JPH1188613A - Image information reader and image information read method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image information reader by which image information is read with high image quality and at a high speed, without resorting mechanical countermeasures of suppressing vibration onto an optical system. SOLUTION: Reference patterns 20a, 30b are read at both sides of an original at a specified distance from a placing position of an original in a vertical direction (subscanning direction) of a line sensor of an original platen 2. A position (pixel) of the reference patterns is respectively detected from image information including the read reference pattern, a fluctuation amount caused in the image information from the detected value is detected by fluctuation amount detection circuits 50a, 50b and the direction of the fluctuation is detected by a fluctuation direction comparator circuit 51, the correction method is discriminated based on the detection result, and the entire image information of the read original is subject to correction processing to obtain high image quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, relatively moving a document surface and an optical system to optically scan a document, forming reflected light from the document on a line sensor, and converting the reflected light into an electric signal. Accordingly, the present invention relates to an image information reading device and an image information reading method for reading image information of a document.

[0002]

2. Description of the Related Art Generally, this kind of image information reading apparatus is
An optical system including a light source and a mirror is mounted on a carriage that reciprocates along a fixed platen, and by moving the optical system together with the carriage, the document placed on the platen is optically scanned. The reflected light from the document is imaged on the light receiving surface of the fixed line sensor via the mirror or the like, and is converted into an electric signal by the line sensor.

[0003] Such an image information reading apparatus has recently been widely used in facsimile apparatuses, copying machines, image information recognition apparatuses, optical filing apparatuses and the like. In these devices, since the demand for high precision and high image quality is rapidly increasing, it is increasingly important to accurately read image information. In addition, the enlargement and reduction ratios tend to be more and more widespread, and in particular, in reading of enlarged image information, the vibration at the time of low speed driving of the optical system is emphasized as the fluctuation of the image information by the image processing in the main scanning direction. There was a problem.

Therefore, various methods for suppressing vibration to the optical system have been conventionally performed. However, in each case, a method of mechanically reducing vibration to the optical system has been mainly performed. For example, by mounting a damper (inertia load such as a flywheel) on the drive shaft of a motor that drives a carriage equipped with an optical system, vibrations to the optical system are suppressed by reducing speed fluctuations of the motor. is there.

[0005] As means for correcting such fluctuations in image information caused by mechanical vibration, for example, Japanese Patent Application Laid-Open No. 5-207231 has proposed. This means that one reference pattern provided in the range in which the photoelectric conversion means can perform photoelectric conversion and outside the document position range along the moving direction is simultaneously read, and the position of the reference line is determined from image information including the reference pattern. The amount of change in the image information of the document is detected from the detected value, and the image information is corrected by shifting the image data based on the amount of change.

However, this method cannot correct image information accurately. This is because the manner in which the image information fluctuates differs depending on where the optical system vibrates. For example, when both ends of the carriage vibrate alternately in the moving direction (sub-scanning direction) while the carriage equipped with the optical system is reading image information while moving relative to the document, The photoelectrically converted image information becomes an image shifted with respect to the photoelectric conversion direction (main scanning direction).

On the other hand, when the reflection mirror mounted on the carriage generates a flexural vibration in the primary vibration mode in which the maximum amount of flexure is at the center in the longitudinal direction, the center of the photoelectric conversion means is moved with respect to the direction of photoelectric conversion. The image information is enlarged or reduced as the center. In this case, the above-described correction method for shifting the image information has a disadvantage of deteriorating the image.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has been developed to provide high-speed, high-quality images without taking measures to mechanically suppress vibration to an optical system. An object of the present invention is to provide an image information reading apparatus which can read image information.

[0009]

An image information reading apparatus according to the present invention optically scans the original by an optical system that moves relatively to the original surface, and forms light from the original on a photoelectric conversion unit. In the image information reading apparatus that reads the image information of the original by converting the electric information into an electric signal, the electric signal is within the photoelectric conversion range of the electric photoelectric conversion unit, and both sides outside the original position in the moving direction. The position of the reference pattern on both sides is detected based on a linear reference pattern that is provided along and is photoelectrically converted together with the image information of the original, and image information that includes the reference pattern obtained from the photoelectric conversion unit. A variation detecting means for detecting a variation in the image information of the document from the position of the reference pattern detected on both sides of the conversion means, and the variation on both sides of the photoelectric conversion means. A variation direction comparing means for comparing the directions of variation of the detected reference pattern by the detection means,
A correction processing unit configured to correct image information of the document obtained from the photoelectric conversion unit based on a fluctuation amount detected by the fluctuation amount detecting unit and a result of comparison by the fluctuation direction comparing unit.

