JP2003283773A - Flare correction data measurement method, flare correction method, storage medium, image reader, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure with high accuracy flare correction data for correcting flare being a pseudo signal caused by the scattering or reflection of incident light to read an original so as to correct read image data with high accuracy. <P>SOLUTION: A point light source 68 is provided to the read surface of a measurement original 61 which is formed of a diffuse reflection face, a linear imaging element 21 images light reflected on the entire read face receiving the light emitted from the point light source 68, image signal strength distribution data divided into image areas by using a light emission image area of the point light source 68 for a basic unit are generated from a signal outputted from the linear imaging element 21, flare correction data are calculated from the generated image signal strength distribution data and illuminance distribution data of the read face detected by radiating in advance the light of the light source 12 of a read optical system so as to detect the state of flare due to an original face reflection component with a simple configuration. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flare correction data for correcting a flare, which is a pseudo signal generated by scattering or reflection of incident light for reading an original when the image of the original is read by a scanner or a copying machine. The present invention relates to a flare correction data measuring method and a flare correcting method, a storage medium storing these programs, an image reading apparatus, and an image forming apparatus.

[0002]

[Prior art]

[Patent Document 1] Japanese Unexamined Patent Publication No. 7-23226

[Patent Document 2] Japanese Patent Laid-Open No. 10-48048

[Patent Document 3] Japanese Patent Laid-Open No. 10-112799

[Patent Document 4] Japanese Patent Laid-Open No. 11-355636

When the image of the original is read by the image reading device of the scanner device or the copying machine, as shown in FIG. 23, the contact glass 10 is included in the illumination light emitted from the light source 12. The light irradiating an area other than the image pickup area 90 of the document 11 placed on the document 1
This is a phenomenon in which the image pickup area 90 is illuminated by being reflected from No. 1 and reflected or scattered by, for example, the reflector 13. When this phenomenon occurs in the image reading device, the imaging region 90 is irradiated with the light and flare as a pseudo signal is generated. Due to this flare, the image density of the document around the imaging area changes, the read signal level changes, and image reading failure occurs.

In order to eliminate the influence of this flare, the surface of the reflector or the like is painted black to reduce the surface reflection. Since the cost is increased by coating the surface of the reflector in this way, it is desirable to apply the coating only to the part where flare light is generated, but in order to specify the part where flare light is generated, It was necessary to apply black paint to each site such as a reflector where a flare light image is expected to be generated, and to evaluate from the read image, which took time to evaluate and the effect was limited.

Further, when a document is read by a copying machine or the like, the background of the document is processed by image processing called ground skipping. That is, for a document or the like having a light background color, the gradation of the light background color is erased by the ground removal process so that the color of the recording paper itself is obtained. Also, if ground skipping is not performed in order to maintain the background color, it is thought that the illumination light will be reflected by the document surface other than the imaging area, the light will return to the optical system, and this time it will occur by illuminating the imaging area. Due to the influence of the reflected flare on the original surface, a black area and a whitish area sandwiched between the black areas are smeared black and copied. Furthermore, in order to save energy, the reading light source tends to shift from the halogen light source to the xenon light source, but it is known that the xenon light source has a stronger influence of the document surface reflection flare than the halogen light source. is necessary.

Therefore, for example, the image reading apparatus disclosed in Patent Document 1 uses the output signal obtained from the _target pixel S _xy
Output signal obtained from the pixel of interest Sxy and peripheral pixels PS
A value obtained by multiplying an output signal obtained from _xy by a reading-specific coefficient is subtracted to faithfully read the density of the original. This means that when the document reflectance is R, the line sensor output S is not only proportional to the document reflectance R but also is affected by the higher order of the document reflectance R, and a coefficient depending on the illumination system of the document reading apparatus is α (for example, α = 0.1 to 0.15), the line sensor output S is an output with a reflectance of 100% S = 1.
It is based on the premise that S∝R + αR ² + αR 3 + ... Then, the correction output CS _{xy of the} pixel of interest is corrected by the following correction formula. CS _xy = S _xy −αΣ (S _xy · PS _xy ) / Σn
_xy where Σn _xy is the sum of the number of surrounding pixels

Further, the image evaluation method disclosed in Patent Document 2 is
As shown in FIG. 23A, a white circular image 92 centered on the measurement position 91, a detection area 93 formed in a white fan shape only in one direction around the circular image 92, and other than the detection area 93. The measurement pattern 94 in which the portion is black is read by the image reading device to be measured, and the flare amount due to the document surface is detected by the image signal intensity of the read image at the measurement position. Then, the detection area 93 with respect to the measurement position 91
The position of is changed so that the flare amount around the measurement position 91 is detected. This measurement result data is shown in FIG.
As shown in 3 (b), it is represented by an image intensity signal at the measurement position. In this case, when the detection area is on the right side of the measurement position, it indicates that particularly strong flare is occurring.

The flare correction method disclosed in Patent Document 3 is
The imaging area is divided into surface elements, the position of the two-dimensional image data of interest is i, the position of any two-dimensional image data is j, and the distance between the two-dimensional image data I (i) and I (j) is r ( i, j)
As the flare amount for each surface element is obtained as a flare spread function f {r (i, j)}, a correction formula using the function f is applied to the read two-dimensional image data I (i). I am trying to correct flare.

Further, the image pickup device disclosed in Patent Document 4 is
In a CCD camera whose aperture and focal length vary, flare ghosts that occur in the image pickup optical system are corrected and reduced.

Further, in the image processing apparatus disclosed in Patent Document 5, the reading error correction unit detects the thin line area on the white background in the document and corrects the density decrease in the thin line area.

[0010]

In the image reading apparatus disclosed in Patent Document 1, when the line sensor output S = 1, the correction output CS _xy = 1-α of the target pixel is obtained, and α is an approximate value from the total amount of light reflection. However, the method of deriving α is not disclosed, and it is expected to be difficult to implement. In addition, it is known that the light reflection condition actually varies depending on the lamp light amount distribution on the document surface and the pixel reading position corresponding to it.
Since this condition is not added to the correction formula, the correction accuracy is poor.

Further, the image evaluation method disclosed in Patent Document 2 has a disadvantage that it is possible to detect only the flare amount in one direction by one measurement and it is also impossible to grasp the relationship between the distance from the arbitrary reading position and the flare amount. is there.

The flare correction method disclosed in Patent Document 3 corrects the flare effect on the image data of interest only by the distance r (i, j), and since the direction is not taken into consideration, the accuracy of flare correction deteriorates. There is a disadvantage.

