JPH11220568A - Color image reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate color image data without deterioration in luminance with production with less noise. SOLUTION: A CCD-type image sensor 10 has plural blue light-receiving elements 11, plural red light-receiving elements 12 and plural green light- receiving elements 13, the blue light-receiving elements 11 and the red light- receiving elements 12 are arranged on a light-receiving element array L1 along a main scanning direction 14 alternately and the green light-receiving elements 13 is arranged on a light receiving element array L2. In the case of generating 1-dot color image data, received data outputted from the four light-receiving elements are used. For example, in the case of generating 1st dot color image data, the green light-receiving element 13 placed at the dot position, the red light-receiving element 12 on the same coordinate as that of the green light- receiving element 13, and the two blue light receiving elements 11 at both sides of the coordinate are used and color image data are generated from received data G2, R1, B1, B2 in each color outputted from them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image reading method used in a color image reading device or the like.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
Some of them were described in the following documents. Document: JP-A-5-56218 In a general color image reading apparatus, a CCD (Charge Cou
pled Dvice) An image sensor is used. This C
A color image reading apparatus using a CD image sensor uses a plurality of light receiving elements in which color filters of red (R), green (G), and blue (B) are attached to a light receiving surface, and a white light source is used as a document. , And an on-chip filter system that receives signals spectrally separated by the light receiving elements and generates color image data is employed. In the above document,
An example of the arrangement of the color filters is shown.

FIGS. 2A and 2B are diagrams showing a configuration of a first CCD image sensor used in a conventional first color image reading method. In the first conventional color image reading method,
When forming color image data of one dot, reception data of three light receiving elements is used. A set of light receiving elements used to compose the color image data of one dot is hereinafter referred to as a color pixel. The first CC that is a line sensor
The D image sensor 1 includes a plurality of blue light receiving elements 2 that receive blue light and output blue received data B1, B2, B3, respectively, and red received data R1 and R that receive red light.
A plurality of red light receiving elements 3 respectively outputting 2, R3,.
And receive green and receive green data G1, G2, G3
And a plurality of green light receiving elements 4 for respectively outputting
These are the first light receiving element arrays L along the main scanning direction 5.
1 and the second light receiving element array L2. First
In the light receiving element array L1, the blue light receiving elements 2 and the red light receiving elements 3 are alternately arranged, and the second light receiving element array L2
, A plurality of green light receiving elements 4 are arranged in one row. Color pixel CG1 in conventional first color image reading method
Is a set of one blue light receiving element 2, one red light receiving element 3 adjacent thereto, and one green light receiving element 4.
The CCD image sensor 1 generates color image data from the output signals of the light receiving elements 2 to 4 constituting the color pixels while moving the color pixels CG1 by one dot along the main scanning direction 5.

For example, a color pixel CG1 of the first dot in the main scanning direction 5 outputs a blue light receiving element 2 for outputting blue receiving data B1 and a red receiving data R1 as shown in FIG. And a green light receiving element 3 that outputs green received data G1 and generates color image data from these output data. As shown in FIG. 2B, the color pixel CG1 of the second dot includes a blue light receiving element 2 that outputs blue received data B2, a red light receiving element 3 that outputs red received data R1, and a green received data G2.
3A and 3B for generating color image data from these output data. FIGS. 3A and 3B show a second CCD image sensor used in a second conventional color image reading method. FIG. The second CC used in the second color image reading method
The arrangement of the blue light receiving element 2, the red light receiving element 3, and the green light receiving element 4 in the D image sensor 1 is the same as that in FIG. However, in the second color image reading method, a color pixel CG2 is formed by four light receiving elements, and color image data is generated from output signals of the respective light receiving elements 2 to 4 forming the color pixel CG2.

For example, as shown in FIG. 3A, a color pixel CG2 of the first dot in the main scanning direction 5 outputs a blue light receiving element 2 for outputting blue reception data B1 and a red light reception data R1. Red light receiving element 3 and two green light receiving elements 3 for outputting green received data G1 and G2, respectively.
And color image data is generated from these output signals. The color pixel CG2 of the second dot is shown in FIG.
, A blue light receiving element 2 that outputs blue received data B2, and a red light receiving element 3 that outputs red received data R1.
And output green reception data G2 and G3, respectively.
Green light receiving elements 3 and generate color image data from these output data.

