    Inventor: Z. Erol Smith, III
  • Patent number: 5444553
    Abstract: An image data processing apparatus binary-codes an image signal obtained from an image sensor of the CCD type or the like so as to output a binary-coded image signal. The image signal obtained from the image sensor A/D-converted into digital image data. Based upon the digital image data, average values of luminance values of the digital image data are calculated for an array of pixels in a preselected area of the CCD. This average value is used as a threshold level for binary coding the image data for these pixels at the center portion of this preselected area. Furthermore, to detect coutours this data processing apparatus calculates a gradient in the luminance values of the pixels in a portion of the preselected area of the CCD in an X direction and a Y direction, and the gradient value is used to obtain binary-coded data in accordance with the above-described method.
    Type: Grant
    Filed: July 21, 1994
    Date of Patent: August 22, 1995
    Assignee: Casio Computer Co., Ltd.
    Inventors: Takashi Sato, Teruo Sano
  • Patent number: 5442461
    Abstract: A halftone screen, at a desired screen angle and ruling, is generated by concatenating strips of an ideal angled screen pattern. Artifacts are reduced by aligning the vertical boundaries between adjacent strips. In one embodiment, a screen pattern is generated by storing a plurality of double width strips from an ideal angled screen pattern, and concatenating a sequence comprising a portion of each double width strip in a selected order. Regardless of the choice of starting point in the strip for each successive scan line, a sufficient portion of the double width strip is clocked out until the edge of the strip aligns with the strip above it. In a second embodiment, strips of a rational angled screen are concatenated to approximate an irrational angled screen. Errors which accumulate with each successive pixel are corrected by occasionally jumping to a new point in the strip.
    Type: Grant
    Filed: July 13, 1992
    Date of Patent: August 15, 1995
    Inventor: Raphael L. Levien
  • Patent number: 5438634
    Abstract: A dither processing method generates a binary-value image from an original image. The original image is converted to a binary-value image by a dither process. For each area in the dither image that corresponds to a dither cell, a representative density is calculated from the number of black (or white) pixels produced by the dither process. A median value of representative densities is then used as a threshold, and the original image is converted to a binary-value image using the threshold. By using the median of representative values, lighting of the original image is corrected.
    Type: Grant
    Filed: May 23, 1994
    Date of Patent: August 1, 1995
    Assignee: Ezel Inc.
    Inventor: Ryohei Kumagai
  • Patent number: 5434931
    Abstract: A method of picture image processing, and system for carrying out same, involves generation of a composite mapping function, for transforming gray scale values to different values in order to enhance contrast. A reduced range histogram is generated, involving removing a percentage of the total histogram counts from bottom and top sub-ranges and also removing spikes. The reduced histogram is then density averaged in order to obtain a first map function. A second map function is generated for interfacing with the characteristics of the printer to be used, and a composite mapping transform is generated by combining the two generated functions. After the composite mapping function is generated, each gray value of the image data set is transformed in accordance with the composite function, for use in printing, thereby providing an enhanced contrast image.
    Type: Grant
    Filed: April 20, 1994
    Date of Patent: July 18, 1995
    Assignee: Educational Testing Service
    Inventors: Dennis Quardt, Keith S. Reid-Green
  • Patent number: 5422735
    Abstract: The invention provides an image processing method and an image processing apparatus suitably applied to an image reading apparatus such as an OCR or a facsimile, by which a drop or a break of a thin line which is caused by a little inclination of an original can be prevented with certainty by a simple processing procedure without emphasizing noise and besides sharp binary digitization processing which does not cause blurring or distortion can be performed even where color characters are present discretely in the original. When a density value of a noticed picture element upon binary processing is lower than a predetermined threshold level, a binary value error of a picture element on the opposite side to the noticed picture element in a main scanning direction or a sub scanning direction is added to the density value of the noticed picture element to obtain a sum value, and the sum value is compared with the predetermined threshold level.
    Type: Grant
    Filed: May 27, 1994
    Date of Patent: June 6, 1995
    Assignee: Fujitsu Limited
    Inventor: Nobuo Ogawa
  • Patent number: 5414531
    Abstract: An image forming apparatus includes an image forming unit for forming an image on a recording medium, and a measurement unit which measures the density of the image formed on the recording medium. A control unit determines an operation condition of the image forming unit on the basis of the measurement result from the measurement unit. A storage unit stores the operation condition determined by the control unit, and a display unit reads out the operation condition at a predetermined time for display. The control means controls a subsequent operation of the image forming apparatus according to the stored operation condition.