Further, the image pickup apparatus disclosed in Japanese Patent Laid-Open No. 2004-242242 has a large difference from the scanner apparatus or the like in which the optical system has no aperture and the focal length is always constant, and the flare to be corrected is also different. There is a disadvantage that flare cannot be corrected accurately.

Further, as shown in Japanese Patent Application Laid-Open No. 2004-242242, when correcting a density decrease in a thin line area on a white background in an original document,
The purpose is to correct the decrease in the density of low-contrast characters on the white background, and there is a disadvantage that the component affected by flare cannot be corrected from an arbitrary image in which characters and pictures are mixed.

The present invention solves the above disadvantages and provides a flare correction data measuring method capable of accurately measuring flare correction data for correcting flare which is a pseudo signal generated by scattering or reflection of incident light for reading an original. The flare correction method that corrects the read image data with high accuracy by the flare correction data, the storage medium that stores these programs, the flare correction data are measured with high accuracy, and the read image data is corrected with high accuracy to obtain high quality. An object is to provide an image reading apparatus and an image forming apparatus capable of outputting an image.

[0016]

In the flare correction data measuring method according to the present invention, an illuminating means for irradiating the reading surface of a document placed on the document mounting surface with light and a reading surface of the document are illuminated. A flare correction data measuring method for an image reading device that picks up an image of a reading surface by light and an image reading device that generates image signal data from a signal output from the image pickup means, wherein the reading surface is a diffuse reflection surface. The document is provided with a point light source, the light emitted from the point light source is reflected on the entire surface of the reading surface by an image pickup means, and an image area in which a light emission image area of the point light source is a basic unit from a signal output from the image pickup means The image signal intensity distribution data divided into two is generated, and the flare correction by the document surface reflection component is corrected from the generated image signal intensity distribution data and the illuminance distribution data of the reading surface detected by emitting the illumination means in advance. And calculates the over data.

The image signal intensity distribution data and the illuminance distribution data on the reading surface are multiplied for each image area to calculate flare correction data corresponding to the original surface.

The flare correction method of the present invention is a flare correction method using the flare correction data calculated by the above flare correction data measuring method, and is calculated in advance with the image signal data of the original read by illuminating the illumination means. It is characterized in that the image signal data in which the flare component is corrected is generated by the flare correction data, and the read image is converted into a high-quality image in which flare is removed.

When correcting the flare, the image signal data of the read original is divided into image regions of the flare correction data, and the noticed data of the divided image signal data corresponds to the image regions other than the noticed data. The amount of original surface reflection flare is calculated from the matrix calculation with the flare correction data, and the amount of original surface reflection flare calculated from the target data is subtracted to generate image signal data in which the flare component is corrected,
Improves the quality of the read image.

According to another flare correction method of the present invention, an illuminating means for irradiating the reading surface of the original placed on the original mounting surface with light, and an image of the reading surface with the light applied to the reading surface of the original. A flare correction method for an image reading device that generates image signal data from an image pickup means and a signal output from the image pickup means, wherein a point light source is provided on a measurement document whose reading surface is a diffuse reflection surface. The light reflected from the entire reading surface by the light emitted from the image pickup device is imaged by the image pickup device, and the image signal intensity distribution data obtained by dividing the signal output from the image pickup device into image regions with the light emission image region of the point light source as a basic unit is obtained. Generate,
It is possible to convert the generated image signal intensity distribution data into flare intensity distribution data and perform flare correction of the image signal data from the converted flare intensity distribution data and the illuminance distribution data of the reading surface detected by emitting the illumination means in advance. Characterize. When correcting this flare, the image signal data of the read document is divided into image regions of the flare intensity distribution data, and the data of interest of the divided image signal data is
An image in which the flare component flare amount is calculated from the matrix calculation of flare intensity distribution data and illuminance distribution data corresponding to the image area other than the target data, and the flare component is corrected by subtracting the document surface flare amount calculated from the target data. Generates signal data and enhances the quality of the read image.

The storage medium of the present invention stores one or both of the processing program of the flare correction data measurement method and the processing program of the flare correction method, and enhances the versatility of the flare correction data measurement processing and the flare correction processing. .

In the image reading apparatus of the present invention, the illumination means for irradiating the reading surface of the original with light, the image pickup means for picking up the reading surface with the light irradiated on the reading surface of the original, and the signal output from the image pickup means. An image reading apparatus for generating image signal data from an image reading apparatus has an arithmetic processing unit and a storage unit, and the arithmetic processing unit has a reading surface formed of a diffuse reflection surface and a measurement original having a point light source on the original placing surface. When the light is emitted from the point light source when it is placed, the light reflected from the entire reading surface by the light emitted from the point light source is imaged by the image pickup means, and the light emission image area of the point light source is determined from the signal output from the image pickup means. Generate image signal intensity distribution data divided into image areas that are basic units,
The flare correction data is calculated from the generated image signal intensity distribution data and the illuminance distribution data of the reading surface detected by emitting light from the illuminating means in advance and stored in the storage means, and the image signal of the document read by emitting the illuminating means. It is characterized in that the image signal data in which the flare component is corrected is generated from the data and the flare correction data stored in the storage means, and a read image with good image quality is output.

The storage means stores a plurality of flare correction data for each specific area of the document, or a plurality of flare correction data for each scaling factor when the document is read, and scales when the document is read. Even if is changed, flare correction is performed using flare correction data according to the scaling factor, and a high-quality image is output.

Further, the calculation means calculates flare correction data from the flare correction data at the same magnification in accordance with the magnification change at the time of reading the original, and does not increase the storage capacity of the storage means, even at the time of magnification change. Flare correction is performed using flare correction data according to the scaling ratio, and a high quality image is output.

In another image reading apparatus of the present invention, an illuminating means for irradiating the reading surface of the document with light, an imaging means for imaging the reading surface with the light irradiated on the reading surface of the document, and an output from the imaging means. An image reading apparatus for generating image signal data from a signal having an illuminance distribution data storage means, an arithmetic processing means, and a flare intensity distribution data storage means. The detected processing illuminance distribution data is stored, and the arithmetic processing unit causes the point light source to emit light when a measurement document having a point light source, the reading surface being a diffuse reflection surface, is placed on the document placement surface. In addition, the light reflected from the entire reading surface by the light emitted from the point light source is imaged by the image pickup means, and the signal output from the image pickup means is divided into image areas in which the light emission image area of the point light source is a basic unit. Originals read by generating signal intensity distribution data, converting the generated image signal intensity distribution data to flare intensity distribution data, storing the converted flare intensity distribution data in flare intensity distribution data storage means, and illuminating the lighting means The flare-corrected image signal data is generated based on the image signal data, the flare intensity distribution data stored in the flare intensity distribution data storage unit, and the illuminance distribution data stored in the illuminance distribution data storage unit.

