Abstract: Image forming apparatus and method for forming half tone images by pulse width modulating multi-valued image signals comprises first and second pattern signal generators which generate pattern signals each having the same period and a phase shifted from each other, first and second pulse width modulators for pulse width modulating said image signals using the first and second pattern signals, respectively, a selector for selecting either of the first and second pulse width modulated signals and a controller for controlling the selector to obtain a screen angle of 45.degree..Further, image forming apparatus and method which realizes a screen angle .theta. wherein tan .theta. is represented by a rational number.

Abstract: When read image data is mapped outside the range of a page memory, the invention allows a coordinate value to be stored in the page memory to be mapped after being shifted into the page memory, thereby allowing efficient utilization of the page memory, and in order to achieve the above-described object, the invention employs the configuration that when an integral number coordinate value (X.sub.int, Y.sub.int) is out of the range of an image memory, an X-coordinate conversion circuit and a Y-coordinate conversion circuit shift the coordinate value so that it comes in the range and outputs a coordinate value (XINT, YINT) and this shifting process allows read image data outside the image memory to be shifted into the area of the image memory to be stored therein and when image data stored in the image memory is read out, the coordinate is read out in reverse on the assumption that a shifted origin coordinate O (X.sub.smin, Y.sub.

Abstract: A digital copying machine provided with a device for forming color images by the formation, superposition of the images for each color in the order of the color face including a device for coding, compressing of a plurality of image signals separated in color by one page portion of the document so as to store in memory, a device for decoding, extending a plurality of compressed image signals stored in the memory, a color correcting device for converting a plurality of extended image signals into the color image signals for image formation so as to make the memory capacity smaller.

Abstract: An image signal compression apparatus which divides image data into plural blocks, encodes each block, orthogonally transforms the image data by each block, and outputs the transformation coefficients. Blocks which contain text and blocks which contain dot images are discriminated from the features of the absolute values of the AC coefficients, which are a subset of the transformation coefficients. One of plural quantization tables is selected for each block based on the discrimination result, and by adaptively quantizing the transformation coefficients using the selected quantization table, text images can be reproduced free of fuzziness, and good expanded images of the dot areas can be obtained with high compression by reducing the high frequency component.

Abstract: An image scanner is occasionally used with an external host computer and includes an optical system and a CCD image sensor for reading an image of a document placed on a document platform. The image scanner further includes a small computer system interface (SCSI) for connecting the image scanner to the external host apparatus, and a CPU, a nonvolatile memory, an SCSI controller etc. for emulating a file system contained in the external host computer.

Abstract: An image forming apparatus which is used with an external host computer. The image forming apparatus includes an interface for connecting the image forming apparatus to the external host computer. The image forming apparatus further includes a file system emulator which emulates a file system contained in the disk storage apparatus of the external host computer. The file system emulator makes the image forming apparatus look like the disk storage apparatus to the external host computer connected to the image forming apparatus to transfer images from the external host computer to the image forming apparatus via the interface device.

Abstract: An imaging apparatus comprising a counterfeiting prevention arrangement and reliably preventing counterfeit reproduction of currency, negotiable certificates, and other registered documents is provided by preventing modification or removal of the counterfeiting prevention arrangement. Modification or removal of the counterfeiting prevention arrangement is prevented in this imaging apparatus by integrating circuit elements or components of the counterfeiting prevention arrangement with circuit elements or components of the image processors of the imaging system in a single chip, or sealing these components in a single mold, effectively preventing modification or removal of the counterfeiting prevention arrangement without disabling the imaging system.

Abstract: Image forming apparatus and method for forming half tone images by pulse width modulating multi-valued image signals comprises first and second pattern signal generators which generate pattern signals each having the same period and a phase shifted from each other, first and second pulse width modulators for pulse width modulating said image signals using the first and second pattern signals, respectively, a selector for selecting either of the first and second pulse width modulated signals and a controller for controlling the selector to obtain a screen angle of 45.degree..Further, image forming apparatus and method which realizes a screen angle .theta. wherein tan .theta. is represented by a rational number.

Abstract: A digital color copying machine improves the quality of an image of black characters by reproducing them with only black toner and prevents the edges of each black character from being colored with a color. The machine includes a monochromatic signal generator for generating a monochromatic signal in response to inputted plural color signals and an edge emphasizer for emphasizing edge components of the color signals with a predetermined edge emphasis amount. Either a digitizer for digitizing the monochromatic signal and outputting a binary signal of the monochromatic signal or a pseudo digitizer for generating a pseudo binary signal by steepening the contrast of the monochromatic signal is provided. A first area detector, second area detector, and third area detector are respectively provided for detecting first through third image areas.

