Abstract: In a method for white balance of an optoelectronic scan unit of a scan apparatus for the image-point-by-image-point and line-by-line scanning of an image original, in a light/voltage converter unit of the scan light, modulated with the densities of the scanned image points, is converted into image values. A white level is predetermined and a white balance is carried out by a reference white of a balance strip. The amplification of the light/voltage converter unit is modified in such a way that the image value produced in scanning the brightest point of the image original, the white point, corresponds to the white level.

Abstract: Color digital imaging quality is improved by quickly, accurately and robustly estimating illuminant information associated with a color digital image to correct color of the image based on the illuminant. A "correlation matrix memory" or "associative matrix memory" is used to achieve identical results to the Color in Perspective method, and to improve it by adding Bayesian or other correlation statistics. The new method is insensitive to aperture colors and provides an effective framework on top of estimation. It will effortlessly return the maximum likelihood answer. A correlation matrix memory is built to correlate the data from any picture image to reference images under a range of illuminants. When a camera, scanner, or the like, produces a picture image, the data is converted to chromaticity and a vector is created corresponding to the values existing in the scene. This vector is multiplied by each column in the correlation matrix giving a new matrix.

Abstract: When a color film original is read, a shading correction or the like is executed without using a color base film. An apparatus has: an RAM 115 in which output ratios of RGB signals from an RGB sensor (CCD) 106 for an unexposed portion of a color film have previously been stored; an amplifier 107 to amplify the signals from the CCD line sensor 106 by gains based on the RGB signal output ratios from the RAM 115 without transmitting through the base film when shading correction data is read; and a shading correction circuit 110 to give the shading correction data to an RAM 111 on the basis of outputs of the amplifier 107.

Abstract: An image reading apparatus including a backing member arranged on the original transport path, a light source for emitting the light toward the original reading position in the original transport path in the direction of a predetermined incident optical axis, a detector capable of detecting the light reflected at the original reading position in the direction of a predetermined reading optical axis, and an image processing apparatus. The reflection surface of the backing member is configured in such a manner that the amount of the light reflected by the backing member and detected by the detector is not less than the amount of the light corresponding to a white reference value and that the amount of the light passing through the original, reflected by the backing member, re-passing through the original and detected by the detector, is not more than the amount of the light capable of preventing the imaging from the reverse side.

Abstract: An image forming apparatus which forms an image according to image data made up of pixel data on colors of pixel constituting an original image, characterized by comprising a color region discriminator for determining to which color region each pixel data belongs, an image region discriminator for determining whether the pixel data belongs to a uniform density region or whether it belongs to an edge portion, a corrective condition deciding unit for determining MTF corrective conditions for the image data of each color region depending on the discrimination results of both the color region discriminator and the image region discriminator, and an MTF correction unit for performing MTF corrections on the image data according to the MTF corrective conditions determined by the corrective condition deciding unit.

Abstract: A method of digital photofinishing comprising the steps of: producing a digital color image in optical printing densities of a color image captured on photographic media; processing the digital color image with a scene balance algorithm to produce a balanced digital color image; mapping the balanced digital color image through a hard copy media characteristic curve to produce a balanced digital color image mapped to print densities of the hard copy media; sharpening the mapped balanced digital color image with a sharpening algorithm optimized to avoid unacceptable artifacts; and digitally printing the sharpened digital color image in hard copy media.

Abstract: A system for reducing toner or ink consumption in rendering images, in which a transfer function is used to modify screening of the image to be rendered. Rendering systems including the use of single or multiple colors can employ the present invention. An algorithm is used in the present system to read in an arbitrary halftone dot and for each pixel in the halftone cell the output is a replicate of the threshold, Ta or Tb, surrounded by three pixels of white thresholds, a smooth transition from white to the now reduced maximum area coverage (such as 25%), while creating or maintaining the appearance of image uniformity at this reduced maximum area coverage.

