Abstract: To accurately discriminate a dot region within an image, the image processing apparatus includes first through fourth isolated dot discriminating portions each judging, for each of a plurality of pixels included in the image, whether the pixel corresponds to a center pixel of an isolated dot, an isolated dot size determining portion detecting an isolated dot size, a dot region discriminating portion judging whether a target pixel is included in a dot region based on a position of the pixel judged as being the center pixel of the isolated dot, and a dot region determining portion determining the dot region based on a position of the target pixel judged as being included in the dot region and the detected isolated dot size.

Abstract: It is intended to provide an image forming apparatus and image forming method capable of partial magnification corrections on various partial variations of magnification as well as constant and uniform positional shift regardless of any sections. A modulated image clock of a reference color (black) is generated from a clock generated at an image clock generating section 23 and an address is generated at an address generating circuit 36 basing on the modulated image clock. Output sections 30 for respective colors other than the reference color read out correction coefficients from correction coefficient memories 15 of respective colors following the address generated. Frequency modulator circuits 31 modulate image clocks in accordance with correction coefficients. PWM 33 outputs a driving pulse to a laser driver 6 basing on modulated image clocks synchronized with a reference signal 40 by synchronizer circuits 32 and inputted image data.

Abstract: It is intended to provide an image processing apparatus capable of precisely discriminating a halftone dot region and a figure such as a character arranged on the halftone dot region and applying appropriate image processing to the halftone dot region and the character separately. An isolated point discriminating section detects presence of an isolated point and detects a size of the detected isolated point. A temporary halftone dot region discriminating section 42 determines a temporary halftone dot region by counting the number of isolated point signals detected. Thereby, a region where isolated points concentrate is regarded as a temporary halftone dot region. An isolated point magnifying section 43 magnifies the detected isolated point signal to its original size so as to determine a magnified isolated point region. A halftone dot region restricting section 44 takes an AND computation results of the temporary halftone dot region and the magnified isolated point region.

Abstract: It is intended to provide an image forming apparatus and image forming method capable of partial magnification corrections on various partial variations of magnification as well as constant and uniform positional shift regardless of any sections. A modulated image clock of a reference color (black) is generated from a clock generated at an image clock generating section 23 and an address is generated at an address generating circuit 36 basing on the modulated image clock. Output sections 30 for respective colors other than the reference color read out correction coefficients from correction coefficient memories 15 of respective colors following the address generated. Frequency modulator circuits 31 modulate image clocks in accordance with correction coefficients. PWM 33 outputs a driving pulse to a laser driver 6 basing on modulated image clocks synchronized with a reference signal 40 by synchronizer circuits 32 and inputted image data.

Abstract: In order to improve character edge reproducibility in reproducing a color document image, a boundary between a character and a background is detected in color image data. Further, if the detected edge exists at the side of a character, it is decided as a true edge, and the image data are subjected to edge emphasis. Then, when an image is reproduced, undesirable partial whitening in characters in the image can be prevented.

Abstract: In order to improve character edge reproducibility in reproducing a color document image, a boundary between a character and a background is detected in color image data. Further, if the detected edge exists at the side of a character, it is decided as a true edge, and the image data are subjected to edge emphasis. Then, when an image is reproduced, undesirable partial whitening in characters in the image can be prevented.

Abstract: The amount in offset of toner or the like is used to determine two points sandwiching lattice points of input data and divide the region between the two points equally in N−1. The output values at the two points and each point equally dividing the region are obtained to calculate gradients m1-m8 between any two adjacent ones of the points. Then, difference values dm1-dm7 in gradient between any two adjacent ones of the straight lines are calculated and (N−1) lattice points serving as dividing points are selected from the difference values in descending order. It should be noted that N is smaller than M. Then, the input and output values of the determined (N+1) lattice points N0-N4 are plotted and they are bounded by straight line and thus plotted to linearly interpolate the output data for the input data. Thus, an image processing apparatus can be provided capable of precisely modifying output images with reduced memory capacity.

Abstract: A data processing system has the following construction in order to reduce the memory capacity and the cost. There are provided a plurality of processors to execute to input image data a series of processings including Log conversion, MTF correction, gamma correction and binarization in a prescribed order and a memory to store pixel data to be processed and a state flag to represent the state of processing the pixel data in association with each other. Processings by the plurality of processors are executed asynchronously. The plurality of processors share the memory.

Abstract: A pixel interpolating device using the IM-GPDCT method and capable of preventing noise generation divides an original image into a plurality of blocks and picks up a block to be processed as a target block. Further, an image peripheral to the target block is extracted as a peripheral image. By using the peripheral image as an extension region, DCT transform is carried out. Thereafter, the peripheral image is magnified, and the IM-GPDCT processing is carried by using the magnified image.

Abstract: In an image processing method, a tone of a target pixel and tones of peripheral pixels around the target pixel are detected. Also, a tone difference between the target pixel and each peripheral pixel is detected. Then, smoothing processing is executed upon image data of the target pixel, based on the tone differences between the target pixel and the peripheral pixels, in such a way as to reduce a change of the tone of the target pixel.

Abstract: An image processing apparatus that can carry out an error diffusion process without degrading the quality of image data generates a density histogram according to pixels included in the input image data. Reference densities S1 and S2 are calculated from pixels having a certain density in a set range. Threshold values T1-T3 are calculated according to the obtained reference densities S1 and S2.

Abstract: An image processing apparatus having a first area judgment unit for judging whether an inputted pixel is an edge pixel of a character image, a second area judgment unit for judging whether the pixel in a edge area having an intensity variation level equal to, or grater than an intensity variation level of a halftone image edge area, a natural image edge selection unit for specifying an edge pixel of a halftone image based on judgments of the first area judgment unit and second area judgment unit, and a first correction unit for conduction edge enhancement processing on edge pixels of a character image, and a second correction processing unit for conducting sharpness enhancement processing on edge pixels of a halftone image.

Abstract: In an image reading apparatus, three line sensors simultaneously read images in different positions of a document and output respective image signals. Line memories receive the image signals and output them with a timing corresponding to the positions in which the images represented by the image signals have been read. Analog signal processing for the image signals is executed in a parallel manner to thereby allow a high-speed image read operation to be achieved with a low-speed analog processing circuit.

Abstract: An image processor converts pixel data represented with m gradations into pixel data represented with n gradations by using the error diffusion method. The m and n are both given integers and satisfy 2<n<m. Not only the error but also a weight assigning value is added to pixel data to be converted. The weight assigning value is determined according to the values of m and n.

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.