JPH04101565A - Image reader - Google Patents

Abstract

PURPOSE:To simplify the structural configuration of an image reader and to reduce its manufacture cost by discriminating color on the basis of image data smaller than image data that is used to prepare density data for resolution of gradation and by outputting discriminated color data. CONSTITUTION:The first slider unit 21 is moved by a driving means in the direction shown by arrowhead, the second slider unit 25 keeps the conjugate length of light path between the surface of an original and a CCD line sensor unit 31 constant. The CCD line sensor unit 31 is equipped with the first CCD line sensor 32 and the second CCD line sensor 33, in each of which light receiving elements are laid out for each picture element in the direction vertical to paper surface. Analog processing and A/D conversion sections 41 and 51 output density data or red component density data for each picture element, respectively. Red component density data is delayed by an image-formation delay time to correct image dislocation in the subscanning direction.

Description

[Detailed Description of the Invention] The present invention is used, for example, in an image scanner or a copying machine, and reads image data of a document image and outputs density data and color discrimination data for each pixel. The present invention relates to an image reading device.

Traditionally, as disclosed in JP-A-58-186254, for example, original images are read with mutually different color characteristics, and density data indicating the density of each pixel and color distinction are generated. An image reading device that outputs color discrimination data is known.

This type of image reading device detects the density of each pixel using, for example, a CCD sensor and outputs density data. Further, for example, the density of only the red component of each pixel is detected by a CCD sensor equipped with a red light transmission filter, and the color of each pixel is determined based on the obtained red component density data and the density data. It is supposed to be done.

More specifically, for example, as shown in FIG. 6, density data and red component density data having the same number of bits as this density data, that is, the same gradation resolution, are stored in the MAP-ROM 92 of the color discrimination section 91. It is now entered as an address. This MAP-ROM92 has
A color discrimination map is stored in advance, and data corresponding to an address is read out as color discrimination data, thereby determining the color of each pixel.

However, in the conventional image reading device described above, color discrimination is performed based on density data and red component density data having the same gradation resolution as this density data. MAP-ROM 92 requires large storage capacity. Also, from the CCD sensor to MAP-ROM9
In addition, the number of wires between 2 and 2 increases, and if a delay element or frame memory is used to synchronize the density data with the red component density data, for example, this delay element also requires a large storage capacity. shall be.

Therefore, the structure of the image reading device tends to be complicated and large-scale, and the manufacturing cost is also high.

In view of the above points, the present invention aims to provide an image reading device that can simplify the configuration of the device and reduce manufacturing costs.

In order to achieve the above object, the present invention provides an image reading device that reads an original image and outputs density data indicating the density of each pixel and color discrimination data indicating the different colors.
Image reading means that reads a document image with at least two types of color characteristics and outputs image data used for generating density data and color discrimination data, and gradation resolution is used for generating density data. The present invention is characterized by comprising a color discrimination means for outputting color discrimination data based on image data smaller than the image data.

According to the above configuration, the color discrimination means discriminates the color based on the image data whose gradation resolution is smaller than the image data used to generate the density data, and outputs the color discrimination data. do.

EMBODIMENT OF THE INVENTION One embodiment of the present invention will be described based on FIGS. 1 to 5.

FIG. 1 is a cross-sectional front view showing the configuration of the image reading device, FIG. 2 is a block diagram showing the configuration of the signal processing section 35, FIG. 3 is a block diagram showing the configuration of the delay memory section 61, and FIG. 4 is a color Block diagram showing the configuration of the determination unit 71, FIG. 5(a)-
(C) is an explanatory diagram showing an example of a color discrimination map.

In FIG. 1, 11 is the document table glass, J2 is the shading correction reflector, 21 is the first slider unit,
22 is an exposure lamp, 23 is a lamp light reflecting mirror, and 24 is a first
Mirror 25 is a second slider unit, 26 is a second mirror, 27 is a third mirror 28 is an optical lens, 31 is a CCD
A line sensor unit, 35 is a signal processing section, and D is a document. In FIG. 2, 32 is a first CCD line sensor, 33 is a second CCD line sensor, 34 is a red light transmission filter, 41 and 51 are analog processing/A/D conversion sections, 42 and 52 are shading correction sections, and 61 71 is a color discrimination section, 81 is an electric scaling section, and 82 is a color discrimination data/density data correction section.

The first slider unit 21 is provided so as to be moved in the direction shown by the arrow (hereinafter referred to as the sub-scanning direction) by driving by a driving means (not shown). The second slider unit 25 moves in synchronization with the first slider unit 21 to keep the conjugate length of the optical path from the document surface to the CCD line sensor unit 31 constant. That is, it moves in the sub-scanning direction at 1/2 the speed of the first slider unit 21. Further, the optical lens 28 is configured to form an image of the document onto the light receiving surface of the CCD line sensor unit 31.

Each of the CCD line sensor units 31 includes a first CCD line sensor 32 in which light receiving elements for each pixel are arranged in a direction perpendicular to the paper (hereinafter referred to as the main scanning direction).
and a second CC'D line sensor 33 are provided. A red light transmitting filter 34 is provided on the light receiving surface side of the second CCD line sensor 33. That is, the first CCD line sensor 32 detects the density of all color components of each pixel, while the second CCD line sensor 32 detects the density of all color components of each pixel.
The D line sensor 33 is configured to detect the density of only the red component of each pixel.

Here, the image of the portion of the document imaged on the second CCD line sensor 33 is
, the image is formed with a delay of a time (hereinafter referred to as imaging delay time) corresponding to the distance between the second CCD line sensor 33 and the first CCD line sensor 32 and the sub-scanning speed of the first slider unit 21. Therefore, the first CCD line sensor 32 receives a line clock signal (not shown) whose timing is delayed by the imaging delay time as compared to the 12 ccD line sensor 33, and a reference clock signal.

The analog processing/A/D conversion sections 41 and 51 each have
It performs analog processing such as amplification of the analog signals output from the first and second CCD line sensors 32 and 33, and converts them into 8-bit digital signals, and outputs density data of each pixel or red component density data. It has become.

The shading correction units 42 and 52 correct density data or red component density data based on signals output from the first and second CCD line sensors 32 and 33 when the shading correction reflection plate 12 is exposed, respectively. This is done to correct variations in light-receiving sensitivity, etc.

As shown in FIG. 3, the delay memory section 61 is provided with a delay memory 62 and an address control section 63, and delays the red component density data by the imaging delay time, so that the delay memory 61 can be used for the first and second CCD lines. Sensor 32/3
3, the deviation in the sub-scanning direction of the original image is corrected. Here, only the upper six bits of the 8-bit red component density data output from the shading correction section 52 are input to the delay memory 62.

The color discrimination section 71 includes a delay memory section 6 as shown in FIG.
A selector 73 is provided and a MAPROM 72 to which the upper 6 bits of the 6-bit red component density data outputted from the shading correction section 1 and the 8-bit density data outputted from the shading correction section 42 is input as an address. It is configured.

The above MAP-ROM 72 contains information in advance as shown in FIG. 5 (a).
) to (c), three types of color discrimination maps for determining whether a pixel is a black pixel or a color pixel are stored and input in correspondence with red component density data and density data. Depending on the address, three types of color discrimination data are output by focusing three of the four bits of output data. The selector 73 is configured to selectively output any one of the three types of color discrimination data described above based on a control signal (not shown).

The electric magnification unit 81 performs predetermined processing on the color discrimination data output from the color discrimination unit 71 and the density data output from the shading correction unit 42 to produce an image that is enlarged or reduced in the main scanning direction. It is designed to convert to data. Note that enlargement or reduction in the sub-scanning direction can be achieved by changing the scanning speed of the first slider unit 21.
It is about to take place.

The color discrimination data/density data correction unit 82 performs image processing such as correction of image quality deterioration caused by noise, color inversion, and gradation characteristic conversion.

In the above configuration, reading of the original image is performed as follows.

First, when the first slider unit 21 and the second slider unit 25 start scanning in the sub-scanning direction, the first slider unit 21 and the second slider unit 25 start scanning in the sub-scanning direction.
An image of the document is formed on the second CCD line sensors 32 and 33.