Abstract: A detecting unit generates defference data between optical black level of digital input data and a predetermined black level and generates .gamma. characteristics selection signal. An offset signal obtained from the difference is added to the input data by an adding circuit. A .gamma. characteristics setting unit is supplied with the difference data and the output signal of the adding circuit and outputs a signal in which a white level, black level and .gamma. characteristics are corrected.

Abstract: A film image, which is taken into the developed photographic film, is picked up, and a reference maximum value and a reference minimum value of an image signal are determined by the image signal which is obtained when the image is picked up. The reference maximum value and the reference minimum value are used in the signal processing for adjusting the tone of the image, etc. Moreover, the exposure state of the film image is determined based on at least one of the reference maximum value, the reference minimum value, and the average value. If the exposure state is determined to be underexposured, the gamma in the gamma correction is smaller than the gamma during the standard exposure, so that the middle tone can be prevented from being dark. On the other hand, if the exposure state is determined to be overexposured, the gamma in the gamma correction is larger than the gamma during the standard exposure, so that the middle tone can be prevented from being too bright.

Abstract: A compact color image reader for scanning an image in a short time is disclosed. The color image reader includes three fluorescent lamps 17 of red, green, and blue, a lighting circuit 15 for lighting the three fluorescent lamps sequentially, a CCD 183 for reading an image illuminated by the three fluorescent lamps and a control circuit 16 for controlling a lighting period of each of the fluorescent lamps 17 and the reading of the CCD. In order to perform the scanning of a color image in a short time, the lighting circuit 15 lights each of the three fluorescent lamps at a lamp current higher than a rated value and the CCD performs the fast reading in a period corresponding to the lighting period.

Abstract: There is disclosed an image reading apparatus comprising plural line sensors for converting light from an object into image signals, charge transfer unit for transferring the image signals, converted by the line sensors, mutually among the line sensors, correction unit for correcting signal levels of the image signals and control unit for effecting control so as to vary a manner of correction by the correction unit, according to a direction of transfer of the image signals by the charge transfer means among the line sensors.

Abstract: An image reading apparatus compensates inter-deviations of and a change in a color temperature of a light source while compensating a difference in the sensitivities between linear image sensors and a change in the sensitivity difference. Three linear image sensors for R, G and B of a multi-line linear image sensor read white reference image data, and a line memory stores the image data. A CPU controls an output state of each second timing signal within a timing generator line by line and independently of a first timing signal, in such a manner that peak values of the white reference image data for three lines stored in the line memory each belong to a predetermined appropriate range. This optimizes a charge accumulating time within each linear image sensor, whereby an RGB balance becomes even at an output side of each linear image sensor.

Abstract: The invention relates to a device for correcting the tone of color pictures recorded by a video camera, in particular an endoscope camera. A control device works in combination with a preferably triangular keyboard so that a free tone correction of the three ground colors of the video picture may be effected independently of the color temperature of the recorded object, i.e. in particular, independently of the light source employed. The switching surface is in the form of a surface PAD keyboard which allows the evaluation of the location of a finger tip or likewise at any position on the triangle, and thus represents a very effective input medium for the tone correction according to the invention. A similarly provided automatic white balancing function permits the white point of the camera color space to lie in the surface center of the surface PAD keyboard.

Abstract: A photographic color printer includes a color video camera for making specialty prints. A memory is provided to store different color compositions for printing light including an initial color composition and additional color compositions which surround the initial color composition. The memory also stores camera adjustment parameters for each additional color composition so that, when the color composition of the printing light is shifted away from the initial color composition, the camera can be adjusted to the new color composition. The camera is adjusted to the initial color composition by exposing the camera to light of this composition. Following such exposure, the camera is sequentially exposed to light of the various additional color compositions. The camera is adjusted to each additional color composition in order to obtain the camera adjustment parameters which are to be stored in the memory.

Abstract: This invention discloses a method of correcting the measurement of the amount of light reflected by a document that is being processed by a digital image acquisition apparatus. A typical image acquisition apparatus measures the amount of light reflected from the surface of the original document and sets a corresponding set of electrical signals to a printing or storage module. Image acquisition usually requires illuminating the original document with a reflecting cavity, which causes the measurement of the amount of light present on the surface of the document to become distorted. The method disclosed by the present invention corrects this phenomenon by calculating the amount of light that reaches the surface of the original document by being reflected from the illumination system and the surrounding cavity. This allows the measured reflectance to be corrected, and the true reflectance to be used for subsequent output or storage.