The flare intensity distribution data storage means stores a plurality of flare intensity distribution data for each specific area of the original document, or a plurality of flare intensity distribution data for each scaling factor when reading the original document. Flare correction is performed according to the magnification, and a high quality image is output.

The image forming apparatus of the present invention is characterized by having the above-mentioned image reading apparatus and forming an image by the image data from which the flare is removed, which is output from the image reading apparatus, to form a high quality image.

[0028]

1 is a block diagram showing the structure of the present invention. As shown in the figure, the digital copying machine 1 includes a copying machine body 2 and an automatic document feeder (hereinafter referred to as ADF).
3 and an automatic sorting device 4. The copying machine main body 2 has a scanner unit 5 for reading a document, an image forming unit 9 including a writing unit 6, an engine unit 7 and a paper feeding unit 8. The ADF 3 sends the document to be read to the scanner unit 5, and collects the document read by the scanner unit 5.

As shown in the perspective view of FIG. 2A and the side view of FIG. 2B, the scanner section 5 includes a light source 12 for irradiating the original 11 placed on the contact glass 10 with reading light and a reflector. 13 and a first traveling body 15 having a mirror 14, and a second traveling body 17 having a plurality of mirrors 16.
The drive transmission means 19 for moving the first traveling body 15 and the second traveling body 17 in parallel with the contact glass 10 by the rotation of the drive motor 18, and the light from the mirror 8 of the second traveling body 17 are collected. It has a lens 20 that emits light, a one-dimensional image pickup device 21 that is made of, for example, a line CCD that receives the light condensed by the lens 20, and an output port 22. Then, the document sent by the ADF 3 is scanned and read.

The writing unit 6 has a laser light source, a polygon mirror, etc., and emits a laser beam 23 containing image information to the engine section 7. The engine unit 7 includes an image forming unit 24, a primary transfer unit 25, a secondary transfer unit 26, and a fixing unit 27, as shown in the configuration diagram of FIG. The image forming unit 24 includes a charger 29 arranged around the photoconductor 28, a color developing unit 30 including cyan (C), magenta (M), yellow (Y), and black (K), and a drum cleaning unit 31. A laser beam 23 emitted from the writing unit 6 forms an electrostatic latent image on the photoconductor 28 charged by the charging charger 29, and the formed electrostatic latent image is visualized by the color developing unit 30 to form a toner image. To form. The primary transfer unit 25 includes an intermediate transfer belt 32, a primary transfer portion 33, and a tension roller 34.
The secondary transfer roller 35, the cleaning unit 36, and the reference position sensor 37 are provided, and the toner image formed on the photoconductor 28 is primarily transferred to the intermediate transfer belt 32 to superimpose the toner images of the respective colors. The intermediate transfer belt 32 is separated from the surface of the photoconductor 28 by a contact / separation mechanism except when the toner image on the photoconductor 28 is primarily transferred, and is pressed against the surface of the photoconductor 28 only when the image is primarily transferred to the intermediate transfer belt 32. To be done. The secondary transfer unit 26 secondarily transfers the toner image transferred onto the intermediate transfer belt 32 onto a recording sheet. The fixing unit 27 fixes the toner image transferred onto the recording paper with heat and pressure. The paper feeding unit 8 has a plurality of paper feeding cassettes 38 a to 38 c and a manual tray 39, and sends the recording paper to the secondary transfer unit 26.
The automatic sorting device 4 has a plurality of sorting bins 40a to 40n.
The recording paper on which the image is formed is sorted and discharged.

The control section 41 of the digital copying machine 1 includes
As shown in the block diagram of FIG.
D conversion unit 43, shading correction unit 44, image signal generation unit 45, calculation processing unit 46, program storage unit 47, data storage unit 48, correction data storage unit 49, and image processing unit 5
0, an external output unit 51, and an external storage medium control unit 52. The central control unit 32 is a CPU that controls the operation of the entire device.
The operation of the entire apparatus is managed under various printing conditions input from the operation display unit 53 when the image of the original 11 is read and printed. As shown in FIG. 5, the data storage unit 48 includes an illuminance distribution data storage area 481, an image signal intensity distribution data storage area 482, a flare intensity distribution data storage area 483, and an image data storage area 484. The image processing unit 50 includes an image recognition unit 54, a scaling unit 55, and a filter unit 5.
6 and a γ correction unit 57 and a gradation processing unit 58. The external storage medium control unit 52 controls input / output from / to the external storage medium 59 such as a flexible disk or an optical disk.

When the image forming cycle of the document 11 read by the scanner section 5 in the digital copying machine 1 starts, if the image to be formed is one color, a toner image is formed on the photoconductor 28 by the image data of the read document 11. The formed toner image is primarily transferred onto the intermediate transfer belt 32. The secondary transfer unit 26 transfers the toner image onto the recording paper fed in accordance with the tip of the toner image transferred onto the intermediate transfer belt 32.
Next transfer. The recording paper on which the toner image has been transferred is sent to the fixing unit 27 and heated and pressed to be fixed. The recording paper on which the toner image is fixed is discharged to the automatic sorting device 4. Further, the toner remaining on the intermediate transfer belt 32 is collected by the cleaning unit 36.

When the image to be formed has two or more colors, the reference mark provided on the intermediate transfer belt 32 is used as the reference position sensor 37.
The original portion 11 is read by the scanner unit 5 on the basis of the detection result in step 1, the toner image of the first color is formed on the photoconductor 28 based on the read image data, and the toner image formed on the photoconductor 28 is transferred to the intermediate transfer belt 32. Primary transfer is performed. Subsequently, a second-color toner image is formed on the photoconductor 28,
The toner image formed on the intermediate transfer belt 32 is primarily transferred to the intermediate transfer belt 32. The image formation on the photoconductor 28 and the primary transfer on the intermediate transfer belt 32 are repeated for each color. That is,
When forming a two-color image, the intermediate transfer belt 32 is set to two.
In the case of rotating to form a full-color image, the intermediate transfer belt 32 is rotated four times, and the toner image formed on the photoconductor 28 is primarily transferred to the intermediate transfer belt 32 for each rotation to form an image of each color. Stack them without misalignment. After the toner image of a predetermined color is transferred to the intermediate transfer belt 32, the toner image is secondarily transferred to the recording paper fed in accordance with the leading edge of the toner image transferred to the intermediate transfer belt 32, and the fixing unit 27
Heat and press to fix.

