JP2002300392A - 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 thoroughly eliminate noises from white shading correction data by excluding pixels subjected to the influence of dust, dirt and flaw or the like. SOLUTION: An averaging circuit 32 generates shading correction data used for white shading correction from image data obtained by reading a white reference board. An averaging circuit 29 applies weighted mean processing to data by a plurality of lines at the head of image data of the white reference board (reference data generating area) to generate reference data. A comparator circuit 31 discriminates whether or not a relation of 'image data after the reference data generating area < reference data - a prescribed value NOREF' holds and excludes the image data after the reference data generating area from the object of generating the shading correction data by the averaging circuit 32 for each pixel selectively when the relation holds.

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 The present invention relates to a shading correction data generation method for generating shading correction data from a white reference.

[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.

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

It is an object of the present invention to obtain accurate shading correction data without reducing the number of pixels that can be used for generating shading correction data.

An object of the present invention is to adjust reference data to an appropriate value and accurately obtain accurate shading correction data.

An object of the present invention is to adjust a preset value to an appropriate value and accurately obtain accurate shading correction data.

An object of the present invention is to accurately generate shading correction data by averaging image data after reference data between lines.

An object of the present invention is to accurately generate shading correction data even when generating shading correction data by multiple averaging, excluding the influence of dust, dirt, scratches, and the like on the last line. .

An object of the present invention is to accurately generate shading correction data in accordance with the total number of lines of white-based image data.

An object of the present invention is to appropriately select a range in which reference data is to be created in accordance with a white reference reading speed.

An object of the present invention is to make the system configuration simple and low-cost.

An object of the present invention is to reduce the influence of dust, dirt, scratches, and the like even in a continuous white line over a plurality of continuous lines, and to accurately generate shading correction data.

[0018]

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. Shading correction data generating means for statistically generating data for a plurality of lines at the head of the direction to generate reference data, and comparing means for performing a comparison operation on the image data and the reference data after the reference data in the sub-scanning direction An exclusion unit for selectively excluding image data subsequent to the reference data on a pixel-by-pixel basis based on the result of the comparison operation from the target of the shading correction data creation; and Creates the shading correction data based on the image data of It is the shading correction data creation device according to claim which includes a shading correction data creation means.

Therefore, comparison is made between the reference data created by statistically quantifying 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.

According to a second aspect of the present invention, in the shading correction data creating apparatus according to the first aspect, the reference data corresponding to the pixel to be excluded instead of the image data to be excluded. Is provided as replacement means for creating the shading correction data.

Therefore, accurate shading correction data can be obtained without reducing the number of pixels that can be used for generating shading correction data.

The invention described in claim 3 is the first or second invention.
In the shading correction data creation device described in the above,
The comparing means compares the magnitude of a value obtained by subtracting a preset value from the reference data with image data after the reference data, and the exclusion means compares the image after the reference data in the comparison. When the data is smaller, the exclusion is performed.

Therefore, the reference data can be adjusted to an appropriate value, and accurate shading correction data can be accurately obtained.

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, when the magnitude of the preset value is instructed, It is characterized by comprising a first variable means for setting the magnitude of the preset value according to an instruction.

Therefore, by adjusting the preset value to an appropriate value, accurate shading correction data can be accurately obtained.

According to a fifth aspect of the present invention, in the shading correction data generating device according to any one of the first to fourth aspects, the shading correction data generating means includes:
The shading correction data is created by averaging the image data after the reference data between lines.

Therefore, by averaging the image data after the reference data between the lines, it is possible to accurately generate the shading correction data.

According to a sixth aspect of the present invention, in the shading correction data generating apparatus according to the fifth aspect, the shading correction data generating means performs a multiple averaging as the averaging process.

Therefore, even when shading correction data is created by multiple averaging, shading correction data can be created accurately without the influence of dust, dirt, scratches, etc. on the last line.

According to a seventh aspect of the present invention, there is provided the shading correction data creating apparatus according to the sixth aspect, wherein a plurality of lines for which the reference data is to be created in accordance with information indicating the total number of lines of the image data. 2nd variable range
Is provided.

Therefore, when the total number of lines of the white reference image data which cannot be formed so broadly is small, the range in which the reference data is to be created is made small, and the shading correction data is sufficiently obtained using the lines subsequent to the reference data. When the total number of lines is large, the range in which the reference data is to be created is made larger, accurate reference data can be created, and shading correction data can be created accurately.

According to an eighth aspect of the present invention, in the shading correction data creating apparatus according to the seventh aspect, the second variable means uses information indicating the total number of lines as information on an image reading speed of the image data. It is characterized by the following.

Therefore, the range in which the reference data is to be created can be appropriately selected according to the white-based image reading speed.

According to a ninth aspect of the present invention, in the shading correction data generating apparatus according to any one of the first to eighth aspects, the number of lines of image data for which the shading correction data is to be generated is 2 ^n. (N = 1, 2, 3,
..) Are provided.

