JP2002300391A - Shading correction data generator, white shading correction device, image reader, image forming device, shading correction data generating method, program and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate shading correction data with high accuracy taking into account deterioration in the scanning optical system. SOLUTION: An averaging circuit 29 applies averaging processing to m-lines image data read from a white reference board at a top in the subscanning direction to generate reference data. A gain setting circuit 71 sets an amplification factor of an amplifier of a signal processing circuit 22. A NOREF arithmetic circuit 72 acquires the amplification factor as information denoting a degree of deterioration in a scanning optical system. Then a setting value NOREF is obtained from the amplification factor. A comparator circuit 31 compares a value subtracting the setting value NOREF from data read from the white reference board after the reference data with read image data after the reference data. When the image data after the reference data are found to be smaller according to the comparison arithmetic operation, the image data after the reference data are excluded. Then shading correction data are generated by using the image data after the exclusion for the object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shading correction data generating apparatus for generating shading correction data from a white reference, a white shading correction apparatus having the shading correction data generating apparatus, an image reading apparatus and an image forming apparatus, and a white reference. The present invention relates to a shading correction data creating method, a program, and a storage medium for creating shading correction data from a program.

[0002]

2. Description of the Related Art In general, in a digital image reading apparatus, unevenness in sensitivity of each pixel of a CCD line sensor constituting a reading scanning optical system, variation in transmitted light amount in a lens, and unevenness and deterioration of an illumination light source and an optical system are caused. The output from the light receiving element corresponding to each pixel is not always uniform.

[0003] As a means for correcting these, white shading correction is known. In the white shading correction, a white reference is illuminated prior to the actual document reading process, the reflected light is read, and obtained as shading correction data for shading correction of each pixel. Then, based on the shading correction data, white shading correction of the read image data of the document is performed.

In order to accurately perform white shading correction, noise due to dust, dirt, scratches, and the like must be reduced from read data of a white reference (a white reference plate or the like is used). For example, in a system in which read data has much noise, accurate shading correction data cannot be generated, and a read image corrected by the shading correction data becomes an output image affected by noise.

In order to solve such a problem, in the technique disclosed in Japanese Patent Application Laid-Open No. H11-289432, shading correction data is generated by performing simple averaging on a plurality of lines based on white, thereby reducing the influence of noise. It is designed to minimize

Further, since the simple averaging has a complicated circuit configuration and is costly, the technique disclosed in Japanese Patent Application Laid-Open No. H11-289432 discloses a weighted average (multiple averaging) that can be realized by a simple and low-cost circuit. It is also conceivable to perform

[0007]

However, in each of the above techniques, the influence of dust, dirt, scratches, etc. on the white standard cannot be completely eliminated. In particular, when shading correction data is generated from multiple averaging of multiple lines, the influence of the last line is the most affected.Therefore, if there is dust, dirt, scratches, etc. on the last line, the influence on the shading correction data Is large.

Further, in this case, deterioration of the optical system for reading the white reference due to aging or the like, for example, a decrease in the light amount of the light source, dirt on the mirror, etc. occurs. Correction data must be created.

An object of the present invention is to eliminate pixels affected by white reference dust, dirt, flaws, etc., and to sufficiently remove noise from white shading correction data.

An object of the present invention is to create high-precision shading correction data in consideration of deterioration of an optical system.

An object of the present invention is to create white shading correction data from which noise has been sufficiently removed.

An object of the present invention is to determine the degree of deterioration of an optical system based on an amplification factor set in a signal processing circuit, and to create highly accurate shading correction data in which deterioration of the optical system is also taken into consideration. .

An object of the present invention is to determine the degree of deterioration of an optical system based on a variation in the value of image data obtained by reading a white reference, and to create high-precision shading correction data in which the deterioration of the optical system is also taken into consideration. It is.

An object of the present invention is to enable easy detection of variations in image data with a simple circuit configuration.

An object of the present invention is to determine the degree of deterioration of the optical system from the total lighting time of the light sources of the optical system, and to generate highly accurate shading correction data in consideration of the deterioration of the optical system. .

An object of the present invention is to determine the degree of deterioration of an optical system from the number of read images and create highly accurate shading correction data taking into account the deterioration of the optical system.

[0017]

According to a first aspect of the present invention, there is provided a shading correction data creating apparatus for creating shading correction data to be used for white shading correction from image data obtained by reading a white reference. Reference data creating means for creating reference data by performing statistical processing on a plurality of lines at the head of the direction, acquiring means for acquiring information indicating the degree of deterioration of the optical system for reading the image data, Value setting means for presetting a value of the corresponding size, and adjusting the magnitude of the image data after the reference data and the image data after the reference data in the sub-scanning direction using the preset value. And comparing means for comparing the image data after the reference data is smaller than the reference data. Shading correction data generating means for generating the shading correction data for the image data after the reference data after the exclusion, and shading correction data generating means for generating the shading correction data for the image data after the reference data after the exclusion. It is a correction data creation device.

Therefore, comparison is made between reference data created by statistically quantifying a plurality of lines at the head of the white reference and image data after the reference data, and pixels affected by dust, dirt, scratches, etc. are excluded. Therefore, noise can be sufficiently removed from the white shading correction data. In addition, since the value of a preset value is changed according to the degree of deterioration of the optical system that reads the white reference, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a second aspect of the present invention, in the shading correction data creating apparatus according to the first aspect, the comparing means sets the preset as the adjustment from the image data after the reference data in the sub-scanning direction. The subtracted value is subtracted.

Therefore, by subtracting a preset value from the read image data of the white reference after the reference data in the sub-scanning direction, it is possible to create shading correction data with high accuracy in consideration of the deterioration of the optical system. it can.

The third aspect of the present invention is the first or second aspect.
In the shading correction data creation device described in the above,
The reference data creation means performs an averaging process as the statistic process.

Therefore, white shading correction data from which noise has been sufficiently removed can be created by using reference data created by averaging a plurality of lines at the head of the white reference.

According to a fourth aspect of the present invention, in the shading correction data creating apparatus according to any one of the first to third aspects, the acquiring unit outputs the analog image output from the photoelectric conversion element that reads the white reference. The amplification factor setting means for setting the amplification factor of a signal processing circuit that performs predetermined signal processing on the data so as to suppress a decrease in the signal level due to the deterioration of the analog image data is used to obtain information on the set value of the amplification factor from the optical It is characterized in that it is obtained as information indicating the degree of system degradation.

Therefore, it is possible to determine the degree of deterioration of the optical system from the amplification factor set in the signal processing circuit, and to generate highly accurate shading correction data in which the deterioration of the optical system is also taken into consideration.

According to a fifth aspect of the present invention, in the shading correction data creating apparatus according to any one of the first to third aspects, the acquisition means detects a variation in the value of the image data and performs the optical operation. It is characterized in that it is obtained as information indicating the degree of system degradation.

Therefore, it is possible to determine the degree of deterioration of the optical system from the variation in the value of the image data obtained by reading the white reference, and to create highly accurate shading correction data that also takes into account the deterioration of the optical system.

According to a sixth aspect of the present invention, in the shading correction data creating apparatus according to the fifth aspect, the acquiring means detects a maximum value of the variation of the image data.

Therefore, by detecting only the maximum value of the variation, the variation can be easily detected with a simple circuit configuration.

