Dainippon Screen Mfg. Co., Ltd.

Shigeo Murakami

Takaharu Yamamoto

Nobuhito Kohara

Kuniharu Okuda

Hideki Morikawa

A representative color determining step is executed to determine, from image data, a representative color characterizing an image of a print, and positions of the representative color. A gray control color determining step is executed to determine, from the image data, a gray control color expressed in an achromatic color and positions of the gray control color. A reading step is executed to read an image of reference paper and an image of an actual print. Then, a calculating step is executed to carry out a comparative calculation of color data in the positions of the representative color of the image of the reference paper and color data in the positions of the representative color of the image of the print, and a comparative calculation of color data in the positions of the gray control color of the image of the reference paper and color data in the positions of the gray control color of the image of the print, to create control data for controlling ink feeding rates of a printing machine.

Print quality measuring method and print quality measuring apparatus

A print tone measuring method includes a reference paper image pickup step for reading an image of reference paper to obtain first image data, a designated control point setting step for setting designated control points, a first reference point setting step for setting a pair of first reference points for specifying image positions, a print reading step for reading an image of an actual print to obtain second image data, a second reference point setting step for setting a pair of second reference points corresponding to the first reference points, a calculating step for calculating positions of corresponding control points corresponding to the designated control points from the first reference points and the second reference points, an extracting step for extracting image data adjacent each of the designated control points and image data adjacent each of the corresponding control points, and a correcting step for correcting the position of each corresponding control point in the second image data by comparing the image data adjacent each designated control point and the image data adjacent each corresponding control point.

Print tone measuring method

An ink feeding rate control method includes a reference print preparing step for making a printing plate by recording an image thereon based on first image data for recording a reference chart, and obtaining a reference print, a reference print colorimetric step for obtaining color data by reading the reference print, a conversion table preparing step for preparing a conversion table from the first image data and the color data of the reference print, a reference color data converting step for converting second image data for recording an image into reference color data by using the conversion table, a print preparing step for making a printing plate by using the second image data, and printing a print, a print colorimetric step for obtaining print color data by reading the print, and an ink feeding rate adjusting step for comparing the reference color data and the print color data, and adjusting ink feeding rates.

Ink feeding rate control method and an ink feeding rate control apparatus

A printing apparatus has a manual control mode. The manual control mode has a proportion indication, a proportion adjustment key, a selected range adjustment key, and region selection keys. In the manual control mode, an operator selectively touches the region selection keys to select a region in which an ink key opening is to be changed. Next, the operator touches the selected range adjustment key to change the ink key opening of the selected region. The ink key opening is increased or decreased by the percentage indicated at the proportion indication the number of times the selected range adjustment key is touched. The settings made in the manual control mode are stored in a storage section, and are used to control the amount of ink supply during automatic control. Thus, the printing apparatus having the function of automatically controlling the printed density can make partial tone changes.

Printing apparatus for automatically controlling ink supply device

After an ink feeding rate or a dampening water feeding rate is varied, a variation in the ink feeding rate or dampening water feeding rate is prohibited for a waiting period. The waiting period for prohibiting a variation in the ink feeding rate is determined by a pattern area rate of a corresponding region. The waiting period for prohibiting a variation in the dampening water feeding rate is determined by an average pattern area rate of all regions or a minimum pattern area rate among pattern area rates of all regions. When one of the ink feeding rate and dampening water feeding rate is varied, a variation in the other feeding rate is prohibited for a set period of time.

Printing machine for controlling feeding rates by color density measurement

In a first printing process in Steps S through S , ink supply is controlled so that a measured printed density (Vn) is approximately equal to a first target density (V ). This provides a uniform amount of ink remaining on ink rollers after the first printing process. Thereafter, in a second printing process in Steps S through S , printing is performed using a second target density (V ) lower than the first target density (V ). This provides a slightly reduced, uniform amount of ink remaining on the ink rollers. Thus, a novel method of presetting ink is provided which facilitates the formation of a distribution of the new amount of ink at the beginning of the next printing operation and which stabilizes the early start of printing.

Method of presetting ink

A positive image which resembles an object is obtained from a negative image which has various color distributions. An image analysis part judges how far image data of a negative image are from a gray line, and finds an intensity value of one optional color which provides a point on the gray line when combined with each of other colors, to thereby identify an HP (highlight point) and an SP (shadow point) on the negative image. At this stage, a pixel at which the sum of RGB-values on the negative image is approximately the largest is defined as a first HP candidate. Maximum values in the negative image are calculated for planes of the respective colors, and one set of the RGB-values is defined as a second HP candidate. Whether the first HP candidate is close to the gray line is judged. If the first HP candidate is close to the gray line, the first HP candidate is directly used as an HP. If the first HP candidate is far from the gray line, whether the second HP candidate is close to the gray line is judged. If the second HP candidate is close to the gray line, the second HP candidate is directly used as an HP. If the second HP candidate is far from the gray line, RGB-values in a white and a black regions in a gray scale are used as an HP and an SP. An image conversion part converts the negative image which is read from an image holding part into image data of a positive image which has a proper contrast, based on information regarding the HP and the SP on the negative image supplied from the image analysis part.