[0010] In the image information reading apparatus, the correction processing means may be configured to output the image information of the document obtained from the photoelectric conversion means when the result of comparison by the fluctuation direction comparison means fluctuates in the same direction. To correct the image information of the original.

In the image information reading apparatus, the correction processing means may include an image of the document obtained from the photoelectric conversion means when a result of comparison by the fluctuation direction comparing means fluctuates in different directions. Expand the information, or
The image information of the document is corrected by reducing the size.

The correction processing means, when the amount of change of the reference pattern detected by the change amount detecting means is different, converts the image information of the document obtained from the photoelectric conversion means in the direction of the change. The image information of the document is corrected by shifting the image information based on the image information and enlarging or reducing the image information.

Also, an optical system that moves relatively to the original, optical scanning of the original by the optical system, a photoelectric conversion unit that forms an image of light from the original and converts the light into an electric signal, A linear reference pattern that is provided along the moving direction of the optical system on both sides of the photoelectric conversion range of the conversion unit and outside the range of the document position, and is photoelectrically converted together with image information of the document. In the image information reading method for reading the image information of the original by the image information reading device, the position of the reference pattern is detected from the image information including the reference pattern obtained from the photoelectric conversion means, and based on the detected value, The amount of change generated at the time of reading the reference pattern is detected by a change amount detection unit, and the reference amount detected by the change amount detection unit on both sides of the photoelectric conversion unit. The change directions of the turns are compared by a change direction comparing means, and based on the result of the change amount detected by the change amount detecting means and the change direction compared by the change direction comparing means, the change direction obtained from the photoelectric conversion means is obtained. It is characterized in that image information of a document is corrected.

(Operation) According to the image information reading apparatus of the first aspect and the image information reading method of the fifth aspect, when reading the image information by moving the optical system as in the prior art, Measures to suppress vibration, such as anti-vibration devices to suppress the reflection mirror from vibrating and mechanisms to suppress the optical system from rotating and oscillating right and left with respect to the moving direction, are provided with high Image quality can be improved.

Further, according to the image information reading apparatus of the present invention, the image information shifted for each line by the vibration of the optical system is used for the two reference patterns provided on both sides of the photoelectric conversion means. By judging from the amount of change and the direction of change and correcting the image information line by line, it is possible to easily achieve high image quality.

According to the image information reading apparatus of the third aspect, the vibration of the optical system enlarges the image information line by line.
Alternatively, the reduced image information is determined based on the variation amount and the variation direction of two reference patterns provided on both sides of the photoelectric conversion unit, and the image information is reduced or enlarged for each line and corrected. Thus, high image quality can be easily achieved.

According to the image information reading device of the present invention, it is possible to easily increase the image quality by combining the shift method and the enlargement / reduction method even when the reference patterns have different amounts of variation.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 schematically shows an image information reading apparatus according to an embodiment of the present invention.

In FIG. 1, a document table 2 made of transparent glass is fixed on the upper surface of the apparatus main body 1.
A document 3 to be read is placed on the document table 2. A document scanning unit 4 that optically scans the document 3 on the document table 2 is provided at a portion corresponding to the document table 2 in the apparatus main body 1.

The original scanning section 4 includes a first carriage 6 on which a bar-shaped light source 5 for illuminating the original 3 is illuminated, a second carriage 9 on which mirrors 7 and 8 for bending an optical path are mounted, and a condensing light. A lens block 10, a CCD type line sensor 11 as a photoelectric conversion unit for receiving reflected light from the original 3 guided through each of these optical paths and converting the reflected light into an electric signal
And a fixed optical system 12 having

A document position regulating plate 13 is provided on the document table 2 so as to be adjustable so that the position of the document 3 can be regulated. Also, the original position regulating plate 13 has a white reference plate 1 for performing shading correction (details of shading correction will be described later) at a position where light from the light source 5 is reflected.
4, and a light-shielding plate 15 is provided at a position separated from the white reference plate 14 by a certain distance.

The first carriage 6 includes, in addition to the light source 5, a reflector 16 serving as a reflecting mirror for collecting the light from the light source 5 on the original 3, and a light quantity distribution improvement for equalizing the quantity of the reflected light from the original 3. The plate 17, the mirror 18 for guiding the reflected light from the document 3 toward the second carriage 9, the home position sensor 19 for detecting the home position (reference position) of the first carriage 6, and the frame 2 on which these are mounted
It has 0.

