Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black.

Abstract: Image distortion is corrected in a color printer wherein print units for a plurality of colors are aligned to form a color image by superposing images formed by the print units. Images of the colors of a predetermined pattern formed by the print units are detected by a sensor. Based on the detection result, image distortion quantities and a setting error of the position of the sensor are detected. Then, the detected color shift on image forming is corrected according to the image distortion quantities and the setting error.

Abstract: In a digital full color image processor, color data are obtained by reading a color image with a color image sensor. An image forming mode of the color image such as background level and magnification is specified, and the image forming mode is changed according to the specified image forming mode when the color data is processed. A reference value for area discrimination is changed according to the image forming mode. Then, an area such as a black portion or a dot area in the color data is discriminated for image processing of the color data with the reference value, and the color data is processed according to the area discrimination.

Abstract: In a digital full color copying machine, image signals of red, green and blue are converted to a value signal, and histograms of the value signal for chromatic dots and achromatic dots respectively are generated. Then, a document type, such as a color standard document, a color photograph document, a color standard document having a colored background, a black-and-white standard document, or a black-and-white photograph document, is determined automatically based on the histograms. Background level of a copy is controlled automatically at an appropriate level both for a color document and for a black-and-white document having a white background according to the document type by gradation correction of the value signal. Thus, background processing is performed irrespective of a color document or a black-and-white document.

Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black. When color balance is adjusted on one of the data of cyan, magenta, yellow and black, the density is kept constant.

Abstract: When a monochromatic image is reproduced, a user can select desired mixing coefficients of red, green and blue in order to control gradation data for the reproduction of a monochromatic image as well as a monochromatic reproduction color. When a document is automatically determined not to be a color document, the mixing coefficients of red, green and blue are changed according to the type of the document. If a monochromatic copy mode is selected, the mixing coefficients can be set manually. Preferably, in order to help a user to select mixing coefficients, a plurality of images of monochromatic colors of various mixing coefficients of red, green and blue can be printed on a single sheet of paper.

Abstract: In a digital full color copying machine, one pixel on a photoconductor is divided into four subdivided small pixels. Functions a-d are assigned to each subdivided small pixel. Functions a-d are linear functions with density data as a parameter. The slope of functions a-d becomes smaller in sequential order. Exposure data of the four subdivided small pixels is calculated according to the density data of a pixel and functions a-d to expose each subdivided small pixel. A peak can be established in the exposure amount distribution to form a deeper latent image. Accordingly, resolution and graininess of the halftone area are improved.

Abstract: In an image processor, an image of document is read by an image sensor. A reduction ratio of the image is set. Then, interpolation is performed on the image data between a pixel under interest and a pixel adjacent to the pixel under interest according to the reduction ratio. After the interpolation, pixel data in the image data are thinned out to an image data having a size determined by the reduction ratio, and an image is formed on a sheet of paper based on the thined-out data. Because the interpolation is performed before the thinning-out of the image data, defects in a reduced image such as vanishment of a narrow line are reduced, and image quality is improved.

Abstract: In an image processing apparatus, a color image is read with pixels aligned along a direction to provide first color data on the color image. The first color data includes red, green and blue data at each pixel. A first operator calculates first chroma data according to the first color data. On the other hand, a phase shift device generates second color data by shifting a phase of red data and by shifting a phase of blue data in the first color data, and a second operator calculates second chroma data according to the second color data. A selector selects chroma data having a lower chroma, and a black edge of a character a the color image is discriminated according to the selected chroma data.

Abstract: A digital image of a document having chromatic and achromatic colors is read, and an edge of a black character is discriminated. Further, an outside area and an inside area of the edge are detected. Edge emphasis is performed on an inside area of the edge for data of achromatic colors. On the other hand, data of chromatic colors in an inside area of the edge is substituted with a minimum data of the pixel under interest and pixels surrounding the pixel. Data of chromatic colors and of achromatic colors in the outside area is substituted with a minimum data of the pixel under interest and pixels surrounding the pixel.

Abstract: An image reading apparatus comprises a photoelectric converter including three linear image sensors of red, green and blue aligned in parallel to each other along a main scan direction. When a document is scanned, a document is read by the photoelectric converter by moving it relative to the document. The moving direction is set to be a first direction, for a prescan and a second direction reverse to the first direction, for a normal scan. Analog output signals of the first to third linear image sensor are converted to digital signals. In a prescan, a selector exchanges the digital signals of the first and third linear image sensors, while in a normal scan, the selector does not exchange them.

Abstract: In an image processing apparatus of the invention, HVC conversion is performed stably. THat is, an image sensor reads image data of red, green and blue of a document, while a memory stores brightness data V of a color patch. When the image data are converted to a brightness data V and color difference data WR and WB, coefficients used in the conversion of the HVC conversion are calculated by an operator based on the image data of red, green and blue of the color patch read by the image sensor and the brightness data V stored in the memory.

Abstract: An image processing device in accordance with the present invention processes image data obtained by reading an original image including an image portion and a background portion to subdivide the original image into a plurality of images, the image data including density data representing density of each image. The device includes a device for outputting background density data, a device for outputting density coefficient data, a background color removing device for decreasing a value of density data corresponding to the background portion based on the background density data, and a density correcting device for increasing a value of density data corresponding to the image portion based on the density coefficient data.

Abstract: The present invention relates to an image processing apparatus for carrying out a variable scale magnification processing for contracting or enlarging an original image. The image processing apparatus including a variable scale moving unit for increasing pixels in accordance with a variable scale magnification in order to enlarge the original image includes a smoothing processing unit for smoothing pixel data. The smoothing processing unit detects the number of increased pixels for each pixel by an increased pixel number determining unit, so as to smooth image data output from the variable scale magnification moving unit by employing smoothing filters of a matrix size selected in accordance with the result of the detection. This results in an image processing apparatus that can prevent a degradation in image quality by an appropriate smoothing processing independently of whether a variable scale magnification in enlargement is integer or not.

Abstract: A magnetic core having a low core loss and having stable characteristics in a low magnetic permeability region can be obtained at a high yield by applying a heat treatment to a magnetic core main body obtained by winding or laminating a ferrous amorphous ribbon In a wet atmosphere containing a limited amount of steam.

Abstract: An image reading apparatus in accordance with the present invention reads a color image to separate the image into three primary colors by an image sensor and outputs image data corresponding to each of the colors. This image reading apparatus comprises a scanning device for making the image sensor relatively scan for a reference chart and an original, an A/D converter for converting an output of the image sensor into digital data corresponding to each of the primary colors, an operation device for evaluating correction data of each color from the output of the image sensor generated when the image sensor scans the reference chart, a multiplier for multiplying the digital data of each color by the correction data evaluated, an adder for adding a result of the multiplication and digital data before being multiplied, a shading correction circuit provided at a succeeding stage of the adder, and a line memory provided at a succeeding stage of the shading correction circuit.

Abstract: In an image reading apparatus, the standard data for the normalization of the image read data are obtained with use of a line memory of one line from the standard data of a plurality of lines. The white level data and the black level data are used for the normalization. The weight average of the input data of the standard data received successively one line by one converges gradually. The converged average is used for the correction of read data of an image, and the effect of image noises is reduced and the image read data is normalized at a high precision. In a continuous reading, only the white level may be updated for shortening the time for reading.

Abstract: In an image possessor, two kinds of color differences in the orthogonal coordinate axes in the hue plane in the color space are separated from the digital data of three primary colors, and the separate color signals are synthesized to generate the chroma signal. When the digital data of the three primary colors are converted to the data of the reproduction colors with use of the under color remove amount and the black paint amount, an under color remove amount is subtracted from the digital data of the three primary colors, while a black paint amount which is the black data obtained from the digital data is generated to print with black toners. The under color remove amount and the black paint amount are increased with increase in the chroma signal according to the color data of the three primary colors and the chroma signal at the same pixel position.

Abstract: The characteristics such as hue, saturation, edge portion or flat portion of image data are decided for each pixel based on read data of three primary colors. The decision is performed on the data which have been subjected to spatial filtering, and the processing of the image data such as smoothing or edge emphasis are changed according to the detected characteristics. For example, the masking coefficient is selected according to the detected hue. The color data is decreased and the black data is generated, according to the detected saturation. The edge is decided only when the sign of the gradients of the three color data agree with each other. Further, edge detection quantity is detected in the edge decision and the edge emphasis or the smoothing is performed by comparing the edge detection quantity with threshold values only when the edge is detected.

Abstract: In a color image data processing apparatus for processing three color image data of three primary colors for representing a specified pixel, in response to one color image data preselected among the three color image data, a threshold data generator generates threshold data for representing upper and lower limits of respective ranges in which two color image data other than the preselected one color image data are to be present when the specified pixel is a monochrome pixel of white, black or half-tone black, and a monochrome pixel detector compares the other two color image data with the threshold data generated by the generation means, and judges that the specified pixel is the monochrome pixel when both of the other two color image data are respectively fallen in the respective ranges from the upper limit to the lower limit.