Therefore, the operation can be performed only by the bit shift on the digital circuit, and the system configuration can be simplified and the cost can be reduced.

The invention described in claim 10 is the invention according to claims 1 to 9
In the shading correction data creation device according to any one of the above, the shading correction data creation means sets a line for which the reference data is created in the image data at every other or a plurality of lines. I do.

Therefore, even if dust, dirt, scratches, and the like are present on a plurality of continuous lines, the effect thereof can be reduced and shading correction data can be created accurately.

The eleventh aspect of the present invention relates to the first to first aspects.
0, and a white shading correction unit that performs white shading correction on image data of a read image of a document using 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 tenth aspects are exhibited.

According to a twelfth aspect of 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 a white shading correction on image data of the read image. An image reading apparatus characterized in that:

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

According to a thirteenth aspect of the present invention, there is provided the image reading device according to the twelfth 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 twelfth aspect are obtained.

According to a fourteenth aspect of the present invention, in the shading correction data creating method for creating 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 shading correction data creating step of creating reference data by statisticizing minute data, a comparing step of performing a comparison operation on the image data and the reference data after the reference data in the sub-scanning direction, and a result of the comparison operation An exclusion step of selectively excluding image data after the reference data for each pixel from a target of the shading correction data based on the
A shading correction data generating step of generating the shading correction data based on the image data after the reference data which has not been excluded.

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 to exclude pixels affected by dust, dirt, scratches, and the like. Therefore, noise can be sufficiently removed from the white shading correction data.

According to a fifteenth aspect of the present invention, in the shading correction data generating method according to the fourteenth aspect, the shading correction data generating step includes replacing the image data to be excluded with the pixel to be excluded. The shading correction data is created based on the reference data corresponding to (1).

Therefore, accurate shading correction data can be obtained without reducing the number of pixels that can be used for generating shading correction data.

According to a sixteenth aspect of the present invention, in the shading correction data creating method according to the fourteenth or fifteenth aspect, the comparing step includes a step of subtracting a preset value from the reference data and a value after the reference data. The size of the image data is compared with the size of the image data, and the exclusion step performs the exclusion when the image data after the reference data is smaller in the comparison.

Therefore, the reference data can be adjusted to an appropriate value, and accurate shading correction data can be accurately obtained.

The invention according to claim 17 is the invention according to claims 14 to
16. In the shading correction data creating method according to any one of the items 16, when the instruction of the magnitude of the preset value is issued, the magnitude of the preset value is set according to the instruction. It is characterized by comprising a first variable step.

Therefore, by adjusting the preset value to an appropriate value, accurate shading correction data can be accurately obtained.

The invention according to claim 18 is the invention according to claims 14 to
17. In the shading correction data creation method according to any one of 17, the shading correction data creation step includes creating the shading correction data by averaging image data after the reference data between lines. It is characterized by.

Therefore, by averaging the image data after the reference data between the lines, it is possible to accurately generate the shading correction data.

According to a nineteenth aspect of the present invention, in the shading correction data creating method according to the eighteenth aspect, the shading correction data creating step performs a multiple averaging as the averaging process.

Therefore, even when shading correction data is created by multiple averaging, shading correction data can be accurately created without the influence of dust, dirt, scratches, and the like on the last line.

According to a twentieth aspect of the present invention, in the shading correction data creation method according to the nineteenth aspect, prior to creation of the reference data, the shading correction data is prepared in accordance with information indicating a total number of lines of the image data of the image data. A second variable range of a plurality of lines for which the reference data is created;
Characterized by a variable step.

Therefore, when the total number of lines of the white reference image data which cannot be formed so broadly is small, the range in which the reference data is to be created is made smaller, and the shading correction data is sufficiently obtained using the lines subsequent to the reference data. When the total number of lines is large, the range in which the reference data is to be created is made larger, accurate reference data can be created, and shading correction data can be created accurately.

According to a twenty-first aspect of the present invention, in the shading correction data creating method according to the twentieth aspect, the second variable step includes the step of converting the information indicating the total number of lines into the information of the image reading speed of the image data. It is characterized by the following.

Therefore, it is possible to appropriately select the range in which the reference data is to be created in accordance with the image reading speed of the white reference.

The invention according to claim 22 is the invention according to claims 14 to
21. The shading correction data described in any one of 21.
The shading correction data creation process
The process is the object of the shading correction data creation.
2 lines of image data ⁿ(N = 1, 2, 3, ...)
It is characterized by the numerical value represented by

Therefore, the operation can be performed only by the bit shift on the digital circuit, and the system configuration can be simplified and the cost can be reduced.

The invention according to claim 23 is the invention according to claims 14 to
22. The shading correction data generation method according to any one of 22., wherein the shading correction data generation step sets one or more lines of the reference data in the image data to be generated. And

Therefore, even if dust, dirt, scratches and the like are present on a plurality of continuous lines, the influence thereof can be reduced and shading correction data can be created accurately.

According to a twenty-fourth 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. Shading correction data generation processing for statistically generating data for a plurality of lines at the head in the scanning direction to generate reference data, and comparison processing for performing a comparison operation on the image data and the reference data after the reference data in the sub-scanning direction And an exclusion process for selectively excluding image data after the reference data for each pixel based on the result of the comparison operation from the object of generating the shading correction data, and the reference data not being excluded. Based on the subsequent image data, Is a program for causing execute shading correction data creation processing for creating a grayed correction data, to the computer.

Therefore, 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 pixels affected by dust, dirt, scratches, etc. are excluded. Therefore, noise can be sufficiently removed from the white shading correction data.

According to a twenty-fifth aspect of the present invention, in the program according to the twenty-fourth aspect, the shading correction data creation processing is performed in accordance with the pixel to be excluded in place of the image data to be excluded. The shading correction data is created based on the reference data.

Therefore, accurate shading correction data can be obtained without reducing the number of pixels that can be used for generating shading correction data.

According to a twenty-sixth aspect of the present invention, in the program according to the twenty-fourth or twenty-fifth aspect, the comparison processing comprises:
The value obtained by subtracting a preset value from the reference data is compared with the image data after the reference data, and the exclusion process is such that the image data after the reference data is smaller in the comparison. In some cases, the exclusion is performed.

Therefore, the reference data can be adjusted to an appropriate value, and accurate shading correction data can be accurately obtained.

The invention according to claim 27 is the invention according to claims 24 to
26. In the program according to any one of the items 26, when an instruction for the magnitude of the preset value is given, a first variable for setting the magnitude of the preset value in accordance with the instruction. It is characterized by causing a computer to execute processing.

Therefore, by adjusting the preset value to an appropriate value, accurate shading correction data can be accurately obtained.

The invention according to claim 28 is the invention according to claims 24 to
27. The program according to any one of items 27, wherein the shading correction data creation processing creates the shading correction data by averaging image data after the reference data between lines. .

Therefore, by averaging the image data after the reference data between the lines, it is possible to accurately generate the shading correction data.

According to a twenty-ninth aspect of the present invention, in the program according to the eighteenth aspect, the shading correction data creating process performs a multiple averaging as the averaging process.

Therefore, even if shading correction data is created by multiple averaging, shading correction data can be created accurately without the influence of dust, dirt, scratches, etc. on the last line.

According to a thirtieth aspect of the present invention, in the program according to the thirty-ninth aspect, prior to creation of the reference data, the reference data of the image data is stored in accordance with information indicating a total number of lines of the image data. It is characterized by causing a computer to execute a second variable process for changing the range of a plurality of lines to be created.

Therefore, when the total number of lines of the white reference image data which cannot be formed so broadly is small, the range in which the reference data is to be created is made smaller, and the shading correction data is sufficiently obtained using the lines subsequent to the reference data. When the total number of lines is large, the range in which the reference data is to be created is made larger, accurate reference data can be created, and shading correction data can be created accurately.

According to a thirty-first aspect of the present invention, in the program according to the thirty-third aspect, the second variable processing uses information indicating the total number of lines as information on an image reading speed of the image data. Features.

Therefore, it is possible to appropriately select the range in which the reference data is to be created according to the image reading speed based on the white reference.

The invention according to claim 32 is the invention according to claims 24 to
31. The program according to any one of 31., wherein the shading correction data creation processing includes setting the number of lines of image data to be created of the shading correction data to 2 ⁿ (n = 1, 2, 3,...). It is characterized by the numerical value represented.

Therefore, the operation can be performed only by the bit shift on the digital circuit, and the system configuration can be simplified and the cost can be reduced.

The invention according to claim 33 is the invention according to claims 24 to
32. The program according to any one of 32, wherein the shading correction data creation processing sets one or more lines of the reference data to be created in the image data.

Therefore, even if dust, dirt, scratches and the like are present over a plurality of continuous lines, the influence thereof can be reduced and shading correction data can be created accurately.

The invention according to claim 34 is the invention according to claims 24 to
33 is a storage medium storing the program according to any one of 33.

Therefore, the same operation and effect as those of the invention according to any one of claims 24 to 33 can be obtained.

[0086]

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 overall 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 for exposure and a first reflection mirror 5, a second reflection mirror 7 and a third
A second carriage 9 including a reflection mirror 8 and a CCD linear image sensor 10 (hereinafter, referred to as a photoelectric conversion element)
A lens unit 11 for forming an image on the CCD 10, a white reference plate 12 serving as a white reference for correcting white shading, a first carriage 6 and a second carriage 6.
And a stepping motor 14 for driving the carriage 9. The CCD 10 is provided on a sensor board substrate 13. The halogen lamp 4, the first, second, and third reflecting mirrors 5, 7, 8 and the lens unit 11 constitute a scanning optical system.

The halogen lamp 4 irradiates light at a certain angle with respect 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 original 2 is first and second.
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.

When the selector 28 is switched, the comparison circuit 31 switches the shading correction data input path 25 from 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 equation (1), pixels for which no data for generating shading correction data are output are replaced with reference data obtained by comparison of equation (1) and replaced by an averaging circuit. 32. This implements the replacement means and the shading correction data creation step.

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. Thereby, shading correction data creating means,
A shading correction data creation process is realized. The created shading correction data Dsh is stored in FIFO
33. As described above, the averaging circuit 29, the comparison circuit 31, the averaging circuit 32, and the like constitute the shading reference 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 transmitted from the data input path 24 to the FIFO when the original image is read.
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 12 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 document 12. 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.

CPU 35 for controlling image reading apparatus 1
Receives the operation of the operation panel 36 for operating the image reading apparatus 1 and varies the magnitude of the value NOREF set in the register of the comparison circuit 31 in accordance with this operation. The comparison circuit 31 receives the control signal and sets it in a register, thereby realizing a first variable unit and a first variable step.

A change with time of the amount of light incident on the CCD 10, for example, a decrease in the amount of light of the halogen lamp 4, the mirrors 5, 7, 8
And a decrease in the amount of light incident on the CCD 10 due to contamination of the scanning optical system constituted by the lens unit 11 and the like.
The amplification factor of the signal processing circuit 22 increases with time. As the amplification factor increases, the noise will be amplified accordingly.
In this embodiment, since the value NOREF can be adjusted to an appropriate value, noise that has increased due to such an increase in the amplification factor can be accurately removed. Further, when maintenance of the image reading apparatus 1 is performed by a serviceman, for example, replacement of the halogen lamp 4 or cleaning of the scanning optical system is performed, the amount of light incident on the CCD 10 is increased as compared to before maintenance, so that the signal processing circuit 22 is used. It is also necessary to adjust the amplification factor. Even in such a case, noise can be accurately removed by adjusting NOREF. in this way,
The predetermined value NOREF can be appropriately adjusted to an appropriate size, and accurate shading correction data Dsh can be accurately obtained.

Further, the CPU 35 sets the information indicating the total number of lines in the shading gate period, for example, the number m of lines indicating the reference data generation area used in the selector 28 in accordance with the reading scanning speed of the image reading apparatus 1. The set value can be changed. By setting the number of lines m in the selector 28, a second variable means is realized.

That is, the white reference plate 12 cannot be configured so widely. Therefore, for example, when the image reading apparatus 1 can set the reading scanning speed mode in two stages of “high speed” and “low speed”, the total number of white-based image data is small because of “high speed”. At this time, the value of the number m of lines is reduced, the range of the reference data generation area is reduced, and the shading correction data generation area is prevented from becoming relatively narrow.
Make it possible to create Dsh enough. When the total number of lines is large because the speed is "low speed", the range of the reference data generation area is made large, accurate reference data is created, and shading correction data Dsh is created accurately.

At this time, the number m of lines is 2 ⁿ (n = 1,
2, 3, ...). As a result, the averaging circuit 29 and the like can perform the operation only by the bit shift, so that the system configuration can be made simple and low cost.

Further, the CPU 35 may cause the selector 28 to selectively output data to the reference data input path 26 at every other or multiple lines of the reference data generation area. In this case, dust,
Even if dirt, scratches, and the like are present over a plurality of continuous lines, the effect can be reduced and shading correction data can be created accurately.

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

The image reading apparatus 1 according to the second embodiment is different from the image reading apparatus according to the first embodiment in that
1 is not provided, and instead, white shading correction having the same contents as in the first embodiment is performed by the CPU 3.
5 is based on a predetermined white shading correction program, thereby realizing a shading correction data creation device and a white shading correction device. Other points are the same as those in the first embodiment,
The same reference numerals as those in FIGS. 1 to 3 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. 8 is a block diagram showing the electrical connection of the control system of the image reading apparatus 1. As shown in FIG. 8, the RA connected to the CPU 35 via the bus 76.
The M72 controls the IPU (Image Proc) under the control of the CPU 35.
essing Unit) 74 stores shading correction data obtained as a result of the calculation described later. The ROM 71 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 71 is controlled by the CPU 35 to control the I / O
The program can be rewritten to a program downloaded from an external device (not shown) via the O port 73. CPU3
Reference numeral 5 obtains information indicating the degree of deterioration of the scanning optical system in addition to the above restrictions, and calculates the value of NOREF.

A sensor board substrate (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) 71 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.

FIGS. 4 and 5 are flowcharts for explaining the processing procedure of the white shading correction processing performed under the control of the CPU 35. As shown in FIG.
Receives an instruction for setting the magnitude of the set value NOREF by operating the operation panel 36 (Y in step S1),
The designated value NOREF is stored in a non-volatile memory (not shown).
And so on (step S2).

As shown in FIG. 5, when a series of image reading operations is started (Y in step S11), the CPU 35 reads the value NOREF set in the processing of FIG. (Not shown) (step S12), and depending on whether the mode setting of the scanning speed is the "high speed" mode or the "low speed" mode (step S1).
3) The value of the number m of lines in the reference data generation area is set (steps S14 and S15). Step S12 implements a first variable means and a first variable step. The second variable means and the second variable step are realized by steps S13 to S15.

Then, 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 S16). This implements reference data creation means and a reference data creation step.

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 S17) to generate shading correction data. If the following relationship is satisfied (Y in step S17), the image data of each line after the reference data generation area is excluded for each pixel (step S18). Then, the reference data is replaced with the reference data (step S1)
9). In step S17, the comparing means and the comparing step are performed, and in step S18, the removing means and the removing step are performed in step S18.
19 implements replacement means and shading correction data creation step. Then, a weighted average is obtained for the image data of each line after the reference data generation area after the replacement. (Step S20). This implements shading correction data creation means and a shading correction data creation step.

When the multiple averaging is obtained up to the last line of the shading correction data generation area (Y in step S21), the finally obtained multiple averaging value is used as shading correction data in a predetermined RAM.
And the like (step S22).

When the reading of the document 2 is started (Y in step S23), the read image data of the document 2 is read line by line using the shading correction data as in the first embodiment. White shading correction is performed (step S24). Step S24 implements a white shading correction unit and a white shading correction step. When the white shading correction has been completed up to the last line of the document 2 (Y in step S25), a series of processing ends.

According to the image reading apparatus 1, as in the first embodiment, the read image data of the white reference
Since the comparison is made between the reference data created by statisticizing the plurality of (m) lines at the head and the image data after the reference data, pixels affected by dust, dirt, scratches, etc. can be excluded. , White shading correction data Ds
Noise can be sufficiently removed from h.

In this case, pixels for which shading correction data generation data is not output are replaced with reference data instead (step S19), so that accuracy can be reduced without reducing the number of pixels that can be used to generate shading correction data Dsh. Good shading correction data can be obtained.

When the reference data is compared with the image data after the reference data, a predetermined value NOREF is subtracted from the reference data in advance and the comparison is performed (step S17). By adjusting the value to an appropriate value, accurate shading correction data Dsh can be accurately obtained.

Since the averaging process performed between lines is a multiple averaging (step S20), the influence of dust, dirt, scratches, etc. on the last line can be effectively eliminated by the above-described means, and shading correction can be performed. Data can be created accurately.

Operation panel 36 for operating image reading apparatus 1
Is received (step S1), and in response to this operation,
Since the magnitude of the value NOREF set in the register of the comparison circuit 31 is varied (step S2), the setting value NOREF can be appropriately adjusted to an appropriate size, and the accurate shading correction data Dsh can be obtained. It can be obtained accurately.

In addition, information indicating the total number of lines in the shading gate period, in this example, the set value of the number m of lines indicating the reference data generation area is varied according to the reading scanning speed of the image reading apparatus 1. (Steps S13 to S15), the shading correction data Dsh can be accurately created according to the total number of lines in the shading gate period.

Note that, as in the first embodiment, step S
In step 16, the target of the reference data generation may be set to every one or more lines in the reference data generation area. In this case, dust, dirt,
Even if a flaw or the like is present over a plurality of continuous lines, the effect thereof can be reduced and shading correction data can be created accurately.

Further, the shading correction data creation program may be stored in the ROM 71 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 M71.
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 71 under the control of the CPU 35 via the I / O port 73.

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

FIG. 6 is a block diagram showing a schematic configuration of a digital copying machine 51 according to the third embodiment. As shown in FIG. 6, the digital copying machine 51 implements the image forming apparatus of the present invention, and includes the 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.

Since the configuration of the image reading apparatus 1 is the same as that of the first or second embodiment, the same reference numerals as those of the first and second embodiments are used below, and 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 unit 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 and second embodiments can be achieved for the white shading correction of the image data.

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

FIG. 7 is a block diagram showing a schematic configuration of a printing system 61 according to the fourth embodiment. As shown in FIG. 7, the printing system 61 implements the image forming apparatus of the present invention, and includes a PC (Pers) capable of performing various types of 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.

Since the configuration of the image reading apparatus 1 is the same as that of the first or second embodiment, the same reference numerals as those of the first and second embodiments are used below, and 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 type thermal transfer method, a silver halide photographic method, a direct thermal recording method. Various known printing 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 and second embodiments can be achieved for the white shading correction of the image data.

[0142]

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.

According to a second aspect of the present invention, in the shading correction data generating apparatus according to the first aspect, accurate shading correction data can be obtained without reducing the number of pixels that can be used for generating shading correction data. it can.

The invention described in claim 3 is the invention according to claim 1 or 2
In the shading correction data creation device described in the above,
By adjusting the reference data to an appropriate value, accurate shading correction data can be accurately obtained.

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, a preset value is adjusted to an appropriate size to achieve high accuracy. Shading correction data can be obtained accurately.

According to a fifth aspect of the present invention, there is provided the shading correction data generating apparatus according to any one of the first to fourth aspects, wherein the image data after the reference data is averaged between lines, thereby achieving the shading correction. Data can be created accurately.

According to a sixth aspect of the present invention, in the shading correction data creating apparatus according to the fifth aspect, even if shading correction data is created by multiple averaging, the influence of dust, dirt, scratches, and the like on the last line. Except for the above, shading correction data can be created accurately.

According to a seventh aspect of the present invention, in the shading correction data creating apparatus according to the sixth aspect, when the total number of lines of white-based image data that cannot be configured so widely is small, the reference data is to be created. The range is made smaller so that the shading correction data can be created sufficiently using the lines after the reference data, and when the total number of lines is large, the range in which the reference data is created is made larger and accurate. By creating reference data, shading correction data can be created accurately.

According to an eighth aspect of the present invention, in the shading correction data creating apparatus according to the seventh aspect, a range in which reference data is created is appropriately selected according to a white-based image reading speed. Can be.

According to a ninth aspect of the present invention, in the shading correction data generating apparatus according to any one of the first to eighth aspects, the operation can be performed only by bit shift on the digital circuit, and the system configuration can be simplified. The cost can be reduced.

The invention according to claim 10 is the invention according to claims 1 to 9
In the shading correction data creation device according to any one of the above, even if dust, dirt, scratches, and the like are attached to a plurality of continuous lines, the effect can be reduced and shading correction data can be created accurately. it can.

The eleventh aspect of the present invention relates to the first to first aspects.
0 has the same function and effect as the invention described in any one of the first aspect.

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

The thirteenth invention has the same function and effect as the twelfth invention.

According to the fourteenth aspect of the present invention, a comparison is made between reference data created by statistically analyzing 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.

According to a fifteenth aspect of the present invention, in the shading correction data creating method according to the fourteenth aspect, accurate shading correction data can be obtained without reducing the number of pixels that can be used for generating shading correction data. it can.

According to a sixteenth aspect of the present invention, in the shading correction data creating method according to the fourteenth or fifteenth aspect, the reference data is adjusted to an appropriate value, and accurate shading correction data can be accurately obtained. .

The invention according to claim 17 is the invention according to claims 14 to
In the shading correction data generation method according to any one of the sixteenth aspects, it is possible to accurately obtain a high-precision shading correction data by adjusting a preset value to an appropriate value.

The invention according to claim 18 is the invention according to claims 14 to
In the shading correction data generation method according to any one of the first to seventeenth aspects, the shading correction data can be accurately generated by averaging image data after the reference data between lines.

According to a nineteenth aspect of the present invention, in the shading correction data creating method according to the eighteenth aspect, even if shading correction data is created by multiple averaging, the influence of dust, dirt, scratches, and the like on the last line. Except for the above, shading correction data can be created accurately.

According to a twentieth aspect of the present invention, in the shading correction data generating method according to the nineteenth aspect, when the total number of lines of the white-based image data which cannot be formed so broadly is small, the target of the reference data is not generated. The range is made smaller so that the shading correction data can be created sufficiently using the lines after the reference data, and when the total number of lines is large, the range in which the reference data is created is made larger and accurate. By creating reference data, shading correction data can be created accurately.

According to a twenty-first aspect of the present invention, in the shading correction data creating method according to the twentieth aspect, a range in which reference data is created is appropriately selected according to a white-based image reading speed. Can be.

The invention according to claim 22 is the invention according to claims 14 to
21. In the shading correction data creation method according to any one of 21., the operation can be performed only by bit shifting on the digital circuit, and the system configuration can be simplified and low cost.

The invention according to claim 23 is the invention according to claims 14 to
22. In the shading correction data generating method according to any one of the above, even if dust, dirt, scratches, and the like are present over a plurality of continuous lines, the effect is reduced, and shading correction data is generated accurately. Can be.

According to a twenty-fourth 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, etc. Since the received pixels can be excluded, noise can be sufficiently removed from the white shading correction data.

According to a twenty-fifth aspect of the present invention, in the program according to the twenty-fourth aspect, it is possible to obtain accurate shading correction data without reducing the number of pixels that can be used for generating shading correction data.

According to the invention of claim 26, in the program of claim 24 or 25, the reference data is adjusted to an appropriate value, and accurate shading correction data can be obtained accurately.

The invention according to claim 27 is the invention according to claims 24 to
26, in the program according to any one of the items 26, a preset value is adjusted to an appropriate value, and accurate shading correction data can be accurately obtained.

The invention according to claim 28 is the invention according to claims 24 to
27, in the program according to any one of (27), by averaging image data after the reference data between lines,
Shading correction data can be created accurately.

According to a twenty-ninth aspect of the present invention, in the program of the eighteenth aspect, even if shading correction data is created by multiple averaging, the effects of dust, dirt, scratches, etc. on the last line are eliminated. Shading correction data can be created accurately.

According to a thirty-first aspect of the present invention, in the program according to the thirty-ninth aspect, when the total number of lines of white-based image data that cannot be configured very widely is small, the range in which the reference data is created is reduced. So that the shading correction data can be sufficiently created using the lines after the reference data, and when the total number of lines is large,
By making the range in which the reference data is created large, accurate reference data can be created, and shading correction data can be created accurately.

According to a thirty-first aspect of the present invention, in the program according to the thirty-third aspect, a range in which reference data is to be created can be appropriately selected according to a white-based image reading speed.

The invention described in claim 32 is the invention according to claims 24 to
In the program according to any one of the items 31, the operation can be performed only by the bit shift on the digital circuit, and the system configuration can be simplified and the cost can be reduced.

The invention according to claim 33 is the invention according to claims 24 to
32. The program according to any one of 32.
Even if dirt, scratches, and the like are present over a plurality of continuous lines, the effect can be reduced and shading correction data can be created accurately.

The invention according to claim 34 is the invention according to claims 24 to
The same operation and effect as the invention according to any one of the thirty-third invention are exerted.

[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 flowchart illustrating a white shading correction process performed by an image reading apparatus according to a second embodiment of the present invention;

FIG. 5 is the same flowchart.

FIG. 6 is an explanatory diagram illustrating an overall configuration of a digital copying machine according to a third embodiment of the present invention;

FIG. 7 is an explanatory diagram illustrating an overall configuration of a printing system according to a fourth embodiment of the present invention;

FIG. 8 is a block diagram illustrating electrical connection of a control system of the image reading apparatus according to the second 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

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Eie Kisara 3-1 Shinmei-do, Meiji, Shimada-cho, Shibata-cho, Shibata-gun, Miyagi F-term in Tohoku Ricoh Co., Ltd. 5B047 AA01 BA02 CA07 CB07 CB11 CB16 DA04 DC01 DC20 5C072 AA01 BA08 FB12 RA16 UA03 UA12 UA14 UA20 XA01 5C077 LL02 LL04 MM27 PP06 PP44 PP46 PP62 PQ08 PQ17 PQ20 SS01 TT06

Claims (34)

[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 data of a plurality of lines at the head of the image data in a sub-scanning direction is statistically obtained. Reference data generating means for generating reference data; comparing means for performing a comparison operation on the image data and the reference data after the reference data in the sub-scanning direction; and based on the result of the comparison operation, Exclusion means for selectively excluding image data from the object of generating the shading correction data for each pixel; and shading for generating the shading correction data based on image data after the reference data which has not been excluded. Correction data creating means. Shading correction data generating device, characterized in that. 2. The image processing apparatus according to claim 1, further comprising: a replacement unit configured to generate the shading correction data using the reference data corresponding to the pixel to be excluded instead of the image data to be excluded. The shading correction data creation device according to claim 1, wherein 3. The comparison unit compares the value obtained by subtracting a preset value from the reference data with image data after the reference data, and the exclusion unit performs the comparison in the comparison. 3. The shading correction data creating device according to claim 1, wherein the exclusion is performed when image data after the reference data is smaller. 4. The apparatus according to claim 1, further comprising a first variable unit configured to set the magnitude of the preset value in response to the instruction of the magnitude of the preset value. The shading correction data creation device according to any one of claims 1 to 3, wherein 5. The shading correction data generating unit according to claim 1, wherein the shading correction data generating unit generates the shading correction data by averaging image data after the reference data between lines. The shading correction data creation device according to any one of the preceding claims. 6. The shading correction data generating apparatus according to claim 5, wherein said shading correction data generating means performs a multiple averaging as said averaging process. 7. The image processing apparatus according to claim 1, further comprising: a second variable unit configured to vary a range of a plurality of lines for which the reference data is to be created according to information indicating a total number of lines of the image data. 7. The shading correction data creation device according to 6. 8. The shading correction data creating apparatus according to claim 7, wherein the second variable means uses the information indicating the total number of lines as information on an image reading speed of the image data. 9. The number of lines of image data for which shading correction data is to be generated is 2 ⁿ (n = 1, 2, 2)
9. The shading correction data creating device according to claim 1, further comprising a second setting unit that sets a numerical value represented by (3,...). 10. The method according to claim 1, wherein the shading correction data creating means sets one or more lines for which the reference data is created in the image data. A shading correction data creation device according to claim 1. 11. A shading correction data generating apparatus according to claim 1, wherein said shading correction data generated by said shading correction data generating 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. 12. A photoelectric conversion element for reading an image of a document, and a white shading correction device according to claim 11, which performs white shading correction on the image data of the read image. Image reading device. 13. An image forming apparatus comprising: the image reading device according to claim 12 for reading an image of a document; and forming an image on a recording medium based on the read image of the document. 14. 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 data of a plurality of lines at a head of a sub-scanning direction of the image data is statistically obtained. A shading correction data creating step of creating reference data; a comparing step of performing a comparison operation on the image data and the reference data after the reference data in the sub-scanning direction; and after the reference data based on a result of the comparison operation An exclusion step of selectively excluding the image data for each pixel from the object of the shading correction data creation; and creating the shading correction data based on the image data after the reference data that has not been excluded. Shading correction data creation Shading correction data creation method characterized by comprising the, the. 15. In the shading correction data creating step, the reference data corresponding to the pixel to be excluded is set as an object of the shading correction data in place of the image data to be excluded. The method of generating shading correction data according to claim 14, wherein: 16. The comparing step of comparing a value obtained by subtracting a preset value from the reference data with image data subsequent to the reference data, and the removing step includes the step of: 16. The shading correction data creating method according to claim 14, wherein the exclusion is performed when image data after the reference data is smaller. 17. A method according to claim 17, further comprising the step of: when receiving an instruction for the magnitude of the preset value, setting a magnitude of the preset value in response to the instruction. 17. The shading correction data creating method according to claim 14, wherein 18. The shading correction data creating step according to claim 14, wherein the shading correction data creating step creates the shading correction data by averaging image data after the reference data between lines. The shading correction data creation device according to any one of the preceding claims. 19. The shading correction data generating apparatus according to claim 18, wherein the shading correction data generating step performs a multiple averaging as the averaging process. 20. A second variable that varies a range of a plurality of lines for which the reference data is to be created according to information indicating a total number of lines of the image data of the image data before the creation of the reference data. 20. The method according to claim 19, comprising a step. 21. The shading correction data generating method according to claim 20, wherein the second variable step uses information indicating the total number of lines as information on an image reading speed of the image data. 22. In the shading correction data creation step, the number of lines of image data for which the shading correction data is created is set to 2 ⁿ (n = 1, 2, 3,...)
2. A numerical value represented by the following formula:
22. The shading correction data creation method according to any one of 4 to 21. 23. The method according to claim 14, wherein in the shading correction data creating step, one or more lines for which the reference data is created in the image data are set. The shading correction data creation method according to one of the above. 24. A computer-readable program that causes a computer to execute shading correction data 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 a sub-scanning direction are provided. A shading correction data creating process of creating reference data by statisticizing minute data; a comparison process of performing a comparison operation on the image data and the reference data after the reference data in the sub-scanning direction; a result of the comparison operation An exclusion process of selectively excluding the image data after the reference data from the object of generating the shading correction data on a pixel-by-pixel basis, based on the image data after the reference data that has not been excluded. Create the shading correction data A program characterized by executing the shading correction data creation processing that, to the computer. 25. The shading correction data creation process, wherein the reference data corresponding to the exclusion target pixel is set as the shading correction data creation target instead of the image data set as the exclusion target. The program according to claim 24, characterized by: 26. The comparing process for comparing the magnitude of a value obtained by subtracting a preset value from the reference data with image data after the reference data, wherein the exclusion process is performed in the comparison. 26. The program according to claim 24, wherein the exclusion is performed when image data after the reference data is smaller. 27. When there is an instruction of the magnitude of the preset value, the program causes the computer to execute a first variable process of setting the magnitude of the preset value in response to the instruction. The program according to any one of claims 24 to 26, characterized in that: 28. The shading correction data generating process according to claim 24, wherein the shading correction data generating process generates the shading correction data by averaging image data after the reference data between lines. The program according to any one of the above. 29. The program according to claim 18, wherein the shading correction data creation processing performs a multiple averaging as the averaging processing. 30. A second variable that varies a range of a plurality of lines for which the reference data is to be generated according to information indicating a total number of lines of the image data of the image data before the generation of the reference data. 30. The program according to claim 29, wherein the program causes a computer to execute the processing. 31. The program according to claim 30, wherein the second variable processing uses information indicating the total number of lines as information on an image reading speed of the image data. 32. The shading correction data creation process sets the number of lines of image data for which the shading correction data is created to 2 ⁿ (n = 1, 2, 3,...)
3. A numerical value represented by the following formula:
The program according to any one of Items 4 to 31. 33. The shading correction data creating process according to claim 24, wherein the line for which the reference data is created in the image data is set at every other line or at every other line. The program according to one. 34. A storage medium storing the program according to claim 24.