JP2003264669A - Color image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accelerate a read speed while suppressing the deterioration of a picture quality when reading a color image. <P>SOLUTION: A photodetector 35 is provided with a filter in which a Y filter for transmitting a red component and a green component and a C filter for transmitting the green component and a blue component are located corresponding to pixels. Thus, when a G light source 31G is turned on, a G signal is outputted from the photodetector 35. Besides, when an M light source 31M is turned on, an R signal is outputted in the case of the Y filter and a B signal is outputted in the case of the C filter. With respect to the B signal to be lacked in the case of the Y filter and the R signal to be lacked in the case of the C filter, a (b) signal corresponding to the B signal and an (r) signal corresponding to the R signal are obtained by utilizing interpolation methods such as maximum proximity, weighted mean and three-dimensional convolution. Thus, R, G and B signals can be obtained regardless of the status of the filter. <P>COPYRIGHT: (C)2003,JPO

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 apparatus for sequentially lighting a plurality of light sources of different colors to illuminate a subject, and receiving reflected light to obtain a color image.
In particular, the present invention relates to a color image reading device which has a high reading speed.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus such as a color facsimile machine, a color image scanner, a color copying machine and a combination machine of these, a red light source is used as a color light source.
Green and blue light sources are used to photoelectrically convert reflected light from a subject such as a document by a light receiving element to acquire image data.

At this time, the subject is read by a line-sequential reading method, such as red (red), green (green), and blue (blue).
A color image is separated and read by alternately turning on the three light sources of e) at one storage time interval.

Hereinafter, the three light sources of red, green, and blue will be referred to as R light source, G light source, and B light source, and the color information (color signal) obtained by color separation will be described as R signal, G signal, and B signal, respectively. .

[0005]

However, when photographing an object using an area sensor such as an endoscope,
Since three frames of R signal, G signal, and B signal are required to obtain one color image, there is a problem that the dynamic resolution is lowered.

When a subject is read using a line sensor such as a scanner, the R light source, the G light source, and the B light source are sequentially turned on to obtain a color image, and scanning is performed three times accordingly. Therefore, it is necessary to obtain a color signal for one line and it is difficult to increase the reading speed.

Of course, it is possible to increase the reading speed by increasing the scanning speed, but in such a case, the image quality deteriorates.

Therefore, an object of the present invention is to provide a color image reading apparatus capable of increasing the reading speed while suppressing the deterioration of the image quality and the decrease of the dynamic resolution.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 illuminates a subject by switching a plurality of light sources, and the reflected light is received by a light-receiving element to obtain a color signal of the subject. In a color image reading device for reading a color image by separately obtaining the first color, the second color, and the third color, and synthesizing the three colors, the light source includes a first light source having a different emission color and a first light source. It consists of two light sources and
When the light receiving element illuminates the subject with the first light source,
A first spectral sensitivity characteristic that allows reception of only reflected light of the same color as that of the first light source, and two other colors out of the three colors that cannot be received by the first spectral sensitivity characteristic when the subject is illuminated by the second light source. And a second spectral sensitivity characteristic that enables reception of the reflected light of ## EQU1 ## and that the reading speed is increased while suppressing deterioration of image quality.

In the invention according to claim 2, the first light source is the first
The second light source emits light of a color, the second light source emits light including the second color and the third color, and the first spectral sensitivity characteristic allows the first color and the second color to receive light, and the second spectral It is characterized in that the sensitivity characteristic is formed so that the first color and the third color can be received.

The invention according to claim 3 is the first light source and the second light source.
When the color light is read by illuminating the object by switching between the light source and the light source and reading the color image, the cycle of lighting the first light source and the second light source as one cycle is repeated, or the first light source,
It is characterized in that a cycle of turning on the second light source and the first light source as one cycle is repeated.