Abstract: The image processing apparatus for smoothing edges in a reproduced image includes an image data generating circuit for generating image data including a specified pixel and a plurality of pixels surrounding the specified pixel; a sub-pixel data generating circuit for dividing the specified pixel included in the image data into N sub-pixels, for detecting the condition of the specified pixel and the condition of the plurality of pixels surrounding the specified pixel included in the image data by matching the image data with a plurality of predetermined patterns, and for generating sub-pixel data for determining the number and position of sub-pixels to be exposed of the N sub-pixels, based on the condition of the specified pixel and the condition of the plurality of pixels surrounding the specified pixel; and supplying circuit for supplying the sub-pixel data to exposure circuit which makes exposure.

Abstract: An image processing apparatus performs an edge correction process for image signals of respective pixels sequentially inputted, each image signal having a density level corresponding to a pixel. An edge amount detector of the image processing apparatus calculates a difference between a density level of an image signal of a specified pixel from among the image signals and a product of a predetermined value and the sum of the density levels of peripheral pixels located at a predetermined distance from the specified pixel, and outputs a detection signal having a level of an edge amount of the calculated difference, and an edge amount convertor converts the edge amount of the detection signal into a converted edge amount in a predetermined manner, and outputs a conversion signal having level of the converted edge amount.

Abstract: A color image forming apparatus with plural photoconductor drums has a plurality of color image forming arrangements, each arrangement includes an image signal processor for processing an image signal for one of black, cyan, magenta and yellow, and for producing a modulated image signal, a semiconductor laser diode for emitting laser beam in accordance with the modulated image signal, a scanning device for scanning the laser beams on a photoconductor surface. The laser beam passes through a slit or an elongated opening provided between the semiconductor laser diode and the photoconductor surface for reforming the laser beam to have a cross-section shape of an ellipse with its short axis parallel to the laser scanning direction.

Abstract: An image processing apparatus performs an edge correction process for image signals of respective pixels sequentially inputted, each image signal having a density level corresponding to a pixel. An edge amount detector of the image processing apparatus calculates a difference between a density level of an image signal of a specified pixel predetermined from among the image signals and a product of a predetermined value and the sum of the density levels of peripheral pixels located at a predetermined distance from the specified pixel, and outputs a detection signal having a level of an edge amount of the calculated difference, and an edge amount convertor converts the edge amount of the detection signal into a converted edge amount in a predetermined manner, and outputs a conversion signal having level of the converted edge amount.

Abstract: A phenolic novolak resin comprising a compound represented by the general formula [I]: ##STR1## wherein X is H or ##STR2## R is an alkyl group having 1 to 4 carbon atoms, and n is 1 to 10, particularly a phenolic novolak epoxy resin, and material, and a cured substance therefrom, and a process for producing the resin are disclosed. This resin is excellent in heat resistance and in reluctance to absorb water as compared with conventional phenolic resins, and useful in sealing electronic parts, molding, and laminating.

Abstract: An image processing apparatus is for exactly reproducing color originals. The apparatus includes a circuit for removing a ground color contained in an input color signal by forcibly changing an input signal having a level larger than a predetermined level to white. The apparatus may include a gamma correction circuit having therein a plurality of selectable gamma collection data. The apparatus may also include a circuit for producing a natural monochromatic signal from signals corresponding to three primary color signals R, G and B by performing an operation expressed as [(signal corresponding to R).times.2.sup.I +(signal corresponding to G).times.2.sup.I +(signal corresponding to B).times.2.sup.K ]/2.sup.L wherein I, J, K and L are integers and 2.sup.I +2.sup.J +2.sup.K =2.sup.L.

Abstract: A copier comprises an original table for placing thereon an original sheet, a sub-scanning unit including an image reading sensor for reading an image on the original sheet and for scanning the original sheet on the original table, a printing unit which prints the image read by the image reading sensor on a printing sheet, and a control unit which controls the operation of the sub-scanning unit by selectively using a position profile control and a speed profile control. The operation start position and operation starting timing control of the sub-scanning unit using the position profile control permits high-speed continuous repetitive copying and high-accuracy enlargement, reduction, and transfer copying.