Abstract: An image processing apparatus includes an image processing unit, a counter, and a determining unit. The image processing unit processes image data between first and second color values of an input image. The counter counts generation frequencies of the respective color values of the input image. The determining unit determines the first and second color values on the basis of the count result obtained by the counter.

Abstract: A system and method for automatically adjusting image color in a document processing system are discussed. The system operates by generating a digital representation of a printed document. The digital representation includes a plurality of pixels. A brightness value is calculated for each of the pixels, and a "brightest" list is generated comprising a plurality of the pixels having the largest brightness values. Also, a "darkest" list comprising a plurality of the pixels having the smallest brightness values is generated. An average bright color of pixels in the "brightest" list is generated, and an average dark color of pixels in the "darkest" list is generated. Red, green, and blue scaling functions each having a white point set equal to the average bright color and a black point set equal to the average dark color are generated. The digital representation is scaled in accordance with the red, green, and blue scaling functions to produce a modified image.

Abstract: This invention provides a method for transforming an input color space to an output color space where each of a plurality of specified colors and/or color regions are constrained to be transformed by any one of a plurality of explicitly specified color calibration or color enhancement strategies. The method involves a two step process: 1) constraints are applied to some subset of the points in the input color space explicitly specifying the transform into the output color space; 2) the reminder of the points are then transformed by a mapping strategy which preserves color continuity. The mapping strategy used in the preferred embodiment is based on a computer graphics geometric morphing technique. In the preferred embodiment, multi-dimensional look-up tables are used to implement the color transformation.

Abstract: An image forming apparatus which can reduce a difference between the hues of the images printed to both surfaces when a two-sided printing is executed is provided. For this purpose, a control unit changes gradation correcting characteristics of a gradation correction circuit or changes a color correcting state in accordance with the surface of the recording paper onto which an image is formed.

Abstract: A method and apparatus for automatically correcting the tone values of a digitally stored image includes compiling a histogram of the relative occurrence of gray values in the stored image in memory. The histogram is processed by adding a constant, taking the square root, and digital filtering. The processed histogram is numerically integrated and then normalized to form a tone correction function. The present tone correction method may be used to tone correct color images by applying separate tone correction functions generated for each of the three color planes independently, or in the alternative, by applying a composite tone correction function corresponding to the average of histograms of the respective individual color planes. A switch is provided to allow the operator to view the results of both methods of automatic tone correction for color images, and choose the best resulting image.

Abstract: The average value of each of yellow, magenta and cyan color image data of a color-to-be-converted which data are obtained at the time of pre-scanning of a copying machine and stored in memories, respectively, is calculated, and then, predetermined set values are respectively added to and subtracted from the calculated average values of yellow, magenta and cyan to obtain upper and lower limit values of the conversion range. When the lower limit value obtained by subtraction is below a predetermined lower limit restriction value, the lower limit restriction value is set as the lower limit value of the conversion range. With this feature, when an extremely pale color is specified as a color-to-be-converted in a region other than a background portion of a color original where no letters, etc. are printed, the color of the background portion is not converted together with the specified color.

Abstract: In a printer which produces images as a function of the combination of cyan (C), magenta (M), yellow (Y) and black (K) colorants on an output color print, responsive to device independent colorimetric description of an image, there is provided a method of calibrating the response of the printer to an image described in terms of colorimetric values, including the steps of first, gray balancing or linearizing colorant signals; secondly, adding black to an ideal device dependent description of a color image in accordance with a predetermined black addition process, and thirdly, providing a color correction transformation process, where the color correction transformation is accomplished via a method of interpolating printer responses from a look-up table indexing colorimetric descriptions of measured real responses, which take into account subsequent black addition and signal linearization.

Abstract: An image scanner-reader has an image read unit, and an employing control unit. The image read unit is used to read an original document and provide image data of the original document. The employing control unit is used to control the relative moving speed between the original document and the image read unit, and when an original document reading operation is suspended, the employing control unit controls the restart of the reading operation after decreasing the relative moving speed to a slow reading speed of the original document. Therefore, when the image data buffer becomes full enough to cause a suspension state, and the read operation is restarted after changing control conditions, so that the quantity of data transferred to the image data buffer is reduced. Namely, according to the present invention, the number of occurrences of the suspension state can be greatly reduced, and thereby the overal reading speed can be improved without increasing the data receiving speed of a host device.

Abstract: An electronic method measures the color cast of a digital representation of a natural scene. Colors of the natural scene are represented in digital electronic form as pixels. Neighborhoods of pixel colors in a chrominance histogram are isolated. Neighborhoods may be isolated by convolving the chrominance histogram with a two-dimensional filter. Lighting color from the scene is measured from isolated color neighborhoods by: a) determining lines in a chrominance plane which lie along major axis of isolated color neighborhoods, and b) selecting a convergence-chrominance value near which the detected lines converge. Lines in the chrominance plane may be weighted so that lines from neighborhoods that are more reliable indicators of lighting contribute more to the convergence-chrominance than less lines from less reliable neighborhoods. The image is then transformed so as to map the measured lighting value to another value, such as neutral.