According to a fourth aspect of the present invention, when a light source is turned on to obtain a color image of a subject, the subject is line-scanned to obtain a color signal, and at this time, the first light source is turned on to obtain a color signal. The scanning speed is different between the case of obtaining the color signal and the case of obtaining the color signal by turning on the second light source.

The invention according to claim 5 is characterized in that only one of the first light source and the second light source is turned on so that only a specific color signal can be acquired.

In the invention according to claim 6, the first color is green.
The second color is red or blue, and the third color is blue or red.

According to a seventh aspect of the present invention, the light receiving ratio when the first color and the second color are received by the first spectral sensitivity characteristic and the first color and the third color are received by the second spectral sensitivity characteristic. The feature is that they are set to the same ratio.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a facsimile apparatus equipped with a color image reading apparatus according to the present invention.

The facsimile apparatus has a control unit 1 for controlling the system, a memory unit 2 used for storing set values and image data read or received, and a reading unit 3 for converting a subject into read image data. A recording unit 4 for outputting output at the time of copying and a transmission image, an operation display unit 5 having a key SW, a display unit, and the like, a communication unit 6 for performing communication control of lines and the like,
An encoding / decoding unit 7 having a function of compressing / decompressing image data transmitted / received by facsimile is provided.

FIG. 2 is a diagram showing a schematic configuration of the reading unit 3,
Reference white plate 1 arranged under the contact glass 11
2, light source 13, first carriage 14, second carriage 1
5, the optical system 16, the light receiving element 17 and the like are provided, and the subject P placed on the contact glass 11 is read.

The first carriage 14 and the light source 13 are integrally formed, and the scanner motor 19 causes the first carriage 14 and the second carriage 15 to contact the contact glass 1.
It can move in parallel to 1.

As a result, the light emitted from the light source 13 is applied to the subject P, and the reflected light is reflected by the first carriage 14,
The light enters the optical system 16 via the second carriage 15.

Then, the light is condensed by the optical system 16 and incident on the light receiving element 17, and the light is converted by the light receiving element 17 to read an image. The reference white plate 12 is used when the image processing unit 23, which will be described later, performs shading correction.

FIG. 3 shows light sources 13 (13a-1 to 13a) of different colors.
FIG. 3 is a block diagram showing a schematic configuration of a light source switching type reading unit 3 that switches 3c) to perform color reading.

The light source 13 is switched line by line or frame by frame, whereby the light reflected from the object P is photoelectrically converted by the light receiving element 17 and converted into a digital signal by the A / D converter 18. It is temporarily stored in the image memory unit 24 via the image processing unit 23.

When the color signals of three colors of R, G and B are accumulated in the image memory unit 24, the image memory unit 2 concerned.
The image data of the subject P read out from No. 4 to the image processing unit 23 and combined is output via the bus 26.

The light source control section 21 controls the lighting of the light source 13, and the light receiving element control section 22 controls the light receiving element 17.
The scanner motor 19 is controlled by the motor controller 25.
By each.

FIG. 4 is a diagram showing the relationship between the light source 13 which is turned on for each line / frame in such a color image reading apparatus, the color signal at that time, and the image data.

In order to obtain a color signal for one line / frame, one line / frame is used for the R light source 13a, one line / frame is used for the G light source 13b, and one line / frame is used for the B light source 13c. Need to read.

For this reason, the dynamic resolution is lowered and the reading speed is lowered. Therefore, in the present invention, the light sources 31 to 33 and the light receiving element 35 as shown in FIG. 5 are used.

FIG. 5 is a diagram showing a schematic configuration of the light sources 31 to 33 and the light receiving element 3, and FIG.
As the light source 31 for irradiating
A case is shown in which an M (magenta) light source 31M including G and a red component and a blue component is used.

FIG. 5B shows a light source 3 for illuminating the subject P.
2, R light source 32R, G light source 32G, B light source 32B
Shows the case of using. In this configuration, the R light source 3
By turning on the 2R and B light sources 32B at the same time, the same operation as that of the M light source 31M in FIG.