Abstract: The present invention achieves an exposure control for getting an image with the best SN without a mechanical iris and an image processing which is good at the color-reappearance and the gradation property with a simple digital processing circuit. When the film image is read by the line sensor 14 which has an electric shutter function, the electric shutter, the film feeding speed and the analog amplifier 16 are controlled totally so as to obtain images with the best SN from high to low transmittance negatives.

Abstract: A method for automatic partial correction of color images for non-white illumination. The images are processed in a manner similar to that by which the visual system processes signals related to color vision to achieve "color constancy".

Abstract: A system and method for color characterization and transformation obtain color data representing output of a color imaging system, and convert the color data using a color space having a white reference vector that is adjusted during the conversion. The white reference vector can be adjusted according to intensities of the color data being converted. Adjustment of the white reference vector serves to avoid nonuniformities for color imaging systems having different imaging bases, and thereby eliminates, or at least reduces, the amount of empirical adjustment necessary to obtain an acceptable visual match between the color imaging systems.

Abstract: There is provided an image pickup apparatus excellent in color reproducibility without requiring a complicated circuit. In image pickup operation, a sum pixel signal (S.sub.CCD) output from a color image pickup element (100) is converted into digital sum pixel data (D.sub.CCD) through a sample/hold circuit (102) and an A/D converter (104). The digital sum pixel data is stored and held in a frame memory (106). In image reproduction, an arithmetic operation unit (108) executes an arithmetic processing program in a program memory (110) to read out the sum pixel data (D.sub.CCD) from the frame memory (106). The pixel data are multiplied by predetermined white balance adjustment coefficients, and color difference signals (B-Y) and (R-Y) of the horizontal lines are calculated.

Abstract: The present invention is an image scanner adapted to be used for scanning a color image which includes an image sensor which converts the scanned color image into three analog voltage signals, a clock generator which provides a clock for the image sensor outputting the three analog voltage signals in response to the clock, three amplifying switches electrically connected to the image sensor through three respective independent signal paths and respectively having three disablers thereon for respectively enabling/disabling the amplifying switches by utilizing an impedance thereof in order to respectively amplify the three analog voltage signals and transmit one of the amplified voltage signals therethrough at a time, an analog-to-digital converter electrically connected to the three amplifying switches which respectively converts the three analog voltage signals into digital signals and a data-processing device electrically connected to the analog-to-digital converter which receives and stores the digital sign

Abstract: The invention provides a white level information correction apparatus for an image reading apparatus suitably used as an image scanner, which is improved in that analog to digital conversion can be performed effectively for originals of different ground colors with a high degree of accuracy. In the image reading apparatus, image information of a paper sheet being transported along a paper transport path is optically read at a fixed location of the paper transport path using an optical image reading unit and analog data obtained by the optical image reading unit are converted into digital data using white level information of the image information as an index to a conversion reference.

Abstract: In a film image input method, a line sensor is used as an image sensor to reduce the cost. Image data can be corrected in accordance with the taking environment, which occurs in a case of using the line sensor, for every frame. A line sensor is provided in which photoelectric transfer elements are arranged in a direction perpendicular to a feeding direction of a long roll of developed film for a still camera. The film is fed at the first speed continuously to take the rough image data of all frames through the line sensor. The taking environment for every frame is detected based on the taken rough image data. Thereafter, when reproducing one frame, the film is fed at the second speed which is lower than the first speed, whereby the fine image data of the desired frame are adjusted in accordance with the detected taking environment of the frame and stored in the CCD buffer. Then, the image signals are output to the TV monitor based on the stored fine image data.