The home position sensor 19 detects the home position of the first carriage 6 by detecting the light shielding plate 15 provided on the document position regulating plate 13, and uses, for example, an optical sensor. I have.
The second carriage 9 has a frame 21 on which mirrors 7 and 8 are mounted.

The first carriage 6 and the second carriage 9 are connected to each other by a wire (not shown).
Guide rail 2 supported by apparatus main body 1 below platen 2
2 is reciprocated in the direction of the arrow shown in the figure by a motor (not shown) via the sliding member 23. In this case, the second carriage 9 moves in the same direction at half the speed of the first carriage 6 so that the optical scanning can be performed so that the optical path length to the lens block 10 is always constant. Has become.

The fixed optical system 12 includes a lens block 10
In addition to the line sensor 11, a lens cover 24 is attached to the optical system base 25 so that light other than light reflected from the document 3 does not enter the line sensor 11. In addition,
Line sensor 1 at the optimal focal position of lens block 10
A mechanism (not shown) capable of adjusting the relative position of the lens block 10 and the line sensor 11 is attached to the optical system base 25 so that the light receiving surfaces of the lens block 10 and the light receiving surface of the lens block 10 coincide with each other.

FIG. 2 shows the relationship between the line sensor 11 and the document table 2. The document table 2 is made of transparent glass. The sub-scanning direction (carriage 6, 9
(A moving direction), linear reference patterns (for example, linear) 30a and 30b are provided. The background of the reference pattern is white or
It has a high reflectance surface.

The pixel size of the line sensor 11 is, for example, 7500 pixels per line.
The pixel size of the document 3 corresponds to a maximum of 7016 pixels. Therefore, the pixel size of the line sensor 11 and the original 3
A remainder of 484 pixels occurs between the pixel size and the pixel size. Of the 484 pixels, 242 pixels each function as a reference pattern reading area A and a reference pattern reading area B for reading the reference pattern 30 existing on both sides, and 7016 pixels therebetween serve as a document reading area.

A reference pattern reading area A provided on both sides of the document table 2 and a reference pattern reading area B
The reference pattern 30a and the reference pattern 30b
Are provided on the surface opposite to the surface on which the original is placed, that is, on the original scanning unit 4 side. Here, a black straight line parallel to the moving direction (sub-scanning direction) of the optical system is shown as the reference pattern.

FIG. 3 shows the reference patterns 30a and 30a.
3 shows an outline of image information read including b. The image information obtained by reading the reference patterns 30a and 30b has been shaken due to the vibration generated in the optical system. In addition, the image information of the document 3 also fluctuates. These image information reference patterns 30a,
The degree of fluctuation is detected from the image information of the document 30b, and the entire image information of the document 3 is corrected.

In the correction method, first, before the reading operation is started, the first carriage 6 is moved to a position where the reference patterns 30a and 30b can be read, and image information is recorded with the carriage stopped. In the image reading area A, position detection is performed in order from the left side of the image information, a reference level is provided, and black is processed below the reference level and white is processed above it. The head position where the black level appears several pixels in a row is stored as the reference position on the line sensor 11 of the reference pattern 30a. In the reading area B, position detection is performed sequentially from the right side of the image area, and similarly, the reference position of the reference pattern 30b on the line sensor is stored.

Next, after returning the first carriage 6 to the home position 19, the reading of the original is started.
One-line image information is fetched, the positions of the reference patterns 30a and 30b on the line sensor are detected in order from the first pixel, and the difference from the previously obtained reference position is detected by the fluctuation amount detecting means. Next, the reference pattern 30
Whether the difference from each of the reference positions a and 30b from the reference position is the positive direction or the negative direction is compared by the change direction comparing means, and the image correction method is determined according to the combination pattern of the change directions.

For example, the image correction methods are classified as shown in Table 1 below according to the direction and magnitude of the amount of fluctuation in the reference pattern reading area A and the reference pattern reading area B.

When the absolute value of the variation d ₁ of the reference pattern in the area A is equal to the absolute value of the variation d ₂ of the reference pattern in the area B, that is, when | d ₁ | = | d ₂ |, d ₁ and d ₂ If the code is different, the shift method is used, and if the code is the same, enlargement or reduction image correction is performed.