[0006]

However, the first and second color image reading methods have the following problems. FIGS. 4A and 4B are explanatory diagrams of the problems in FIGS. 2A and 2B. A white manuscript with black line 6
FIG. 4A shows the concept of reading by the method shown in FIGS. 2A and 2B. Here, in order to facilitate understanding, the state when the black line 6 formed on the CCD image sensor 1 is read is shown by superimposing the black line 6 on the CCD image sensor 1 by making it transparent. I have. Also,
FIG. 4B shows the state of the read color image data.
Is shown in

The color image data corresponding to the first dot when the original shown in FIG. 4A is read out is output from the blue light receiving element R1 output from the blue light receiving element 2 constituting the color pixel and from the red light receiving element 3 output. Since the red reception data R1 and the green reception data G1 output by the green light receiving element 4 are both bright, they become bright color image data. In the second dot, the color pixel CG1 crosses the black line 6. At this time, the red reception data R1 output from the red light receiving element 3 and the green reception data G output from the green light receiving element 4
1 is bright data, but the blue reception data B2 output from the blue light receiving element 2 is dark. Therefore, a color shift between red and blue and a color shift between blue and green occur at the boundary between the black line 6 and the background. When the color shift is large, noise is generated at the boundary between white and black even though the original is a black and white image due to the red or blue color shift.

FIGS. 5 (a) and 5 (b) show FIGS.
It is explanatory drawing of the subject of (b). FIG. 5A shows the concept of reading a white document on which the black line 6 is written by the method shown in FIGS. 3A and 3B. here,
As in FIG. 4A, the state when the black line 6 formed on the CCD image sensor 1 is read is shown by superimposing the black line 6 on the CCD image sensor 1 by making it transparent. . In addition, the state of the read color image data is
This is shown in FIG. In the first dot when the original shown in FIG. 5A is read, the blue reception data B1 output from the blue light receiving element 2 constituting the color pixel CG2, the red reception data R1 output from the red light receiving element 3, The green reception data G1 and G2 output by the two green light receiving elements 4 are both bright, and the average value of the green reception data G1 and G2 is also bright. In the second dot, the blue light receiving element 2 forming the color pixel CG2 and the green light receiving element 4 outputting the green received data G2 cross the black line 6. Therefore, the blue reception data B2 becomes dark. On the other hand, the green reception data G1 is bright and the green reception data G2 is dark. Therefore, the green component in the color image data is at an intermediate level between the green received data G1 and G2. Therefore, FIG.
Compared with (b), color shift can be reduced. However,
Since the luminance component of the color image depends on the green output,
By averaging the green reception data of the two green light receiving elements, the modulation transfer function of the luminance component decreases,
The image deteriorates.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for receiving a first color of light provided from an object to be read and generating first color reception data. A plurality of second color light receiving elements for receiving the second color of the light and generating the second color reception data by receiving the second color of the light, and receiving the third color reception data by receiving the third color of the light respectively A plurality of third color light receiving elements to be generated, wherein the first color light receiving elements and the second color light receiving elements are alternately arranged in a first array along the main scanning direction; Using an image sensor having at least one element array in which color light receiving elements are arranged in one line in a second arrangement along the main scanning direction, the first, second, and second obtained for each dot to be read. The color image data for each dot in the main scanning direction is obtained from the third color reception data. The respective determined line processing Re, in the color image reading method sequentially performed in the vertical sub-scanning direction in the main scanning direction, and the line processing as follows. That is, in the line processing, third color reception data output by the third color light receiving element at the position of the dot to be read,
The first or second color reception data output by the first color light receiving element or the second color light receiving element at the same position as the third color light receiving element in the main scanning direction, and the coordinates in the main scanning direction are The two second light receiving elements on both sides of the third color light receiving element
The color image data for each dot in the main scanning direction is obtained using the two second or first color reception data output from the color light receiving element or the third color light receiving element.