The invention according to claim 7 is the invention according to claim 5 or 6
In the shading correction data creation device described in the above,
The acquisition means calculates a standard deviation from a plurality of pixels to detect the variation.

Therefore, it is possible to determine the degree of deterioration of the optical system from the standard deviation of a plurality of pixels in the image data obtained by reading the white reference, and to generate highly accurate shading correction data that also takes into account the deterioration of the optical system. it can.

The invention described in claim 8 is the first or second invention.
In the shading correction data creation device described in the above,
The acquisition unit may acquire information indicating a total lighting time of a light source of the optical system as the information indicating the degree of the deterioration.

Therefore, it is possible to determine the degree of deterioration of the optical system from the total lighting time of the light source, and to generate highly accurate shading correction data in consideration of the deterioration of the optical system.

According to a ninth aspect of the present invention, in the shading correction data creating apparatus according to any one of the first to third aspects, the acquisition means includes a number of images read by a photoelectric conversion element for reading the white reference. Is obtained as information indicating the degree of deterioration of the optical system.

Therefore, it is possible to determine the degree of deterioration of the optical system from the number of read images, and to create high-precision shading correction data in consideration of the deterioration of the optical system.

The tenth aspect of the present invention is the first to ninth aspects.
And a white shading correction unit that performs white shading correction on image data of a read image of a document by the shading correction data generated by the shading correction data generation device. , And a white shading correction device.

Therefore, the same operation and effect as the invention according to any one of the first to ninth aspects can be obtained.

According to the present invention, there is provided a photoelectric conversion element for reading an image of a document, and a white shading correction device for performing white shading correction on the image data of the read image. An image reading apparatus characterized in that:

Accordingly, the same operations and effects as those of the tenth aspect are provided.

According to a twelfth aspect of the present invention, there is provided the image reading apparatus according to the eleventh aspect, which reads an image of a document, and forms an image on a recording medium based on the read image of the document. Image forming apparatus.

Therefore, the same operations and effects as those of the eleventh aspect are obtained.

According to a thirteenth aspect of the present invention, in the shading correction data generating method for generating shading correction data used for white shading correction from image data obtained by reading a white reference, a plurality of lines at the head of the image data in the sub-scanning direction are provided. A reference data creation step of creating reference data by performing a statistical process on the image data; an acquisition step of acquiring information indicating the degree of deterioration of the optical system that reads the image data; and a magnitude value according to the degree of deterioration. A value setting step of setting in advance the size of the image data after the reference data and the size of the image data after the reference data in the sub-scanning direction are adjusted using the preset value and then compared. And if the image data after the reference data is smaller by this comparison operation, the image after the reference data A shading correction data creating step of creating the shading correction data for the image data after the reference data after the exclusion, and a shading correction data creating step of creating the shading correction data. Is the way.

Accordingly, comparison is made between reference data created by statisticizing a plurality of lines at the head of the white reference and image data after the reference data, and pixels affected by dust, dirt, scratches, and the like are excluded. Therefore, noise can be sufficiently removed from the white shading correction data. In addition, since the value of a preset value is changed according to the degree of deterioration of the optical system that reads the white reference, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a fourteenth aspect of the present invention, in the shading correction data creating method according to the thirteenth aspect, the comparing step includes the step of performing the adjustment based on the image data after the reference data in the sub-scanning direction. The subtracted value is subtracted.

Therefore, by subtracting a preset value from the read image data of the white reference after the reference data in the sub-scanning direction, it is possible to create high-precision shading correction data in consideration of deterioration of the optical system. it can.

According to a fifteenth aspect of the present invention, in the shading correction data generating method according to the thirteenth or fourteenth aspect, the reference data generating step performs an averaging process as the statistical process.

Therefore, it is possible to create white shading correction data from which noise has been sufficiently removed by using the reference data created by averaging a plurality of lines at the head of the white reference.

The invention according to claim 16 is the invention according to claims 13 to
15. In the shading correction data creating method according to any one of the fifteenth to fifteenth aspects, the obtaining step includes setting an amplification factor of a signal processing circuit that performs predetermined signal processing on analog image data output by a photoelectric conversion element that reads the white reference. The information of the set value of the amplification factor is obtained as information indicating the degree of deterioration of the optical system from an amplification factor setting unit that sets so as to suppress a decrease in signal level due to the degradation of the analog image data. .

Therefore, it is possible to determine the degree of deterioration of the optical system from the amplification factor set in the signal processing circuit, and to generate highly accurate shading correction data in consideration of the deterioration of the optical system.

The invention according to claim 17 is the invention according to claims 13 to
15. The shading correction data creating method according to any one of the fifteenth to fifteenth aspects, wherein the acquiring step detects variation in the value of the image data and acquires the information as information indicating a degree of deterioration of the optical system. I do.

Therefore, it is possible to determine the degree of deterioration of the optical system from the variation in the value of the image data obtained by reading the white reference, and to create highly accurate shading correction data that also takes into account the deterioration of the optical system.

According to an eighteenth aspect of the present invention, in the shading correction data creating method according to the seventeenth aspect, the obtaining step detects a maximum value of the variation of the image data.

Therefore, by detecting only the maximum value of the variation, the variation can be easily detected with a simple circuit configuration.

According to a nineteenth aspect of the present invention, in the shading correction data creating method according to the seventeenth or eighteenth aspect, the obtaining step calculates the standard deviation from a plurality of pixels to detect the variation. And

Therefore, it is possible to determine the degree of deterioration of the optical system from the standard deviation of a plurality of pixels in the image data obtained by reading the white reference, and to create high-precision shading correction data that also takes into account the deterioration of the optical system. it can.

The twentieth aspect of the present invention relates to the thirteenth to thirteenth aspects.
15. The shading correction data generating method according to any one of the fifteenth to fifteenth aspects, wherein the obtaining step obtains information indicating a total lighting time of the light source as the information indicating the degree of the deterioration.

Therefore, it is possible to determine the degree of deterioration of the optical system from the total lighting time of the light source, and to generate highly accurate shading correction data in which the deterioration of the optical system is also taken into consideration.

According to the twenty-first aspect of the present invention,
15. In the shading correction data creating method according to any one of 15, the acquiring step acquires information on the number of images read by the photoelectric conversion element that reads the white reference as information indicating a degree of deterioration of the optical system. It is characterized by the following.

Therefore, it is possible to determine the degree of deterioration of the optical system from the number of read images, and to generate highly accurate shading correction data in consideration of the deterioration of the optical system.

According to a twenty-second aspect of the present invention, there is provided a computer-readable program for causing a computer to execute a process of generating shading correction data used for white shading correction from image data obtained by reading a white reference. A reference data creating process for creating a reference data by applying a statistical process to a plurality of lines at the head in the scanning direction; an acquiring process for acquiring information indicating a degree of deterioration of an optical system that reads the image data; and a degree of the deterioration. Value setting processing for presetting a value of a size according to the above, and adjusting the magnitude of the image data after the reference data and the image data after the reference data in the sub-scanning direction using the preset value. And comparing the image data after the comparison, and the image data after the reference data is smaller by the comparison operation. In this case, the computer executes an exclusion process for excluding image data after the reference data, and a shading correction data creation process for creating the shading correction data for the image data after the exclusion. The program is characterized by causing

Therefore, a comparison is made between the reference data created by statisticizing a plurality of lines at the head of the white reference and the image data after the reference data, and pixels affected by dust, dirt, scratches, etc. are excluded. Therefore, noise can be sufficiently removed from the white shading correction data. In addition, since the value of a preset value is changed according to the degree of deterioration of the optical system that reads the white reference, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a twenty-third aspect of the present invention, in the program according to the twenty-second aspect, in the comparison process, the preset value is subtracted from the image data after the reference data in the sub-scanning direction as the adjustment. It is characterized by doing.

