Abstract: An image processing apparatus and method which can be selectively used in a variable mode and a fixed mode. In the variable mode, the quantizing values and thresholds for converting high valued image gradation into low valued image gradation can be changed so as to vary the surface gray levels of a printable image at a fixed laser gradation value. In the fixed mode, constant thresholds and quantizing values are used. The use of selectable operation modes enables easy printing operation with increased quality. Also, constant quality of printable images despite environmental changes may be realized by sensing and comparing currently read reference data with initially stored reference data and subsequently correcting quantizing values and thresholds in accordance with the compared result.

Abstract: An image read-out and processing apparatus comprises an image read-out section, which carries out a preliminary readout and a final readout, and an image processing section. In the final readout, the amount of light irradiated to an image storage sheet, on which an image has been recorded, and/or the light accumulation time of a photoelectric conversion device is adjusted appropriately in accordance with preliminary read-out image information obtained from the preliminary readout. The image processing section is provided with a color and density correcting device for correcting the final read-out image information such that the color and the density of the image may become appropriate, and for determining the degree of correction, which is carried out on the final read-out image information, in accordance with a parameter, which is set in accordance with the preliminary read-out image information. A parameter correcting device corrects the parameter in accordance with the final read-out image information.

Abstract: An image rendering system, for generating discrete tone image data representing a continuous-tone image for rendering by a rendering device, the image rendering system includes a stochastic threshold array generating arrangement and an image data processing section. The stochastic threshold array generating arrangement generates a plurality of stochastic threshold arrays from a random seed pattern that have been subsequently optimized to reduce image artifacts in the rendering of tones. Each pattern is optimized to reflect (i) a selected trade-off between grain and possible mottle in the rendered image, (ii) distortions introduced by the rendering device in rendering an image defined by the pattern and an observer in viewing the image, and (iii) boundary effects so that the patterns, when tiled together, have optimal visual characteristics proximate their respective edges.

Abstract: A printer driver for a color printer employs an error-diffusion-type half-toning process in which different quantization thresholds are employed for different ones of the color components. The color component whose value is highest after augmentation by accumulated error is compared with a relatively low threshold to determine the binary output value for that component. The lowest error-augmented component value is compared with a relatively high quantization threshold, and the component whose value is between those of the other two is compared with an intermediate-valued quantization threshold. Varying the thresholds in this manner tends to discourage coincidences of different-colored imaging agents at the same pixels and thus tends to result in light colors' having a smoother appearance.

Abstract: An apparatus comprising a scanner, a histogram preparation circuit, a circuit for analyzing a histogram to calculate a background density of a document and a character density, a circuit for correcting an input pixel density based on the background density and character, and a printer for forming an image based on a corrected pixel density. The histogram preparation circuit prepares a density histogram of each scanning line based on the pixel density input from the scanner, and accumulates a frequency (number of pixels) corresponding to each density. However, the frequency of the histogram, which is prepared up to the previous scanning line, is multiplied by a weighting factor in accordance with the number of scanning lines, and the frequency of the histogram of the present scanning line, is also multiplied by a weighting factor in accordance with the number of scanning lines. Thereafter, the results of the multiplication are added, and the density histogram is prepared.

Abstract: An image processing system for converting an input pixel into n subpixels P1, P2, . . . , Pn, said system includes a comparator for comparing density threshold values D1, D2, . . . , Dn (where D1<D2<. . . <Dn) corresponding to the subpixels P1, P2, . . . , Pn with a density of the input pixel, Din; and a density setting unit for setting subpixels P1, P2, . . . , Pk corresponding to density threshold values D1, D2, . . . , Dk of the density threshold values D1, D2, . . . , Dn (where k<n) less than the density Din to a high density, setting subpixels Pk+2, . . . , Pn to a low density, and setting subpixel Pk+1 to an intermediate density.

Abstract: An image processing method that employs a threshold matrix to binarize image signals obtained by reading an image recorded on a film such as microfilm. A middle tone image brightness range, which corresponds to a middle or half tone image, is discriminated by referring a brightness histogram for image signals. The upper- and lower-most brightness values of the middle tone image brightness range are used to convert the elements of a threshold matrix in accordance with a predetermined conversion expression, and the converted threshold matrix used for binarization processing. Even if a film density variation occurs or if there is a background density change, binary conversion (a dithering process) can be performed, without deterioration of image quality, within a middle tone density area of, for example, a photograph.

