JP2000261678A - Color original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure performance of a color original reader with respect to color reproducibility by clearly specifying a reference value of the color reproducibility of a read value of the color original reader. SOLUTION: This color original reader is provided with a gray chart spectral reflectance storage device 46, that stores a spectral reflectance distribution of a gray chart, a color patch spectral reflectance storage device 52 that stores the spectral reflectance distribution of a color patch, and an arithmetic circuit 51 that calculates each amplification factor of amplifiers 42a, 42b, 42c to amplify an output of each photoelectric conversion element 20 to an output value with a prescribed level range on the basis of the spectral reflectance distribution of the gray chart and the gray chart spectral reflectance read by each photoelectric conversion element 20 in each color and calculates a predicted output valve outputted from the amplifiers 42a, 42b, 42c on the basis of the reflectance distribution of the color patch, the color patch spectral reflectance and each amplification factor of the each element 20 at reading of an original in an optional color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color original reading apparatus for correcting the color of a read image, and to each color read in conformity with a difference in individual characteristics of each color original reading apparatus and a difference in individual characteristics of an output apparatus. The present invention relates to a color document reading apparatus that performs correction or conversion of color originals.

[0002]

2. Description of the Related Art Conventionally, as a color original reading apparatus, a reading unit in a digital color copying machine and a color scanner which is an input device for taking an image into a personal computer are known. In such a color document reading apparatus, unlike a color television, a color VCR, a color photograph, or the like, after reading a color document, the color document and the reading result are immediately compared by a display output or a printout output. Therefore, the read value at the time of reading is very important. Specifically, for the read value, how closely the print color when the read image is printed out by the printing device or the display color when the read out image is displayed on the display is similar to the color of the original document. It is required that the color reproducibility, which indicates whether the color is performed, is good. There are two causes for deteriorating the color reproducibility, one of which is the correction of the reading value of the color original reading device due to the fact that the reading value of the color original in the color original reading device is not clearly defined. Is not appropriate, the color reproducibility is deteriorated. On the other hand, color reproducibility is deteriorated due to improper color conversion values at the time of display output or printout output of the read value by the color document reading apparatus. In a digital color copying machine, a reading unit as a color original reading device and an output unit as a printer are integrated, so that at first glance, the combination of the reading unit and the output unit is fixed, and color conversion values can be easily defined. However, in practice, the reading unit and the output unit are individually set for evaluation items for structural reasons or because the reading unit and the output unit are clearly separated as a production method. Performance is assured. This is because the types of output units that can be combined with a certain reading unit are made as large as possible, for example, from the viewpoint of the product lineup of digital color copying machines and the viewpoint of cost reduction at the time of model change. Therefore, the color conversion value cannot be easily defined not only in the color document reading apparatus but also in the digital color copying machine, and the color reproducibility of the color document reading apparatus is improved, that is, the correction of the reading value is appropriately performed. It is necessary and important to do so.

FIG. 6 shows a configuration for measuring a correction value for correcting a reading value of a color image reading apparatus and a color conversion value for outputting by a output unit. FIG. 6 is a diagram showing a configuration (a) and an inspection chart (b) used for an inspection or the like performed to determine a correction value of a read value of a color image reading device in a manufacturing process, for example. In the configuration of FIG. 6A, the inspection chart 2 in which several types of patches are attached on the reading surface of the color original reading device 1 (for inspection) to be inspected by this configuration has a chart surface (patch surface). It is set down. The other end of the data line 4 connected to the output end 3 of the color original reading device 1 is connected to a personal computer (hereinafter referred to as a personal computer) 5 for inspecting the output of the color original reading device 1. Further, a spectral reflection measuring device 6 for obtaining a spectral reflectance distribution of the inspection chart 2 is connected to the personal computer 5 via a data line 7.
As an inspection by the personal computer 5, for example, a value obtained by measuring the inspection chart 2 with the spectral reflectance measuring device 6 is set as a central value, and a value having an allowable value of a predetermined width at the center value is set as a standard value. It is determined whether or not the output value is within the allowable value of the standard value. If the output value of the color document reading device 1 is out of the allowable range of the standard value, a correction amplification factor for correcting the output value by the amplifier in the color document reading device 1 is calculated. To the color original reading device 1. The color document reading apparatus 1 outputs the measured value amplified by the received correction amplification factor, and the personal computer 5 determines again whether the output value is within the allowable value of the standard value. FIG. 6B is a diagram illustrating an example of the inspection chart 2. White patches for obtaining gray (white) balance: W, gray patches: G, black patches: K, red patches for obtaining color correction reference values: R, green patches: G, blue patches: B, read Yellow patches for obtaining reference values for color conversion of R, G, B inputs to C, M, Y, K outputs: Y, magenta patches:
M, cyan patches: C, (black patches commonly use the gray balance) are attached to one side of the inspection chart 2.

FIG. 7 is a side view showing the internal structure of a general color document reading apparatus. 7 includes a contact glass 11 on which a document is placed,
The scanner frame 12 constituting the housing of the color document reading apparatus 1, the first carriage 15 and the second carriage 18 which move in the sub-scanning direction when reading the document, and the reading surface of the document set in the first carriage 15 are A light source lamp 13 for irradiation, a first mirror installed on the first carriage 15 for changing the direction of light reflected from the document, and a light source lamp 13 installed in the second carriage 18 to change the direction of light reflected from the document. It includes a second mirror 16 and a third mirror 17, a lens 19 for collecting reflected light, a color CCD 20 for receiving reflected light, and a white reference plate 22 used for shading correction and the like. The light emitted from the light source lamp 13 is reflected by the original on the contact glass 11, is redirected by the first mirror 14, the second mirror 16, and the third mirror 17, and is changed by the lens 19 to the color CCD 20.
Focused on top. At this time, the first carriage 15 and the second carriage 18 are read while being scanned over the entire surface of the document by being moved rightward in the drawing by a driving source (not shown). The color CCD 20, which is provided at a position where an image on the document is formed by the lens 19, is a three-line color CCD, and obtains an image signal by photoelectrically converting an image (imaging) obtained by reading the document. I have.

FIG. 8 is a plan view showing the structure of a three-line color CCD. In the color CCD 20 shown in FIG. 8, a photoelectric conversion element group of three lines is installed in parallel on a base in a ceramic package 31, and a glass 3 is placed on the photoelectric conversion element group.
2 is covering. Blue (B), green (G), and red (R) color filters (not shown) are provided between the photoelectric conversion element group and the glass 32 in order from the top in FIG. I have. The reflected light from the document is separated into R, G, and B by the color filters of R, G, and B, and received by the sensor line 33. FIG. 9 is a graph showing an example of the relative distribution of the sensor line of each color, the light source lamp, the infrared cut filter, and the spectral sensitivity of the reference achromatic gray chart in the color CCD. The achromatic gray chart is, for example, a gray patch for obtaining a gray (white) balance shown in the inspection chart 2 of FIG. 6B. As shown in FIG. 9, the irradiation light of the light source lamp 13 has a peak on the long wavelength side (infrared light), and the sensor line 33 of each color also has some sensitivity in the band of the infrared light. Therefore, infrared light is removed by an infrared cut filter. Further, as shown in FIG. 9, the achromatic gray chart has a characteristic that the reflectance distribution with respect to the wavelength is uniform. Note that the graph of FIG. 9 is a graph showing an example of a case where standard components are used for the components such as the sensor line 33, the light source lamp 13, and the infrared cut filter. The values in this graph fluctuate due to temporal changes due to factors such as the following.