As described above, when the image of the original 11 is read by the scanner unit 5, of the illumination light emitted from the light source 12, the light radiated to the area other than the image pickup area of the original 11 placed on the contact glass 10. Reflected from the original 11,
The reflected light is reflected or scattered by the reflector 13 or the like to illuminate the image pickup area to generate a flare which is a pseudo signal. Due to this flare, the image density of the document around the imaging area changes, the read signal level changes, and image reading failure occurs. In order to correct this flare, a processing program for measuring flare correction data and a flare correction is stored in advance in the program storage unit 47 of the control unit 41, and the flare correction data is measured in advance and stored in the correction data storage unit 49. deep. First, the configuration and processing when measuring this flare correction data will be described.

For measuring flare correction data, FIG.
As shown in the configuration diagram (a), a point light source device 60 and an original document 61 for flare measurement are used. The point light source device 61 includes a light source device 62, an optical fiber bundle 63, an optical fiber 65 connected to the optical fiber bundle 63 by a connection jig 64, and a fixing jig 66 for fixing the optical fiber 66 to the dedicated document 61. The light source device 62 uses a halogen light source when a halogen lamp is used as the light source 12 of the scanner unit 5. The exclusive document 61 is made of, for example, A3 size, and the reading surface that comes into contact with the contact glass 10 is formed of a diffuse reflection surface. As shown in FIG. 6B, the optical fiber 66 is provided at the measurement point.
Is provided with a minute hole 67 for fixing the tip end of the optical fiber 66 to the hole 67 by a fixing jig 66 to form a point light source 68 on the reading surface of the dedicated document 61. Here, when the dedicated document 61 transmits the light emitted from the tip of the optical fiber 66, the dedicated document 61 is not provided with the hole 67.
The tip of the optical fiber 66 may be fixed to the surface of the. The light emitting portion of the point light source 68 is actually difficult to fit within one pixel and has a certain image area. Therefore, the emission image area of the point light source 68 is used as a basic unit for flare measurement and flare correction. Further, the operation display unit 53 is provided with a screen for setting flare measurement, a setting function, a touch panel, an operation function for starting flare measurement, and the like.

A process for measuring flare correction data using the point light source device 60 and the flare measuring original document 61 will be described with reference to the flowchart of FIG.

First, the light source 12 of the scanner unit 5 is previously prepared.
Is turned on, the illuminance on the document surface is measured with an illuminometer, and illuminance distribution data for each basic unit of the flare intensity distribution is created and stored in the illuminance distribution data storage area 481 of the data storage unit 48 of the control unit 41. (Step S1). As shown in the illuminance distribution contour line display example of FIG. 8, the illuminance distribution on the document surface has the highest light intensity in the imaging area 69, and the imaging area 69
The light intensity decreases with increasing distance from. The light intensity of the image pickup area 69 is set to 1.0, and converted into a relative value according to the light intensity to create the document surface illuminance distribution data 70 shown in FIG. Here, the main scanning direction is the first traveling body 15 and the second traveling body.
The traveling direction is orthogonal to the traveling direction of the traveling body 17, and the sub-scanning direction is the traveling direction of the first traveling body 15 and the second traveling body 17.

In this state, the special document 61 having the point light source 68 fixed thereon is placed on the contact glass 10, and the operation display section 53 is displayed.
Is operated to set flare measurement, and flare measurement is started (step S2). When the flare measurement is started, the light source device 62 is turned on, the point light source 68 is caused to emit light, and the scanner unit 5
The first traveling body 15 and the second traveling body 17 are scanned from the leading edge to the trailing edge of the dedicated document 61 without turning on the light source 12 and the optical signal reflected by the reading surface of the dedicated document 61 is reflected by the one-dimensional image pickup device 21. Light is received (step S3). One-dimensional image sensor 21
Converts the received optical signal into an electric signal and sends it to the control unit 41. The control unit 41 converts the sent signal into a digital signal by the A / D conversion unit 43, performs shading correction on the converted digital signal by the shading correction unit 44, and the dedicated original document 61 having the point light source 68 by the image signal generation unit 45. All the image data of are stored in the image data storage area 484 of the data storage unit 48 (step S4). This image data storage area 4
The image data stored in 84 is cut out by the arithmetic processing unit 46 for each basic unit, divided into each basic unit to generate as image signal intensity distribution data, and stored in the image signal intensity distribution data storage area 482 of the data storage unit 48 ( Step S5
S6). The data of each basic unit of the image signal intensity distribution data is an average value obtained by dividing the reading value of each basic unit by the number of pixels of the basic unit. For example, FIG. 10 shows a display example 71 of the image signal intensity distribution in which the number of pixels in the basic unit is 25 and 17 areas are provided in each of the main scanning direction and the sub scanning direction. As shown in FIG. 10, the image signal intensity is highest in the region of the point light source 68, and regions having different image signal intensities due to flare are dispersed in the peripheral region. The basic unit may be one pixel, and it is advisable to determine an optimum unit depending on the characteristics of the scanner unit 5.

Next, the arithmetic processing section 46 takes out the image signal intensity distribution data stored in the image signal intensity distribution data storage area 482 and calculates the flare intensity distribution (step S).
7). Since the image signal intensity distribution data is the degree of influence of flare on the peripheral image by the point light source 68, the basic unit of interest is converted into the flare intensity distribution which is the degree of influence of flare received from the surroundings and the flare intensity distribution data is stored. The data is stored in the area 483. In this conversion processing, the flare intensity distribution is created by performing point symmetric movement around the basic unit having the point light source 68 with respect to the image signal intensity distribution data. For example, in FIG.
Point light source 68 of image signal intensity distribution data 72 shown in (a)
With a basic unit X33 having
The basic unit X44 is transposed to the position of the basic unit X22 to the position of 4, and the flare intensity distribution data 73 shown in FIG. 11B is created. This is, for example, in the area on the left 1 from the basic unit X33 having the point light source 68, the basic unit X3
If the flare influence amount from 3 is 0.015, the flare amount entering here is 0.015 when focusing on the position on the left 1, and it can be considered that it enters from the direction of 1 on the right.

After that, the arithmetic processing unit 46 takes out the flare intensity distribution data stored in the flare intensity distribution data storage area 483 and the illuminance distribution data stored in the illuminance response data storage area 481, and multiplies both data by each element. Then, flare correction data in consideration of the illuminance distribution on the document surface is calculated and stored in the correction data storage unit 49 (step S8). An example of the actual flare correction data 74 is shown in FIG.

Next, the processing for performing flare correction using the flare correction data when the image of the original 11 is read by the scanner section 5 will be described with reference to the flowchart of FIG. In this case, it is assumed that the image data storage area 484 of the data storage unit 48 has a storage capacity for storing the image data of all the images of the original 11.

When the original 11 is placed on the contact glass 10, the magnification is set to 100% on the operation display unit 53, the flare correction process is designated, and the start button is pressed, the light source 12 illuminating the original 11 takes an image. The area is irradiated with light, the first traveling body 15 and the second traveling body 17 move, the original 11 is scanned from the beginning to the end to perform image reading, and the reflected light from the original 11 is one-dimensionally imaged. The light is focused on the element 21 (step S11). The one-dimensional image pickup device 21 converts the received optical signal into an electric signal and sends it to the control unit 41. The control unit 41 converts the sent signal into a digital signal by the A / D conversion unit 43, performs shading correction on the converted digital signal by the shading correction unit 44, and generates image signal data of the original 11 by the image signal generation unit 45. Then, the image data is stored in the image data storage area 484 of the data storage unit 48 (steps S12 and S13).
Next, the arithmetic processing unit 46 extracts the flare correction data stored in the correction data storage unit 49 and the image signal data stored in the image data storage area 484, and performs a matrix operation on the flare correction data and the image signal data to correct the flare component. The calculated image signal data is calculated and stored in the image data storage area 484 (steps S14, S15, S16). The flare correction data and the image signal data are subjected to a matrix calculation, for example, as shown in FIG. 14, in the image signal data 75, the flare correction data 74 is used for the flare amount affected by the attention area X33 and the area X21. K11
× X21 / K23, and the flare amount affected by the area X31 is K21 × X31 / K23. This calculation is applied to the image signal data of all areas other than the area of interest X33, and the flare amount for each peripheral pixel is summed to obtain X33 /
By multiplying by 255 and subtracting from the reading value of the region of interest X33, it is possible to obtain image signal data without the influence of flare. By performing this processing on all image signal data, flare corrected image signal data can be generated.

The image processing section 50 has an image data storage area 48.
The flare correction image signal data stored in 4 is taken out and various processing is performed. For example, the image recognition unit 54 determines whether it is a character region or a pattern region according to the image signal data, the scaling unit 55 performs enlarging, reducing, or equal-magnification processing in the main scanning direction, and the filter unit 56 uses the image forming unit. Smoothing processing and sharpening processing are performed using an M × N spatial filter based on the frequency characteristics of 9 and the determination result of the image recognition unit 54. Also, the γ correction unit 5
Reference numeral 7 changes the γ curve based on the frequency characteristic of the image forming unit 9 and the determination result of the image recognition unit 54 to execute the correction process,
The gradation processing unit 58 performs quantization such as dither processing based on the frequency characteristic of the image forming unit 9 and the determination result of the image recognition unit 54. The variously processed image data is sent to the image forming unit 9, and the image forming unit 9 forms an image on the recording paper. If requested, the external output unit 51 outputs the corrected image signal data.

For example, as shown in FIG. 15A, a white area of plain white paper is partially cut out so that a narrow white area 77 sandwiched by a wide black area 76 is formed so that the influence of flare becomes noticeable. (B) shows an image 78 formed on a recording sheet without the flare correction process by reading the original 11 with the scanner unit 5 and showing an image formed on the recording sheet after the flare correction process. 79 is shown in (c). Here, the black region is a portion where the document 11 is cut out, and the pressure plate of the scanner unit 5 is opened so that light is not intentionally reflected.
As shown in FIG. 15B, the reading value of the narrow white area 77 sandwiched between the wide black areas 76 is smaller than that of the other white areas.
As shown in (c), by performing the flare correction process, the narrow white area 77 can be made uniform with other white areas.

Further, the flare correction process when the image data storage area 484 of the data storage unit 48 does not have a storage capacity for storing the image data of all the images of the original 11 is shown in FIG.
As shown in the flowchart of (b), when the image of the document 11 is read by the scanner unit 5, the flare correction data is extracted from the correction data storage unit 49 by the arithmetic processing unit 46 (step S21), and the image signal generation unit is generated. The image signal data generated in 45 is proportional to the matrix calculation, for example, when the entire area of the read image in the main scanning direction is one line, the image signal data for seven lines is held in the image data storage area 484 (step S22, S23). The flare component is corrected using the held image signal data for 7 lines and flare correction data (step S24).
The image signal data after the flare correction is sequentially processed by the image processing unit 50 and output (step S25). In this way, flare correction can be performed without being affected by the storage capacity of the data storage unit 48, and a high quality image can be output stably.

When flare correction is performed on the image signal data read by the scanner unit 5 as described above, it is necessary to highly accurately correct the entire image region with the flare correction data. Further, in the normal scanner unit 5, the image of the original 11 may be read by changing the magnification, and it is necessary to correct the flare with high accuracy even when the image is read by changing the magnification. Therefore, for example, the original reading surface 10a of the contact glass 10 on which the A11 original 11 is placed is divided into a plurality of regions, for example, 6 as shown in FIG. 16A or 9 as shown in FIG. 16B. The flare correction data is measured for each area and stored in the correction data storage unit 49. Then, when flare correction is performed on the read image signal data, flare correction may be performed using flare correction data of the area where the image signal data is read. By performing flare correction with the corresponding flare correction data for each area in which the image of the document 11 is read in this manner, the read image signal data can be corrected with high accuracy.

Further, when the image of the original 11 is read by the scanner section 5 with a variable magnification, as shown in FIG. 17B, when 100 pixels in the sub-scanning direction of equal-magnification image data are used as a reference, 2
As shown in FIG. 17A, when the magnification is changed to 00%, 200 pixels of the image data are changed to 50% when the magnification is changed to 50%, as shown in FIG.
As shown in, the 50 pixels of the image data are read first. The read image signal data is processed by the image processing unit 50.
The image processing is performed to adjust the scaling factors in the main scanning direction and the sub scanning direction. When the magnification is 200%, the scanning linear velocity becomes slower than when the magnification is equal to 50%, and when the magnification is 50%, the scanning linear velocity becomes faster than when the magnification is equal. Therefore, the corresponding flare correction data also changes. Therefore, a plurality of flare correction data corresponding to the scaling factor is stored in the correction data storage unit 49, and when flare correcting the image signal data, the flare correction data corresponding to the scaling factor is extracted and flare corrected. Is also good.