Abstract: The present invention is a dynamic thresholding means for distinguishing dark and light portions of a scanned image, particularly useful where background noise is present obscuring the image. A three dimensional low pass filter applied to the output of optical sensor elements reading the original document, is used as the basis for establishing a three dimensional threshold curve above which data is designated as dark pixels of the image. One means for generating the threshold curve is by raising the output voltage of the low pass filter by a constant voltage for each pixel in the image. Another means for generating the threshold curve is by varying the increment of the low pass filter's output, based on the actual voltage of the low pass filter output for each pixel in the image producing a variable threshold curve.

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.

Abstract: A method and apparatus for processing image data of pixels to be rendered for efficient storage in a memory or efficient transmission wherein a grey level value of a rendered pixel is represented by multiple bits including a most significant bit (MSB) and a least significant bit (LSB). The method and apparatus provide for modifying of the density values of successive pixels in accordance with an error diffusion operation. The modified density values are then subject to a thresholding operation wherein the thresholding operation employs position of a pixel to determine the digital value of the LSB of the rendered pixel. There is thereby provided a pattern structure to the LSB data. The rendered pixel values may then be compressed to provide for efficient storage in a memory or for efficient transmission over a communication pathway.

Abstract: A printing system that uses a halftone processor is driven to halftone selected areas of an image based on a selected halftone dot, wherein the halftone dot has the properties of maintaining a dot fill order of a desired dot, while also maintaining a preselected percentage of the dot as untilled space.

Abstract: A technique for compressing digital video data provides improved compression over conventional block compression techniques. In this technique, image data is broken down into cells and iteratively compressed. The cells are compressed using compression formats that are most appropriate for the contents of the cells. A determination is first made whether a cell is substantially identical to a succeeding cell in a previous frame. If the cell is substantially identical to the cell in the previous frame, the cell is encoded in compressed form as a duplicate of the previous cell. Moreover, solid-color compression approaches, two-color compression approaches and eight-color compression approaches may be integrated into the compression technique.

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

Abstract: In accordance with the present invention, a quadratic differential values is first calculated, based on differences in the density data between an object pixel and respective peripheral pixels around the object pixel. The square value SS of the quadratic differential value S and the sum .SIGMA.SS obtained by adding up the square values SS of quadratic differential values for continuous five pixels are employed as determination values (step n1). The square sum .SIGMA.SS is compared with respective threshold values a, b and d, and the square value SS is compared with respective threshold values c, e and f (steps n2 to n6 and n8). Based on these comparison results, it is judged which image area among a character image area, gray-scale image area and dotted image area the object pixel belongs to.

Abstract: An image processing method for preparing a document for printing or other further processing. Document images often contain information in several intensity levels. Detecting these levels will help separate logically separate regions in the image. A multithresholding process separates different significant intensity levels in a document image by recursively finding locally optimum threshold locations, and then selecting only the significant thresholds by studying the intensity transitions in the image.

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.

Abstract: The problem of thresholding is considered from a clustering point of view and a novel weight-based clustering method (WCThresh) is implemented in a neural network image processor 50. The neural network image processor 50 uses weights 51-53, representing clusters of gray scale pixels of an image of document 43, to provide a threshold for the image of document 43. The processor 50 modifies weights 51-53 with the input pixels and comparator 60 using a nearest value criterion to provide the threshold.

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.

Abstract: There is disclosed a method for converting multi-level image data into binary image data and an apparatus therefor. An average density is calculated from the already binarized density of pixels positioned in a predetermined area around an object pixel, and the threshold value for binarization is set by adding a fixed bias value and varying dither signals to the average density, and the error generated in the binarization is distributed to the unbinarized pixels positioned behind. The addition of the fixed bias prevents formation of a spot-free white area in the vicinity of an edge or in the initial stage of processing, and the addition of dither signals prevents texture formation in the low density area.

Abstract: This invention discloses an improved method and apparatus for generating a screened reproduction of an image. The apparatus comprises a matrix defining an arrangement of a plurality of areas within a printing dot, each having an assigned reference value. The screening logic apparatus receives input density information with respect to an image and includes apparatus for assigning to each input density a corresponding plurality of reference values. The apparatus also includes a method for combining with each of the plurality of reference values a random additional reference value, thereby defining a randomized plurality of reference values. The apparatus also causes the exposure of those areas in the matrix having reference values which correspond to the randomized plurality of reference values.

Abstract: A method and device for parallel intralinear halftoning of digitized grey value images divided into lines pixels, including (1) successive thresholding of grey values of the pixels and (2) transportation of a quantization error for each pixel to at least one neighboring pixel still to be thresholded by adjusting the grey value of the at least one neighboring pixel with at least a portion of the quantization error. The halftoning includes: dividing each of the lines of pixels into at least two disparate groups of pixels; separately thresholding each group of pixels within each line; and transporting the quantization error from a pixel of one group to at least one pixel of at least one other disparate group.

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.

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).