FIG. 10 is a block diagram showing an example of a signal processing circuit in a color original reading apparatus. The color CCD 20 in FIG. 10 outputs R, G, and B colors individually. The color document reading device 1 includes a color CCD 2.
There are three identical output circuits for each of the 0 color outputs.
The output circuit of FIG. 10 includes sample and hold circuits 41a, 41b, and 41c that sample and hold an analog image signal from the color CCD 20, and amplifiers 42a and 4a that amplify the sampled and held analog signal to a predetermined voltage value.
2b and 42c, and A / D converters 43a and 4c for converting the amplified analog signal into, for example, an 8-bit digital signal.
3b, 43c and shading correction circuits 44a, 44b, 44c for performing shading correction on a digital signal using a value obtained by reading light reflected from the white reference plate 22 or the like.
And a gray chart spectral reflectance storage device 46 for storing the spectral reflectance when the achromatic gray chart is read by the color CCD 20 and the spectral reflectance distribution when the achromatic gray chart is read by the spectral reflectance measuring device 6.
And the spectral reflectance when the achromatic gray chart is read by the color CCD 20 is calculated, and the amplifiers 42a, 42b, and 4 are calculated based on the spectral reflectance and the spectral reflectance distribution.
And an arithmetic circuit 45 for calculating the individual amplification factors 2c.

In the production line of the ordinary color original reading apparatus 1, first, in order to adjust the gray balance of the color original reading apparatus 1 by the configuration shown in FIG. 6, for example, an amplifier 42a for each color shown in FIG. 42b, 4
Adjust individual amplification factors of 2c. In this adjustment, the digital data output from the output circuit for each color (R, G, B) shown in FIG. 10 when the reference achromatic gray chart is read is set to the same constant value (within a certain range) for each color. )
Adjust so that The reason is that an achromatic color such as gray data becomes uniform with respect to the spectral reflectance. For example, the reflectance of the reference gray chart is set to 8
Assuming that the digital data having a reflectance of 0% is assigned to “0” and the digital data having a reflectance of 100% is assigned to be a full scale of 255 of 255 bits, the read value of the color document reading apparatus 1 is a reflection value. Since the ratio is proportional to the ratio, the digital data output from the output circuit for each color is 204 for each color. Note that the output value obtained by reading the original with the color CCD 20 is represented by the spectral distribution of the light source lamp 13 at each wavelength, the spectral transmittance of the infrared cut filter,
The product of the spectral distribution of the reflection of the original and the spectral sensitivity distribution of the color CCD 20 is added over all wavelengths.
(Integrated). The amplifiers 42a, 42b, 4
The operation of adjusting the amplification factor of each color by 2c includes, for example,
When the gray chart is read, the amplification outputs of the amplifiers 42a, 42b, and 42c over the entire wavelengths so that the integrated output shown in the graph of the sensitivity distribution of the sensor line 33 for each color in FIG. This is the task of adjusting the rate. The tuned amplifiers 42a, 42b, 4
The output value of 2c is shown by a dotted line in FIG. The gray balance by the conventional color document reading apparatus 1 is adjusted so that the value when the gray chart is read by the sensor line 33 for each color becomes a constant value as described above. In addition, a result obtained by measuring a gray chart with the spectral reflectometer 6 was used as a reference value for obtaining a gray balance. However, the conventional color document reading apparatus 1
There was no provision for the color reproducibility of the read values, and the trial and error were performed using a color chart (color patch).

[0008]

However, in a color original reading apparatus which is required to have good color reproducibility, the absence of a reference value for the color reproducibility of the read value means that the color original reading apparatus relating to the color reproducibility does not exist. This leads to a problem that reliability of the performance of the device is reduced. In addition, regardless of the above-described regulation of the color reproducibility of the read value of the color document reading apparatus, for example, the colorimetric value L
There are values theoretically obtained from *, a *, b * and tristimulus values X, Y, Z, that is, theoretical values that should be originally output from the color document reading apparatus. When correcting the reading value of the color document reading apparatus to the theoretical value (color correction), a predetermined correction formula is used, and it is necessary to determine some variables used in the correction formula. In the past, the variables used in this correction formula were determined by actually reading several types of color patches with a color document reading device. There is a problem that it must be determined through repeated trial and error, that is, it takes time and effort to find a variable for the color correction processing, and the reliability of the variable is also lacking. Also, in a digital color copier equipped with an output device as well as a color document reading device, a process called color conversion for converting a read value of the color document reading device into a value suitable for the output device for image formation is required. However, the variables used in this color conversion process must also be determined by trial and error as described above, and it takes time and effort to find the variables for the color conversion process, and the reliability of the variables is lacking. There is a problem that. Also, when the user is using the color document reading device, the color of the light source lamp, which is a part of the color document reading device,
Since there is a change with time such as fading of various filters, the read value of the color original reading device changes and the color reproducibility deteriorates, and the variables of the correction processing and the color conversion processing can cope with the change with time. There is a problem of disappearing.

SUMMARY OF THE INVENTION The present invention of claim 1 has been made to solve the above-mentioned conventional problems, and by clearly defining a reference value of color reproducibility of a read value in a color document reading apparatus. It is another object of the present invention to provide a color document reading device capable of guaranteeing the performance of the color document reading device with respect to color reproducibility. According to a second aspect of the present invention, there is provided a color document reading apparatus capable of further ensuring the performance of color reproducibility of a read value by providing a range of an allowable value to the reference value of the first aspect. The purpose is to: According to the third aspect of the present invention, by using the reference value defined in the first aspect at the time of color correction,
It is an object of the present invention to provide a color document reading apparatus that can reduce the time and effort required for obtaining a variable of a color correction process and increase the reliability of the variable. According to the fourth aspect of the present invention, by using the reference value defined in the first aspect at the time of color conversion, it is possible to reduce the time and effort required to obtain a variable for the color conversion process and to increase the reliability of the variable. It is an object to provide a color document reading device. According to the fifth aspect of the present invention, a gray chart and a color patch for obtaining a reference value are installed in a color original reading apparatus, and the gray chart and the color patch are read at an arbitrary time interval, and the read value is normal or abnormal. It is an object of the present invention to provide a color document reading apparatus capable of making the correction process variables and the color conversion process variables correspond to changes over time by detecting the above.

[0010]

According to a first aspect of the present invention, there is provided a color document reading apparatus, comprising: a light source for irradiating a document surface; and a light reflected from the document surface. A photoelectric conversion element array having a photoelectric conversion element for each color, which receives a reflected light and photoelectrically converts the received reflected light to output a read signal, and is provided separately for each output of the separated colors. An amplifier that amplifies the output value of each photoelectric conversion element to an output value within a predetermined range, a gray chart spectral reflectance storage device that stores a gray chart spectral reflectance distribution, and a color that stores a spectral reflectance distribution of a color patch A patch spectral reflectance storage device, and an arithmetic circuit, wherein the arithmetic circuit is based on a reflectance distribution of the gray chart and a spectral reflectance obtained by reading the gray chart with the photoelectric conversion element array. Calculating the individual amplification factors of the respective amplifiers, the reflectance distribution of the color patches when reading an original of an arbitrary color, the spectral reflectance obtained by reading the color patches with the photoelectric conversion element array, and A predicted output value output from each of the amplifiers is calculated based on the individual amplification factor of the photoelectric conversion element. According to a second aspect of the present invention, in the color original reading apparatus according to the first aspect, when the arithmetic circuit outputs a value having an allowable value of a predetermined width as an output reference value based on the output predicted value, A determination circuit is provided for determining that an output value to be output is within an allowable value of the output reference value. According to a third aspect of the present invention, in the color document reading apparatus of the first aspect, a color correction circuit is provided for correcting each output value output from each of the amplifiers to be within an allowable value of the output reference value. It is characterized by the following. According to a fourth aspect of the present invention, there is provided the color document reading apparatus according to the first aspect, further comprising a color conversion circuit for converting each output value output from each of the amplifiers for input to a print output device, wherein the color conversion circuit is And converting each output value output from each of the amplifiers to be within an allowable value of the output reference value. According to a fifth aspect of the present invention, in the color original reading apparatus according to the first or second aspect, the arrangement positions of the gray chart and the color patches are determined by reflecting the reflected light from the gray chart and the color patches in the color original reading apparatus. It is characterized in that the photoelectric conversion element row is a place where light can be received and an arbitrary place outside the original reading range.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a block diagram showing a schematic overall configuration of a color document reading apparatus according to a first embodiment of the present invention. 1, 3, 4, and 5, portions having the same functions as those of the conventional device shown in FIG. 6 are denoted by the same reference numerals, and redundant description will be omitted. The color original reading apparatus 1 of the present embodiment shown in FIG. 1 is a color patch spectral reflectance storage device that stores a color patch light reflectance obtained by reading a color patch 2 whose spectral reflectance distribution is known in advance by a sensor line 33. 52 comprising:
In that the arithmetic circuit 51 calculates the output predicted value output from each amplifier based on the reflectance distribution of the color patch, the spectral reflectance of the color patch, and the individual amplification factor of each sensor line 33 when reading an original of an arbitrary color. This is different from the conventional color document reading apparatus 1 shown in FIG. next,
Before describing the operation of the present embodiment, the spectral reflectance of a color patch will be described. FIG. 2 shows a yellow color patch as an example of the spectral reflectance of the color patch.
4 is a graph showing a spectral reflectance measured by the spectral reflectance measuring device 6 shown in FIG. As shown in FIG. 2, the spectral reflectance of the yellow color patch is relatively smaller on the short wavelength side than on the low wavelength side. Accordingly, by using the spectral reflectance of the yellow color patch in place of the spectral reflectance of the gray chart in FIG. 9 to execute the operation of the arithmetic circuit 51, the output predicted values of the R, G, and B colors are obtained. Will be done. However, the amplifiers 42a, 42b, 4
Since the amplification factor 2c is adjusted to match the gray balance, each of the R, G, and B outputs is also within the range adjusted to match the gray balance. In the present embodiment in which chromatic colors including the primary colors are read, similarly to the conventional color document reading apparatus 1 in FIG. 10, the amplification factors of the amplifiers 42a, 42b, and 42c are adjusted to match the gray balance and output. At the same time, the arithmetic circuit 51 uses the spectral reflectances of the color patches of each color stored in the color patch spectral reflectance storage device 52 and the read values obtained by reading the original with the color CCD 20 to calculate the R, G, and B outputs. Calculate and output the predicted value. For example, 15 in the order of R, G, B
Predicted values of 0, 160 and 50 are obtained. That is,
All charts (patches) such as gray, primary colors and neutral colors
On the other hand, as long as the spectral reflectance is known, a predicted value can be obtained by calculating in the same manner as in the case of the gray chart. At this time, the predicted value of each output of R, G, and B is output as a reference value including a tolerance. The outputs of R, G, and B amplified by the amplifiers 42a, 42b, and 42c and the reference value calculated by the calculation circuit 51 are shown in FIG.
(A) is input to the personal computer 5, and the determination circuit 55 in the personal computer 5 determines whether each output of R, G, B is within the reference value, and outputs the determination result. . In addition,
In FIG. 1, the personal computer 5 having the determination circuit 55 and the like is configured separately from the color document reading device 1. However, the configuration may be such that the determination circuit 55 and the like are built in the color document reading device 1.

FIG. 3 is a block diagram showing a schematic overall configuration of a color document reading apparatus according to a second embodiment of the present invention. The color document reading apparatus 1 of the present embodiment shown in FIG. 3 has a color correction circuit 60 for correcting each output of R, G, and B.
And an output value storage device 53 for storing a theoretical value of how much each output of R, G, and B originally takes. The theoretical value and the color patch at the time of reading an original of an arbitrary color. The operation circuit 51 calculates the output predicted value output from each amplifier based on the reflectance distribution of the color patch, the spectral reflectance of the color patch, and the individual amplification factor of each sensor line 33, and inputs the predicted value to the color correction circuit 60. The first shown in FIG.
This is different from the color document reading apparatus 1 of the first embodiment. Next, the present embodiment is to correct each output of R, G, and B to a theoretical value based on the predicted value described in the first embodiment. Before the description, the above theoretical values will be described. The theoretical values of the R, G, and B outputs are independent of the values read by the color document reading device, such as originals and color patches. For example, colorimetric values L *, a *, b *, Stimulus values X, Y, Z
Is the value displayed as. It is assumed that these values are measured in advance by a measuring instrument. By using each of the above values in a predetermined conversion formula, a theoretical value corresponding to the output value of R, G, B can be obtained. In order to correct the R, G, and B outputs to theoretical values, a 3 × 3 matrix as shown in the following equation (Equation 1) is generally used.

(Equation 1)

Since the conventional color document reading apparatus has no concept of "predicted value" and cannot obtain "predicted value", the variable a of the matrix in the mathematical expression (Equation 1) is used.
Are determined by performing trial and error many times on the result of actually reading several types of color patches by the color original reading device in consideration of the variation in spectral sensitivity of each color original reading device. Therefore, in the present embodiment, the result (read value) of reading a conventional actual color chart
By using the "prediction value" in place of the above, it is possible to correct each output of R, G, B for each individual product using the prediction value (theoretical value) as a design center value (reference value). Become. Specific correction values include, for example, green: 10% of G and red: 5 of R in the sensitivity distribution in each output of R, G, and B.
It is assumed that the area corresponding to% is output more than the theoretical value. The output of blue: B 'in that case is as follows. B '=-0.05.R-0.1.G-0.05.B Similarly, the outputs of R' and G 'are as follows. R ′ = − 1.15 · R−0.1 · G−0.05 · B G ′ = − 0.05 · R−1.1 · G−0.05 · B ), The following equation (Equation 2) is obtained.

(Equation 2) According to this formula (Equation 2), the values before and after the conversion of the image data when an arbitrary color patch is read are as follows. (Resolution of image data is 8-bit: full scale is 255) Although the values of the white patch and the gray patch in the above are not different between before and after the conversion, this is set by setting each value so that the sum of the values of each row of the 3 × 3 matrix becomes 1. This is because the coloring is not changed. In this way,
In the present embodiment, the R, G, and B outputs can be corrected for each individual product using the predicted value (theoretical value) as a reference value. In addition, the value of each row of the 3 × 3 matrix may be changed in order to intentionally change and output the saturation of the original when performing the correction.

FIG. 4 is a block diagram showing a schematic overall configuration of a color document reading apparatus according to a third embodiment of the present invention. The color document reading apparatus 1 of the present embodiment shown in FIG. 4 includes a color conversion circuit 70 that converts each output of R, G, and B into each output of C, M, Y, and K; A C, M, Y, and K output value storage device 54 for storing a theoretical value of how much each output of K originally should be, and that the arithmetic circuit 51 At the time of reading a color document, a predicted output value output from each amplifier is calculated based on the reflectance distribution of the color patch, the spectral reflectance of the color patch, and the individual amplification factor of each sensor line 33, and input to the color conversion circuit 70. This is different from the color document reading apparatus 1 of the second embodiment shown in FIG. Next, in the present embodiment, each output of R, G, B is to be converted into each output of C, M, Y based on the predicted value described in the first embodiment. Before describing the operation of the present embodiment, the above-described C, M, and Y conversion will be described.
The output of each of C, M, and Y has the spectral distribution opposite to that of each of the R, G, and B outputs of the R, G, and B outputs, which are referred to as the three primary colors. R for each,
It is called a complementary color of each color of G and B. In order to convert the output image data of R, G, and B to respective outputs of C, M, and Y, a 3 × 3 matrix such as the following equation (Equation 3) is generally used.

(Equation 3) As specific conversion values, for example, each output of R, G, B is an ideal output (R ′,
G ′, B ′), the following equation (Equation 4) is theoretically possible.

(Equation 4) However, each value in the 3 × 3 matrix is
In general, the values are changed from the values in the mathematical expression (Equation 4) in order to control individual differences and intentional saturation in the colorants of the C, M, and Y toners.

By the way, in a general electrostatic copying type color printer or the like, in addition to C, M, and Y colors as toner, black:
K toner is provided. This means that all three colors of C, M, and Y can be displayed basically, but C, M, and Y3
When displaying an achromatic color such as black or gray, which is a color in which colors are mixed at substantially the same ratio, C, M, and Y colors are added to the display color. This is because it is necessary to use black toner. Therefore, the output levels common to all three colors of C, M, and Y are converted to C, M, Y, and K image outputs by replacing the output levels with black: K. For example, the output of the lowest level is selected from the output of the three colors C, M, and Y, and the black output is performed at the same level as the output, and the output is used as a threshold to set the output level of the other two colors. , And output C, M, Y, and K. When converting into C, M, Y, and K outputs, the black: K output does not need to match the lowest level output of each of the C, M, and Y outputs, and is common to C, M, and Y. It can be any value in the output level. When the color document reading apparatus 1 is used, the read image data may be stored in a memory or the like of the personal computer 5 or displayed on a display, but is often printed out by a color printer. . Therefore, as described above,
When converting each output of G and B into each output of C, M, Y and K, the output of each of R, G and B described in the second embodiment is converted to the output of R′G′B ′. The correction (conversion) and the conversion of the R'G'B 'output to C, M, Y, and K described in the third embodiment are simultaneously performed, and the following equation (5) is generally used. ) Is used.

(Equation 5) As described above, in the present embodiment, each output of R, G, and B is set to C,
It can be converted to M, Y, K outputs. In addition, the value of each row of the 3 × 4 matrix may be changed in order to intentionally change and output the saturation of the original at the time of conversion. Next, in the color original reading apparatus 1 which is shipped to the market and used by the user, the spectral distribution of the light source lamp 13, the infrared cut filter or the color CCD 20 is used.
A description will be given of a fourth embodiment of the present invention for correcting the above-described correction value and conversion value in response to a temporal change such as fading of a middle filter.

FIG. 5 is a side view (a) showing an internal structure of a part of a color document reading apparatus according to a fourth embodiment of the present invention, and an example (b) of a color patch. The color document reading apparatus 1 of the present embodiment shown in FIG. 5A has a detection color patch 23 shown in FIG. 5B installed adjacent to a white reference plate 22 for shading correction. 2 is different from the conventional color original reading apparatus 1 shown in FIG. The detection color patch 23 shown in FIG. 5B is made up of several types of color patches that are extremely resistant to fading. Any location that is readable and outside the document reading range is selected.
Therefore, generally, the detection color patch 23 shown in FIG. 5B is installed near or adjacent to the white reference plate for shading correction. In the present embodiment, the second
And the "reference value" described in the third embodiment are stored for each patch, and the color patch 23 for detection shown in FIG. Sometimes read. Next, an arithmetic circuit 51 such as a CPU in the color original reading apparatus 1 detects (determines) whether or not the read value of the detection color patch 23 is within the tolerance of the reference value. Light source lamp 13, infrared cut filter or color CCD 2
A message is displayed to prompt the user to replace a component such as a zero filter. That is, the same inspection as that of the color original reading apparatus 1 in the manufacturing process is performed by the color original reading apparatus 1 itself when the power is turned on. In this manner, in the present embodiment, even if the internal components have changed with time in the color document reading apparatus 1 shipped to the market, the correction values and the conversion values are corrected in accordance with the changes with time. can do. Although the color document reading apparatus of each of the above embodiments uses a three-line color CCD, the present invention is not limited to this. For example, a type in which a color filter is changed by a one-line CCD to read a document a plurality of times is used. Can be dealt with by calculating the predicted value for each color.

[0017]

As described above, according to the first aspect of the present invention, since the reference value of the color reproducibility of the read value in the color document reading device can be clearly defined, the color document related to the color reproducibility can be used in the color document reading device. The performance of the reader can be guaranteed. According to the second aspect of the present invention, since the reference value of the first aspect has a range of an allowable value, it is possible to further ensure the performance of the color reproducibility of the read value. According to the third aspect of the present invention, since the reference value defined in the first aspect is used for color correction, it is possible to reduce the time and effort required to obtain a variable for the color correction processing and to increase the reliability of the variable. According to the fourth aspect of the present invention, since the reference value defined in the first aspect is used at the time of color conversion, it is possible to reduce the time and effort required to obtain a variable for the color conversion process and to increase the reliability of the variable. According to the fifth aspect of the present invention, a gray chart and a color patch for obtaining a reference value are installed in a color original reading apparatus, and the gray chart and the color patch are read at an arbitrary time interval, and the read value is normal or abnormal. Is detected, it is possible to make the variable of the correction process and the variable of the color conversion process correspond to the change with time.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic overall configuration of a color document reading apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a spectral reflectance of a yellow color patch measured by a branch reflection measuring device 6;

FIG. 3 is a block diagram illustrating a schematic overall configuration of a color document reading apparatus according to a second embodiment of the present invention.

FIG. 4 is a block diagram illustrating a schematic overall configuration of a color document reading apparatus according to a third embodiment of the present invention.

FIG. 5A is a side view showing an internal configuration of a part of a color document reading apparatus according to a fourth embodiment of the present invention, and FIG. 5B is a view showing an example of a color patch.

6A is a diagram illustrating a configuration used for an inspection or the like performed to determine a correction value of a read value of a color image reading device, and FIG. 6B is a diagram illustrating an inspection chart.

FIG. 7 is a side view showing an internal configuration of a general color document reading apparatus.

FIG. 8 is a plan view showing a configuration of a three-line color CCD.

FIG. 9 is a diagram illustrating an example of a relative distribution of spectral sensitivity of a sensor line of each color, a light source lamp, an infrared cut filter, and a reference achromatic gray chart in a color CCD.

FIG. 10 is a block diagram illustrating an example of a signal processing circuit in the color document reading device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Color original reading device, 2 ... Inspection chart, 3 ... Output terminal, 4 ... Data line, 5 ... PC, 6 ... Spectral reflection measuring device, 7 ... Data line,
11 contact glass, 12 scanner frame, 13 light source lamp, 14 first mirror,
15: first carriage, 16: second mirror, 1
7 ... third mirror, 18 ... second carriage, 19
... Lens, 20 ... Color CCD, 22 ... White reference plate, 23 ... Color patch for detection, 31 ... Ceramic package, 32 ... Glass, 33 ... Sensor line, 41a , 41b, 41c ... sample and hold circuit, 42a, 42b, 42c ... amplifier, 4
3a, 43b, 43c A / D converters, 44a, 4
4b, 44c: shading correction circuit, 45, 5
Reference Signs List 1 ... arithmetic circuit, 46 ... gray chart spectral reflectance storage device, 52 ... color patch spectral reflectance storage device, 53 ... output value storage device, 54 ... C, M,
Y and K output value storage devices, 55... Determination circuit, 60
... Color correction circuit, 70 ... Color conversion circuit

Claims (5)

[Claims] 1. A light source for irradiating a document surface, and a photoelectric conversion element that separates reflected light from the document surface to receive light for each color and photoelectrically converts the received reflected light to output a read signal. A photoelectric conversion element array provided for each color, an amplifier provided separately for each color-separated color output to amplify the output value of each photoelectric conversion element to an output value within a predetermined range, and a spectral reflection of a gray chart A gray chart spectral reflectance storage device for storing the spectral distribution, a color patch spectral reflectance storage device for storing the spectral reflectance distribution of the color patches, and an arithmetic circuit, wherein the arithmetic circuit includes a reflectance of the gray chart. The individual amplification factors of the respective amplifiers are calculated based on the distribution and the spectral reflectance obtained by reading the gray chart with the photoelectric conversion element array. A reflectance distribution of a patch, the spectral reflectance obtained by reading the color patch by the photoelectric conversion element array,
A color document reading apparatus for calculating an output predicted value output from each of the amplifiers based on an individual amplification factor of each of the photoelectric conversion elements. 2. When the arithmetic circuit outputs a value having an allowable value of a predetermined width as an output reference value based on the output predicted value, an output value output from each of the amplifiers is an allowable value of the output reference value. 2. The color document reading apparatus according to claim 1, further comprising a determination circuit for determining that the image data is within the range. 3. The color original according to claim 1, further comprising a color correction circuit for correcting each output value output from each of the amplifiers to be within an allowable value of the output reference value. Reader. 4. A color conversion circuit for converting each output value output from each of the amplifiers to be input to a print output device, wherein the color conversion circuit outputs each output value from each of the amplifiers. 2. The color document reading apparatus according to claim 1, wherein the conversion is performed so that the output reference value falls within an allowable value. 5. An arrangement in which the gray chart and the color patches are arranged is a place where the photoelectric conversion element array in the color original reading apparatus can receive the reflected light from the gray chart and the color patches and read the original. 3. The color document reading device according to claim 1, wherein the color document reading device is set at an arbitrary place outside the range.