    Type: Grant
    Filed: February 20, 1992
    Date of Patent: May 9, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventors: Koji Amemiya, Akio Suzuki, Tatsuo Takeuchi, Hisashi Fukushima, Takashi Hasegawa, Haruhiko Moriguchi, Rie Saito, Takao Ogata, Nobuatsu Sasanuma
  • Patent number: 5408339
    Abstract: An image area dicriminating device for a digital copier, facsimile machine, scanner or similar imaging equipment. The device determines whether areas constituting an input image each has undergone dot processing or not automatically.
    Type: Grant
    Filed: March 14, 1994
    Date of Patent: April 18, 1995
    Assignee: Ricoh Company, Ltd.
    Inventors: Tomio Sasaki, Shinji Kobayashi, Masahito Obata
  • Patent number: 5408336
    Abstract: There is disclosed an image processing apparatus capable of smoothing the image in obtaining a binary image, by eliminating notches through comparison of the input image data with certain notch image patterns stored in the apparatus in advance. In order to maintain an effect of smoothing even when the resolution of the input image data is increased, the image patterns employed for the above-mentioned comparison are varied according to the resolution of the input image data.
    Type: Grant
    Filed: January 22, 1992
    Date of Patent: April 18, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventor: Shinichi Ishida
  • Patent number: 5389887
    Abstract: A binary coding circuit that enables a clear image to be obtained by removing noise elements while retaining the target character and image information, improves image compression efficiency, reliably binarizes low-contrast characters and images and minimizes information loss, thereby providing clearer and more accurate binarized images of character and image information.
    Type: Grant
    Filed: April 19, 1993
    Date of Patent: February 14, 1995
    Assignee: Eastman Kodak Company
    Inventor: Seiichi Mizukoshi
  • Patent number: 5387987
    Abstract: A method and apparatus for reproducing half-tone images by converting continuous-tone image data into a multi-valued level density code using a predetermined threshold or thresholds includes adding an output adjusting error to a difference error between image data of a target pixel and a threshold level and diffusing the difference error to which the output adjusting error has been added into pixels surrounding the target pixel.
    Type: Grant
    Filed: September 25, 1992
    Date of Patent: February 7, 1995
    Assignee: Fuji Xerox Co., Ltd.
    Inventor: Naosuke Ino
  • Patent number: 5386301
    Abstract: An image processing apparatus includes a reading part for reading an image by raster scanning of a document and for producing a multilevel image data relating to one pixel of the image, a memory part for storing a plurality of predetermined weight matrix patterns, each weight matrix pattern having N.times.N weight coefficients arranged in an N.times.
    Type: Grant
    Filed: August 18, 1993
    Date of Patent: January 31, 1995
    Assignee: Ricoh Company, Ltd.
    Inventors: Kazuhiro Yuasa, Kazumasa Koike
  • Patent number: 5367385
    Abstract: A method and apparatus for processing block coded image data wherein each block comprises a plurality of pixels. A local pixel is selected from a first block of pixels. The selected pixel is preferably near a border between the first block of pixels and a second block of pixels. At least one external pixel is selected from the second block of pixels. The selected external pixel(s) is (are) also near the border. The selected local pixel is modified to reduce the difference between the local pixel and the selected external pixel(s). The selected pixel value is modified as follows. A low pass filter coefficient is selected for each selected local pixel value and for each selected external pixel value. The selected local pixel value and the external pixel values are each multiplied by their corresponding low pass filter coefficient. The products of these multiplications are summed together to form a low pass filtered pixel value.
    Type: Grant
    Filed: May 7, 1992
    Date of Patent: November 22, 1994
    Assignee: PictureTel Corporation
    Inventor: Xiancheng Yuan
  • Patent number: 5363215
    Abstract: An apparatus for converting an image data with a threshold value into a bi-level data. The apparatus includes a processing circuit for processing image data of pixels neighboring a target pixel to generate membership functions and for obtaining a fuzzy set from the membership functions, and a threshold value generation circuit for generating a threshold value on the basis of the fuzzy set. The threshold value is used to convert the image data of the target pixel.
    Type: Grant
    Filed: September 15, 1992
    Date of Patent: November 8, 1994
    Assignee: Konica Corporation
    Inventors: Takashi Sekimoto, Kunio Nakano, Toshiya Eguchi