Image reading apparatus with improved output correction of image signal
First Claim
1. An image reading apparatus for reading a color image to separate the image into three primary colors by an image sensor and outputting image data corresponding to each of the colors, comprising:
- scanning means for making the image sensor relatively scan for a reference chart and an original;
A/D conversion means for converting an output of said image sensor into digital data corresponding to each of the three primary colors;
operation means for evaluating correction data of said each color from the output of said image sensor when said image sensor scans said reference chart;
multiplication means for multiplying digital data of said each color by said evaluated correction data; and
addition means for adding digital data before being multiplied to a result of the multiplication by said multiplication means.
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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.
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Citations
10 Claims
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1. An image reading apparatus for reading a color image to separate the image into three primary colors by an image sensor and outputting image data corresponding to each of the colors, comprising:
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scanning means for making the image sensor relatively scan for a reference chart and an original; A/D conversion means for converting an output of said image sensor into digital data corresponding to each of the three primary colors; operation means for evaluating correction data of said each color from the output of said image sensor when said image sensor scans said reference chart; multiplication means for multiplying digital data of said each color by said evaluated correction data; and addition means for adding digital data before being multiplied to a result of the multiplication by said multiplication means. - View Dependent Claims (2, 3, 4, 5)
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6. In an image reading apparatus for reading a color image to separate the image into three primary colors by an image sensor and outputting image data corresponding to each of the colors, a method of correcting a white balance among the colors comprising the steps of:
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scanning a reference chart prior to an original; A/D converting an output of said image sensor for said reference chart to output digital data; evaluating correction data for said each color from digital data of said each color; and correcting digital data for said original by employing the correction data, said correction step comprising the steps of multiplying the digital data of said each color by the correction data, and adding digital data of a selected one of said colors to a result of the multiplication. - View Dependent Claims (7, 8)
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9. An image reading apparatus for reading an image of an original by an image sensor and outputting image data, comprising;
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scanning means for making said image sensor relatively scan for a reference chart and the original; storage means for storing image data of the reference chart corresponding to one line for each element of said image sensor; reciprocal conversion means for reading the image data from said storage means, converting the read image data into reciprocal data and outputting the reciprocal data; multiplication means for multiplying the image data of the original by the reciprocal data outputted from said reciprocal conversion means; and control means for controlling said reciprocal conversion means and said multiplication means so that reciprocal data is outputted in correspondence with the image data of the original read for said each element of said image sensor, and said image data read is multiplied by the reciprocal data while scanning the image of the original. - View Dependent Claims (10)
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Specification