Therefore, by subtracting a preset value from the read image data of the white reference after the reference data in the sub-scanning direction, it is possible to create shading correction data with high accuracy in which the deterioration of the optical system is taken into consideration. it can.

According to a twenty-fourth aspect of the present invention, in the program according to the twenty-second or twenty-third aspect, the reference data creating process performs an averaging process as the statistic process.

Therefore, it is possible to create white shading correction data from which noise has been sufficiently removed by using the reference data created by averaging a plurality of lines at the head of the white reference.

The invention according to claim 25 is the invention according to claims 22 to
24. The program according to any one of 24, wherein the acquisition processing is performed by setting an amplification factor of a signal processing circuit that performs predetermined signal processing on analog image data output from the photoelectric conversion element that reads the white reference. The information on the set value of the amplification factor is obtained as information indicating the degree of degradation of the optical system from an amplification factor setting unit that sets the signal level to be reduced due to the degradation.

Therefore, it is possible to determine the degree of deterioration of the optical system from the amplification factor set in the signal processing circuit, and to create highly accurate shading correction data in which the deterioration of the optical system is also taken into consideration.

The invention according to claim 26 is the invention according to claims 22 to
24. The program according to any one of 24, wherein the obtaining process detects a variation in the value of the image data and obtains the information as information indicating a degree of deterioration of the optical system.

Therefore, it is possible to determine the degree of deterioration of the optical system based on the variation in the value of the image data obtained by reading the white reference, and to create highly accurate shading correction data in which the deterioration of the optical system is also taken into consideration.

According to a twenty-seventh aspect of the present invention, in the program according to the twenty-sixth aspect, the acquisition processing detects a maximum value of a variation in the image data.

Therefore, by detecting only the maximum value of the variation, the variation can be easily detected with a simple circuit configuration.

The invention according to claim 28 is the program according to claim 26 or 27, wherein the acquisition processing is
The variation is detected by calculating a standard deviation from a plurality of pixels.

Therefore, it is possible to determine the degree of deterioration of the optical system from the standard deviation of a plurality of pixels in the image data obtained by reading the white reference, and to create highly accurate shading correction data in consideration of the deterioration of the optical system. it can.

The invention described in claim 29 is the invention according to claims 22 to
24. The program according to claim 24, wherein the acquisition process acquires information indicating a total lighting time of the light source as information indicating the degree of the deterioration.

Therefore, it is possible to determine the degree of deterioration of the optical system from the total lighting time of the light source, and to create highly accurate shading correction data in which the deterioration of the optical system is also taken into consideration.

The invention according to claim 30 is the invention according to claims 22 to
24. The program according to any one of 24, wherein the acquisition process acquires information on the number of images read by a photoelectric conversion element that reads the white reference as information indicating a degree of deterioration of the optical system. I do.

Therefore, it is possible to determine the degree of deterioration of the optical system from the number of read images, and create highly accurate shading correction data in consideration of the deterioration of the optical system.

The invention according to claim 31 is the invention according to claims 22 to
30 is a storage medium storing the program according to any one of 30.

Therefore, the same operation and effect as those of the invention according to any one of claims 22 to 30 can be obtained.

[0079]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment of the Invention] One embodiment of the present invention will be described as a first embodiment of the present invention.

FIG. 1 is a longitudinal sectional view showing the entire configuration of the image reading apparatus 1 according to the first embodiment of the present invention. As shown in FIG. 1, an image reading apparatus 1 is of a flat bed type, and includes a contact glass 3 on which a document 2 is placed, and a document 2.
A first carriage 6 including a halogen lamp 4 and a first reflection mirror 5 as a light source for the exposure, a second carriage 9 including a second reflection mirror 7 and a third reflection mirror 8,
CCD linear image sensor 10 as a photoelectric conversion element
(Hereinafter simply referred to as a CCD 10), a lens unit 11 for forming an image on the CCD 10, a white reference plate 12 serving as a white reference for white shading correction, and stepping for driving the first carriage 6 and the second carriage 9. And a motor 14. The CCD 10 is provided on a sensor board substrate 13. Halogen lamp 4, first, second and third reflecting mirrors 5, 7, 8 and lens unit 11
Constitutes a scanning optical system.

The halogen lamp 4 irradiates light at a certain angle to the reading surface of the white reference plate 12 and the contact glass 3, and the light reflected by the white reference plate 12 or the document 2
Second and third reflection mirrors 5, 7, 8 and lens unit 1
The light enters the CCD 10 via 1. The CCD 10 outputs a voltage corresponding to the amount of incident light as analog image data. The first and second carriages 6 and 9 are moved in the sub-scanning direction by the driving of the stepping motor 14 while keeping the distance between the reading surface of the document 2 and the CCD 10 constant, and expose and scan the document 2.

FIG. 2 is a timing chart for explaining gate signals used in the scanning operation by the image reading apparatus 1. That is, the shading gate is connected to the white reference plate 1.
The image data output from the CCD 10 is captured when the shading gate is at the L level. The gate signal XFGATE indicates the reading range of the document 2 (document reading area). When the gate signal XFGATE is at the L level, image data output from the CCD 10 is captured.

FIG. 3 is a block diagram of the white shading correction device 21 provided in the image reading device 1. The white shading correction device 21 is configured in a predetermined ASIC. As shown in FIG. 3, the analog image data output from the CCD 10 is subjected to signal processing such as waveform shaping, sample hold, and amplification by a signal processing circuit 22, and A
After being converted into digital image data by the / D converter 23, the digital image data is output to the white shading correction device 21.

The shading correction device 21 includes:
A data input path 24, an input path for digital image data after A / D conversion, a shading correction data input path 25, and a reference data input path 26 are provided.

A line synchronization signal is input to the line number counter 27, and counts the number of the current line. The data of the count value is input to the selector 28. The selector 28 also receives a shading gate and a gate signal XFGATE. The selector 28 selectively distributes the image data output from the A / D converter 23 to the paths 24, 25, 26 based on these input signals.

The averaging circuit 29 outputs a predetermined number of lines m (m = 1, 2, 3,...) From the point in time when the shading gate goes low and the white reference plate 12 starts reading, Input of image data for the first m lines (reference data generation area) of the read image data of the reference plate 12 in the sub-scanning direction is received from the reference data input path 26 by switching of the selector 28. And the averaging circuit 29
Generates reference data by performing statistic processing on input m-line image data, for example, averaging processing such as weighted averaging or simple averaging for each pixel, and the reference data is stored in a FIFO (first-in first-out circuit). 30 is stored. This implements reference data creation means and a reference data creation step.

The switching of the selector 28 causes the comparison circuit 31 to switch from the shading correction data input path 25 after the first m lines of the read image data of the white reference plate 12 in the sub-scanning direction, that is, after the reference data generation area (shading). Input of data in the correction data generation area) is accepted. The comparison circuit 31 performs the following comparison operation based on the reference data stored in the FIFO 30 and the image data input from the shading correction data input path 25. This provides a means of comparison,
The comparison process has been realized.

That is, a value set in advance from the reference data
NOREF is subtracted, and this “reference data−NOREF” is compared with the image data (shading correction data generation data) of each line of the shading correction data generation area for each pixel.

When the relationship of shading correction data generation data <reference data−NOREF (1) is satisfied, the corresponding shading correction data generation data is excluded for each pixel. That is,
Only the shading correction data generation data not related to the equation (1) is selectively output to the averaging circuit 32 for each pixel, and the shading correction data generation data related to the equation (1) is not output. This implements an exclusion unit and an exclusion step.

At this time, because of the relationship of the equation (1), pixels for which no data for generating shading correction data are output are replaced with reference data obtained by comparison of the equation (1), and the averaging circuit is used instead. 32.

In the averaging circuit 32, the image data output from the comparison circuit 31 is averaged between lines, for example, multi-addition averaging to generate shading correction data Dsh. This implements shading correction data creation means and a shading correction data creation step. The created shading correction data Dsh is F
It is stored in the IFO 33. As described above, the averaging circuit 2
9, a comparison circuit 31, an averaging circuit 32, and the like constitute a shading correction data creation device 37.

When the original 2 is read, the selector 28 is switched so that the read image data Di of the original 2 is read from the data input path 24 through the FIFO at the time of reading the original image.
33, the shading correction data Dsh for each pixel is output, and based on an algorithm of an arithmetic expression for shading correction stored in the ROM 34 in advance, the shading correction data Dsh is processed by a look-up table method. White shading correction is performed based on the shading correction data Dsh, and the corrected image data Do of the document 2 is generated. This implements a white shading correction unit and a white shading correction step.

The image data Do after the white shading correction is subjected to image processing such as black shading correction, MTF correction, filter processing, scaling processing, γ conversion, and background removal processing of the original 2. The processed image data is output from the image reading device 1. Since the specific contents of these processes are well known, detailed description will be omitted.

According to the image reading apparatus 1, the white reference plate 1
For the read image data of No. 2, a comparison is made between the reference data created by statistically averaging the plurality of (m) lines at the top and the image data after the reference data, and dust, dirt,
Pixels affected by scratches etc. can be excluded,
Noise can be sufficiently removed from the white shading correction data Dsh.

In this case, pixels for which shading correction data generation data is not output are replaced with reference data instead, so that the number of pixels that can be used for generating shading correction data Dsh is not reduced.
Accurate shading correction data can be obtained.

When comparison is made between the reference data and the image data subsequent to the reference data, a predetermined value NOREF is subtracted from the reference data in advance, and the comparison is performed. The shading correction data Dsh can be accurately obtained by performing the adjustment.

In particular, when the averaging circuit 32 creates the shading correction data Dsh by the multiple averaging between lines, the influence of dust, dirt, scratches, etc. on the last line can be effectively eliminated, and Correction data can be created accurately.

By the way, in the image reading apparatus 1, the variation in the output level of the CCD 10 due to the variation of the light amount of the halogen lamp 4, the contamination of the mirrors 5, 7, 8 and the variation of the sensitivity of the CCD 10 caused by aging is represented by A / A. D
In order to match the dynamic range of the converter 23, an amplifier circuit (not shown) for amplifying the image signal is provided in the signal processing circuit 22. The gain of this amplifier circuit is set by a gain setting circuit 71.

The adjustment of the amplification factor is performed when (1) the main power of the image reading apparatus 1 is turned on, (2) the image reading apparatus 1 returns from the standby state (energy saving mode), and (3) the image reading apparatus 1 Is executed by reading the white reference plate 12 with the CCD 10 in each case when is maintained by a serviceman.

The feed hack system for adjusting the amplification factor is as follows.
The process up to the middle is the same as the flow of data for shading correction data creation. That is, among the read image data of the white reference plate 12, the leading m lines are statistically processed by the averaging circuit 29 and stored in the FIFO 30. The data after the m-th line is compared with the “reference data NOREF” by the comparison circuit 31, and the data that satisfies the relationship of the expression (1) is excluded and replaced with the reference data instead. At this time, the data is averaged by the averaging circuit 32 and stored in the FIF033. At this time, the difference from the creation of the white shading correction data Dsh is that the amplification value set by the CPU 35 in the gain setting circuit 71 is a default value (initial value), and NORE
The value NOREF calculated by the F calculation circuit 72 is also a value corresponding to this default value.

The data stored in the FIFO 33 is output to the peak detection circuit 77, where the peak value (white peak) is detected, and the detected peak value is input to the CPU 35. The CPU 35 calculates a new amplification factor based on the input peak value. For example, the value of the input peak value (8-bit data) is 190, and the predetermined target white output (the target value of the maximum output value of the A / D converter 23) is 22.
In the case of 0, the amplification factor (220/190) is calculated so that the peak value 190 becomes the target white output 220. The calculated amplification factor is set in the gain setting circuit 71 by the CPU 35, and the white shading correction data is calculated based on the amplification factor.
The value NOREF when the Dsh is created is calculated by the NOREF calculation circuit 72.

The shading correction data generating device 37 includes a NOREF operation circuit 72. This NOREF
The calculation circuit 72 receives an amplification rate setting signal set by the gain setting circuit 71 (this implements an acquisition unit and an acquisition step), and performs an operation based on the amplification rate indicated by the setting signal. A set value NOREF is obtained (this implements a value setting means and a value setting step). Then, the obtained set value NOREF is set in (the register of) the comparison circuit 31.

The calculation of the set value NOREF in the NOREF calculation circuit 72 is performed, for example, by the following calculation formula (may be calculated by a data table).

NOREF = NOREF_DEF × GAIN × NOREF_ADJ (2) where, NOREF_DEF: initial value of NOREF GAIN: amplification rate NOREF_ADJ: correction coefficient

As described above, the degree of deterioration of the scanning optical system such as the variation in the amount of light of the halogen lamp 4 and the contamination of the mirrors 5, 7, and 8 is detected based on the amplification factor of the amplifier circuit in the signal processing circuit 22. Since the set value NOREF can be changed in accordance with the amplification factor, it is possible to create high-precision shading correction data in consideration of deterioration of the scanning optical system.

Thus, the set amplification factor is small,
When the data variation of the read image data is small (S / N is good), the setting value NOREF is set to a small value, and only the data outside the noise component of the white level is made valid, thereby obtaining more accurate shading correction data. It becomes possible.

On the other hand, when the amplification factor to be set is large and the data variation of the read image data is large (S / N is bad), the set value NOREF is increased and the data used as valid data is increased. Can be increased, and more accurate shading correction data can be calculated.

[Second Embodiment of the Invention] Another embodiment will be described as a second embodiment of the present invention.

In the following description, members and circuit elements common to the first embodiment are denoted by the same reference numerals as in the first embodiment, and detailed description is omitted. The difference between the image reading apparatus 1 according to the second embodiment and the first embodiment is that a data distribution detecting circuit 73 is provided in the shading correction data generating apparatus 37 as shown in FIG. The input path 74 extends to the data distribution detecting circuit 73 and the read image data is input to the data distribution detecting circuit 73.

In this configuration, the variation in the light amount of the halogen lamp 4 and the variation in the sensitivity of the CCD 10
After the gain setting circuit 71 performs adjustment for adjusting the output level of D10 to the dynamic range of the A / D converter 23, the data distribution detection circuit 73 detects that the adjustment has been completed, and outputs the white reference plate. Twelve reading level variations (the maximum value and the minimum value of the read image data or the standard deviation of the variations) are detected (this implements an acquisition unit and an acquisition step). Then, the set value NOREF is calculated by the NOREF calculation circuit 72 according to the variation (this realizes a value setting means and a value setting step).

More specifically, the data distribution detection circuit 73
It holds the past read data for a specific pixel, detects the maximum value and the minimum value from the current read data and the past read data, and calculates the difference between the detected maximum value and the minimum value. The NOREF calculation circuit 72 calculates the set value NOREF based on the difference value. The fact that the difference value increases with time indicates that the gain set in the gain setting circuit 71 increases with time. That is, it means that the noise included in the image data is also amplified with the increased amplification factor. Therefore, if the set value NOREF is calculated according to the difference value, the noise thus amplified can be appropriately removed.

The data distribution detecting circuit 73 may calculate the standard deviation σ instead of the difference value. That is, for the specific pixel, the distribution (normal distribution) of the data is detected based on the past read data and the present read data, and the standard deviation σ is calculated from the distribution. The NOREF calculation circuit 71 calculates the standard deviation σ calculated by the data distribution detection circuit 73,
The set value NOREF is calculated according to the following equation (3).

NOREF = σ × 3 (3)

Accordingly, the variation in the value of the read image data of the white reference plate 12, that is, the maximum value, the minimum value, the standard deviation of the variation of the read image data, etc. , 8, etc., the degree of deterioration of the scanning optical system can be determined, and highly accurate shading correction data can be created in consideration of the deterioration of the scanning optical system.

In this case, the detection of the variation in the value of the read image data is performed for a plurality of pixels in the main scanning direction. Further, if the data distribution detecting circuit 73 detects only the maximum value of the variation, the variation can be easily detected with a simple circuit configuration.

[Third Embodiment of the Invention] Another embodiment will be described as a third embodiment of the present invention.

In the following description, members and circuit elements common to the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description is omitted. As shown in FIG.
The image reading apparatus 1 according to the third embodiment is different from the image reading apparatus 1 according to the first embodiment in that the gain setting circuit 71 first sets the AGC (Auto
This is a configuration in which gain control is performed by hardware using a gain control circuit, and the set amplification factor cannot be recognized by the shading correction data generation device 37. Therefore, the CPU 35 operates the operation time detection unit 75
As a result, the total value of the operation time of the halogen lamp 4 is detected, and the detected value is input to the NOREF calculation circuit 72 (this realizes the obtaining means and the obtaining step). The operating time detecting unit 75 detects whether the halogen lamp 4 is lit from the voltage of the lighting circuit of the halogen lamp 4 or the like, counts the lighting time, and stores the past total value of the lighting time in a nonvolatile memory or the like. .

[0118] The NOREF operation circuit 72 includes the halogen lamp 4
Based on the total value of the operation time of, for example, NOREF is calculated by the following calculation formula (whereby the value setting means,
Value setting process).

NOREF = NOREF_DEF × TIME × NOREF_ADJ (4) NOREF_DEF: NOREF initial value TIME: Total value of operating time of halogen lamp 4 NOREF_ADJ: Correction coefficient

Therefore, the degree of deterioration of the scanning optical system is determined from the total lighting time of the halogen lamp 4 as the light source of the scanning optical system, and highly accurate shading correction data is created in consideration of the deterioration of the scanning optical system. be able to. Moreover, it can be realized with a relatively simple configuration.

The setting of the amplification factor in the signal processing circuit 22 is slightly different from that described above with reference to FIGS. Is directly input to the gain setting circuit 71, and the amplification factor is set by hardware.

[Fourth Embodiment of the Invention] Another embodiment will be described as a fourth embodiment of the invention.

In the following description, members, circuit elements, and the like common to the third embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description is omitted. The difference between the image reading apparatus 1 of the fourth embodiment and the third embodiment is that, as shown in FIG. Is provided, and the number-of-read-sheets detecting unit 76 for counting the number of sheets in a nonvolatile memory or the like is provided.

The total value of the number of read images of the original 2 is input from the read number detection unit 76 to the NOREF calculation circuit 72 (this implements an acquisition unit and an acquisition step), and based on the total value, for example, , NORE
F is calculated (this implements a value setting means and a value setting step).

NOREF = NOREF_DEF × PAGE × NOREF_ADJ (5) NOREF_DEF: NOREF initial value PAGE: Total value of the number of read images of document 2 NOREF_ADJ: Correction coefficient

In this case, it is possible to determine the degree of deterioration of the scanning optical system from the total number of read images of the document 2, and to create highly accurate shading correction data in consideration of the deterioration of the scanning optical system. Also in this case, it can be realized with a relatively simple configuration.

[Fifth Embodiment] Another embodiment will be described as a fifth embodiment of the present invention.

The image reading apparatus 1 according to the fifth embodiment differs from the first to fourth embodiments in that the white shading correction device 21 is not provided, and the image reading apparatus 1 according to the first to fourth embodiments is used instead. White shading correction with the same content as
The point is that a shading correction data creation device and a white shading correction device are realized by the CPU 35 performing based on a predetermined white shading correction program. Other points are the same as those in the first embodiment, and the same reference numerals as those in the first embodiment are used, and the detailed description is omitted.

Hereinafter, the contents of the white shading correction processing performed by the CPU 35 based on the white shading correction program will be described.

First, FIG. 10 is a block diagram showing the electrical connection of the control system of the image reading apparatus 1. As shown in FIG. 10, the RAM 82 connected to the CPU 35 via the bus 86 controls the IPU (Imag
e Processing Unit) 84 stores shading correction data obtained as a result of a calculation described later. The ROM 81 serving as a storage medium is a nonvolatile memory such as a flash memory, and stores a shading correction data creation program, a white shading correction program, and the like. The program stored in the ROM 81 is a CPU
Under the control of 35, the program can be rewritten to a program downloaded from an external device (not shown) via the I / O port 83. In addition to the above restrictions, the CPU 35 obtains information indicating the degree of deterioration of the scanning optical system and calculates the value of NOREF.

Sensor board (SBU: Sensor Proce
The ssing unit 13 is a board on which the CCD 10, the signal processing circuit 22, and the A / D converter 23 are mounted.
4 calls a shading correction data creation program and a white shading sig correction program from a ROM (flash memory) 81 under the control of the CPU 35 to perform shading correction data creation and white shading correction calculations. CP when creating shading correction data
The value of NOREF is set by U35.

FIG. 7 is a flowchart for explaining the processing procedure of the white shading correction processing. As shown in FIG. 7, the CPU 35 controls the IPU 84 and the like to perform the following processing. That is, when a series of image reading operations is started (Y in step S1), information indicating the degree of deterioration of the scanning optical system is obtained (step S2). This implements an acquisition unit, an acquisition step, and an acquisition process. That is, specifically, as in the first embodiment, the signal processing circuit 2
The amplification factor may be set in the second amplification circuit, may be variation in read image data of the white reference plate 12 as in the second embodiment, or may be variation in the halogen lamp 4 as in the third embodiment. Or the total value of the number of sheets of the document 2 read as in the fourth embodiment.

Then, based on the information indicating the degree of deterioration of the scanning optical system obtained in step S2, for example, the above-described calculations (1) to (4) are performed to obtain the set value NOREF (step S3). Is set as a setting value NOREF to be used (step S4). This implements a value setting means, a value setting step, and a value setting process.