Further, in the image data of the entire surface of the A3 size original 11, for example, flare correction data at the same size is 120 mm × 20 mm as shown in FIG.
18B, the region 81 of the flare correction data at the time of 200% scaling requires twice the region 80 of the flare correction data at the same size as shown in FIG. 18B. Yes, area 82 of flare correction data at 50% magnification change
Is required to be 1/2 times. Assuming that the basic unit at the same magnification for correcting flare is main scanning 30 × sub scanning 10 pixels, main scanning 30 × sub scanning 20 pixels at 200% scaling,
At the time of changing the magnification by 50%, the flare correction calculation may be performed using 30 × main scanning 5 pixels as a basic unit. That is, in this case, when the flare correction is performed by the arithmetic processing unit 46, the flare correction data at the same magnification stored in the correction data storage unit 49 is used, and the number of sub-scanning pixels = (sub-scanning basic at the same magnification) By determining the image area to which the flare correction is applied at the time of zooming by the number of pixels x scaling ratio and performing the flare correction, the flare correction data itself need only store the data at the same size.

In the above description, the illuminance distribution data is created by measuring the illuminance on the document surface with an illuminance meter or the like, but it may be calculated from the illuminance distribution image captured by a CCD camera. An illuminance distribution measuring device that creates illuminance distribution data from an illuminance distribution image captured by this CCD camera is, as shown in the configuration diagram of FIG. 19, a diffuse transmission plate 85 mounted on the contact glass 10, a CCD camera 86, and a calculation. It has a processing device 87. The diffuse transmission plate 85 is shown in FIG.
As shown in the sectional view of FIG.
1 and an ND filter (neutral density filter) 852. Then, the light source 12 is caused to emit light, the diffused light 88 from above the diffuse transmission plate 85 is imaged by the CCD camera 86, and the image of this diffused light is processed by the arithmetic processing unit 87 to obtain 2
The three-dimensional illuminance distribution data is calculated and stored in the illuminance distribution data storage area 481 of the feed control unit 4 in the digital copying machine 1. When the two-dimensional illuminance distribution data is calculated by the arithmetic processing unit 87, the average value of the illuminance distribution in the entire area of the document surface may be used as the illuminance distribution data, or the average value of several typical document surface may be used as the illuminance distribution data. Also good. Further, in the case of a color scanner, it is sufficient to have RGB data. By causing the light source 12 to emit light and creating two-dimensional illuminance distribution data in this way, it is possible to accurately correct the flare component that affects the image signal data.

In the above description, the flare intensity distribution is calculated from the image signal intensity distribution data, the flare correction data is calculated from the calculated flare intensity distribution data and the previously detected illuminance distribution data, and the flare correction data is stored in advance in the correction data storage unit 49. If you read the image of the document 11,
The case where flare correction is performed using the flare correction data stored in the correction data storage unit 49 for the read image data has been described. However, the illuminance distribution data and the flare intensity distribution data are stored in the data storage unit 48 in advance. Area 481 and flare intensity distribution data storage area 483
Alternatively, the flare intensity distribution data and the illuminance distribution data may be read to perform flare correction when the image of the document 11 is read and the flare correction is performed.

A case will be described in which the flare intensity distribution data and the illuminance distribution data are read and the flare correction is performed when the image of the original 11 is read and the flare correction is performed.

First, the contact glass 10 is provided with a point light source 68.
11 is placed, the point light source 68 is made to emit light without turning on the light source 12 of the scanner unit 5, and flare measurement is performed. As shown in FIG.
2 is generated and stored in the image signal intensity distribution data storage area 482 of the data storage unit 48. The calculation processing unit 46 calculates a flare intensity distribution from the image signal intensity distribution data 72 stored in the image signal intensity distribution data storage area 482, and stores the flare intensity distribution data 73 in the flare intensity distribution data storage area 483.

In this state, the image of the original 11 is read by the scanner section 5, and the read image signal data 75 is stored in the image data storage area 484 of the data storage section 48. Next, as shown in FIG. 21, the arithmetic processing unit 46 of the control unit 41.
Is the flare intensity distribution data 73 stored in the flare intensity distribution data storage area 483 and the illuminance distribution data storage area 481.
The illuminance distribution data 89 stored in 1 is extracted, and the flare correction is performed by performing a matrix calculation with the image signal data 75 stored in the image data storage area 484. In this matrix calculation, for example, the flare amount in which the attention area X33 of the image signal data 75 is affected by the area X21 is F11 × S1 using the flare intensity distribution data 73 and the illuminance distribution data 89.
1 × X21 / F23, and the flare amount affected by the region X31 is F21 × S21 × X31 / F23.
This calculation is applied to all the image signal data other than the area X33, and the flare amount for each peripheral pixel is summed to obtain the result X33.
By multiplying by / 255 and subtracting from the reading value of the attention area X33, image signal data without influence of flare can be obtained. This operation is performed on all the image signal data to generate flare correction image signal data, which is stored in the correction data storage unit 49. By correcting the flare component affecting the image signal data 75 from the flare intensity distribution data 73 and the illuminance distribution data 89 in this way, a high quality image can be read and a high quality image can be formed.

In the above description, the case where the image of the original 11 can be read by being magnified by the scanner section 5 has been described, but as shown in the perspective view of FIG. 22A and the side view of FIG. The same applies to the scanner unit 5a provided with the light source 12 for irradiating the original 11 placed on the glass 10 with the reading light, the reflector 13, and the lens 20, and the same-magnification imaging element 83 on the traveling member 84. it can.

Although the digital copying machine 1 has been described above, flare correction data is similarly created in a scanner device that reads an image of an original 11 and outputs it to a terminal device such as a personal computer, and the created flare correction is performed. The flare correction of the image signal data read by the data can be performed.

Further, in the above description, the case where the processing program for the flare measurement and flare correction data and the flare correction data is stored in the program storage unit 47 of the control unit 41 has been described. Is stored in the external storage medium 59, and the processing program for flare correction is stored in the program storage unit 4.
7, the flare correction data may be created by reading a processing program for flare measurement and creation of flare correction data from the external storage medium 59 by the central control unit 42 when creating flare correction data. . In addition, a processing program for flare measurement and flare correction data creation and flare correction is stored in the external storage medium 59, and the flare correction processing program is stored in the external storage medium 59 together with the processing program for flare measurement and flare correction data creation. The central control unit 42 may read these processing programs from the external storage medium 59 when creating flare correction data and performing flare correction. By storing these processing programs in the external storage medium 59 in this way, the versatility of flare correction is enhanced and a flare-corrected high-quality image is read and formed even in an existing copying machine or scanner device. be able to.