Image conversion method and record medium

A method of identifying defective pixels included in a digital image. The method includes the steps of designating a pixel adjacent the defective pixels in the digital image, setting an evaluation area, setting a defective pixel candidate, computing, as a line average, an average pixel value of each of lines above, below, leftward and rightward of the defective pixel candidate, diminishing the evaluation area by selecting an upper line, a lower line, a left line and a right line, computing a threshold pixel value for determining the defective pixels, from an average pixel value of each line, and comparing values of all pixels with the threshold pixel value to determine the defective pixels.

Method of identifying defective pixels in digital images, and method of

A gray edge component and RGB color components of each pixel in an original image are generated. Saturation of each pixel in the original image is evaluated, and a mixing ratio is determined according to the saturation. Mixed edge components are generated for each pixel by mixing the gray edge component and the respective RGB edge components in the mixing ratio determined. The mixed RGB edge components are added to the RGB components of each pixel in the original image, respectively, to output a sharpened image. Apart from the mixing ratio determined from saturation of each pixel, a common fixed mixing ratio may be designated by the operator for application to all pixels.

Image sharpness processing method and apparatus

An apparatus for correcting contrast of a selected range without changing lightness and color tone of a pixel designated as a central object of processing. The apparatus includes a frame memory for storing original image signals; a conversion table for converting the original image signals to CIE-Lab values; a data input device for designating a color to be corrected and to act as the central object of processing, a distance in CIE-Lab perceived color space indicating an effective range of processing, and a characteristic parameter for the processing; a lookup table for contrast correction; a lookup table initializer for matching input/output relations of the color to be corrected, and initializing the lookup table for other input/output relations based on the characteristic parameter; a mixing ratio computing unit for determining whether or not pixels in an original image are within the effective range, and computing a mixing ratio; and a mixing processor for mixing the original image signals and output data of the lookup table at the mixing ratio. The invention also includes an apparatus in which an effective range of contrast correction is designated with hue, saturation and lightness which are the three attributes of perceived color.

Contrast correcting apparatus

A sharpness processing apparatus for enhancing or suppressing tone variations in an original image. A lookup table for converting RGB signals into HSL values which are the three attributes of perceived colors is used to obtain HLS values of pixels in the original image stored in a frame memory. The HSL values of the pixels are successively compared with HSL values indicating an effective range of sharpness processing determined with reference to a designated reference color, to determine pixels to be subjected to the processing. The processing is effected by applying a parameter to the RGB signals of the pixels subjected to the processing. In this way, the apparatus facilitates designation of a region of sharpness processing. Besides, the value of the parameter is variable with differences between the HSL values of the pixels corresponding to the reference color and the HSL values of the pixels determined to be subjected to the processing, whereby the sharpness processing is effected without impairing smoothness of the original image.

Sharpness processing apparatus

Where color components of output signals are RGB signals, a pixel in an original image displayed on a monitor screen is designated to designate RGB signals of a color to be corrected. At the same time, RGB signals of a target color are inputted through a data input device. An effective range of tone correction processing is designated through the data input device based on hue H, saturation S and lightness L with reference to the color to be corrected. Default values are used as an alternative to the designation. The RGB values of pixels in the original image are converted into HSL values to determine whether the pixels are within the effective range expressed by the HSL values. If the pixels are within the effective range, a tone correction is effected by applying parameters derived from the color to be corrected (RGB signals) and target color (RGB signals) to the RGB signals of the pixels. These parameters are amended to be the smaller toward boundaries of the effective range.

Color tone correcting apparatus

Detail enhancement is performed through effectively intensifying an image signal component having a predetermined spatial frequency. Based on the size of an image to be reproduced, a standard observation distance between the image and an observer is computed. A spatial frequency to be intensified is found so that it corresponds to about 12 cpd at the standard observation distance. The size of a pixel area suitable in producing an unsharp signal (U) is set to be inversely proportional to the spatial frequency. Signals (U13-U15) for various pixel areas are prepared, and one of these signals which is obtained for the suitable pixel area is selected to be the unsharp signal (U). An enhanced image signal (S+k(S-U)) is produced on the basis of the unsharp signal and a sharp signal (S).

Method of and apparatus for performing detail enhancement

A multi-gradation image signal obtained by multi-gradationization of a signal obtained by reading through a CCD an original having a half tone is supplied to an unsharp signal producing part, which in turn outputs an unsharp signal produced from the multi-gradation image signal and the multi-gradation image signal itself. A comparator discriminates a shadow portion of the original by comparing the multi-gradation image signal with a reference value. As a result, a signal which is unsharp in the shadow portion of the original is produced from the multi-gradation image signal and the unsharp signal.

Method of and apparatus for noise reduction in multi-gradation image

Amounts of read position errors in subscanning direction with respect to respective scanning positions of line image sensors, which are provided in parallel with main scanning direction, are found in advance by a number of scanning lines. In actual scanning, output image signals from the line image sensors are delayed, in respective main scanning positions of the output image signals, by respective line numbers corresponding to the respective found amounts of read position errors in the subscanning direction, and are output.

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Kyoto, Japan

Shigeo Murakami