Thereafter, shading correction data is created as follows. That is, as in the case of the first embodiment, averaging processing such as weighted averaging or simple averaging is performed for each pixel up to the last line of the reference data generation area to obtain reference data (step S5). This implements a reference data creation means, a reference data creation step, and a reference data creation process.

Next, a comparison operation based on the above equation (1) is performed on the reference data obtained in step S6 and the image data of each line after the reference data generation area (step S6) to generate shading correction data. If there is a relation of data for use <reference data-NOREF (1) (Y in step S6), the image data of each line after the reference data generation area is excluded for each pixel (step S7). Next, the data is replaced with the reference data subjected to the comparison operation (step S8). Step S6 implements the comparison means, comparison step, and comparison processing, and step S7 implements the exclusion means, exclusion step, and exclusion processing. Then, a weighted average is obtained for the image data of each line after the reference data generation area after the replacement. (Step S9). This implements shading correction data creation means, shading correction data creation process, and shading correction data creation processing.

When the multiple averaging is calculated up to the last line of the shading correction data generation area (Y in step S10), the finally calculated multiple averaging value is used as shading correction data in a predetermined RAM.
And the like (step S11).

When reading of the original 2 is started (Y in step S12), the read image data of the original 2 is read line by line using the shading correction data in the same manner as in the first embodiment. White shading correction is performed (step S13). By step S24, white shading correction means, white shading correction step,
The white shading correction processing is realized. When the white shading correction has been completed up to the last line of the document 2 (Y in step S14), a series of processing ends.

According to the image reading apparatus 1, as in the first to fourth embodiments, the read image data of the white reference plate 12 has the reference data created by statistically forming the top m lines, and the reference data after the reference data. The pixel data affected by dust, dirt, scratches, etc. can be excluded by comparing with the image data of the white shading correction data Dsh.
, Noise can be sufficiently removed.

When comparison is made between the reference data and the image data subsequent to the reference data, a predetermined value NOREF is subtracted from the reference data before comparison (step S6), and the reference data is compared. Adjust to an appropriate value,
Accurate shading correction data Dsh can be obtained accurately.

In this case, information indicating the degree of deterioration of the scanning optical system, that is, the amplification factor set in the amplifier circuit of the signal processing circuit 22, the variation of the read image data of the white reference plate 12, the lighting time of the halogen lamp 4 And the degree of deterioration of the scanning optical system, such as variations in the amount of light from the halogen lamp 4 and dirt on the mirrors 5, 7, and 8, is determined based on the total value of , It is possible to create high-precision shading correction data in consideration of the deterioration of the shading.

The shading correction data creation program may be stored in the ROM 81 in advance,
At the time of product shipment, the conventional shading correction data creation program that creates shading correction data from the average value of data for multiple lines reading the white reference
Stored in M81
A shading data creation program according to this embodiment, which is stored in a storage medium such as a D-ROM,
A program such as a (Personal Computer) may be read once by a readable external device, and the read program may be downloaded to the ROM 81 under the control of the CPU 35 via the I / O port 83.

[Sixth Embodiment of the Invention] Another embodiment will be described as a sixth embodiment of the invention.

FIG. 8 is a block diagram showing a schematic configuration of a digital copying machine 51 according to the sixth embodiment. As shown in FIG. 8, the digital copying machine 51 implements the image forming apparatus of the present invention, and includes an image reading device 1, a printer engine 52, a microcomputer for controlling the entire digital copying machine 51, and the like. And a control unit 53.

The construction of the image reading apparatus 1 is the same as that of the first to third embodiments.
5 is similar to any one of the first to fifth embodiments.
5, the detailed description is omitted.

The printer engine 52 forms an image on a recording medium such as paper. The printing method is an electrophotographic method, an ink jet method, a sublimation type thermal transfer method, a silver halide photographic method, a direct thermal recording method. Various types of well-known methods such as a method and a fusion-type thermal transfer method can be used.

The control section 53 controls the image reading device 1 and the printer engine 52 to read the original 2 with the image reading device 1 and forms an image with the printer engine 52 based on the read image data.

Therefore, according to the digital copying machine 51, the same operation and effect as those of the first to fifth embodiments can be achieved for the white shading correction of the image data.

Seventh Embodiment Another embodiment will be described as a seventh embodiment of the present invention.

FIG. 9 is a block diagram showing a schematic configuration of a printing system 61 according to the seventh embodiment. As shown in FIG. 9, the printing system 61 implements the image forming apparatus of the present invention, and includes a PC (Pers) capable of performing various information processing based on a given program with the image reading apparatus 1.
The image reading apparatus 1 and the printer 63 are connected to the information processing apparatus 62 via a predetermined interface.

The configuration of the image reading apparatus 1 is the same as that of the first to third embodiments.
5 is similar to any one of the first to fifth embodiments.
5, the detailed description is omitted.

The printer 63 forms an image on a recording medium such as paper. The printing method is an electrophotographic method, an ink jet method, a sublimation heat transfer method, a silver halide photographic method, a direct thermal recording method. Various known methods such as a fusion-type thermal transfer method can be used.

The information processing device 62 stores driver software for driving the image reading device 1 and the printer 63. When the information processing device 62 is operated, the image reading device 1 and the printer 63 are controlled based on the driver software. Then, the document 2 can be read by the image reading device 1 and an image can be formed by the printer engine 52 based on the read image data.

Therefore, according to the printing system 61, the same operation and effect as those of the first to fifth embodiments can be achieved for the white shading correction of the image data.

[0154]

According to the first aspect of the present invention, dust, dirt, scratches, and the like are compared by comparing the reference data created by statisticizing a plurality of lines at the head of the white reference with the image data after the reference data. Can be excluded, so that noise can be sufficiently removed from the white shading correction data. In addition, since the value of a preset value is changed according to the degree of deterioration of the optical system that reads the white reference, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a second aspect of the present invention, in the shading correction data creating apparatus according to the first aspect, a preset value is subtracted from white-reference read image data after the reference data in the sub-scanning direction. Thus, it is possible to create highly accurate shading correction data in consideration of the deterioration of the optical system.

The invention according to claim 3 is the invention according to claim 1 or 2
In the shading correction data creation device described in the above,
By using reference data created by averaging a plurality of lines at the head of the white reference, white shading correction data from which noise has been sufficiently removed can be created.

According to a fourth aspect of the present invention, in the shading correction data generating apparatus according to any one of the first to third aspects, the degree of deterioration of the optical system is determined from the amplification factor set in the signal processing circuit. As a result, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a fifth aspect of the present invention, in the shading correction data creating apparatus according to any one of the first to third aspects, the degree of deterioration of the optical system is determined based on a variation in the value of image data obtained by reading the white reference. Is determined, and highly accurate shading correction data that takes into account deterioration of the optical system can be created.

According to a sixth aspect of the present invention, in the shading correction data creating apparatus according to the fifth aspect, only the maximum value of the variation is detected, thereby achieving a simple circuit configuration.
Variations can be easily detected.

The invention according to claim 7 is the invention according to claim 5 or 6
In the shading correction data creation device described in the above,
It is possible to determine the degree of deterioration of the optical system from the standard deviation of a plurality of pixels with respect to the image data obtained by reading the white reference, and create highly accurate shading correction data that also takes into account the deterioration of the optical system.

The invention described in claim 8 is the invention according to claim 1 or 2
In the shading correction data creation device described in the above,
By judging the degree of deterioration of the optical system from the total lighting time of the light source, it is possible to create highly accurate shading correction data that also takes into account the deterioration of the optical system.

According to a ninth aspect of the present invention, in the shading correction data generating apparatus according to any one of the first to third aspects, the degree of deterioration of the optical system is determined based on the number of read images. , It is possible to create highly accurate shading correction data that also takes into account the deterioration of.

The tenth aspect of the present invention provides the first to ninth aspects.
The same operation and effect as the invention described in any one of the above are exerted.

The eleventh aspect of the invention has the same function and effect as the tenth aspect of the invention.

The twelfth aspect of the invention has the same functions and effects as the eleventh aspect of the invention.

According to a thirteenth aspect of the present invention, a comparison is made between reference data created by statistically quantifying a plurality of lines at the head of the white reference and image data subsequent to the reference data, and the influence of dust, dirt, scratches and the like is obtained. Since the received pixels can be excluded, noise can be sufficiently removed from the white shading correction data. In addition, since the value of a preset value is changed according to the degree of deterioration of the optical system that reads the white reference, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a fourteenth aspect of the present invention, in the shading correction data creating method according to the thirteenth aspect, a predetermined value is subtracted from white-reference read image data after the reference data in the sub-scanning direction. Thus, it is possible to create highly accurate shading correction data in consideration of the deterioration of the optical system.

According to a fifteenth aspect of the present invention, in the shading correction data generating method according to the thirteenth or fourteenth aspect, noise is sufficiently removed by using reference data generated by averaging a plurality of lines at the head of a white reference. White shading correction data can be created.

The invention according to claim 16 is the invention according to claims 13 to
15. In the shading correction data creation method according to any one of 15., the degree of deterioration of the optical system is determined from the amplification factor set in the signal processing circuit, and high-precision shading correction considering the deterioration of the optical system is also performed. Data can be created.

The invention according to claim 17 is the invention according to claims 13 to
15. In the shading correction data creation method according to any one of the fifteenth and fifteenth aspects, the degree of deterioration of the optical system is determined from the variation in the value of the image data obtained by reading the white reference, and the accuracy is high in consideration of the deterioration of the optical system. Shading correction data can be created.

According to an eighteenth aspect of the present invention, in the shading correction data creating method according to the seventeenth aspect, by detecting only the maximum value of the variation, the variation can be easily detected with a simple circuit configuration. it can.

According to a nineteenth aspect of the present invention, in the shading correction data creation method according to the seventeenth or eighteenth aspect, the degree of deterioration of the optical system is determined from the standard deviation of a plurality of pixels in the image data obtained by reading the white reference. As a result, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to the twentieth aspect of the present invention,
15. In the shading correction data generating method according to any one of 15., the degree of optical system deterioration is determined from the total lighting time of the light source, and high-precision shading correction data is generated in consideration of optical system deterioration. can do.

The invention described in claim 21 is the invention according to claims 13 to
15. The method for generating shading correction data according to any one of 15 above, wherein the degree of deterioration of the optical system is determined from the number of read images, and high-precision shading correction data is generated in consideration of the deterioration of the optical system. Can be.

According to the twenty-second aspect of the present invention, a comparison is made between reference data created by statistically quantifying a plurality of lines at the head of the white reference and image data after the reference data, and the influence of dust, dirt, scratches, and the like is obtained. Since the received pixels can be excluded, noise can be sufficiently removed from the white shading correction data. In addition, since the value of a preset value is changed according to the degree of deterioration of the optical system that reads the white reference, highly accurate shading correction data that takes into account the deterioration of the optical system can be created.

According to a twenty-third aspect of the present invention, in the program according to the twenty-second aspect, the preset value is subtracted from the read image data of the white reference after the reference data in the sub-scanning direction, whereby Highly accurate shading correction data can be created in consideration of deterioration.

According to a twenty-fourth aspect of the present invention, in the program according to the twenty-second or twenty-third aspect, white shading correction is performed by using reference data created by averaging a plurality of lines at the head of the white reference to sufficiently remove noise. Data can be created.

The invention according to claim 25 is the invention according to claims 22 to
24, the degree of deterioration of the optical system is determined from the amplification factor set in the signal processing circuit, and high-precision shading correction data is created in consideration of the deterioration of the optical system. be able to.

The invention according to claim 26 is the invention according to claims 22 to
24. The program according to any one of 24, wherein the degree of deterioration of the optical system is determined from the variation in the value of the image data obtained by reading the white reference, and high-precision shading correction data taking into account the deterioration of the optical system is obtained. Can be created.

According to the invention of claim 27, in the program of claim 26, by detecting only the maximum value of the variation, the variation can be easily detected with a simple circuit configuration.

According to a twenty-eighth aspect of the present invention, in the program according to the twenty-sixth aspect or the twenty-seventh aspect, the degree of deterioration of the optical system is determined based on the standard deviation of a plurality of pixels for image data obtained by reading the white reference. It is possible to create highly accurate shading correction data in consideration of system degradation.

The invention according to claim 29 is the invention according to claims 22 to
24, the degree of deterioration of the optical system is determined from the total lighting time of the light source, and high-precision shading correction data can be created in consideration of the deterioration of the optical system. .

The invention according to claim 30 is the invention according to claims 22 to
24, the degree of deterioration of the optical system can be determined from the number of read images, and high-precision shading correction data can be created in consideration of the deterioration of the optical system.

The invention according to claim 31 is the invention according to claims 22 to
30 has the same function and effect as the invention described in any one of the thirty aspects.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the entire configuration of an image reading apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a timing chart illustrating a gate signal used in an image reading operation by the image forming apparatus.

FIG. 3 is a block diagram illustrating a circuit configuration of a white shading correction device of the image forming apparatus.

FIG. 4 is a block diagram illustrating a circuit configuration of a white shading correction device of the image reading device according to the second embodiment of the present invention;

FIG. 5 is a block diagram illustrating a circuit configuration of a white shading correction device of the image reading device according to the third embodiment of the present invention;

FIG. 6 is a block diagram illustrating a circuit configuration of a white shading correction device of an image reading device according to a fourth embodiment of the present invention.

FIG. 7 is a flowchart illustrating a circuit configuration of a white shading correction device of an image reading device according to a fifth embodiment of the present invention;

FIG. 8 is an explanatory diagram showing an overall configuration of a digital copying machine according to Embodiment 6 of the present invention.

FIG. 9 is an explanatory diagram illustrating an overall configuration of a printing system according to a seventh embodiment of the present invention.

FIG. 10 is a block diagram illustrating electrical connection of a control system of the image reading apparatus according to the fifth embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image reading apparatus 2 Document 10 Photoelectric conversion element 12 White reference 21 White shading correction apparatus 35 Shading correction data creation apparatus 51 Image forming apparatus 61 Image forming apparatus

Continuing from the front page (72) Inventor Eie Kisara 3-1 Shinmei-do, Nakaname, Shimada-cho, Shibata-machi, Shibata-gun, Miyagi F-term (reference) in Tohoku Ricoh Co., Ltd. 5B047 AA01 BA02 CA07 CB04 CB11 CB25 DA04 DC01 DC20 5C072 AA01 BA08 FB12 RA16 UA03 UA12 UA14 UA20 XA01 5C077 LL02 LL04 MM27 PP06 PP43 PP46 PP62 PP71 PQ03 PQ18 PQ20 SS01 TT06

Claims (31)

[Claims] 1. A shading correction data generating apparatus for generating shading correction data used for white shading correction from image data obtained by reading a white reference, wherein a statistical processing is performed on a plurality of lines at the head of the image data in a sub-scanning direction. Reference data creating means for creating reference data; acquiring means for acquiring information indicating the degree of deterioration of the optical system that reads the image data; and value setting means for setting a value corresponding to the degree of deterioration in advance. And comparing means for adjusting the magnitude of the image data after the reference data and the image data after the reference data in the sub-scanning direction using the preset value, and comparing the adjusted data. When the image data after the reference data is smaller, an exclusion method for excluding the image data after the reference data is excluded. When shading correction data generating apparatus characterized by comprising: a shading correction data generating means for generating the shading correction data to the reference data after the image data after the exclusion as a target. 2. The shading correction data generation method according to claim 1, wherein the comparison unit subtracts the preset value from the image data after the reference data in the sub-scanning direction as the adjustment. apparatus. 3. The shading correction data creating device according to claim 1, wherein the reference data creating unit performs an averaging process as the statistic process. 4. The image processing apparatus according to claim 1, wherein the obtaining unit sets a gain of a signal processing circuit that performs predetermined signal processing on analog image data output from the photoelectric conversion element that reads the white reference, to decrease a signal level due to the deterioration of the analog image data. The information of the set value of the gain is obtained as information indicating the degree of deterioration of the optical system from the gain setting means that is set so as to suppress the optical system. The shading correction data creation device described. 5. The apparatus according to claim 1, wherein the acquisition unit detects a variation in the value of the image data and acquires the information as information indicating a degree of deterioration of the optical system. The shading correction data creation device described. 6. The shading correction data creation device according to claim 5, wherein the acquisition unit detects a maximum value of the variation of the image data. 7. The shading correction data creation device according to claim 5, wherein the acquisition unit calculates a standard deviation from a plurality of pixels to detect the variation. 8. The method according to claim 1, wherein the acquisition unit acquires information indicating a total lighting time of a light source of the optical system as the information indicating the degree of the deterioration. The shading correction data creation device described. 9. The method according to claim 1, wherein the acquisition unit acquires information on the number of images read by the photoelectric conversion element that reads the white reference as information indicating a degree of deterioration of the optical system. The shading correction data creation device according to any one of the preceding claims. 10. A shading correction data creating apparatus according to claim 1, wherein said shading correction data created by said shading correction data creating apparatus is used for image data of a read image of a document. A white shading correction device comprising: white shading correction means for performing white shading correction. 11. A photoelectric conversion element for reading an image of a document, and a white shading correction device according to claim 10 for performing white shading correction on image data of the read image. Image reading device. 12. An image forming apparatus comprising: the image reading device according to claim 11 for reading an image of a document; and forming an image on a recording medium based on the read image of the document. 13. A shading correction data generating method for generating shading correction data used for white shading correction from image data obtained by reading a white reference, wherein a statistical process is performed on a plurality of lines at the head of the image data in the sub-scanning direction. A reference data creation step of creating reference data; an acquisition step of acquiring information indicating the degree of deterioration of the optical system that reads the image data; and a value setting step of presetting a value corresponding to the degree of deterioration A comparison step of adjusting the magnitude of the image data after the reference data and the image data after the reference data in the sub-scanning direction by adjusting using the preset value, and comparing If the image data after the reference data is smaller, exclude the image data after the reference data. Degree and shading correction data creation method characterized by comprising a shading correction data creating step of creating the shading correction data to image data of the reference data after after the exclusion as a target, a. 14. The shading correction data generation according to claim 13, wherein in the comparing step, the preset value is subtracted from the image data after the reference data in the sub-scanning direction as the adjustment. Method. 15. The shading correction data creating method according to claim 13, wherein in the reference data creating step, an averaging process is performed as the statistic process. 16. The signal processing circuit according to claim 1, wherein the obtaining step includes a step of setting a gain of a signal processing circuit that performs predetermined signal processing on analog image data output by the photoelectric conversion element that reads the white reference to reduce a signal level due to the deterioration of the analog image data. The information on the set value of the amplification factor is obtained as information indicating the degree of deterioration of the optical system from an amplification factor setting unit that sets so as to suppress the noise. The shading correction data creation method described. 17. The method according to claim 13, wherein in the acquiring step, a variation in the value of the image data is detected and acquired as information indicating a degree of deterioration of the optical system. The shading correction data creation method described. 18. The method according to claim 17, wherein the acquiring step detects a maximum value of the variation of the image data.
The shading correction data creation method described in 1. 19. The shading correction data creating method according to claim 17, wherein the obtaining step calculates the standard deviation from a plurality of pixels to detect the variation. 20. The shading according to claim 13, wherein the obtaining step obtains information indicating a total lighting time of the light source as the information indicating the degree of the deterioration. Correction data creation method. 21. The method according to claim 13, wherein the obtaining step obtains information on the number of images read by a photoelectric conversion element that reads the white reference as information indicating a degree of deterioration of the optical system. The shading correction data creation method according to any one of the above. 22. A computer-readable program for causing a computer to execute shading correction data to be used for white shading correction from image data obtained by reading a white reference, wherein a plurality of lines at the head of the image data in the sub-scanning direction are provided. A reference data creation process of creating reference data by performing a statistical process on the image data; an acquisition process of acquiring information indicating a degree of deterioration of the optical system that reads the image data; and a value corresponding to the degree of the deterioration. And a value setting process for setting in advance a comparison between the image data after the reference data in the sub-scanning direction and the image data after the reference data after adjusting using the preset value. If the image data after the reference data is smaller than the reference data, Excluding the image data after the reference data, and shading correction data creation processing for creating the shading correction data for the image data after the reference data after the exclusion. Program to do. 23. The program according to claim 22, wherein the comparing process subtracts the preset value from the image data after the reference data in the sub-scanning direction as the adjustment. 24. The program according to claim 22, wherein the reference data creating process performs an averaging process as the statistic process. 25. The image processing apparatus according to claim 25, wherein the gain of a signal processing circuit that performs predetermined signal processing on analog image data output from the photoelectric conversion element that reads the white reference is reduced by a signal level decrease due to the deterioration of the analog image data. The information on the set value of the amplification factor is obtained as information indicating the degree of deterioration of the optical system from an amplification factor setting unit that sets the optical system to be suppressed, according to any one of claims 22 to 24. The described program. 26. The image processing apparatus according to claim 22, wherein the acquisition process detects variation in the value of the image data and acquires the information as information indicating a degree of deterioration of the optical system. The program described. 27. The acquisition process according to claim 26, wherein a maximum value of the variation of the image data is detected.
The program described in. 28. The program according to claim 26, wherein the acquisition processing calculates a standard deviation from a plurality of pixels to detect the variation. 29. The program according to claim 22, wherein the acquisition processing acquires information indicating a total lighting time of the light source as the information indicating the degree of the deterioration. . 30. The image processing apparatus according to claim 22, wherein the obtaining processing obtains information on the number of images read by the photoelectric conversion element that reads the white reference as information indicating a degree of deterioration of the optical system. The program according to any one of the above. 31. A storage medium storing the program according to claim 22.