FIG. 5C shows a light source 3 for illuminating the subject P.
3, W including all red, green and blue components
A (white) light source 33W is used, and G filters 36G and M as shown in FIG. 5D are provided between the W light source 33W and the subject P.
By arranging the filter 36M of the filter 36M and appropriately switching between the G filter 36G and the M filter 36M, it is possible to obtain the same operation as in FIG. 5A.

With the light sources 31 to 33, the object P
The reflected light is condensed by the optical system 16 and received by the light receiving element 35. At this time, the light receiving element 3
As shown in FIG. 6, Y (yellow) filters 37Y and 38Y that transmit a red component and a green component, and
C (cyan) filter 3 that transmits the green and blue components
7C and 38C are provided correspondingly to the pixels, and filters 37 and 38 are provided in the same number (the same ratio of the light reception ratio).

6A shows a filter 37 when the light receiving element 35 forms a line sensor, and FIG. 6B shows a filter 38 when the light receiving element 35 forms an area sensor.
The square areas in each of the filters 37 and 38 correspond to the pixels in each light receiving element 35.

Next, the color signal output from the light receiving element 35 when the light source 31 is turned on will be described based on the configuration shown in FIG. 6 (a). In this case, the light receiving element 35 forms a line sensor.

First, when the G light source 31G is turned on, the reflected light from the subject P is green component light, so that the filter 37 is set to Y.
Regardless of whether it is the filter 37Y or the C filter 37C, the reflected light passes through the filter 37 and is received by the light receiving element 3
The light is received by 5, and a G signal is output (see FIG. 7A).

When the M light source 31M is turned on, the reflected light from the subject P is a mixture of red and blue components. Therefore, when the filter 37 is the Y filter 37Y, the red component of the reflected light passes through the filter 37, is received by the light receiving element 35, and outputs the R signal.

On the other hand, when the filter 37 is the C filter 37C, the blue component of the reflected light is transmitted through the filter 37 and is received by the light receiving element 35, and the B signal is output (see FIG. 7B). .

As described above, the G signal is output in the case of the G light source 31G, but the filter 37 is output in the case of the M light source 31M.
Only one of the R signal and the B signal is output depending on the difference.

In the present invention, as shown in FIG. 8, the interpolation method such as the closest method, the weighted average method, and the three-dimensional convolution method is used, and when the R signal is output, it is converted into the B signal by interpolation. By obtaining the r signal corresponding to the R signal by interpolating the corresponding b signal when the B signal is output, the R, G, and B signals are obtained regardless of the state of the filter 37.

For example, the filter 37 is the C filter 37C.
When the B signal is output and the B signal is output, in order to obtain the b signal by performing the complement by the nearest neighbor method in FIG. 8, the average value of the adjacent B signals is obtained and used as the b signal. r
The signal can be similarly obtained.

The light source for each line / frame thus obtained and the output from the light receiving element 35 (color signal)
9 and the relationship of the image data obtained by combining these.
Shown in.

As described above, the image data for 1 line / frame is obtained by 1 line / frame for the G light source 31G and 1 line / frame for the M light source 31M including the red and blue components, for a total of 2 lines / frame. Therefore, the color image can be read at high speed while suppressing the deterioration of the image quality.

Next, a second embodiment of the present invention will be described with reference to the drawings. The same components as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

In the above description, the G light source 31G and the M light source 31
The case where the cycle in which M and M are sequentially switched and turned on is set to one cycle has been described. On the other hand, in the present embodiment, the cycle in which the G light source 31G, the M light source 31M, and the G light source 31G are sequentially switched and turned on is one cycle.

FIG. 10 shows the G light source 3 in such a cycle.
It is the figure which showed the color signal output from the light receiving element 35 when 1G, M light source 31M, and G light source 31G are lighted. 10A shows when the G light source 31G is turned on for the first time, FIG. 10B shows when the M light source 31M is turned on, and FIG. 10C shows when the G light source 31G is turned on for the second time. Shows.