[0057]

As described above, according to the present invention, a point light source is provided on a measurement document whose reading surface is a diffuse reflection surface.
The image signal intensity distribution obtained by capturing the light reflected from the entire reading surface by the light emitted from the point light source by the image capturing means, and dividing the signal output from the image capturing means into the image area with the emission image area of the point light source as a basic unit. By generating the data and calculating flare correction data from the generated image signal intensity distribution data and the illuminance distribution data of the reading surface detected by emitting the illumination means in advance, flare due to the document surface reflection component can be calculated with a simple configuration. The state can be detected.

Further, the flare correction data corresponding to the document surface is calculated by multiplying the image signal intensity distribution data and the illuminance distribution data on the reading surface for each image area, thereby accurately determining the flare state due to the document surface reflection component. It can be detected well.

Further, by generating image signal data in which the flare component is corrected by the image signal data of the original read by emitting light from the illumination means and the flare correction data calculated in advance, the quality of the read image in which flare is removed Can be converted into a good image.

When correcting the flare, the image signal data of the read original is divided for each image area of the flare correction data, and the attention data of the divided image signal data corresponds to the image area other than the attention data. The amount of original document surface reflection flare is calculated from the matrix calculation with the flare correction data, and the amount of original document surface reflection flare calculated from the target data is subtracted to generate image signal data in which the flare component has been corrected. The image quality can be improved.

Further, when flare correction is performed on the image signal data of the original, flare correction is performed using the flare intensity distribution data and the illuminance distribution data stored in advance, so that the read image signal data is flare corrected by a simple process. Therefore, it is possible to quickly output a high-quality image from which flare has been removed.

Further, by storing one or both of the processing program of the flare correction data measuring method and the processing program of the flare correction method in the storage medium, the versatility of the flare correction data measuring processing and the flare correction processing is improved. In addition to the enhancement, it is possible to output a read image with flare removed even with an existing scanner device or copying machine.

Further, when the image reading device has a reading surface formed of a diffuse reflection surface and having a point light source and the measurement original is placed on the original placing surface to cause the point light source to emit light, it is emitted from the point light source. The light reflected from the entire reading surface by the light is imaged by the image pickup means, and image signal intensity distribution data is generated by dividing the light output image area of the point light source into an image area as a basic unit from the signal output from the image pickup means. The flare correction data is calculated from the generated image signal intensity distribution data and the illuminance distribution data of the reading surface detected by emitting light from the illumination means in advance and stored in the storage means, or the image signal intensity distribution data is converted into flare intensity distribution data. The image signal data of the original document, which is converted and stored and read by emitting light from the illumination means, is stored using the stored flare correction data or flare intensity distribution data and illuminance distribution data. By correcting the A component, a good read image in the image quality can be stably output.

Further, the image reading device stores a plurality of flare correction data and flare intensity distribution data for each specific area of the document, and a plurality of flare correction data and flare intensity distribution data for each magnification when reading the document. By storing, it is possible to output a high-quality image by performing flare correction according to the scaling factor even if the scaling factor is changed when reading a document.

Further, the arithmetic processing means calculates flare correction data according to the scaling ratio when the original is read from the flare correction data at the same magnification, so that the storage capacity of the storage means is not increased and the magnification is changed. However, it is possible to perform flare correction using flare correction data according to the scaling factor and output a high-quality image.

Further, by providing the image reading apparatus in the image forming apparatus and forming the image by the image data from which the flare is output, the high quality image can be stably formed.

[Brief description of drawings]

FIG. 1 is a block diagram of a digital copying machine of the present invention.

FIG. 2 is a configuration diagram of a scanner unit.

FIG. 3 is a configuration diagram of an engine unit.

FIG. 4 is a block diagram showing a configuration of a control unit.

FIG. 5 is a configuration diagram of a data storage unit.

FIG. 6 is a configuration diagram of an apparatus for measuring flare correction data.

FIG. 7 is a flowchart showing a measurement process of flare correction data.

FIG. 8 is a display diagram of contour lines of the illuminance distribution when the illuminance distribution on the document surface is measured.

FIG. 9 is a configuration diagram of illuminance distribution data on a document surface.

FIG. 10 is a display diagram of an image signal intensity distribution when measuring flare correction data.

FIG. 11 is an explanatory diagram showing a process of creating flare correction data from an image signal intensity distribution.

FIG. 12 is an explanatory diagram showing an example of flare correction data.

FIG. 13 is a flowchart showing a flare correction process.

FIG. 14 is an explanatory diagram showing a flare correction process.

FIG. 15 is a schematic diagram showing an image with and without flare correction processing.

FIG. 16 is a schematic diagram showing a state in which the reading surface is divided into a plurality of pieces when creating flare correction data.

FIG. 17 is a schematic diagram showing a read pixel area at the same magnification and at the variable magnification.

FIG. 18 is a schematic diagram showing a flare correction data area at the same magnification and at the variable magnification.

FIG. 19 is a configuration diagram of an illuminance distribution measuring device.

FIG. 20 is a cross-sectional view showing a configuration of a diffusion transmission plate of the illuminance distribution measuring device.

FIG. 21 is an explanatory diagram showing flare correction processing based on flare intensity distribution data and illuminance distribution data.

FIG. 22 is another configuration diagram of the scanner unit.

FIG. 23 is an explanatory diagram of flare caused by reflection from the reading surface.

FIG. 24 is an explanatory diagram showing a conventional image evaluation method.