[0034]

[Table 1]

When the absolute value of the variation d ₁ of the reference pattern in the area A is different from the absolute value of the variation d ₂ of the reference pattern in the area B,
That is, when | d ₁ | ≠ | d ₂ |, image correction is performed by combining the shift method and the enlargement / reduction method. Table 2 below shows the shift correction and the enlargement / reduction correction in that case.

[0036]

[Table 2]

Based on the above rules, the image information obtained by reading the original 3 is corrected line by line. By performing such a correction, it is possible to minimize the influence on the image information of the vibration generated in the optical system without performing mechanical vibration suppression. Therefore, high-quality and high-speed reading of image information can be performed without taking a conventional measure for mechanically suppressing vibration to the optical system. Further, by using the reference patterns provided on both sides of the document, a more accurate image correction method than in the related art can be realized.

Next, a method of correcting image information when shifting in the same direction as shown in FIG. 3 will be described below. When the fluctuation amounts in the reference pattern reading area A and the reference pattern reading area B are in the same positive direction,
The image information of the document area is corrected by shifting the image information for each line in a direction that eliminates the amount of fluctuation from the reference position.

In the image information before correction shown in FIG. 3, the amount of change of the reference pattern from the reference position is +1 in the first line and +1 in the reference pattern reading area A, respectively.
0, 0, -1, 0, -1, -2, -1, 0, +2.
1, 0, 0, +1, 0, +1, +2, +1, 0, -2. Since the absolute value of the variation amount is the same and the sign of the variation amount is different, in each line, -1, 0, 0, +1 and -1, from the first line with respect to the left end of the reference pattern reading area A.
Shift processing of image information of 0, +1, +2, +1, 0, -2 is performed. One line of image information is read, and the above correction processing is sequentially performed to correct the image information.

Next, a description will be given of a method of correcting image information when shifting is performed in different directions as shown in FIG. When the amounts of variation in the reference pattern reading area A and the reference pattern reading area B are the same but different directions, for example, in FIG. The line data is image information in which an image is enlarged on both sides around the center of the image information due to, for example, bending vibration of a mirror mounted on the carriage.

Therefore, the center of the line sensor is used as the center of the enlargement / reduction processing of the image information, and the image information is corrected by enlarging or reducing the image information according to the magnification for each line obtained from the variation from the reference position. I do.

In the image information before correction shown in FIG. 4, the amount of change of the reference pattern from the reference position is +1, 0, + in the reference pattern reading area A from the first line.
3, +2, +1, 0, -1, -2, 0, +1.
0, +3, +2, +1, 0, -1, -2, 0, +1.

In each line, the absolute value of the amount of change is the same and the sign of the amount of change is the same.
In the line, since the value is +1 in the area A and +1 in the area B, it can be seen that the image information is enlarged around the center of the line sensor. In this case, image information is reduced based on the number of pixels and the amount of change from the center of the line sensor to the reference position. Assuming that the number of pixels from the center of the line sensor to the reference position is L and the variation from the reference position is d, the correction magnification Z is given by the following equation.

[0044]

(1) Z = L / (L + d ₁ + d ₂ ) The image information is corrected by sequentially performing the correction processing for each line with the above correction magnification.

Next, a description will be given of a method of correcting image information in the case where the amount of fluctuation is different as shown in FIG. When the magnitude of the variation amount in the reference pattern reading area A and the reference pattern reading area B is different, first, the image information for each line is obtained from the variation amount of the reference pattern from the reference position in the area A and the area B, Shift by-((d ₁ -d ₂ ) / 2) with reference to the left end of the reference pattern reading area A, and furthermore, enlargement / reduction of L / (L + d ₁ + d ₂ ) in the line direction centering on the center of the image. By performing the correction, the image information of the document area is corrected.

For example, in the image information before correction shown in FIG.
The variation amount of the reference pattern from the reference position in the area A is +1, −1, +3, +2, +2, 0, 0, −1, 0, in the reference pattern reading area A from the first line.
0, and +1, +1, +3, +2, 0, 0, -2, -3, 0, +
It becomes 2. Since the magnitude of the variation amount of the reference pattern in each region is different, first, a correction amount − ((d ₁ −d ₂ ) / 2) is calculated from the variation amount of the reference pattern for each line, and shift correction is performed. I do.

In the uncorrected diagram of FIG. 5, a shift process of the image information of 0, +1, 0, 0, -1, 0, -1, -1, 0, +1 from the first line is performed. Next, for each line, the enlargement / reduction magnification for each line is calculated from the variation amount of the reference pattern in each area and the distance L between the reference patterns in each area, and the enlargement / reduction correction is performed for each line. .

In the figure after the shift correction in FIG. 5, the enlargement / reduction correction magnification for each line is L / (L +
2), 1, L / (L + 6), L / (L + 4), L / (L
+2), 1, L / (L-2), L / (L-4), 1, L
/ (L + 2). According to the correction magnification for each line,
Image correction is performed by performing enlargement or reduction correction centering on the center of each line.

In this embodiment, the shift correction is performed before the enlargement / reduction correction. However, the enlargement / reduction correction is performed first.
Obviously, the same effect can be obtained even if the shift correction is performed.

FIG. 6 is a configuration diagram schematically showing an electric circuit of the image information reading apparatus configured as described above. FIG.
In, the output signal of the line sensor 40 is sent to an analog processing circuit 41, where analog processing such as clamping and sample hold is performed, and then sent to an A / D conversion circuit, where the signal is A / D converted. The digital signal after the A / D conversion circuit is sent to a shading correction circuit 43 for normalization, where the shading correction is performed.
The shading correction is for correcting variations in sensitivity of the line sensor 40, variations in illuminance of the light source 5, differences in light amount between the central portion and both end portions due to the optical system, deterioration of the light source 5, and the like.

The image information after the shading correction is sent to the image fluctuation correction circuit 44 according to the present invention. After the image fluctuation correction, the image data is sent to the enlargement / reduction circuit 45, where enlargement or reduction processing in the main scanning direction is performed. Thereafter, the image data is sent to the image processing circuit 46, where it performs various image processing such as gamma correction and matrix correction, and outputs it to an external device.

FIG. 7 shows an image fluctuation correction circuit 4 according to the present invention.
4 is shown. The image information subjected to the shading correction is input to the area A fluctuation amount detection circuit 50a and the area B fluctuation amount detection circuit 50b. Fluctuation detection circuits 50a, 50
b is the image of the reference patterns 30a and 30b when the image information of the document 2 is taken from the position (reference position) of the reference pattern on the image information detected in advance with the carriage stopped. The difference from the position in the information is output. The change direction comparison circuit 51 includes a region A change amount detection circuit 50a and a region B change amount detection circuit 5
The direction in which 0b fluctuates is compared, and whether the fluctuation direction of region A and region B is positive direction and positive direction, positive direction and negative direction, negative direction and positive direction, and negative direction and negative direction is output. I do.

The variation correction circuit 52 determines the variation correction method as described above from the output result of the variation direction comparison circuit 51 and the output results of the variation amounts of the variation detection circuits 50a and 50b, and executes the correction processing. Do.

As described above, the reference pattern (straight line) is provided on both sides of the original plate at a specific distance from the original mounting position in the vertical direction (sub-scanning direction) with respect to the line sensor on the original plate, The reference pattern is read together with the information, the positions (pixels) of the reference pattern on both sides of the line sensor are detected from the read image information, and the amount of change in the image information is detected from the detected value. The direction in which the fluctuation amount detected on both sides of the sensor fluctuates is compared, and image information is corrected based on the comparison result and the fluctuation amount.

In this correction processing, when the magnitude of the fluctuation amount on both sides of the line sensor is the same, if the fluctuation direction is the same direction, the image information of the read original is changed for each line in accordance with the detected fluctuation amount. If the fluctuation directions are different, the image information of the read document is enlarged or reduced according to the detected fluctuation amount for each line. If the magnitudes of the fluctuation amounts on both sides of the line sensor are different, the reading is performed by shifting the image information of the read document to the left and right and enlarging or reducing the image information for each line according to the detected fluctuation amount.

By performing the correction as described above, it is possible to minimize the influence of the vibration generated in the optical system on the image information without performing the mechanical vibration suppression. Therefore, high-quality and high-speed reading of image information can be performed without taking a conventional measure for mechanically suppressing vibration to the optical system.

In the above embodiment, a straight line is used as the reference pattern. However, the reference pattern need not always be a straight line. For example, another linear pattern such as a gentle curve has the same purpose. Can be achieved. Further, in the example of the above-described embodiment, a black line is used as the reference pattern. However, it is not always necessary to use a black line. For example, when reading a color image, the sensitivity is adjusted according to the sensitivity of each color filter. Choosing a color can achieve a similar goal.

In the above embodiment, the variation correction processing is performed every time one line is taken. However, it is not always necessary to carry out the correction processing every time one line is taken. It is apparent that the variation correction processing may be performed, and the present invention can be implemented with various modifications without departing from the scope of the invention.

[0059]

As described in detail above, according to the image information reading apparatus of the present invention, high quality and high speed image information can be read without taking measures to mechanically suppress the vibration to the optical system. A simple image information reading device can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of an image information reading device.

FIG. 2 is a diagram schematically illustrating a line sensor and a document table.

FIG. 3 is a diagram showing image information before correction and after shift correction of read image information.

FIG. 4 is a view showing image information before correction and after enlargement or reduction correction of read image information.

FIG. 5 is a diagram illustrating image information before correction of read image information and image information after performing image correction by combining shift correction and enlargement / reduction correction;

FIG. 6 is a block diagram schematically showing an electric circuit of the image information reading apparatus.

FIG. 7 is a block diagram illustrating a fluctuation correction process in the image fluctuation correction circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 apparatus main body 2 document table 3 document 4 document scanning unit 5 light source 6 first carriage 7, 8 mirror 9 second carriage 10 lens block 11 line sensor (photoelectric conversion means) 13 document position regulating plate 18 mirror 22 rail 30a, 30b reference Pattern 41 analog circuit 42 A / D conversion circuit 43 shading correction circuit 44 image fluctuation correction circuit 45 enlargement / reduction circuit 46 image processing circuit 50a, 50b fluctuation amount detection circuit (variation amount detection means) 51 fluctuation direction comparison circuit (variation direction comparison) Means) 52 fluctuation correction circuit (correction processing means)

Claims (5)

[Claims] An image of the original is formed by optically scanning the original by relatively moving the original and an optical system, forming light from the original on a photoelectric conversion unit, and converting the light into an electric signal. In the image information reading device for reading information, the image information reading device is provided along the movement direction on both sides outside the range of the document position within the photoelectric conversion range of the photoelectric conversion unit, and performs the photoelectric conversion together with the image information of the document. A linear reference pattern to be detected, and a position of the reference pattern is detected from image information including the reference pattern obtained from the photoelectric conversion unit, and a variation at the time of reading caused in the reference pattern based on the detected value. A fluctuation direction detecting means for detecting a fluctuation amount; and a fluctuation direction comparing means for comparing the fluctuation directions of the reference patterns detected by the fluctuation amount detecting means on both sides of the photoelectric conversion means. And correction processing means for correcting the image information of the document obtained from the photoelectric conversion means, based on the result of the fluctuation amount detected by the fluctuation amount detection means and the fluctuation direction compared by the fluctuation direction comparison means. An image information reading device, comprising: 2. The image processing apparatus according to claim 1, wherein when the result of the change direction compared by the change direction comparing means changes in the same direction, the correction processing means converts the image information of the document obtained from the photoelectric conversion means into the change direction. 2. The image information reading apparatus according to claim 1, wherein the image information of the document is corrected by shifting based on the image information. 3. The image processing apparatus according to claim 1, wherein the correction processing unit enlarges image information of the document obtained from the photoelectric conversion unit when a result of the change direction compared by the change direction comparison unit changes in a different direction. 2. The image information reading apparatus according to claim 1, wherein the image information of the document is corrected by reducing the size. 4. The image processing apparatus according to claim 1, wherein the correction processing unit is configured to, when the variation amount of the reference pattern detected by the variation amount detecting unit is different, change the image information of the document obtained from the photoelectric conversion unit into the variation direction. 2. The image information reading apparatus according to claim 1, wherein the image information of the document is corrected by shifting the image information based on the image information and enlarging or reducing the image information. 5. An optical system which moves relatively to a document, a photoelectric conversion means for optically scanning the document by the optical system, forming light from the document into an image, and converting the light into an electric signal; A linear reference pattern that is provided along the moving direction of the optical system on both sides of the photoelectric conversion range of the conversion unit and outside the range of the document position, and is photoelectrically converted together with image information of the document. In the image information reading method for reading the image information of the original by the image information reading device, the position of the reference pattern is detected from the image information including the reference pattern obtained from the photoelectric conversion means, and based on the detected value, The amount of change generated at the time of reading the reference pattern is detected by a change amount detection unit, and the reference pattern detected by the change amount detection unit on both sides of the photoelectric conversion unit. The variation directions of the two components are compared by a variation direction comparison unit, and the variation direction detected by the variation amount detection unit and the variation direction compared by the variation direction comparison unit are obtained based on the result of the photoelectric conversion unit. An image information reading method comprising correcting image information of a document.