When the M light source 31M is turned on, interpolation as shown in FIG. 8 is performed within one line or one frame. However, for the line / frame of the G_2 signal, the R signal and the B signal can be obtained for only one line / frame, so that a shortage occurs.

Therefore, the lines / frames of the insufficient R signal and B signal are obtained by interpolating between lines or frames as shown in FIG. As the interpolation method, the nearest neighbor method, the weighted average method, the three-dimensional convolution method, etc. can be used.

FIG. 12 shows the relationship among the lighting light source, color signal, and image data for each line / frame obtained in this way.

As described above, the image data for one line / frame has a total of 1.5 lines / frame, that is, one line / frame by turning on the G light source 31G and 0.5 line / frame by turning on the M light source 31M. Therefore, the color image can be read at high speed while suppressing the deterioration of the image quality.

Next, a third embodiment of the present invention will be described with reference to the drawings. The same components as those of the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted as appropriate.

In the color image reading apparatus using the light receiving element 35 of the line sensor, the reading resolution in the sub scanning direction can be changed according to the moving speed of the scanner motor 19.

FIG. 13 shows a case where the light source 32 is switched on for each frame by using the light receiving element 35 of such a line sensor, when the G light source 31G is turned on for reading and when the M light source 31M is turned on for reading. The color signal output from the light receiving element 35 when the reading speed at the time is set to the ratio of 1: 2 is shown.

When the M light source 31M is turned on, the R signal and the B signal are deficient both within and between lines, so the interpolation as shown in FIG. 8 is used to compensate for the deficiency within one line. Similarly, between lines, the shortage is compensated by using the interpolation as shown in FIG.

FIG. 14 shows the relationship between the lighting light source, the color signal and the image data for each line / frame thus obtained.

As described above, for the image data for one frame, the G light source 31G is turned on for one frame, and the M light source 31
By turning on M, it is possible to obtain 0.5 frames for a total of 1.5 frames, and it becomes possible to read a color image at high speed while suppressing deterioration of image quality.

In each of the embodiments described above, the case where a color image of a subject is acquired has been described, but it goes without saying that even with such a configuration, it is possible to acquire image data of a single color. .

In such a case, for example, the G light source 31G
1 to turn on only and acquire green image data.
1 by turning on the G light source for line / frame
Since line / frame image data is obtained, the relationship among the lighting light source, color signal, and image data for each line / frame is as shown in FIG.

[0058]

As described above, according to the present invention,
A light source including a first light source and a second light source having different emission colors is provided, and when a subject is illuminated by the first light source,
A first spectral sensitivity characteristic that allows only reflected light of the same color as that of the first light source to be received, and two other colors out of the three colors that cannot be received by the first spectral sensitivity characteristic when a subject is illuminated by the second light source. Since the light receiving element having the second spectral sensitivity characteristic that enables the reception of the reflected light is provided, the reading speed can be increased while suppressing the deterioration of the image quality, and the convenience is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a facsimile apparatus applied to an explanation of an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a reading mechanism in a reading unit.

FIG. 3 is a block diagram showing a schematic configuration of a reading unit.

FIG. 4 is a diagram showing a relationship among a light source, a color signal, and image data which are turned on for each line / frame when three light sources are sequentially turned on by a line-sequential reading method.

FIG. 5 is a diagram showing a schematic configuration of a light source and a light receiving element according to the present invention, where (a) includes a G light source and an M light source, and (b).
FIG. 4A is a diagram showing a configuration of a filter provided when R light source, G light source, and B light source are provided, FIG. 7C is a case where W light source is provided, and FIG.

FIG. 6 is a diagram showing a configuration of a filter provided in the light receiving element, in which (a) is a case where the light receiving element is a line sensor,
(B) is a case where the light receiving element is an area sensor.