According to the present invention, since the color image reading method is configured as described above, the color image data of one dot is output from the third color light receiving element disposed at the position of the dot. The received data, the first or second color received data output from the first color light receiving element or the second color light receiving element having the same coordinates as the third color light receiving element, and the coordinates of the coordinates on both sides of the third color light receiving element. It is generated from the two-color light receiving element or the second or first color receiving data output from the first color light receiving element.
Here, for example, if the average value of the two second or first color reception data output from the second color light receiving element or the first color light receiving element at the coordinates on both sides of the third color light receiving element is adopted, The difference between the first color light receiving element and the first or second color receiving data output from the first color light receiving element or the second color light receiving element having the same coordinates as the third color light receiving element is reduced. Thereby, in the color image data, noise generated at the boundary of the black line or the like is reduced.
Also, the third color reception data used when generating color image data for each dot is one. Therefore, the above problem can be solved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A to 1C are configuration diagrams of a CCD image sensor showing an embodiment of the present invention.
The CCD image sensor 10 receives a plurality of blue light data B1, B2, B3,..., Which are first color received data, by receiving blue light, which is a first color of light given from a document to be read. A blue light receiving element 11, a plurality of red light receiving elements 12 for receiving red as a second color and outputting red received data R1, R2, R3,... As second color received data, respectively, and a third color , And green reception data G1, G2, G, which is the third color reception data.
And a plurality of green light receiving elements 13 that respectively output 3, 3,... Are arranged in a first light receiving element array L1 and a second light receiving element array L2 along the main scanning direction 14. Each of the blue light receiving elements 11 is provided in the first light receiving element array L1.
And the red light receiving elements 12 are alternately arranged, and the green light receiving elements 13 are arranged in a line in the second light receiving element array L2. The positional relationship between the first light receiving element array L1 and the second light receiving element array L2 is determined by a control circuit (not shown).
By performing the line processing delayed by the number of lines, it is adjusted to read the image at the same position on the document.

In the CCD image sensor 10, a color pixel CG3 for generating one dot of color image data is provided.
However, one green light receiving element 13, a blue light receiving element 11 or a red light receiving element 12 having the same coordinates in the main scanning direction 14 with respect to the green light receiving element 13, and two blue light receiving elements 11 or red on both sides thereof And a light receiving element 12. That is, color image data for each dot is generated from the four received data. For example, as shown in FIG. 1B, a green light receiving element 13 for outputting green received data G2, a red light receiving element 12 arranged at the same coordinates as the green light receiving element 13 and outputting red received data R1, One color pixel is constituted by two blue light receiving elements 11 arranged adjacent to both sides of the light receiving element 12 and outputting the blue received data B1 and B2, respectively. When it is moved rightward by one dot along the main scanning direction 14, as shown in FIG.
Is a green light receiving element 13 for outputting green reception data G3.
And a blue light receiving element 11 arranged at the same coordinates as the green light receiving element 13 and outputting blue reception data B2, and arranged adjacent to both sides of the blue light receiving element 11 to output red reception data R1 and R2, respectively. Two red light receiving elements 1
2 constitutes a color pixel CG3. As described above, the color pixel CG3 moves to the right by one dot in the main scanning direction, and color image data for each dot is generated from four pieces of reception data obtained by each color pixel CG3.

FIG. 6 is a flowchart of a color image reading method. The color image reading method according to the embodiment of the present invention will be described with reference to FIG. When the number of green light receiving elements 13 in the CCD image sensor 10 is W, the total number of blue light receiving elements 11 and red light receiving elements 12 is W, and the array numbers n corresponding to the coordinates in the main scanning direction are 1 to W, When n is 2 (S20 in FIG. 6), a series of line processes S21 to S27 are started. In the first process S21, it is determined whether or not n is an even number. In the light receiving element array L1 of the image sensor 10 in FIG. 1, when the array number n is an even number, the red light receiving element 12 is arranged there, and the blue light receiving elements 11 are arranged on both sides. Therefore, when n is an even number, the process proceeds to the blue color process S22. When the array number n is an odd number, the blue light receiving element 11 is arranged there, and the red light receiving elements 12 are arranged on both sides. As described above, when n is an odd number, the process proceeds to the red color process S23.

