Image reading apparatus, image forming apparatus, and image forming method
First Claim
1. An image reading apparatus for reading a color document as a monochrome image, comprising:
- a composite light source that irradiates the color document and includes plural light sources different in spectral distribution;
a sensor configured to detect an intensity of a reflected light from the color document;
a light emission ratio setting unit configured to changeably set light emission ratios different for the respective light sources; and
a light source control unit to control effective light amounts of the plural light sources with the set light emission ratios, wherein,the light emission ratio setting unit includes a storage unit,the light emission ratio setting unit sets standard light emission ratios stored in the storage unit into the light source control unitthe standard light emission ratios are calculated such thata product of a composite spectral distribution obtained by combining spectral distributions of the plural light sources with specified light emission ratios, spectral distributions of standard color charts, and a spectral distribution of a sensitivity of the sensor is integrated with respect to wavelengths to obtain first lightnesses for the standard color charts,a product of a spectral distribution of a standard light source, the spectral distributions of the standard color charts, and a spectral distribution of a visibility characteristic is integrated with respect to wavelengths to obtain second lightnesses for the standard color charts, anda square sum of errors between the first lightnesses and the second lightnesses with respect to the plural standard color charts different in color becomes a minimum.
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Abstract
In an image reading apparatus for reading a color document as a monochrome image, an image forming apparatus of the invention includes a composite light source that irradiates the color document and includes plural light sources different in spectral distribution, a sensor to detect the intensity of a reflected light from the color document, a light emission ratio setting unit to changeably set light emission ratios different for the respective light sources, and a light source control unit to control effective light amounts of the plural light sources with the set light emission ratios. According to the image forming apparatus of the invention, when the color document is monochromatically read, the reading is performed with the brightness close to the human visual sensitivity, the user can changeably set color sensitivity, and uneven density can be reduced.
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Citations
24 Claims
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1. An image reading apparatus for reading a color document as a monochrome image, comprising:
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a composite light source that irradiates the color document and includes plural light sources different in spectral distribution; a sensor configured to detect an intensity of a reflected light from the color document; a light emission ratio setting unit configured to changeably set light emission ratios different for the respective light sources; and a light source control unit to control effective light amounts of the plural light sources with the set light emission ratios, wherein, the light emission ratio setting unit includes a storage unit, the light emission ratio setting unit sets standard light emission ratios stored in the storage unit into the light source control unit the standard light emission ratios are calculated such that a product of a composite spectral distribution obtained by combining spectral distributions of the plural light sources with specified light emission ratios, spectral distributions of standard color charts, and a spectral distribution of a sensitivity of the sensor is integrated with respect to wavelengths to obtain first lightnesses for the standard color charts, a product of a spectral distribution of a standard light source, the spectral distributions of the standard color charts, and a spectral distribution of a visibility characteristic is integrated with respect to wavelengths to obtain second lightnesses for the standard color charts, and a square sum of errors between the first lightnesses and the second lightnesses with respect to the plural standard color charts different in color becomes a minimum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An image forming apparatus for reading a color document as a monochrome image and forming the monochrome image, the image forming apparatus comprising:
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a composite light source that irradiates the color document and includes plural light sources different in spectral distribution; a sensor configured to detect an intensity of a reflected light from the color document; a light emission ratio setting unit configured to changeably set light emission ratios different for the respective light sources; a light source control unit configured to control effective light amounts of the plural light sources with the set light emission ratios; and an image forming unit configured to form the monochrome image from an output of the sensor, wherein the light emission ratio setting unit includes a storage unit, and the light emission ratio setting unit sets standard light emission ratios stored in the storage unit into the light source control unit the standard light emission ratios are calculated such that a product of a composite spectral distribution obtained by combining spectral distributions of the plural light sources with specified light emission ratios, spectral distributions of standard color charts, and a spectral distribution of the a sensitivity of the sensor is integrated with respect to wavelengths to obtain first lightnesses for the standard color charts, a product of a spectral distribution of a standard light source, the spectral distributions of the standard color charts, and a spectral distribution of a visibility characteristic is integrated with respect to wavelengths to obtain second lightnesses for the standard color charts, and a square sum of errors between the first lightnesses and the second lightnesses for the plural standard color charts different in color becomes a minimum. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An image forming method for reading a color document as a monochrome image and forming the monochrome image, characterized by comprising:
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a step of irradiating the color document by a composite light source including plural light sources different in spectral distribution; a detection step of detecting an intensity of a reflected light from the color document by a sensor; a light emission ratio setting step of changeably setting light emission ratios different for the respective light sources; a light source control step of controlling effective light amounts of the plural light sources with the set light emission ratios; and an image formation step of forming the monochrome image from an output of the sensor, wherein, at the light emission setting step, previously stored standard light emission ratios are set, the standard light emission ratio is calculated such that a product of a composite spectral distribution obtained by combining spectral distributions of the plural light sources with specified light emission ratios, spectral distributions of standard color charts, and a spectral distribution of a sensitivity of the sensor is integrated with respect to wavelengths to obtain first lightnesses for the standard color charts, a product of a spectral distribution of a standard light source, the spectral distributions of the standard color charts, and a spectral distribution of a visibility characteristic is integrated with respect to wavelengths to obtain second lightnesses of the standard color charts, and a square sum of errors between the first lightnesses and the second lightnesses for the plural standard color charts different in color becomes a minimum. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification