JPH04287482A - Picture reader - Google Patents

Abstract

PURPOSE:To prevent mis-discrimination of a color when discriminating whether or not a color is a specific color with respect to the picture reader used for a picture input means for a digital copying machine or a filing system. CONSTITUTION:The picture reader is provided with a color image sensor 16 separating an original picture into at least three colors or more, reading the color and outputting a picture data corresponding to each separated color, designation means 71, 72 designating a specific color, a data selection means 211 to select a picture data corresponding to two colors or over from picture data DR, DG, DB outputted from the color image sensor 16 in response to the designated color designated by the designation means 71, 72 and a color discrimination means 213 to discriminate a color of each picture element based on each picture data selected by the data selection means 211.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device used as an image input means for a digital copying machine or a filing system.

A digital copying machine is composed of an image reading device that reads an image of a document, and a page printer that prints the read image.

Conventionally, in digital copying machines,
For example, it is possible to print in multiple colors of black and red, and there is also a function to reproduce and copy the colors of a two-color original image, black and red, and a function to reproduce the blue part of a two-color original image, for example, black and blue. Some have image editing and copying functions such as printing in red.

[0004] In such a copying machine, the image reading device discriminates the color of the original image for each pixel, and the color discrimination information is output to the page printer in synchronization with the monochrome image information obtained by reading the original image. Ru.

[0005]

2. Description of the Related Art Generally, the color of an image is determined by color-separating the scanning light for an original image using a spectroscopic means such as a filter or prism, and comparing the intensity of the light of each separated color.

In a conventional image reading device, as shown in Japanese Patent Publication No. 62-26634, two separate photoelectric conversion means are arranged at predetermined positions, and each separated color is separated into two colors. The scanning light is made incident on each photoelectric conversion means, and color discrimination is performed to determine whether the color of each pixel is a specific color or not based on the relative ratio of the output signal level of each photoelectric conversion means.

[0007]

Conventionally, regarding information for color discrimination, the color corresponding to the information has been fixed. That is, during color discrimination, information corresponding to the same separated color (usually digital data obtained by quantizing a photoelectric conversion signal) is always input to the color discrimination means.

For this reason, especially when a plurality of colors can be selected as a specific color to be discriminated, that is, a color to be distinguished from other colors, data input to the color discriminating means corresponds to each specific color. Since the range of values for each color is small, it is difficult to distinguish colors, and there is a possibility that misidentification may occur. If misjudgment occurs, a desired copy image cannot be obtained due to the occurrence of color ghost or the like.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention aims to prevent erroneous color discrimination for determining whether or not a particular color is present.

0010

[Means for Solving the Problems] In order to solve the above-mentioned problems, an apparatus according to the invention according to claim 1 reads a document image separated into at least three colors, and obtains image data corresponding to each separated color. a color image sensor to output, a designation means for designating a specific color, and a color image sensor for each of two or more colors from among the image data output from the color image sensor according to the designated color designated by the designation means; The apparatus includes data selection means for selecting corresponding image data, and color determination means for determining the color of each pixel of the document image based on each image data selected by the data selection means.

The apparatus according to the second aspect of the invention has three photoelectric conversion element arrays arranged parallel to each other in the sub-scanning direction of document scanning, and reads the document image by separating it into three colors. a color image sensor that outputs image data corresponding to color separation; a designation unit that designates a specific color; and a color image sensor that outputs image data corresponding to color separation; data selection means for selecting image data corresponding to one of the photoelectric conversion element arrays, the image data selected by the data selection means, and an image corresponding to the photoelectric conversion element array in the center row in the sub-scanning direction; A data transmission delay means for adjusting the transmission timing relative to the data, and a color of each pixel of the document image is determined based on two-color image data whose transmission timing has been adjusted by the data transmission delay means. and color discrimination means.

[0012] In the apparatus according to the third aspect of the invention, the color image sensor has R (red), G (green),
A one-chip full-color image sensor has three photoelectric conversion element arrays corresponding to B (blue), and these photoelectric conversion element arrays are arranged parallel to each other in the order of R, G, and B in the sub-scanning direction. Become.

[0013]

[Operation] The data selection means selects image data of two or more colors according to the specified color specified by the specifying means from among at least three colors read by separating the original image by the color image sensor. The color determining means determines the color of each pixel of the document image based on image data of two or more colors.

[0014] The color image sensor is R (red),
In the case of a one-chip full-color image sensor having three photoelectric conversion element arrays corresponding to G (green) and B (blue), either the front row or the rear row in the sub-scanning direction of document scanning. Image data corresponding to one photoelectric conversion element array and image data corresponding to the photoelectric conversion element array in the center row are applied to the color discrimination means. At this time, the relative transmission timing between the two color image data is adjusted by the data transmission delay means.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 is a sectional front view showing the general structure of a copying machine 1 according to the present invention.

The copying machine 1 includes an image reader unit IR that outputs image information obtained by scanning an original image as an image signal S1, and a laser printer that creates a copy image using electrophotography based on the image signal S1. It is composed of part LP.

In the image reader section IR, the optical system 1
0 includes a scanner 11 that can reciprocate below the document platen glass 18, mirrors 13 and 14, a main lens 15, and a full color image sensor (hereinafter referred to as "image sensor").
It consists of 16 etc. The scanner 11 has an exposure lamp 12 that irradiates the document, and is driven by a motor 17 to scan the document placed on the document table glass 18 .

The original image is read by the image sensor 16 as color signals of three additive primary colors: R (red), G (green), and B (blue). The photoelectric conversion signal S0, which is the output of the image sensor 16, is quantized by the signal processing section 20, subjected to various signal processing depending on the copy mode, and then sent to the laser printer section LP as an image signal S1.

The laser printer section LP includes a laser optical system 30 using a semiconductor laser (not shown) as a light source, and a photosensitive drum 4.
The image forming system 40 is responsible for an electrophotographic process using 1.

The laser optical system 30 includes a polygon mirror 31
, an Fθ lens 32, a reflecting mirror 37, etc., and emits a laser beam controlled by a control unit 50 based on an image signal S1 to expose the photosensitive drum 41.

In the image forming system 40, around the photosensitive drum 41, there are a charger 43 and a developing device 44 for forming an image of the first color, and a charger 4 for forming an image of the second color.
5, a developing device 46, a transfer charger 47, a separation charger 48, a cleaner 49, and the like are provided.

On the surface of the photosensitive drum 41 charged by the chargers 43 and 45, a latent image corresponding to the original image is formed by the above-described exposure. The latent image is developed as a toner image by one or both of developers 44, 46. The toner image is transferred to paper fed from paper cassette 81 or 82.

Note that the developed color of the developing devices 44 and 46 can be arbitrarily selected by replacing the toner, but here, the developed color of the developing device 44 is, for example, black;
It is assumed that the development color No. 6 is red, for example.

The editing copying function of the copying machine 1 will now be explained. In the normal copying mode, a black monochrome image is formed using only the developing device 44, regardless of the color of the original. On the other hand, in the edit copy mode, the portion of the specified color in the original image is copied in red using the developer 46. As the designated color at this time, the copying machine 1 allows selection of three colors: "red", "blue", and "red or blue".

The operation panel (not shown) is provided with operation keys 71 and 72 (see FIG. 1) corresponding to designated colors "red" and "blue", and when the operation key 71 is pressed, the designated color is selected. When the operation key 72 is pressed, the designated color becomes "blue". Further, if the operation keys 71 and 72 are pressed, the designated color becomes "red or blue". For example, when an operator specifies "red or blue" as a designated color during editing copying, red and blue parts in the original image are copied in red, and other parts are copied in black.

In order to realize such editing copying, the image reader section IR uses a signal processing section 2 as described later.
The color of each pixel of the original image is determined within 0 (color determination). The color discrimination data DC obtained as a result of the discrimination is output as an editing signal S2 to the laser printer section LP in synchronization with the image information (image signal S1).

In the editing copy mode, the laser printer section LP performs the above-mentioned two-way printing based on the editing signal S2.
Form a color image.

FIG. 3 is a plan view of the image sensor 16, and FIG. 4 is an enlarged plan view of a portion of FIG.

The image sensor 16 includes three CCD arrays 16R, 16G, 1 extending in the main scanning direction of document scanning.
This is a one-chip solid-state imaging device that integrates 6B. Each C
CD arrays 16R, 16G, 16B each have 500
It has a CCD element corresponding to 0 pixels and can read an A3 size original at a resolution of 16 lines/mm. The light receiving surfaces of the CCD arrays 16R, 16G, and 16B are provided with spectral filters that transmit R, G, and B light, respectively, in order to separate and read the original image into three primary colors.

[0030] Furthermore, the image sensor 16 has a CCD
The arrays 16R, 16G, and 16B are arranged parallel to each other with a pitch of 12 pixels (that is, 12 lines) in the sub-scanning direction. Therefore, for the same pixel,
The output timing of the photoelectric conversion signal by the CCD array 16G is delayed by a certain time (sub-scanning time for 12 lines) with respect to the output timing of the CCD array 16R, and the output timing of the CCD array 16B is delayed from the output timing of the CCD array 16R.
The output timing is delayed by the same amount of time as the 6G output timing. That is, the information of each color, which is read by separating the pixels into three colors, is outputted in the order of R, G, and B with a certain period of time delay. Note that the sub-scanning speed changes depending on the copy magnification, so
The deviation in the output timing of each color also increases or decreases depending on the copying magnification.

FIG. 1 is a block diagram showing the configuration of the signal processing section 20. As shown in FIG.

R output from the image sensor 16,
The photoelectric conversion signals S0 of each color of G and B are input to the input processing section 202. The input processing unit 202 amplifies the photoelectric conversion signal S0 of each color to a predetermined level, quantizes it by A/D conversion, and further adds shading correction to 8
Output as bit (256 gradations) image data DR, DG, DB.

Image data DR, DG, and DB are input to a selector 211 for color discrimination. The selector 211 is controlled by the CPU 201 and selects two color image data from among the three color image data DR, DG, and DB according to the specified color for image editing specified by the operation keys 71 and 72 as described above. Select and output.

When the designated color is red, R and G image data DR and DG are selected, and when the designated color is blue, G and B image data DG and DB are selected. Furthermore, when the designated color is red or blue, R and B image data DR and DB are selected.

The image data of the two colors selected by the selector 211 are added to the color discrimination ROM 213 as address inputs. However, one of these two color image data is stored in a first-in first-out memory (FIFO memory) 21.
2, the image data is delayed by a predetermined time and input to the color discrimination ROM 213 in synchronization with the other image data.

That is, the FIFO memory 212 stores the CCD arrays 16R, 16G, 16B of the image sensor 16.
This is provided to compensate for the deviation in the output timing of the signal S0 due to the arrangement (see FIG. 4), and according to the read control of the CPU 201, the data transmission time corresponding to the sub-scanning time of up to 24 lines of 8-bit data is provided. only to be delayed.

The output of the selector 211 is the image data DR,
In the case of DG, the image data DR is delayed by 12 lines, and the output of the selector 211 is the image data DG, DB.
In this case, the image data DG is delayed by 12 lines. Then, the output of the selector 211 is the image data DR.
, DB, the image data DR is delayed by 24 lines.

The color discrimination ROM 213 discriminates the color of the original image for each pixel based on the two-color image data and the 2-bit designated color data D12 input from the CPU 201. The color discrimination ROM 213 stores color discrimination tables TRG, TBG, and TRB corresponding to specified colors. In other words, the values of the color discrimination data DC to be output are respectively specified by the values "0" to "3" of the designated color data D12 and the values "0" to "255" of the two color image data. 2-bit data indicating .

FIGS. 5(a) to 5(c) show the color discrimination table TR.
FIG. 3 is a diagram schematically showing the contents of G, TBG, and TRB.

When the specified color is "red", two colors, R and G, are selected from the three colors R, G, and B as described above, and as shown in FIG.
Color discrimination is performed using the color discrimination table TRG in a). In other words, by using R and G for color discrimination, as is clear from the comparison between color discrimination table TRG and color discrimination table TBG in FIG. Since there are many combinations corresponding to , that is, the area corresponding to red in the figure is large, it is easy to distinguish red from other colors.

In the color discrimination table TRG, the combination of values of the image data DR and DG corresponds to the red color (red and part of yellow) indicated by diagonal lines in FIG. 5(a). In some cases, the value of the color discrimination data DC is set to "1", and in other combinations, the value of the color discrimination data DC is set to "0".

When the designated color is "blue", two colors, G and B, are selected to facilitate the discrimination between blue-based colors (blue and green) and other colors, and the color discrimination table TBG is Color discrimination is performed using this method. In the color discrimination table TBG, when the combination of the values of the image data DB and DG corresponds to the blue color indicated by diagonal lines in FIG. 5(b),
The value of the color discrimination data DC is set to "2", and for other combinations, the value of the color discrimination data DC is set to "0".

Furthermore, when the specified color is "red or blue", two colors R and B are selected for color discrimination, and the color discrimination table TRB
Color discrimination is performed using In the color discrimination table TRB, when the combination of the values of the image data DR and DB corresponds to the red or blue color indicated by diagonal lines in FIG. 5(c), the value of the color discrimination data DC is determined. is “3”
”, and for other combinations, the color discrimination data D
The value of C is set to "0".

Returning to FIG. 1, on the other hand, among the three color image data DR, DG, and DB output from the input processing section 202, G
The image data DG is extracted as image information obtained by reading the original image, and is sent to the image processing unit 204 via the FIFO memory 203.

[0045] Here, G is a color in a wavelength region having the highest relative luminous efficiency among R, G, and B. In other words, the shading of the original image is recognized by the naked eye mainly based on the G light intensity. Therefore, when copying a document image as a one-color (black) or two-color (black and red) grayscale image, the image data DG
Therefore, it is possible to obtain a copy image with comparable image quality.

FIFO memory 203 stores color discrimination data D.
It is provided to match the transmission timing of C and image data DG, and the image data DB of B is output from the selector 211.
Only when the image data DG is included, the image data DG is delayed by the data transmission time of 12 lines by the read control of the CPU 201.

The image processing unit 204 applies various image processing to the image data DG, including gamma correction to accurately reproduce the density of the original image, and edge enhancement and smoothing to improve image quality.

The image processing section 204 is also provided with a scaling processing section 240 that overlaps pixels or thins out pixels according to the copying magnification. The color discrimination data DC is also input to the scaling processing unit 240 in synchronization with the image data DG, and scaling processing is applied to the color discrimination data DC as well as the image data DG.

The image data DG and color discrimination data DC output from the image processing section 204 are sent to the output interface 2.
05, the image signal S1 and the editing signal S
It is output as 2 to the laser printer section LP.

As for the output form of the image signal S1, it may be an 8-bit digital signal indicating the image density as it is, or it may be bit data converted into a binary value using a dither method or the like. Moreover, it can also be an analog signal.

In the embodiment described above, the CCD arrays 16R and 16G in the image sensor 16
, 16B may be arranged in the order of B, G, and R in the sub-scanning direction. In addition, by appropriately changing the data delay target and delay time, CCD arrays 16R, 16G, 16B
can be arranged in any order.

FIG. 6 is a block diagram of a signal processing section 20B according to another embodiment of the present invention. In the figure, components having the same functions as those in FIG. 1 are given the same reference numerals, and
Components corresponding to are given the same reference numerals with a "B" added.