Abstract: A method for dynamically determining and adjusting the color balance of the light strip along one edge of the scanned area and adjusting the gains of independently controlled red, green and blue channels of a CCD array. Alternatively, the gain of one color channel may be held constant and measured to determine the light intensity of the light source as the temperature of the light source varies. The power to the light is then changed to maintain the intensity of the light source within a predetermined range. The three color channels are then compared to a predetermined color balance. If the color balance is outside of a predetermined range, the other two color channels gains are varied in order to maintain the color balance between the three color channels.

Abstract: Pieces of white balance information indicating color features of a colored picture or picture blocks obtained by partitioning the colored picture are extracted from piece of picture data of the colored picture in an extracting unit. Whether or not a white region exist in the colored picture is judged in a white region judging unit according to the white balance information indicating the color features of the colored picture. When the existence of the white region is judged, a white balance coefficient is calculated in a white balance calculating unit to make the white region white.

Abstract: A chromatic color pattern and a monochromatic color pattern are read by an image sensor. A masking coefficient in a color masking portion or a gamma conversion characteristic of a gamma correction portion are selected in accordance with the ratio V1/V0 of a read value V1 of the chromatic color pattern and a read value V0 of the monochromatic color pattern. An output of an image data is corrected by masking processing with the selected masking coefficient and the like.

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: A method and system of determining a reference value for the intensity associated with a color indication variable and obtained by scanning an original with a color scanning unit the color scanning unit being adapted to scan the original point-by-point, the method comprising determining a locally valid reference value for each scanned point and for each color indication variable, provided the intensity value related thereto deviates from a defined standard value by less than a preset value, by adapting the then locally available reference value by using a fraction of the value representing the intensity in the case of the color indication variable concerned. For example, a white reference value (white point) can be determined for an original point by point, with the result that weak color tones which are perceived as white are also regarded as white, while in addition small variations in these weak color tones (e.g. uneven yellowing) are also noted as white.

Abstract: An image analyzer (10) for adjusting a printer comprises a video image converter device (19).In order to facilitate the adjustment of the color composition of the exposure light emitted by an exposure means (2) of the printer (1), the image analyzer (10) is provided with a means (21) for adapting the spectral sensitivity curve of the video image converter device (19) to that of the photographic material as well as with a white balance control circuit, which is connected to said video image converter device (19) and which is used for producing color component signals for at least two color components of the exposure light emitted by the exposure means (2) of the printer.

Abstract: An image scanning apparatus which can reduce a shading distortion generated by luminous characteristics of a light source, vignetting of a lens, etc. adopts color filters having a geometrical structure which enables to counterbalance a shading distortion and is characterized in that a line sensor is vertically arranged for the radial direction of the rotary filter. The image scanning apparatus can accomplish a simple shading calibration by arranging color filters and the line sensor so that a shading distortion is calibrated geometrically.

Abstract: A method for improving the quality of full-color images is disclosed. An original image is divided into a plurality of pixels. A neutral intensity value is determined for each pixel. A desired black-color intensity value is determined from the neutral intensity value. A printer-producible black value is determined from the desired value. The printer-producible black-color intensity value is used to rescale the original color intensity values of the pixels. The rescaled color intensity values are used to generate output color intensity values. The output image comprising the output color intensity values and the printer-producible black-color intensity value may then be converted to a continuously varying or halftone output image and output to an image output apparatus.

Abstract: A white balance adjustment device includes an image sensor for converting light of an object into an electrical signal, an amplification circuit for amplifying the electrical signal output from the image sensor, a control voltage limiting circuit for limiting a range of a control voltage to be output to the amplification circuit, and a detection circuit for detecting a quantity of ambient light with a hysteresis characteristic. The limited range of the control voltage is arranged to be variable on the basis of an output of the detection circuit.

Abstract: A color processor for reproducing a color image from color image signals. The processor has a scanner or a generator to obtain color image signals, an A/D converter to generate digital image signals from the color image signal, a density converter to generate density signals from the digital image signals, a controller to control the density converter, and an image reproducer to reproduce a color image according to the density signals. The density converter has a plural conversion data in a ROM memory. Color balance, density control, and picture/character mode change are all performed by selecting data from the conversion data and using the data for the density conversion.