Therefore, the second CCD line sensor 33 reads one line of image each time a line crotter signal is input, and outputs an analog signal corresponding to the density of the red component of each pixel each time a reference clock signal is input. . Further, the first CCD line sensor 32 similarly outputs an analog signal corresponding to the density of all color components of each pixel with a delay from the second CCD line sensor 33 by the imaging delay time.

The analog signals output from the second CCD line sensor 33 and the first CCD line sensor 32 are
Analog processing and A/D conversion are performed in analog processing/A/D conversion units 51 and 41, and output as 8-bit red component density data or density data, and shading correction is performed in shading correction units 52 and 42. .

Of the total 8 hints, only the top 6 hints of the red component density data outputted from the shading correction section 52 are input to the delay memory 62 of the delay memory section 61, delayed by the imaging delay time, and then sent to the color discrimination section 71. Output. More specifically, the above delay is performed as follows.

The address control section 63 receives a write address designation signal (hereinafter referred to as the WA multiplication signal) which is incremented every time the reference black signal is input.

) is output. The delay memory 62 stores the red component density data output from the shading correction section 52 in a storage area designated by this WA multiplied signal.

The address control unit 63 also controls the imaging delay based on a deviation amount signal indicating the deviation amount between the second CCD line sensor 33 and the first CCD line sensor 32, a magnification signal indicating the reading magnification of the original image, and a line clock signal. A read address designation signal (hereinafter referred to as RA) indicating the same address as the above-mentioned WA multiplied signal is output with a time delay. The delay memory 62 reads out the stored red component density data from the storage area designated by this RA multiplied signal and outputs it.

That is, the red component density data of the same pixel is outputted from the delay memory 62 at a timing synchronized with the density data outputted from the shading correction section 42 .

Of the 6-bit red component density data output from the delay memory 62 and the 8-pin density data output from the shading correction section 42, the upper 6 bits of density data are input to the MAP-ROM 72 as an address. Therefore, the MAP-ROM 72 outputs three types of color discrimination data based on the color discrimination map, and outputs three types of color discrimination data to the selector 73.
selectively outputs one type of color discrimination data.

For example, when the value of the red component density data is large and the value of the density data is small, color discrimination data indicating that the pixel is red is output. If the data value is large, color discrimination data indicating black is output.

More specifically, for example, as shown in Table 1 below, the value of the 8-focus red component density data output from the shading correction unit 52 is 01101010 to 011 in binary.
10011, when the value of the 8-bit density data output from the shading correction unit 42 is 01000110, the red component density data input to the color discrimination unit 71;
and concentration data values are respectively 01101 in binary
0 to 011100 and 010001, and the pixel is determined to be black. Similarly, if the value of the red component density data output from the shading correction unit 52 is in binary numbers from 01110100 to 01111010, the value of the red component density data input to the color discrimination unit 71 is in binary numbers. 011101 to 011110, and the pixel is determined to be red.

In Table 1, while the density data output from the image reading device has 256 gradations, color discrimination is performed based on red component density data and density data of 64 gradations, respectively. In this case, as shown by the dotted line in FIG. 5(a), compared to the case where color discrimination is performed based on red component density data and density data of 256 gradations,
Although the color discrimination accuracy deteriorates to some extent, when the density data has 256 gradations, the influence of this degree of color discrimination error on image quality can be virtually ignored visually.

On the other hand, as described above, by setting the red component density data delayed by the delay memory section 61 to 6 bits, the storage capacity required for the delay memory 62 is reduced to 6/8=3/ of the case of 8 bits. Reduced to 4. Furthermore, by setting the red component density data and the density data input to the color discrimination section 71 to 6 bits, the storage capacity required for the MAP-ROM 72 is (2'X2'')/(2'X
2'')=1/16.Furthermore, the scale of peripheral circuits and the number of wirings are also reduced.

The color discrimination data output from the color discrimination section 71 and the eight density data output from the shading correction section 42 are input to an electric scaling section 81, and are subjected to data compression and interpolation in the main scanning direction as necessary. etc., conversion to data corresponding to a reduced or enlarged image is performed.

The color discrimination data and density data outputted from the electric scaling unit 81 are subjected to image processing such as color inversion and gradation characteristic conversion in a color discrimination data/density data correction unit 82, and then output. .

For example, when the color discrimination data and density data obtained by the image reading device are used in an electrophotographic image forming device equipped with a plurality of print heads, the print head corresponding to the toner color is It is used for switching and modulating the brightness of laser beams.

In this embodiment, an example using two CCD line sensors 32 and 33 has been described, but the invention is not limited to this.
It is also possible to use three or more detection elements to detect the concentration of other color components such as a blue component. Further, each of the detection elements may be provided with a filter, and the obtained density data for each color component may be combined to generate density data, or the density data of a predetermined color component may be output as density data. It may also be something that has been made into

Alternatively, the density of each color component, etc. may be detected by using one detection element and performing scanning multiple times by switching filters. In this case, it is necessary to provide a frame memory, but the storage capacity required for this frame memory can still be kept small.

Alternatively, the formed image may be divided using a half mirror or the like, and density data without delay may be obtained in one scan. In this case, it may not be necessary to provide a delay memory, but even in such a case, the MAP-ROM
Similar effects such as being able to reduce the storage capacity of 72 can be obtained.

Further, the CCD line sensors 32 and 33 are connected to the optical lens 2.
The sensor is not limited to one that reads an image formed through the sensor 8, and may be a contact type line image sensor.

Further, the color discrimination performed by the color discrimination section 71 is performed by the fifth
As shown in FIGS. (a) to (c), the determination is not limited to only whether a pixel is a color pixel or a black pixel, but it is also possible to determine whether a pixel is a red pixel, a blue pixel, a black pixel, or the like.

Furthermore, as in this embodiment, the analog signal from the second CCD line sensor 33 is A/D converted into 8-bit digital data, and among the data obtained by performing shading correction on this 8-bit digital data, By using only 6 bits for color discrimination, it is possible to perform color discrimination using data that has been shading corrected with high precision. The processing may be performed using 6-bit data.

(2) As described above, according to the present invention, the color discrimination means outputs color discrimination data based on image data whose gradation resolution is smaller than the image data used to generate density data. By including this, it is possible to simplify the configurations of the color discrimination means and peripheral circuits, and to reduce manufacturing costs, without substantially deteriorating visual image quality.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional front view showing the configuration of the image reading device, Figure 2 is a block diagram showing the configuration of the signal processing unit, Figure 3 is a block diagram showing the configuration of the delay memory unit, and Figure 4 is the color discrimination unit. 5(a) to 5(c) are explanatory diagrams showing examples of color discrimination maps, respectively. FIG. 6 is a block diagram showing the structure of a color discrimination section in a conventional image reading device. . 31... CCD line sensor unit, 32... First CCD line sensor, 33... Second CCD line sensor, 34... Red light transmission filter, 61... Delay memory section, 62... Delay Memory, 71...Color discriminating unit, 72...MAP OM Patent applicant Minolta Camera Co., Ltd. Color f-1 A straight number (10 digits) Figure 5 (b)

Claims (2)

[Claims] (1) In an image reading device that reads a document image and outputs density data indicating the density of each pixel and color discrimination data indicating the type of color, the document image is read with at least two types of color characteristics and the density is determined by reading the document image using at least two types of color characteristics. image reading means for outputting image data used to generate data and color discrimination data; An image reading device comprising: color discrimination means for outputting a color discrimination means for outputting a color discrimination means for outputting a color discrimination means for outputting a color discrimination means for outputting a color discrimination means for outputting a color discrimination means for outputting a color discrimination means for outputting a color discrimination means; (2) In an image reading device that reads a document image and outputs density data indicating the density of each pixel and color discrimination data indicating the color distinction, the device is arranged in parallel at a predetermined interval, and each reads the document image from each other. Multiple line image sensors read with different color characteristics and output image data that is used to generate density data and color discrimination data, and the gradation resolution used to generate color discrimination data is the same as that of density data. An image reading device comprising: a delay means for delaying image data smaller than the image data used for generation; and a color discrimination means for outputting color discrimination data based on the image data output from the delay means. Device.