Referring also to FIG. 4, in the signal processing section 20B, the R and B photoelectric conversion signals S0 output from the CCD arrays 16R and 16B in the front and rear rows in the sub-scanning direction of the image sensor 16 are processed. , is applied as a selection input to a selector 210 consisting of an analog switch. Then, the R or B photoelectric conversion signal S0 selected by the selector 210 and the G photoelectric conversion signal S0 are input to the input processing unit 202B.

In the input processing section 202B, the selector 210
By changing the reference voltage of A/D conversion in accordance with the selection operation of
compensate for the offset (level difference). Note that the offset can also be compensated for by changing the amplification factor during amplification before A/D conversion.

Image data DR or image data DB and image data DG output from the input processing section 202B are as follows:
It is input to the selector 214. The selector 214 outputs the image data corresponding to the color on the front row side in the sub-scanning direction of the image sensor 16 from among the input two-color image data to the FIFO 212B, and outputs the image data corresponding to the color on the rear row side in the sub-scanning direction. Data is output to selector 215.

The FIFO memory 212B has a storage capacity capable of delaying 8-bit data by the data transmission time of 12 lines.

Selector 215 selector 214 and F
Among the two color image data input from the IFO 212B, one G image data DG is stored in the color discrimination ROM 21.
3B and the image processing unit 204,
In addition, the correspondence between input and output is switched so that the other R or B image data DR or DB is input only to the color discrimination ROM 213B.

Selector 210 and selector 214,2
15 are all controlled by the CPU 201B in accordance with the designated color of the above-mentioned image editing designated by the operation keys 71 and 72.

When the designated color is red, selector 210 selects signal S0 from CCD array 16R as output to input processing section 202B. Then, the selector 214 inputs the image data DR to the FIFO memory 212B, and inputs the image data DG directly to the selector 215 without going through the FIFO memory 212B. Furthermore, when the designated color is blue, the selector 210 selects the signal S0 from the CCD array 16B as the output to the input processing section 202B, and the selector 214 inputs the image data DG to the FIFO memory 212B. Regardless of the specified color,
The selector 215 inputs one of the image data DR and DB and the image data DG to the color discrimination ROM 213B, and inputs the image data DG to the image processing unit 204.

Further, the CPU 201B performs read control on the FIFO memory 212B so as to delay the image data DR or DG by 12 lines. Thereby, image data DR or DB and image data DG corresponding to the same pixel are simultaneously input to the color discrimination ROM 213B.

The color discrimination ROM 213B stores designated color data D.
12, the color discrimination table TRG or the color discrimination table TBG is used to determine a predetermined value according to the combination of the values of the R and G image data DR, DG, or the combination of the values of the B and G image data DB, DG. The value color discrimination data DC is output.

According to the above embodiment, since the one-chip image sensor 16, 16C in which the CCD arrays 16R, 16G, 16B corresponding to R, G, and B are integrated is used, a separate image is generated for each color. Compared to the case where a sensor is provided, the relative positional accuracy of the light receiving surface for each color is higher, and there is less influence from lens aberrations and temperature changes, so it is possible to obtain image data DR, DG, DB that correctly separates the original image into colors. can. Therefore, there is no misjudgment of color,
Color ghosts due to misjudgment do not occur.

According to the embodiment shown in FIG. 6, the circuit configuration of the signal processing section 20B can be simplified compared to the embodiment shown in FIG. Further, color discrimination is performed by the CCD array 16G in the center row and the CCD array 16R or 16B adjacent thereto, and the input to the FIFO memory 212B is switched by the selector 214, so that the color discrimination data DC and the image data DG are Not only is the FIFO memory 203 for timing adjustment with
The storage capacity of FIFO memory 212B is FIFO memory 2
It is half of 12, which makes it possible to reduce costs.

In the embodiments described above, it is also possible to use delay means other than the FIFO memory, such as a flip-flop circuit, as a means for adjusting the timing of data transmission.

In the above-described embodiment, the color discrimination for the pixel of interest may be performed by referring to the color discrimination results of the surrounding pixels of the pixel of interest.

In the above-described embodiment, the CCD array 16B, CCD array 16G, and CCD array 16R are arranged in the sub-scanning direction so that the colors of each color are separated in the order of B, G, and R in the image sensor 16. It's okay.

In the above embodiment, the reduction type image sensors 16 and 16C were exemplified in which the CCD arrays 16R, 16G, and 16B corresponding to R, G, and B were arranged at a constant pitch in the sub-scanning direction. A contact type image sensor having a light receiving area corresponding to a pixel divided into three parts and provided with a filter that transmits R, G, and B light may be used to read the original image and discriminate the color.

In the above embodiment, the image reader unit IR incorporated in the copying machine 1 was exemplified as an image reading device, but the present invention can also be applied to an image reader device that constitutes a filing system together with an external host computer, etc. can do. In that case, instead of the operation keys 71 and 72, a signal indicating a designated color for image editing is input from the host computer, and this signal corresponds to the designating means of the present invention.

In the above embodiment, since the image data DG of green having the highest relative luminous efficiency was used as the image signal S1 indicating the image density, it is possible to obtain an image signal faithful to the actual image density. Depending on the application, image data of other colors or image data not passed through a spectral filter may be used as the image signal S1.

[0070]

According to the present invention, it is possible to prevent erroneous color discrimination in determining whether or not a particular color is present.

According to the second aspect of the invention, the circuit configuration for color discrimination can be simplified.

According to the third aspect of the invention, since there is no positional shift between the R, G, and B colors during color separation of the original image, color discrimination with high positional accuracy is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a signal processing section of an image reader section according to the present invention.

FIG. 2 is a sectional front view showing the general configuration of a copying machine according to the present invention.

FIG. 3 is a plan view of the image sensor.

FIG. 4 is a plan view showing an enlarged part of FIG. 3;

FIG. 5 is a diagram schematically showing the contents of a color discrimination table.

FIG. 6 is a block diagram of a signal processing unit according to another embodiment of the present invention.

[Explanation of symbols]

IR image reader section (image reading device) 16
Image sensor (color image sensor) R, G,
B Color separation DR, DG, DB Image data 71, 72 Operation keys (specifying means) 211 Selector (data selection means) 213 Color discrimination ROM (color discrimination means) DC Color discrimination data 16R, 16G, 16B CCD array (photoelectric conversion element) array)

Claims (3)

[Claims] 1. A color image sensor that separates and reads a document image into at least three colors and outputs image data corresponding to each separated color; a specifying means for specifying a specific color; and a specifying means for specifying a specific color. data selection means for selecting image data corresponding to two or more colors from among the image data output from the color image sensor according to the designated color; and each image selected by the data selection means. An image reading device comprising: color discrimination means for discriminating the color of each pixel of the document image based on data. 2. Three photoelectric conversion element arrays arranged parallel to each other in the sub-scanning direction of document scanning, which converts the document image into three
a color image sensor that separates and reads the colors and outputs image data corresponding to each separated color; a designating means for designating a specific color; data selection means for selecting image data corresponding to the photoelectric conversion element array in either the front row or the last row; data transmission delay means for adjusting relative transmission timing with image data corresponding to the photoelectric conversion element array; and based on the two-color image data whose transmission timings have been adjusted by the data transmission delay means. An image reading device comprising: color discrimination means for discriminating the color of each pixel of a document image. 3. The color image sensor has three photoelectric conversion element arrays corresponding to R (red), G (green), and B (blue), respectively, and these photoelectric conversion element arrays are arranged in the sub-scanning direction. 3. The image reading device according to claim 2, wherein the image reading device is a one-chip full-color image sensor in which R, G, and B are arranged parallel to each other in the order of R, G, and B.