For example, in FIG.
The color pixel CG3 for generating the color image data of the third dot is four light receiving elements that output the received data B1, R1, B2, and G2, and the array number n of the green light receiving element at this time is 2 It is. In this case, the process proceeds to the blue color process S22. In the blue color process S22, the following formulas (1) to (3) are used for the blue received data B1 and B2, the red received data R1 and the green received data G2, and the blue component B ₁ in the color image data of the first dot. , A red component R ₁ and a green component G ₁ . R ₁ = R ₁ (1) G ₁ = G 2 (2) B ₁ = (B ₁ + B 2) / 2 (3) According to the equation (3), the blue component B ₁ is red received data. Blue received data B1 and B output from two blue light receiving elements 11 adjacent to the red light receiving element 12 outputting R1
An average of 2. That is, the blue component B ₁ represents, becomes an intermediate value of the blue received data B1 and B2.

The color pixel CG3 for generating the color image data of the second dot of the original is provided for each received data R
1, B2, R2, and G3 are output, and the array number n of the green light receiving element 13 at this time is 3. In this case, the process proceeds to the red color process S23. In the red color processing S23, the blue component in the second dot color image data is calculated using the following equations (4) to (6) for the blue received data B2, the red received data R1 and R2, and the green received data G3. B ₂ , red component R ₂ and green component G ₂ are determined. R ₂ = (R1 + R2) / 2 (4) G ₂ = G3 (5) B ₂ = B2 (6) According to the equation (4), the red component R ₂ is the blue reception data. Red reception data R1 and R output from two red light receiving elements 12 adjacent to the blue light receiving element 11 that outputs B2
An average of 2. That is, the red component R ₂ becomes an intermediate value of the red data received R1 and R2.

The color image data in dot units obtained in the blue processing S22 or the red processing S23 is output by the color output processing S24. In step S25, n is incremented, and the result is determined in step. If the incremented n has not reached W, the process returns to S21. Thus, the process S21
By repeating steps S25 to S25, the color image data of one line of dots is read while moving one dot at a time in the main scanning direction 14.

FIGS. 7A and 7B are illustrations showing the image and color image data read in FIG. FIG. 7A shows the concept of reading a white original on which the black line 6 is written by the image sensors shown in FIGS. 1A to 1C. In FIG. 7A, as in FIGS. 4A and 5A, the CCD image sensor 10 is used for easy understanding.
The state when reading the black line 6 formed on the top
The black line 6 is shown transparently on the D image sensor 10. FIG. 7B shows the content of the color image data corresponding to FIG. 7A. When trying to read the first (n = 2) dot when reading the original having the black line 6, the blue light receiving element 11 that outputs the blue reception data B2 in the color pixel CG3 reaches the black line 6. blue component B ₁ of the first dot color image data, as in FIG. 7 (b), becomes bright Karui intermediate value of the blue received data B1 and dark blue received data B2. On the other hand, the red light receiving element 12 and the green light receiving element 1 for outputting the red reception data R1 and the green reception data G2.
Since 1 is not approaching the black line 6, the red received data R1 and the green received data G2 are bright. Therefore, the red component R ₁ and the green component G ₁ become bright.

To read the second (n = 3) dot, the blue light receiving element 11 for outputting the blue received data B2, the red light receiving element 12 for outputting the red received data R1, and the green received data for the color pixel CG3 Since the green light receiving element 13 that outputs G3 reaches the black line 6, the red component R in the color image data of the second dot is obtained.
₂ is an intermediate value between the bright red received data R1 and the dark red received data R2. On the other hand, the blue light receiving element 1 that outputs the blue reception data B2 and the green reception data G3
1 and the green light receiving element 13 reach the black line 6,
The blue reception data B2 and the green reception data G3 become dark. Therefore, the blue component B ₂ and the green component G ₂ become dark. When reading the third (n = 4) dot, the blue light receiving element 11, the red light receiving element 12, and the green light receiving element 13 in the color pixel CG3 all reach the black line 6, so that the third dot is read. The blue component B ₃ , the red component R ₃ and the green component G ₃ in the color image data are all darkened.

As described above, in the present embodiment, the color pixel C
G3 is one green light receiving element 13 and this green light receiving element 1
Blue light receiving element 11 or red light receiving element 1 having the same coordinates as 3
2 and two red light receiving elements 12 or blue light receiving elements 11 at the coordinates on both sides of the green light receiving element 13,
Even if the black line 6 is present, the color shift between the red component and the blue component is reduced, and the red and blue noise generated at the boundary of the black line 6 is reduced in the color image data. In addition, the modulation transfer function of the green component that contributes most to the luminance of the color image data can be increased.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, the CCD image sensor 10 includes one light receiving element array L1 and one light receiving element L2 so as to correspond to one row of dots of the document, and relatively moves the light receiving element arrays L1 and L2 in the sub-scanning direction perpendicular to the main scanning direction 14. To read the original, but the light receiving element array L
It is also possible to adopt a configuration having a plurality of columns 1 and L2. In this case, the light receiving element arrays L1 and L2 may be arranged alternately in the sub-scanning direction.

[0021]

As described above in detail, according to the present invention, the third color reception data output by the third color light receiving element at the position of the dot to be read and the coordinates in the main scanning direction are the third color reception data. The first or second color reception data output by the first color light receiving element or the second color light receiving element at the same position as the color light receiving element, and the two second colors whose coordinates in the main scanning direction are on both sides of the third color light receiving element Since the color image data for each dot is obtained by using the two second or first color reception data output from the light receiving element or the third color light receiving element, for example, a reading target including a black line is read. Even if
Noise of color image data generated at the boundary of the black line is reduced. Also, when generating color image data of one dot, only one third color reception data is used, so that the luminance does not deteriorate.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a CCD image sensor showing an embodiment of the present invention.

FIG. 2 shows a first color image reading method used in a conventional first color image reading method.
1 is a configuration diagram of a CCD image sensor.

FIG. 3 shows a second color image reading method used in a second conventional color image reading method.
1 is a configuration diagram of a CCD image sensor.

FIG. 4 is an explanatory diagram of the problem in FIG. 2;

FIG. 5 is an explanatory diagram of the problem in FIG. 3;

FIG. 6 is a flowchart of a color image reading method.

FIG. 7 is an explanatory diagram showing an image to be read and color image data in FIG. 1;

[Description of Signs] 10 CCD image sensor 11 Blue light receiving element 12 Red light receiving element 13 Green light receiving element 14 Main scanning direction CG3 Color pixel B1, B2, B3, ... Blue receiving data R1, R2, R3, ... Red receiving data G1, G2, G3, green receiving data

Claims (1)

[Claims] 1. A plurality of first color light receiving elements for receiving a first color of light given from an object to be read and generating first color reception data, respectively, and receiving a second color of the light to form a first color light receiving element. A plurality of second color light-receiving elements for respectively generating two-color reception data, and a plurality of third color light-receiving elements for receiving a third color of the light and generating third color reception data, respectively. The first color light receiving elements and the second color light receiving elements are alternately arranged in a first arrangement along the main scanning direction, and the plurality of third color light receiving elements are arranged in a second arrangement along the main scanning direction. Using an image sensor having at least one or more element arrays arranged in rows, a color for each dot in the main scanning direction from the first, second, and third color reception data obtained for each dot to be read Line processing for obtaining image data is performed in a sub-process perpendicular to the main scanning direction. In the color image reading method sequentially performed in the scanning direction, in the line processing, the third color reception data output by the third color light receiving element at the position of the dot to be read and the coordinates in the main scanning direction are the third color. The first or second color receiving data output by the first or second color light receiving element, which is the same as the color light receiving element, and the coordinates in the main scanning direction are the two of the two colors on both sides of the third color light receiving element. Color image data for each dot in the main scanning direction is obtained by using two pieces of the second or first color reception data output from the second color light receiving element or the third color light receiving element. Image reading method.