Abstract: There is disclosed an image processing apparatus for intermediate tone processing of an image signal into a binary signal, capable of providing a reproduced image with excellent resolution and gradation with a simple structure, and without the periodic texture inherent to the conventional error dispersing method or average density conserving method. The disclosed apparatus determines the average density of an already binarized predetermined image area, binary digitizing the image signal of a contemplated pixel, utilizing the determined average density as the threshold value, and distributing the error, generated in the binary digitization, to the image data of plural pixels to be digitized thereafter with certain distribution factors. The distribution factors are randomly changed according to random numbers generated by a generator, so that the reproduced image is free from periodic patterns resulting from periodic distributions of the errors.

Abstract: A method and an apparatus for processing image information by converting binary image data into multi-level image data. After conversion the image data are subjected to a smoothing process to avoid apparent loss in image quality.

Abstract: A system for producing a set of dither matrix signals having local correlation comprises a processor, an input device, a display device, a hard output device, an incremental threshold generator, a pattern generator, an optimizer, a dither matrix storage, and a pixel activator. The incremental threshold generator determines a maximum tolerable error and generates an incremental threshold signal. The maximum tolerable error is the greatest tolerable variation between dither matrices for adjacent gray levels. The incremental threshold signal controls the transition of cells of dither matrices for adjacent gray levels. The pattern generator receives the incremental threshold signal and a dither matrix signal for the previous gray level and generates the possible pattern signals based on a dither matrix signal for an adjacent gray level and the incremental threshold signal.

Abstract: An adaptive thresholding filter generates multiple threshold values for use in thresholding the multi-bit pixels of a gray-scale input image. Each threshold value is based on a current white reference value and a current black reference value. The current white reference value is selected based on a comparison of the current image pixel to a white reference comparator value generated by applying a white reference aging function to a prior white reference value. The current black reference value is selected analogously using a black reference comparator value and a black reference aging function.

Abstract: Differential image data compression systems and techniques are disclosed for use in video telephone systems for full duplex, real time transmission of audio and video images over nominal 3 kHz residential telephone lines and other narrow bandwidth channels. Each video telephone device consists of a transmitting portion and a receiving portion. In the transmitting section a reduced grey-scale (luminance) image, preferably consisting of only black-and-white pixels, is compared in an image processing module with a similarly reduced image derived from previous values to determine pixel positions that have changed. Information representative of the changes is then encoded and modulated and (time or frequency) multiplexed with the audio and/or chrominance signals for transmission. At the receiver, the incoming signal is demodulated and demultiplexed to separate the audio and video portions, the image portion is decoded and the luminance value is updated by an image updating unit.

Abstract: A method of and system for rendering a halftone image of a gray scale image by utilizing a pixel-by-pixel comparison of the gray scale image against a blue noise mask is disclosed in which the gray scale image is scanned on a pixel-by-pixel basis and compared on a pixel-by-pixel basis to an array of corresponding data points contained in a blue noise mask stored in a PROM or computer memory in order to produce the desired halftoned image. Both digital and optically implemented halftone methods are disclosed. Application specific modifications of the blue noise mask as well as its use for producing halftoned color images are also disclosed.

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.

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).

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.

Abstract: An image reading apparatus forms a histogram of image density levels of image signals obtained by reading an image, and processes the image signals in accordance with the histogram. When the histogram is improper for image processing, the apparatus indicates the improperness.

Abstract: A method and apparatus for image scaling of continuous tone images to be rasterized and output to a recording or imaging device using incremental interpolation. The method employs multiple parallel interpolators, each of which contains an accumulation sum to which an accumulation constant is added. When each accumulation sum exceeds a reference value, a transition event is signaled, to be used for selection of contone image data value for processing. By initially loading the accumulation sums with shifted data and employing interpolation logic, multiple transition events can be calculated within one output resolution processing cycle.

Abstract: This invention relates to an image processing system which relies upon quantization and dithering techniques to enable an output device, which has a given number of output levels, to accurately reproduce a image which is generated by an input device, which has a greater or equal number of input levels. Generally, neither the number of input nor output levels need to be a power of two. The present invention is implemented in a number of different embodiments. These embodiments generally rely upon an image processor which, depending on the particular implementation, includes memory devices and an adder, a comparator, or a bit shifter. Additional embodiments use an image adjustment system to refine the raw input levels of the input device, in order to create an improved output image. Also, the particular embodiments of the image processors can be used in connection with imaging systems having bi-tonal, monochromatic, or color input and output devices.