FIG. 7 is a diagram showing a color signal output from a light receiving element when the G light source and the M light source are set to one cycle, and (a) shows G
When the light source is turned on, (b) is when the M light source is turned on.

FIG. 8 is a diagram illustrating complementation of color signals within a line.

FIG. 9 is a diagram showing a relationship among a light source to be turned on, a color signal, and image data for each line / frame when the G light source and the M light source are set to one cycle.

FIG. 10 is a diagram showing a color signal output from a light receiving element when the G light source, the M light source, and the G light source constitute one cycle,
(A) shows the case where the G light source is turned on, (b) shows the case where the M light source is turned on, and (c) shows the case where the second G light source is turned on.

FIG. 11 is a diagram illustrating color signal complementation between lines.

FIG. 12 is a diagram showing a relationship among a G light source, an M light source, a light source that is turned on for each line / frame, a color signal, and image data when the G light source is one cycle.

FIG. 13 is a color signal when the light source of the light source of the line sensor is switched on for each frame and the reading speed is changed when the G light source is turned on for reading and when the M light source is turned on for reading. Is shown.

FIG. 14 is a diagram showing a relationship among a lighting light source, a color signal, and image data for each line / frame in the case of FIG.

FIG. 15 is a diagram showing a relationship among a lighting light source, a color signal, and image data for each line / frame when only G light source is turned on to obtain image data.

[Explanation of symbols]

1 control unit 2 memory section 3 reading section 14 First carriage 15 Second carriage 16 Optical system 19 Scanner motor 21 Light source controller 22 Light receiving element controller 23 Image Processor 24 Image memory section 25 Motor control unit 31-33 light source 31G G light source 31MM Light source 32RR light source 32G G light source 32B B light source 33W W light source 35 light receiving element 36-38 filters 36G G filter 36MM Filter

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Claims (7)

[Claims] 1. Color information of a subject is separated into three colors of a first color, a second color, and a third color by switching a plurality of light sources and irradiating the subject and receiving the reflected light by a light receiving element. In the color image reading device that reads a color image by combining these, the light source is composed of a first light source and a second light source having different emission colors, and the light receiving element is the first light source. When the subject is illuminated by one light source, only the first spectral sensitivity characteristic is set so that only the reflected light of the same color as that of the first light source can be received, and among the three colors when the subject is illuminated by the second light source. And a second spectral sensitivity characteristic for enabling reception of reflected lights of other two colors which cannot be received by the first spectral sensitivity characteristic. 2. The first light source emits the light of the first color, the second light source emits light containing the second color and the third color, and the first spectral sensitivity characteristic is 2. The color image reading device according to claim 1, wherein the first color and the second color can be received, and the second spectral sensitivity characteristic is formed so as to receive the first color and the third color. apparatus. 3. A cycle in which the first light source and the second light source are turned on as one cycle when the first light source and the second light source are switched on and illuminated to illuminate a subject to read a color image. 3. The color image capturing apparatus according to claim 1, wherein the color image capturing apparatus according to claim 1 or 2, wherein the color image capturing apparatus repeats a cycle in which the first light source, the second light source, and the first light source are turned on. 4. When a color image of a subject is obtained by turning on the light source, the subject is line-scanned to obtain color information, and at this time, the first light source is turned on to obtain color information. 4. The color image reading apparatus according to claim 1, wherein the scanning speed can be set to different speeds when the second light source is turned on and color information is obtained. 5. One of the first light source and the second light source
5. Only one of them is turned on so that only specific color information can be acquired.
The color image reading device described in the item. 6. The first color is green, the second color is red,
6. The color image reading device according to claim 1, wherein the third color is blue, the first color is green, the second color is blue, and the third color is red. 7. The light receiving ratio for receiving the first color and the second color according to the first spectral sensitivity characteristic and the same light receiving ratio for receiving the first color and the third color according to the second spectral sensitivity characteristic are set. 7. The color image reading device according to claim 1, wherein the color image reading device is provided.