Abstract: An image processing apparatus, capable of secure color judging regardless of the kind of the original image, is disclosed. The apparatus is provided with color judging means for color judgment from input image data, and background color detection means (CPU) for detecting the background color of the image data, and color judging areas of the color judging means are modified according to the hue, luminocity or saturation of the background color detected by said background color detection means.

Abstract: A color image processing apparatus includes a storage device for storing input image data for one frame and a discriminator for analyzing the color image data stored in the storage device. In the color image processing apparatus, the discriminator discriminates the type of the stored color image data utilizing a membership function.

Abstract: A method of determining light exposure is provided to read information in relation to a color original image and dividing the color original image into many picture elements to analyze the respective picture elements into three color light of red light, green light and blue light for photometry, find a histogram in relation to hue value depending upon data obtained by the photometry and divide the found histogram for each crest. Further, the method is provided to decide to which of the divided crests the respective picture elements of the color original image belong so as to distribute the picture element into a corresponding cluster, and divide the color original image for each cluster, select the most adaptable region to information in relation to the color original image which is read from the divided region as a feature image region. The method is still further provided to determine the light exposure to copy material depending upon image data in the feature image region.

Abstract: A method of improving the contrast in a natural scene image, in which the image is converted from an original set of color coordinates to an expression where one term has a relationship to overall image intensity. A global histogram of the image is derived for that term, which plots the populations of pixels at each possible level of intensity in the image. The signal describing the histogram is operated on with a filter having the characteristic of weakening strong peaks and valleys in the function, but not effecting flat portions of the signal. The filtered histogram signal is used for controlling the TRC mapping in a device at which the image is to be printed. Contrast is improved in areas likely to have the most image information, using the method described above, and further, dividing the image into a number of segments, each describable by a local histogram signal for that image segment. Each local histogram signal is compared to the global histogram, to determine which signals are flatter.

Abstract: An image forming apparatus includes an input unit, a color discriminating unit, a pattern generating unit, and an image forming unit. The input unit inputs an image having a plurality of colors. The discriminating unit discriminates the colors of the image input from the input unit. The pattern generating unit generates a pattern image in accordance with the discrimination result obtained by the discriminating unit. The image forming unit forms the pattern image, generated by the pattern generating unit, on a recording medium. The image forming unit forms the pattern image in different colors in accordance with the discrimination result obtained by the discriminating unit.

Abstract: A data processing system including a normalizing unit for receiving a part of a plurality of pixels in a one-pixel column of image data in parallel and for magnifying or contracting the data in the vertical direction in the one pixel-column, and a transposing unit for transposing image data magnified or contracted in one direction obtained from the normalizing unit and for reprinting the transposed data to the normalizing unit. This invention is applicable to data processing by character recognition devices for reading characters of different sizes.

Abstract: A method of operating a display including providing a display; acquiring an image of a structure by measuring, for each of a plurality of elements, a magnitude representing an element of the structure; providing a plurality of contrast setting control buttons including a first contrast setting button that directly and independently modifies dark parts of the image of the structure and a second contract setting button that directly and independently modifies light parts of the image of the structure; digitizing the magnitudes according to a direct mode by assigning a digitized value d representing the measured magnitude of each of the elements; displaying a direct image by assigning a luminosity l corresponding to the digitized value d of each of the elements and transmitting to the display the luminosity l of each of the elements; transforming the direct image to a transformed image by assigning to each the of elements a digital value i which corresponds to the digitized value d of each of the elements; and d

Abstract: An image processing system redistributes image luminance values in an image represented in u'v'L* space to achieve a near-optimal fit of luminance data to available dynamic range and to enhance the shape and detail of the resultant image. Redistribution may be accomplished by passing the image through a filter having a peak response at a spatial frequency at which the human eye is highly sensitive, and then equalizing a cumulative histogram of filtered pixels. An image may be transformed to compensate for tone compression which accompanies printing processes.

Abstract: In an image forming apparatus according to the present invention, characteristics correcting data for correcting input gray level-output gray level characteristics for each of a plurality of steps into which input gray levels are divided are inputted by inputting means. At the time of image formation processing, input gray level-output gray level characteristic data are corrected on the basis of each of the characteristics correcting data inputted by the inputting means.

Abstract: A method and apparatus for the analysis of a color cast in a color original to be reproduced, by evaluating color values acquired by point-by-point and line-by-line, trichromatic scanning with an image processing input device. For acquiring a color cast in the color original, a region of high luminance values (light image region) and/or a region of low luminance values (dark image region) of the luminance component L* of the color values L*, a*, b* in the color original to be analyzed is/are subdivided into at least one luminance region. The value of a potentially existing color cast in the luminance region is identified by averaging the color components a*, b* of the color values L*, a*, b* in the luminance region. The color cast value to be utilized for the evaluation of the color cast analysis is formed by selection and/or combination of color cast values identified for individual luminance regions.

Abstract: A method of altering the exposure in the reproduction of an electronically encoded natural scene image, including process steps of a) receiving an electronically encoded natural scene image, where the encoding is in terms of red-green-blue signals; b) converting the signals to a luminance-chrominance signal format, wherein at least one signal represents overall image intensity; c) comparing the intensity signal to a pair of preset threshold signals T.sub.light, T.sub.dark, respectively indicating satisfactory brightness and darkness of the image and producing a multi-state signal responsive to the comparison; d) if the signal state indicates that both thresholds are exceeded, or that neither threshold is exceeded, directing the electronically encoded image without alteration to further processing; e) if the signal state indicates that one of the pair of preset thresholds is exceeded, the original electronically encoded signal is processed in accordance with the equation:OutputI=InputI.sup..gamma.

Abstract: Color transformation apparatus for transforming an input color space into an output color space and including a first LUT for transforming a first portion of the input color space into a corresponding first portion of the output color space, a second LUT for transforming a second portion of the input color space into a corresponding second portion of the output color space, and a control unit for channeling input values included in the first and second portions of the color space to the first and second LUTs respectively.

Abstract: A method of improving processing of a color natural scene image defined by color density signals processed by multiple processing elements, wherein after an exposure processor incorporates a luminance signal histogram, a modifying TRC curve is derived and applied to the luminance histogram signal. The resultant modified luminance histogram signal is blurred prior to directing it to a contrast processor. The modifying TRC curves determined at each processor are combined and applied to the color density signals only after combination.

Abstract: Color transformation apparatus for transforming an input color space into an output color space and including a first LUT for transforming a first portion of the input color space into a corresponding first portion of the output color space, a second LUT for transforming a second portion of the input color space into a corresponding second portion of the output color space, and a control unit for channeling input values included in the first and second portions of the color space to the first and second LUTs respectively.

Abstract: An apparatus and method for performing real time color gamut compressions for a source image. The method is performed in a data processing system having a memory, and includes the steps, performed by the data processing system, of storing, in the memory of the data processing system, a multi-pixel image to be output by an image output device, the multi-pixel image having colors of a first color gamut and the image output device being capable of outputting colors of a second color gamut, reading the multi-pixel image from the memory for receipt by the image output device, and converting colors of the multi-pixel image that are not in the second color gamut, after start of the reading step and before completion of the reading step, into colors of the second color gamut.

Abstract: A hue compensation apparatus outputs hue-compensated data of a color designated by an input color selection signal of red, green and blue, responsive to red, green and blue input signals. The hue compensation apparatus uses first, second and third lookup table circuits, a decoder, a polarizing circuit and a synthesizing circuit. The lookup table circuits output hue-compensated red, green and blue signals in response to input red, green and blue signals, respectively. The decoder decodes the input color selection signal, and the polarization circuit polarizes outputs from the first, second and third lookup table circuits according to an output of the decoder. The synthesizing circuit synthesizes the polarized output from the first, second and third lookup table circuits. The synthesizing circuit thus outputs a hue-compensated color signal whose color is designated by the color selection signal by synthesizing the polarized outputs from the polarization circuit.

Abstract: Image processing apparatus comprises a color converter for converting an input value, defining the color component content of a pixel of an image, to an output value, the color converter being adapted to convert groups of input values to respective, common output values.

Abstract: An image processing apparatus and method for performing the steps of grouping colors of a multi-pixel image stored in a memory into sets of colors, determining the average color of each set of colors, selecting a target color, for each set of colors, from a plurality of predetermined target colors, the selected target color being the predetermined target color that is closest to the average color of the set, and remapping the color of each pixel of the image stored in the memory to the target color selected for the set including that pixel. The method and apparatus are applicable to multigeneration color image reproduction devices such as color facsimile machines, color photocopiers, and the like.

Abstract: In a printer which produces images as a function of the combination of cyan (C), magenta (M), yellow (Y) and black (K) colorants on an output color print, responsive to device independent colorimetric description of an image, there is provided a method of calibrating the response of the printer to an image described in terms of colorimetric values, including the steps of first, gray balancing or linearizing colorant signals; secondly, adding black to an ideal device dependent description of a color image in accordance with a predetermined black addition process, and thirdly, providing a color correction transformation process, where the color correction transformation is accomplished via a method of interpolating printer responses from a look-up table indexing colorimetric descriptions of measured real responses, which take into account subsequent black addition and signal linearization.