Abstract: The present invention is a method and apparatus for the enhancement of 1 bit per pixel image signals to produce a multiple-bit per pixel form. A binary input image is passed through a plurality of filters to generate level slices. The filters are stack filters implemented as look-up table or template-based filters, morphological filters, or any similar binary-to-binary filters that could be used to generate level slices. Each of the N-1 filters is used to produce the slices, where N is the number of possible gray-scale levels desired in the output image. Once the slices are generated, the resulting binary image data therein is recombined, by adding or stacking, to produce the desired multiple-bit per pixel output.

Abstract: An error diffusing method and apparatus are used for an image processing in which a tone of each of the pixels of the image is approximated by either a maximum or minimum tone determined from the tone value of that pixel. The pixels are processed sequentially in a predetermined order and either a first code indicative of the maximum tone or a second code indicative of the minimum tone, depending on a magnitude of the tone of the pixel, is allotted to each of the pixels. An error obtained as a difference between the tone value of that pixel and the code allotted thereto is a negative error when the first code is allotted thereto and a positive error when the second code is allotted.

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.

Abstract: The present invention is a method and apparatus for the enhancement of 1 bit per pixel image signals to produce a multiple-bit per pixel form. A binary input image is passed through a plurality of filters to generate level slices. The filters are stack filters implemented as look-up table or template-based filters, morphological filters, or any similar binary-to-binary filters that could be used to generate level slices. Each of the N-1 filters is used to produce the slices, where N is the number of possible gray-scale levels desired in the output image. Once the slices are generated, the resulting binary image data therein is recombined, by adding or stacking, to produce the desired multiple-bit per pixel output.

Abstract: A facsimile system for scanning a graphic image to produce a stream of output bits representative of an m.times.n array of picture elements of the image, each output bit being corrected to compensate for the average tone of a subarray of surrounding picture elements. The average tone is measured by a count of those gray levels, representative of the picture elements of the subarray, that exceed a nominal threshold. Thus the tone of the subarray dynamically adjusts the threshold of the gray level to output bit conversion of each picture element.

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.

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.

Abstract: An adaptive quantizer for digital image processing eliminates the influence of non-information anomalies, such as scratches, dust, etc. that may be present in an image in the course of determining the minimum and maximum signal levels LCHAR and HCHAR, respectively, and more accurately updates respective estimated image information level PREV.sub.-- HCHAR that effectively prevents discontinuities or `jumps` during line-by-line adjustment, thereby effectively obviating the problem of potential corruption of a local mean window and taking into account how `noisy` the background is.

Abstract: Disclosed is a binarization method for binarizing multi-level image data of an object pixel in accordance with binarized data of neighboring pixels of the object pixel which have been binarized. Multi-level image data corresponding to an object pixel are input, then a first portion of the input data is binarized in accordance with a random number, and a second portion of the data is binarized in accordance with the binarized data. The binary data of the first portion and the binary data of the second portion are output as binary data of the object pixel.

Abstract: An image processing apparatus for half-tone processing input image data having different resolutions by using a dither matrix consisting of a plurality of threshold values is disclosed. The apparatus includes an input device to input image data; a high-resolution dither processing unit to half-tone process the image data of a high resolution; a low-resolution dither processing unit to half-tone process the image data of a low resolution; and a selector to select either one of the two processing units in accordance with the resolution of the input image data. The input device includes a reader to read an original image and generate image data and a resolution conversion processing unit to convert the resolution of the image data obtained by the reader. The high-resolution processing unit uses a spiral-type dither matrix. The low-resolution processing unit uses a dither matrix including a plurality of small spiral-type dither matrices. The input images of different resolutions can be accurately reproduced.

Abstract: The method optimizes frequency-modulated rasters for recording black-and-white or chromatic raster images. An image to be recorded is optoelectronically scanned and is digitally stored in the form of the individual gray scale values that were allocated to the individual pixels. Threshold decisions are implemented using the gray scale values, a decision being made as to whether or not a pixel is set in the rastered recording of the image.

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.

Abstract: A method of generating a remapping function for use in converting near-photographic document image pixel gray level data lying in a first range of gray level values to higher contrast, background-suppressed pixel gray level data lying in a second more limited gray level range. Global document information, such as a histogram of all the document's original pixels, is used to generate at least one threshold gray level value and to determine the shape of the remapping function on either side of the threshold. Preferably, the remapping function is implemented by a look-up table addressed in accordance with the original pixel data.

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.

Abstract: A photosensor for measuring the reflectivity of a surface is calibrated for consistent gain and offset. The reflectivities of a plurality of regions of a test surface are measured. An average of the measured reflectivities is calculated, and a threshold value related to the average is derived therefrom. A revised average of the measured reflectivities is then calculated, the revised average being an average of measured reflectivities only of regions having reflectivities of a predetermined relationship to the threshold value. Subsequent signals from the photosensor are then revised according to a function related to the revised average.