[Explanation of symbols]

1; digital copier, 2; copier body, 3; ADF,
4; automatic sorting device, 5; scanner unit, 6; writing unit, 7; engine unit, 8; paper feeding unit, 9; image forming unit, 10; contact glass, 11; document, 12; light source, 13; reflector , 14; mirror, 15; first traveling body, 16; mirror, 17; second traveling body, 19; drive transmission means, 20; lens, 21; one-dimensional image sensor, 2
4; image forming unit, 25; primary transfer unit, 2
6; secondary transfer unit, 27; fixing unit, 41; control unit, 42; central control unit, 46; arithmetic processing unit, 47; program storage unit, 48; data storage unit, 49; correction data storage unit, 60; Point light source device, 61; Original document for flare measurement.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5B047 AA01 AB02 BA02 BB02 BC05                       BC09 BC12 BC14 BC23 CA19                       CB04 CB22 DA03 DC06 DC20                 5C072 AA01 BA17 CA02 CA09 CA11                       CA20 DA02 DA04 EA05 LA18                       UA20 XA01                 5C077 LL04 PP08 PP09 PP47 PP48                       PP68 PQ12 PQ25 SS01 TT06

Claims (17)

[Claims] 1. An illuminating means for irradiating a reading surface of an original placed on the original placing surface with light, an image pickup means for picking up an image of the reading surface by the light irradiating the reading surface of the original, and an output from the image pickup means. A method for measuring flare correction data of an image reading device for generating image signal data from a signal to be read, in which a reading original is provided with a point light source on a measurement document and reading is performed by light emitted from the point light source. The light reflected from the entire surface is picked up by the image pickup means, image signal intensity distribution data is generated by dividing the signal output from the image pickup means into image areas with the light emission image area of the point light source as a basic unit, and the generated image A flare correction data measuring method, characterized in that flare correction data is calculated from signal intensity distribution data and illuminance distribution data of a reading surface detected by emitting light from an illuminating means in advance. 2. The flare correction data measuring method according to claim 1, wherein flare correction data is calculated by multiplying the image signal intensity distribution data and the illuminance distribution data on the reading surface for each image area. 3. A flare correction method using flare correction data calculated by the flare correction data measuring method according to claim 1, wherein the flare correction data is calculated in advance with image signal data of an original read by illuminating an illuminating means. A flare correction method characterized by generating image signal data in which a flare component is corrected by flare correction data. 4. The read image signal data of the original is divided for each image area of flare correction data, and the flared correction data corresponding to the image area other than the focused data is divided with respect to the focused data of the divided image signal data. 4. The flare correction method according to claim 3, wherein the document surface reflection flare amount is calculated from the matrix calculation, and the document surface reflection flare amount calculated from the target data is subtracted to generate image signal data in which the flare component is corrected. 5. An illuminating means for irradiating the reading surface of the original placed on the original mounting surface with light, an imaging means for imaging the reading surface with the light irradiating the reading surface of the original, and an output from the imaging means. Is a flare correction method for an image reading device that generates image signal data from a signal that is read by a measuring document whose reading surface is a diffuse reflection surface, and is provided with a point light source. The light reflected from the entire surface is picked up by the image pickup means, image signal intensity distribution data is generated by dividing the signal output from the image pickup means into image areas with the light emission image area of the point light source as a basic unit, and the generated image signal strength The flare intensity distribution data is converted into distribution data, and flare correction of the image signal data is performed based on the converted flare intensity distribution data and the illuminance distribution data of the reading surface detected by emitting the illumination means in advance. Flare correction method to be. 6. The flare intensity distribution data corresponding to image regions other than the focused data is divided with respect to the focused data of the divided image signal data, by dividing the image signal data of the read document into image regions of the flared intensity distribution data. 6. The flare correction method according to claim 5, wherein the flare amount of the document surface reflection is calculated from the matrix calculation of the illuminance distribution data and the flare amount of the document surface reflection calculated from the data of interest is subtracted to generate image signal data with the flare component corrected. . 7. A storage medium on which a processing program of the flare correction data measuring method according to claim 1 is stored. 8. A storage medium on which a processing program for the flare correction method according to claim 3 is stored. 9. A storage medium which stores the processing program of the flare correction data measuring method according to claim 1 or 2 and the processing program of the flare correction method according to any one of claims 3 to 6. 10. Illuminating means for irradiating the reading surface of the original with light, image pickup means for picking up the reading surface with the light for irradiating the reading surface of the original, and image signal data generated from a signal output from the image pickup means. The image reading apparatus includes an arithmetic processing unit and a storage unit, and the arithmetic processing unit is a point light source in which a measurement document having a reading surface formed of a diffuse reflection surface and having a point light source is placed on the document placing surface. When the light is emitted from the point light source, the light reflected from the entire reading surface by the light emitted from the point light source is imaged by the image pickup means, and the image area using the light emission image area of the point light source as a basic unit from the signal output from the image pickup means. The image signal intensity distribution data divided into two are generated, flare correction data is calculated from the generated image signal intensity distribution data and the illuminance distribution data of the reading surface detected by emitting light from the illumination means in advance and stored in the storage means. An image reading apparatus and generates an image signal data by the flare correction data stored in the image signal data storage means of the original read by emitting illumination means to correct the flare component. 11. The image reading apparatus according to claim 10, wherein the storage means stores a plurality of flare correction data for each specific area of the document. 12. The image reading apparatus according to claim 10, wherein the storage means stores a plurality of flare correction data for each magnification when reading a document. 13. The image reading apparatus according to claim 10, wherein the arithmetic means calculates flare correction data according to a scaling factor when reading an original from flare correction data at the same magnification. 14. Illuminating means for irradiating a reading surface of a document with light, image pickup means for picking up an image of the reading surface with light irradiated on the reading surface of a document, and image signal data generated from a signal output from the image pickup means. The image reading apparatus has an illuminance distribution data storage means, an arithmetic processing means, and a flare intensity distribution data storage means, and the illuminance distribution data storage means detects the illuminance distribution data of the reading surface detected by emitting the illumination means in advance. The arithmetic processing means stores the light emitted from the point light source when the measurement document having the reading surface formed of the diffuse reflection surface and having the point light source is placed on the document placing surface to cause the point light source to emit light. The light reflected from the entire reading surface is picked up by the image pickup means, and image signal intensity distribution data is generated by dividing the light output image area of the point light source into image areas based on the signal output from the image pickup means Then, the generated image signal intensity distribution data is converted into flare intensity distribution data, the converted flare intensity distribution data is stored in the flare intensity distribution data storage means, and the image signal data and the flare of the original read by illuminating the illumination means are read. An image reading apparatus, wherein flare-corrected image signal data is generated based on flare intensity distribution data stored in intensity distribution data storage means and illuminance distribution data stored in illuminance distribution data storage means. 15. The image reading apparatus according to claim 14, wherein the flare intensity distribution data storage means stores a plurality of flare intensity distribution data for each specific area of the document. 16. The image reading apparatus according to claim 14, wherein the flare intensity distribution data storage means stores a plurality of flare intensity distribution data for each magnification when reading a document. 17. An image forming apparatus comprising the image reading apparatus according to claim 10. Description: