WO2015140935A1

WO2015140935A1 - Overhead-type image reading apparatus, image processing method, and program

Info

Publication number: WO2015140935A1
Application number: PCT/JP2014/057400
Authority: WO
Inventors: 夕貴松田; 貴彦深澤; 健李
Original assignee: 株式会社Pfu
Priority date: 2014-03-18
Filing date: 2014-03-18
Publication date: 2015-09-24
Also published as: JPWO2015140935A1; JP6159017B2

Abstract

The present invention acquires: a read image that is provided by having an image reading unit read a medium; and pattern images having changed luminances by having the image reading unit read the medium irradiated with light with changed irradiation positions, said light being radiated from a light source unit. On the basis of the different pattern images, three-dimensional information of the medium is acquired, and on the basis of the three-dimensional information, distortion of the read image is corrected.

Description

Overhead image reading apparatus, image processing method, and program

The present invention relates to an overhead image reading apparatus, an image processing method, and a program.

Conventionally, techniques for supplementing the three-dimensional shape of paper have been disclosed.

Here, the light layers are compared to form a series of stripes across the document being imaged, with the relative spread between adjacent light layers changing in the lateral direction along the light layer, and the spreads compared. An imaging system is disclosed in which stripes are concentrated and projected onto a small area to capture a document image and an image of a light stripe projected onto the document (see Patent Document 1).

In addition, using a high-speed 3D deformation estimation method that introduces the concept of developable surface and an evaluation function for recognizing an optimal shape that introduces local resolution, the paper surface deformation obtained in real time by high-speed 3D sensing A book reading system that adaptively captures a high-definition image only at a timing that is optimal for digitizing a book is disclosed (see Patent Document 2).

Special table 2003-504947 gazette JP 2012-253721 A

However, the conventional imaging system (Patent Document 1 or the like) has a problem in that it cannot be guaranteed that the original state is constant while the light beam is concentrated in a region where distortion is large.

Further, the conventional imaging system (Patent Document 2 and the like) has a problem that it cannot be determined whether a high-resolution three-dimensional shape can be applied to distortion correction.

The present invention has been made in view of the above problems, and is an overhead image reading apparatus capable of acquiring three-dimensional solid information of a document and correcting three-dimensional distortion based on the acquired three-dimensional solid information. An object is to provide an image processing method and a program.

In order to achieve such an object, the overhead image reading apparatus according to the present invention includes a read image in which a medium is read by an image reading unit, and light that has been irradiated from a light source unit with light whose irradiation position is changed. 3D information acquisition for acquiring 3D information of the medium based on a plurality of different pattern images and an image acquisition means for acquiring a pattern image whose brightness is changed by reading the medium by the image reading unit Means, and distortion correction means for correcting distortion of the read image based on the three-dimensional information.

In addition, the image processing method according to the present invention is executed by the overhead image reading apparatus, and the read image obtained by reading the medium by the image reading unit and the light whose irradiation position is changed are irradiated from the light source unit. An image acquisition step of reading the medium by the image reading unit and acquiring a pattern image with changed brightness, and three-dimensional information of acquiring three-dimensional information of the medium based on a plurality of different pattern images An acquisition step, and a distortion correction step of correcting distortion of the read image based on the three-dimensional information.

In addition, the program according to the present invention is a program for causing an overhead image reading apparatus to execute a read image obtained by reading a medium with an image reading unit, and light emitted from a light source unit with light whose irradiation position has been changed. An image acquisition step of acquiring a pattern image in which the medium is read by the image reading unit and changing the brightness, and three-dimensional information acquisition of acquiring three-dimensional information of the medium based on a plurality of different pattern images And a distortion correction step of correcting distortion of the read image based on the three-dimensional information.

According to the present invention, even a manuscript medium having three-dimensional distortion can be corrected to an image having no distortion when it is a developable surface.

FIG. 1 is a side view showing an example of a schematic configuration of an overhead image reading apparatus. FIG. 2 is a front view illustrating an example of a schematic configuration of the overhead image reading apparatus. FIG. 3 is a side view showing an example of the configuration of the overhead image reading apparatus. FIG. 4 is a functional block diagram illustrating an example of the configuration of the overhead image reading apparatus. FIG. 5 is a flowchart showing an example of processing in the overhead image reading apparatus of the present embodiment. FIG. 6 is a diagram illustrating an example of line light irradiation on a medium according to the present embodiment. FIG. 7 is a diagram illustrating an example of line light irradiation on a medium according to the present embodiment. FIG. 8 is a diagram illustrating an example of line light irradiation on the medium according to the present embodiment. FIG. 9 is a diagram illustrating an example of line light irradiation on a medium according to the present embodiment. FIG. 10 is a flowchart illustrating an example of the image and depth information validity determination processing in the present embodiment. FIG. 11 is a diagram illustrating an example of edge detection processing in the present embodiment. FIG. 12 is a flowchart illustrating an example of the three-dimensional shape restoration process in the present embodiment. FIG. 13 is a flowchart illustrating an example of the distortion correction process in the present embodiment. FIG. 14 is a flowchart illustrating an example of processing in the overhead image reading apparatus of the present embodiment. FIG. 15 is a diagram illustrating an example of a pattern irradiation image in the present embodiment. FIG. 16 is a diagram illustrating an example of phase information calculation processing in the present embodiment. FIG. 17 is a diagram illustrating an example of an absolute phase calculation process in the present embodiment. FIG. 18 is a diagram illustrating an example of a three-dimensional shape restoration process in the present embodiment. FIG. 19 is a flowchart illustrating an example of distortion correction processing according to the present embodiment.

Hereinafter, embodiments of an overhead image reading apparatus, an image processing method, and a program according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In particular, in the present embodiment, the medium to be read may be a binding medium such as a book, a medium bound with staples, a newspaper, cloth, original paper, or a print.

[1. Configuration of this embodiment]
An example of the configuration of the overhead image reading apparatus 100 according to the present embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a side view illustrating an example of a schematic configuration of the overhead image reading apparatus 100. FIG. 2 is a front view illustrating an example of a schematic configuration of the overhead image reading apparatus 100. FIG. 3 is a side view showing an example of the configuration of the overhead image reading apparatus 100. FIG. 4 is a functional block diagram illustrating an example of the configuration of the overhead image reading apparatus 100.

As shown in FIGS. 1 and 2, the overhead image reading apparatus 100 includes a light source unit 21 (line light source 21a and area light source 21b) and an image reading unit 22 (line sensor 22a and area sensor 22b). It can comprise.

As shown in FIG. 1, the image reading unit 22 scans a medium (document) such as a binding medium installed upward from above using a line light source 21 a and a line sensor 22 a (linear sensor), and scans the medium ( An original image may be read. For example, when a medium (original) is placed upward and the medium (original) is imaged from above, a one-dimensional image (line image) of a line in the main scanning direction is detected by the line sensor 22a in the main scanning direction of the medium (original). The light arriving from the line may be photoelectrically converted into an analog charge amount for each pixel on the line, and the analog charge amount output from the line sensor 22a by the A / D converter may be converted into a digital signal and output. . When the line sensor 22a is rotated in a predetermined rotation direction by driving the motor, the reading line of the line sensor 22a is accordingly moved in a predetermined sub-scanning direction (for example, a direction from the back side to the near side in the depth direction, etc. ) These are combined to generate a two-dimensional image.

Further, as shown in FIG. 2, the image reading unit 22 scans a medium (original) placed upward by scanning from above using an area light source 21b and an area sensor 22b to read an image on the medium (original). May be. For example, when the medium (original) is placed upward and the medium (original) is imaged from above, the read image (two-dimensional image) of the medium (original) is scanned by the area sensor 22b on the original plane (main scanning direction and sub-scanning). Even if the light reaching from the two-dimensional plane in the direction is photoelectrically converted into an analog charge amount for each pixel and the analog charge amount output from the area sensor 22b by the A / D converter is converted into a digital signal, the light is output. Good.

Next, as shown in FIG. 3, the overhead image reading apparatus 100 (overhead scanner) has at least a main body 10, an optical unit 20, and an area sensor 22b. The overhead image reading apparatus 100 can read an image of a medium (reading medium) S placed on the placing surface 2 below the optical unit 20 in the vertical direction. The area sensor 22b can read a read image (two-dimensional image) of the medium S placed on the placement surface 2. The placement surface 2 is a flat surface such as an upper surface of a desk, for example.

In the overhead image reading apparatus 100 of the present embodiment, the optical unit 20 rotates in a pendulum shape around the rotation axis X. Further, the line sensor 22a is disposed on the outer side in the radial direction of the rotation axis X in the optical unit 20, and images the medium S while rotating around the rotation axis X on the circumference centering on the rotation axis X. Accordingly, as described below, a change in the distance between the line sensor 22a and the reading target position on the medium S while the medium S is scanned is suppressed. Therefore, according to the overhead image reading apparatus 100 according to the present embodiment, it is possible to achieve both reduction in the height position of the optical unit 20 and reduction in the depth of field. In the present specification, unless otherwise specified, “radial direction” indicates a radial direction orthogonal to the rotation axis X. Further, in this specification, unless otherwise specified, “view in the axial direction” indicates a view in the axial direction of the rotation axis X.

In this embodiment, a case where the overhead image reading apparatus 100 is placed on the same surface as the placement surface 2 will be described as an example, but the present invention is not limited to this. The place where the overhead image reading apparatus 100 is placed and the placement surface 2 on which the medium S is placed may be different. As an example, the overhead image reading apparatus 100 may include a mounting table having the mounting surface 2.

The main body 10 has a pedestal part 11, an arm part 12, a support part 13 and a cover part 14. The pedestal portion 11 is placed on the placement surface 2 or the like and supports the entire main body 10, and is a base portion of the main body 10. Operation members such as a power switch and an image reading start switch of the overhead image reading apparatus 100 are disposed on the pedestal 11, for example. The pedestal portion 11 has, for example, a flat shape, and is installed such that the lower surface thereof faces the mounting surface 2. A leg portion 11 b is disposed on the lower surface of the pedestal portion 11. The leg portions 11 b are arranged at the four corners of the lower surface of the pedestal portion 11 and support the pedestal portion 11.

The pedestal portion 11 of this embodiment has a flat rectangular parallelepiped shape or a similar or similar shape, and has a length in the width direction (main scanning direction to be described later) and a length in the depth direction (sub-scanning direction to be described later). The length in the vertical direction is smaller than any of the above. Moreover, the length of the width direction in the base part 11 may be made larger than the length of the depth direction.

The medium S is placed so that one side of the medium S abuts against the front surface 11a which is one of the four surfaces on the side of the pedestal 11. For example, the medium S is placed so as to abut against the two leg portions 11b arranged on the front surface 11a side. That is, the medium S is placed on the placement surface 2 so that one side is parallel to the front surface 11a. In this embodiment, a direction parallel to one side of the front surface 11a of the medium S when the rectangular medium S is placed so as to abut one side of the front surface 11a is referred to as a “width direction” or a “main scanning direction”. Describe. In addition, a direction parallel to a side orthogonal to one side of the front surface 11a side of the medium S is referred to as a “depth direction” or a “sub-scanning direction”. That is, the depth direction is a direction in which the user and the overhead image reading apparatus 100 face each other when the user is facing the overhead image reading apparatus 100 with the medium S interposed therebetween. In the depth direction, the direction from the back surface 11c to the front surface 11a is described as front, and the direction from the front surface 11a to the back surface 11c is described as rear. In addition, the back surface 11c is a surface which mutually opposes the front surface 11a in the depth direction among four surfaces of the side of the base part 11. FIG.

The arm portion 12 is connected to the pedestal portion 11 and extends upward from the pedestal portion 11 in the vertical direction. For example, the arm portion 12 is formed in a columnar shape or a chimney shape having a rectangular cross section. The lower part of the arm part 12 is formed in a tapered shape whose cross-sectional area increases as it goes downward in the vertical direction. More specifically, the length in the width direction of the lower portion of the arm portion 12 is increased toward the lower side in the vertical direction. The arm portion 12 is connected to one side of the upper surface of the pedestal portion 11. Specifically, the arm portion 12 is connected to one side of the four sides forming the edge of the upper surface of the pedestal portion 11 that is opposite to the side where the medium S is disposed. In other words, the arm portion 12 is connected to the end portion on the back surface 11 c side that is far from the medium S in the pedestal portion 11. The arm portion 12 is connected to the central portion in the width direction of the pedestal portion 11.

A support portion 13 is connected to an end portion of the arm portion 12 in the vertical direction. The support portion 13 protrudes forward from the upper end of the arm portion 12 in the sub-scanning direction. Moreover, the support part 13 protrudes from the upper end of the arm part 12 to the both sides of the width direction. That is, the support portion 13 protrudes from the arm portion 12 to the placement side on which the medium S is placed, and extends from the arm portion 12 to both sides in the width direction.

The pedestal 11 and the support 13 are opposed to each other in the vertical direction, and the ends opposite to the medium S side in the depth direction are connected via the arm 12. Further, the support portion 13 protrudes forward in the depth direction from the pedestal portion 11. That is, the front end of the support portion 13 is located in front of the front end of the pedestal portion 11. Therefore, at least a part of the support part 13 faces the medium S in the vertical direction when the medium S is placed on the placement surface 2 so as to abut against the pedestal part 11.

The cover unit 14 is provided on the rotation axis X of the optical unit 20 and covers the support unit 13 and the optical unit 20. The cover part 14 covers the support part 13 and the optical unit 20 from above in the vertical direction, and forms an outer shell of the upper part of the main body including the support part 13 and the optical unit 20. Note that the cover portion 14 may be formed integrally with the support portion 13. That is, the optical unit 20 may be supported by the cover portion 14 so as to be rotatable around the rotation axis X.

The optical unit 20 is a rotation unit that can rotate around the rotation axis X with respect to the main body 10. The rotation axis X extends horizontally in the width direction, that is, the direction parallel to the front surface 11a. That is, the rotation axis X is orthogonal to the vertical axis V. The vertical axis V coincides with the normal line of the placement surface 2. The optical unit 20 includes a line light source 21a, a line sensor 22a, a main body 23, and a shaft portion 24. The shaft portion 24 has a cylindrical shape, and is supported rotatably around the rotation axis X by the support portion 13 via a bearing or the like. Since the shaft portion 24 is supported by the support portion 13, the rotation axis X is at a position protruding from the upper end in the vertical direction of the arm portion 12 to the mounting side with respect to the pedestal portion 11. The main body 23 is connected to the shaft portion 24 and extends from the shaft portion 24 outward in the radial direction of the rotation axis X. The main body 23 is, for example, a hollow member having a rectangular cross-sectional shape when viewed in the axial direction. The line light source 21 a and the line sensor 22 a are disposed in the main body 23.

The drive unit (not shown) is disposed on the support unit 13. The drive unit rotates the optical unit 20 around the rotation axis X. The drive unit includes, for example, an electric motor, and a transmission unit that connects the rotation shaft of the motor and the optical unit 20. The motor is, for example, a stepping motor, and can accurately control the rotation angle of the optical unit 20. Further, the transmission unit includes, for example, a combination of a pulley, a belt, a worm gear, and the like, and reduces the rotation of the motor and transmits it to the optical unit 20.

The line light source 21a has a light emitting unit such as an LED, and can irradiate the medium S with light from above in the vertical direction.

The line sensor 22a is an image sensor having a CCD (Charge Coupled Device), for example, and can image the medium S placed on the placement surface 2. Specifically, the line sensor 22a converts the reflected light reflected by the read image on the read target line L and incident on the line sensor 22a into electronic data by photoelectric conversion, and generates image data of the read image. The line sensor 22 a has a reading lens and a CCD 27. The CCD 27 is an image sensor in which a plurality of pixels for reading an image are arranged in the main scanning direction. The CCD 27 is disposed in the optical unit 20 with the main scanning direction being parallel to the rotation axis X. The reading lens forms an image of the reflected light from the medium S on the light receiving surface 27 a of the CCD 27. Each pixel of the CCD 27 receives the light of the read image formed on the light receiving surface 27a by the reading lens, and outputs an electrical signal corresponding to the received light. The CCD 27 can read an image on the reading target line L of the medium S and generate line image data in the main scanning direction. The number of lines of the CCD 27 may be singular or plural.

The line light source 21a irradiates the image on the reading target line L on the medium S, that is, the read image with light.

In the overhead image reading apparatus 100 of the present embodiment, the line sensor 22a rotates together with the optical unit 20, and scans and images the medium S while rotating around the rotation axis X about the rotation axis X. Thereby, the fluctuation | variation of the optical path length with the line sensor 22a and the reading object line L which is a reading object position is suppressed.

FIG. 3 shows the optical unit 20 in the rotational position when imaging the rearmost side in the readable range. Hereinafter, this rotational position of the optical unit 20 is also referred to as a “last reading position”. The optical unit 20 at the rearmost reading position can read one side of the medium S abutted against the front end of the pedestal 11. The rearmost reading position is a rotational position of the optical unit 20 at the start of image reading.

In the last reading position, the main body 23 of the optical unit 20 is located behind the shaft portion 24. The optical unit 20 at the rearmost reading position extends in a substantially horizontal direction from the rotation axis X. Specifically, the optical unit 20 is slightly inclined so as to be directed downward in the vertical direction as the distance from the rotation axis X increases in the radial direction. Yes. That is, the main body 23 is inclined so that the radially outer portion is positioned rearward in the sub-scanning direction and vertically below the inner portion. The last reading position is also a standby position when the image is not read. That is, when the image is not read, the optical unit 20 is placed at the last reading position and waits until an image reading start command is issued. Note that the standby position may be a position different from the last reading position. For example, the standby position may be a position where the main body 23 is vertically above the last reading position, in other words, a position rotated to a direction opposite to the arrow Y1 direction from the last reading position.

As shown in FIG. 3, the line light source 21a and the line sensor 22a when the optical unit 20 is at a position where the reading of the medium S starts are opposed to the placement surface 2 in the respective optical axis directions. In other words, the line light source 21a and the line sensor 22a in the state of being in the rearmost reading position are in a state in which light can be irradiated on the mounting surface 2 and an image on the mounting surface 2 can be read. As shown in FIG. 3, neither the optical axis A1 of the line light source 21a nor the optical axis A2 of the line sensor 22a intersects the rotation axis X, and is separated from the rotation axis X when viewed in the axial direction. The optical axes A1 and A2 when the optical unit 20 is in the rearmost reading position have an inclination that goes forward as it goes downward in the vertical direction. When viewed in the axial direction, the optical axes A1 and A2 intersect a virtual line W extending from the rotation axis X through the light receiving surface 27a to the outside in the radial direction. In the present embodiment, the optical axes A1 and A2 are orthogonal to the virtual line W. Further, when viewed in the axial direction, the line light source 21a and the line sensor 22a are arranged on the same virtual line extending from the rotation axis X in the radial direction, for example, on the virtual line W. The line light source 21a and the line sensor 22a may be disposed on a common virtual line extending in a different radial direction from the virtual line W passing through the light receiving surface 27a.

When the reading of the medium S is started from the last reading position, the driving unit rotates the optical unit 20 in the arrow Y1 direction. In other words, the drive unit rotates the optical unit 20 so that the main body 23 of the optical unit 20 moves downward in the vertical direction and moves forward. As a result, the position to be read by the line sensor 22a moves forward, and the medium S can be read sequentially from the rear to the front. By the rotation of the optical unit 20, the line sensor 22a moves downward in the vertical direction, whereby the vertical distance between the line sensor 22a and the reading target line L, that is, the vertical component of the optical path length is reduced. On the other hand, the rotation angle of the optical axis A2 of the line sensor 22a with respect to the vertical axis V increases due to the rotation of the optical unit 20, and the distance between the line sensor 22a and the line L to be read in the sub-scanning direction, that is, the optical path length sub-scanning. The direction component increases. As described above, as the optical unit 20 rotates, the vertical component of the optical path length decreases and the sub-scanning direction component increases, so that fluctuations in the optical path length while scanning the medium S are suppressed.

Furthermore, as shown in FIG. 4, the overhead image reading apparatus 100 may be roughly configured to include at least a light source unit 21, an image reading unit 22, and a control unit 102. Here, the light source unit 21 may include a line light source 21a and / or an area light source 21b. Further, the light source unit 21 may irradiate the medium with the pattern light whose phase is changed by changing the irradiation position. The light source unit 21 may further irradiate the medium with uniform light. That is, the light source unit 21 (for example, the area light source 21b) may have a function of irradiating a uniform light source during normal reading and a function of irradiating pattern light for restoring the three-dimensional shape. The light source unit 21 (for example, the line light source 21a) is a laser light source or the like, and may emit laser light as line light.

Further, the image reading unit 22 may include a line sensor 22a and / or an area sensor 22b. The overhead image reading apparatus 100 may further include a storage unit 106 (not shown) and an input / output unit 112 (not shown). Here, these units are communicably connected via an arbitrary communication path.

Further, the overhead image reading apparatus 100 may further include an input / output interface unit (not shown), and the light source unit 21 and the image reading unit 22 may be connected to the control unit 102. Here, the input / output interface unit may connect the input / output unit 112 to the control unit 102. The overhead image reading apparatus 100 may further include a communication interface unit (not shown), and communicates with an external device (for example, a PC) via the communication interface unit via a network. It may be connected as possible. The communication interface unit is an interface connected to a communication device such as an antenna and / or a router connected to a communication line and / or a telephone line, etc., and functions to control communication between the overhead image reading device 100 and the network. You may have.

Here, the storage unit 106 stores various databases, tables, and / or files. The storage unit 106 is a storage unit, and for example, a memory such as a RAM / ROM, a fixed disk device such as a hard disk, a flexible disk, and / or an optical disk can be used. The storage unit 106 may store a computer program or the like for giving a command to a CPU (Central Processing Unit) and performing various processes. Here, the storage unit 106 may store an image or the like.

Also, the input / output unit 112 performs data input / output (I / O). Here, the input / output unit 112 may be, for example, a key input unit, a touch panel, a control pad (for example, a touch pad and a game pad), a mouse, a keyboard, and a microphone. The input / output unit 112 may be a display unit that displays a display screen of an application or the like (for example, a display, a monitor, a touch panel, or the like including a liquid crystal or an organic EL). The input / output unit 112 may be an audio output unit (for example, a speaker) that outputs audio information as audio.

The control unit 102 includes a CPU that controls the overhead image reading apparatus 100 in an integrated manner. The control unit 102 has an internal memory for storing a control program, a program defining various processing procedures, and necessary data, and performs information processing for executing various processes based on these programs. Also good. Here, an example of the configuration of the control unit 102 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 4, the control unit 102 is roughly configured to include at least an image control unit 102a, a front / rear determination unit 102e, a three-dimensional information acquisition unit 102f, and a distortion correction unit 102g. Further, these units are communicably connected via an arbitrary communication path.

The image control unit 102a performs synchronization control between the light source unit 21 and the image reading unit 22, and / or controls image processing. That is, the image control unit 102a may acquire an image by controlling the image reading unit 22. For example, the image control unit 102a controls the image reading unit 22 to rotate and drive the motor, and synthesizes a one-dimensional image for each line that is photoelectrically converted by the line sensor 22a and analog-digital converted by the A / D converter. Thus, the process of acquiring a two-dimensional image and storing it in the storage unit 106 may be controlled.

In addition, for example, the image control unit 102a controls the image reading unit 22, acquires an image photoelectrically converted by the area sensor 22b and analog-digital converted by the A / D converter, and stores the image in the storage unit 106. You may control. That is, the image control unit 102a may have a function of acquiring a continuous image (moving image) by performing motion shooting with the area sensor 22b. Here, the image control unit 102a includes an image acquisition unit 102b, an alarm notification unit 102c, and a crop unit 102d in terms of functional concept.

The image acquisition unit 102b causes the image reading unit 22 to read the medium and acquires an image. Here, the image acquisition unit 102b causes the image reading unit 22 to read the read image obtained by reading the medium by the image reading unit 22 and the medium irradiated from the light source unit 21 by changing the irradiation position. A pattern image with varying brightness is acquired. Here, the pattern image may be obtained by changing the phase pattern of brightness. For example, the pattern image may be an image in which the phase pattern of brightness is changed based on a sine wave. The read image may be an image obtained by reading the entire medium.

Further, the image acquisition unit 102b causes the image reading unit 22 to read the read image obtained by reading the medium with the image reading unit 22 and the medium irradiated with the pattern light from the light source unit 21, and the phase pattern of brightness. A pattern image obtained by changing the pattern may be acquired. Further, the image acquisition unit 102b may cause the image reading unit 22 to read the medium before and after acquiring the pattern image, and acquire the two read images as a front image and a back image. The image acquisition unit 102b may acquire a read image obtained by causing the image reading unit 22 to read a medium irradiated with uniform light from the light source unit 21. The image acquisition unit 102b may store an image or the like in the storage unit 106.

The alarm notification unit 102c notifies an alarm for prompting image reading again when the front / rear determination unit 102e determines that there is a position change.

The crop unit 102d performs a crop process on the medium image in the read image.

The front-rear determination unit 102e determines a change in position between the medium image in the previous image and the medium image in the rear image. Here, the back-and-forth determination unit 102e may determine the position change based on the edge coordinates of the medium image in the previous image and the edge coordinates of the medium image in the subsequent image.

Further, the front / rear determination unit 102e may determine the position change based on the number of coordinates indicating a difference between the edge coordinates of the medium image in the previous image and the edge coordinates of the medium image in the subsequent image. The front-rear determination unit 102e functions as a depth information validity determination unit that determines the validity of the depth information using images acquired before and after the medium depth information reading process (the front image and the rear image). May be.

The three-dimensional information acquisition unit 102f acquires three-dimensional information on the medium based on a plurality of different pattern images. Here, the three-dimensional information acquisition unit 102f may acquire the three-dimensional information of the medium based on a plurality of different pattern images when the front-rear determination unit 102e determines that there is no position change. The three-dimensional information acquisition unit 102f may function as a depth information calculation unit that calculates the depth information of the medium.

The distortion correction unit 102g corrects the distortion of the read image based on the three-dimensional information. Here, the distortion correction unit 102g may correct the distortion of the read image by flattening the three-dimensional shape of the medium based on the three-dimensional information and mapping the color information using the read image. . Further, the distortion correction unit 102g flattens the three-dimensional shape of the medium based on the three-dimensional information, and corrects the distortion of the read image by mapping the color information using the previous image and / or the subsequent image. May be. The distortion correction unit 102g may correct the distortion of the medium image based on the three-dimensional information.

Further, the distortion correction unit 102g may correct the distortion of the image and obtain a corrected image. Here, the distortion correction unit 102g may correct the distortion of the image by performing projective transformation (for example, projective transformation as if taken from the front direction). Further, the correction may be geometric correction. The distortion correction unit 102g may store the corrected image in the storage unit 106.

Note that the control unit 102 may output the image via the input / output unit 112. Here, the control unit 102 may cause the input / output unit 112 to display an image (for example, a read image, a pattern image, a previous image, a subsequent image, a medium image, or a corrected image). The control unit 102 may cause the input / output unit 112 to display an image read by the image reading unit 22.

Note that the overhead image reading apparatus 100 according to the present embodiment may further include a loading platform for a medium (for example, a binding medium). Further, the image reading unit 22 may be arranged on the upper part of the loading table and may image the loading table. Further, the control unit 102 may control the image reading unit 22.

[2. Processing of this embodiment]
An example of processing executed by the overhead image reading apparatus 100 having the above-described configuration will be described with reference to FIGS.

[2-1. Processing (1)]
An example of processing in the overhead image reading apparatus 100 of the present embodiment will be described with reference to FIGS. FIG. 5 is a flowchart illustrating an example of processing in the overhead image reading apparatus 100 of the present embodiment.

As shown in FIG. 5, first, the image acquisition unit 102b causes the area sensor 22b to read (capture) the medium irradiated with uniform light by the area light source 21b before acquiring the pattern image. A read image (previous image) that has been read is acquired (step SA-1).

Then, the image control unit 102a controls the line light source 21a and the image reading unit 22, and the line sensor 22a and the area sensor 22b read the medium irradiated with light from the line light source 21a with the irradiation position changed ( Scan) is started (step SA-2).

Then, the image acquisition unit 102b causes the area sensor 22b to read the medium, and acquires a pattern image (depth information image) in which the brightness on the medium is changed (step SA-3).

At the same time, the image acquisition unit 102b causes the line sensor 22a to read the medium, and acquires a read image (mapping image) obtained by reading the entire medium (step SA-4).

Here, an example of image acquisition in the present embodiment will be described with reference to FIGS. 6 to 9 are diagrams illustrating an example of line light irradiation on a medium according to the present embodiment.

As shown in FIG. 6, the image acquisition unit 102b has a boundary (in the drawing) between a position on the medium irradiated with the line light from the line light source 21a (line light irradiation position) and a position on the medium not irradiated. A medium region including a dotted line) (a region that changes in brightness on the medium) is read by the area sensor 22b, and an area image for acquiring a three-dimensional shape of the medium is acquired.

Then, as shown in FIG. 7, the image acquisition unit 102b continuously displays areas that change in brightness on the medium while the irradiation position of the line light emitted from the line light source 21a changes on the medium. To obtain an area image for acquiring the three-dimensional shape of the medium. As described above, in the present embodiment, the three-dimensional shape restoration process can be started first by using the area image of the portion where the contrast changes from the normal reading position.

Further, in the present embodiment, as shown in FIG. 8, the line light source 21a may irradiate while moving the laser beam on the medium. Then, as shown in FIG. 8, the area sensor 22b reads the medium area including the boundary between the position on the medium irradiated with the laser light and the position on the medium not irradiated, and the medium as shown in FIG. You may acquire the area image for acquiring the whole height information. Thus, in this embodiment, a dense three-dimensional shape can be acquired by using an image in which line light is moved.

On the other hand, as shown in FIG. 6, the image acquisition unit 102b causes the line sensor 22a to read the position on the medium irradiated with the line light from the line light source 21a (solid line in the figure: normal reading position). Get a line image. Then, as shown in FIG. 7, the image acquisition unit 102b causes the line sensor 22a to continuously read the normal reading position while the irradiation position of the line light irradiated from the line light source 21a changes on the medium. Then, a read image (two-dimensional image) obtained by reading the entire medium is acquired.

Returning to FIG. 5, the image acquisition unit 102 b causes the area sensor 22 b to read (capture) the medium irradiated with uniform light by the area light source 21 b after acquiring the pattern image, and read the entire medium. (After image) is acquired (step SA-5).

Then, the front / rear determination unit 102e determines whether the image and the depth information are valid (step SA-6). That is, the front / rear determination unit 102e determines whether the mapping image and the depth information image are valid for use in the distortion correction process. For example, the front / rear determination unit 102e may determine whether an image suitable for distortion correction and a high-resolution three-dimensional shape can be acquired.

Here, with reference to FIG. 10, an example of the validity determination process of the image and depth information in the present embodiment will be described. FIG. 10 is a flowchart illustrating an example of the image and depth information validity determination processing in the present embodiment.

First, following the processing in step SA-5, the front-rear determination unit 102e detects the edge coordinates (pixels) of the medium in the previous image acquired by the image acquisition unit 102b (step SB-1).

Here, an example of edge detection processing in the present embodiment will be described with reference to FIG. FIG. 11 is a diagram illustrating an example of edge detection processing in the present embodiment.

As shown in FIG. 11, in the present embodiment, based on the luminance information of the read image, coordinates (pixels) that change a predetermined (for example, large) luminance from the outer edge of the read image are detected, so that Edge coordinates (pixels) may be detected. For example, in this embodiment, edge coordinates (pixels) of a medium such as a book may be detected by detecting a group of coordinates that change linearly from the outer edge of the read image.

Returning to FIG. 10, the front-rear determination unit 102e detects the edge coordinates (pixels) of the medium in the post-image acquired by the image acquisition unit 102b (step SB-2).

Then, the front / rear determination unit 102e counts different points (coordinates) between the detected edge coordinates in the previous image and the detected edge coordinates (step SB-3).

Then, the front / rear determination unit 102e determines whether the counted different points (coordinates) are equal to or less than a certain number (step SB-4).

Then, when the front / rear determination unit 102e determines that the counted different points (coordinates) are equal to or less than a certain number (step SB-4: Yes), the subject medium is not moving, that is, the image and depth information It is determined (determined) that it is valid (step SB-5), and the process proceeds to step SA-8. That is, the front / rear determination unit 102e determines the validity using the two-dimensional images before and after acquiring a high-resolution three-dimensional shape.

On the other hand, if the forward / backward determination unit 102e determines that the counted different points (coordinates) are not equal to or less than a certain number (step SB-4: No), the subject medium has moved, that is, the image and depth information are valid. It is determined (determined) that there is no property (step SB-6), and the process proceeds to step SA-7.

As described above, in this embodiment, by using the difference information based on the edge detection of the images before and after the depth information image reading process for the determination, it is possible to detect the movement of the subject without adding hardware. That is, in the present embodiment, it is not necessary to add hardware by determining the movement detection of the subject by image processing. In this embodiment, by using edge information as difference information, the edge detection result can be used for distortion correction processing, and the overall processing time can be reduced.

Returning to FIG. 5, when the front-rear determination unit 102e determines that the image and depth information are not valid (inappropriate) (step SA-6: No), the alarm notification unit 102c prompts the user to read the image again. Alarm is notified (step SA-7), and the process proceeds to step SA-1.

On the other hand, when the three-dimensional information acquisition unit 102f determines that the image and depth information are valid (appropriate) by the front / rear determination unit 102e (step SA-6: Yes), based on a plurality of different pattern images, Obtain (generate) three-dimensional information (depth information) of the medium (step SA-8).

Here, an example of the three-dimensional shape restoration process in the present embodiment will be described with reference to FIG. FIG. 12 is a flowchart illustrating an example of the three-dimensional shape restoration process in the present embodiment.

As shown in FIG. 12, the three-dimensional information acquisition unit 102f performs a three-dimensional shape restoration process on the medium based on a plurality of different pattern images (step SC-1).

Then, the crop unit 102d performs a crop process on the medium image in the read image (step SC-2), and ends the process.

Referring back to FIG. 5, the distortion correction unit 102g corrects the distortion of the medium image based on the three-dimensional information (Step SA-9), and ends the process. That is, in the present embodiment, there is provided a technique for acquiring a paper float or a three-dimensional crease as a three-dimensional shape and using the data to correct the image without distortion.

Here, an example of the distortion correction processing in the present embodiment will be described with reference to FIG. FIG. 13 is a flowchart illustrating an example of the distortion correction process in the present embodiment.

As shown in FIG. 13, the distortion correction unit 102g flattens the distortion shape of the medium based on the three-dimensional information (step SD-1).

Then, the distortion correction unit 102g corrects the distortion of the medium by mapping the color information using the two-dimensional image (mapping image) read by the line sensor 22a (step SD-2), and ends the processing. To do.

As described above, in the present embodiment, functions for image reading and three-dimensional shape measurement (depth information detection) (that is, acquisition of an image for depth information and an image for mapping) are the same light source (that is, only the line light source 21a). ), A simple device configuration can be realized. In the present embodiment, an image reading apparatus capable of correcting steep distortion can be realized by the above processing. In other words, in the present embodiment, it is possible to deal with steep distortion of a medium (original) by obtaining depth information with high resolution.

In this embodiment, it is possible to prevent an unnatural correction result from being determined by determining whether an image suitable for correction and depth information can be acquired. Further, in the present embodiment, it is possible to realize the motion detection by image processing without adding hardware. In the present embodiment, the validity information of the depth information can also be used for the crop processing by using the difference information of the document edges of the preceding and following images. In the present embodiment, an unintended correction result can be prevented by notifying the user of an alarm.

[2-2. Processing (2)]
An example of processing in the overhead image reading apparatus 100 of the present embodiment will be described with reference to FIGS. FIG. 14 is a flowchart illustrating an example of processing in the overhead image reading apparatus 100 of the present embodiment.

As shown in FIG. 14, first, the image control unit 102a controls the area light source 21b (uniform light source) that emits uniform light to turn on the area light source 21b (uniform light source) (step SE-1).

Then, before acquiring the pattern image, the image acquisition unit 102b causes the area sensor 22b to read the medium irradiated with uniform light by the area light source 21b, and acquires a read image (previous image) that has read the entire medium. (Step SE-2).

Then, the image control unit 102a controls the area light source 21b (uniform light source) to turn off the area light source 21b (uniform light source) (step SE-3).

Then, the image control unit 102a controls the area light source 21b, changes the irradiation position, and irradiates the area light source 21b with the pattern light whose phase has been changed (step SE-4).

Then, the image acquisition unit 102b causes the area sensor 22b to read the medium irradiated with the pattern light whose phase has been changed from the area light source 21b, and acquires a pattern image in which the brightness phase pattern has been changed (step SE). -5).

Then, the control unit 102 determines whether or not the medium reading with the designated number of irradiation positions changed is completed (completed) (step SE-6).

Then, when the control unit 102 determines that the medium reading after changing the irradiation position for the designated number of times is not completed (completed) (step SE-6: No), the process proceeds to step SE-4.

On the other hand, when it is determined by the control unit 102 that the medium reading with the designated number of irradiation positions changed is completed (completed) (step SE-6: Yes), the image control unit 102a is configured to irradiate uniform light. The light source 21b (uniform light source) is controlled to turn on the area light source 21b (uniform light source) (step SE-7).

Here, with reference to FIG. 15, an example of the pattern irradiation image in the present embodiment will be described. FIG. 15 is a diagram illustrating an example of a pattern irradiation image in the present embodiment.

As shown in FIG. 15, the image acquisition unit 102 b causes the area sensor 22 b to read the medium irradiated with the pattern light whose phase has been changed from the area light source 21 b, and the pattern image ( A plurality (for example, three or more) of pattern irradiation images may be acquired.

Returning to FIG. 14, after acquiring the pattern image, the image acquisition unit 102 b causes the area sensor 22 b to read the medium irradiated with uniform light by the area light source 21 b and read the entire medium (post-image). Is acquired (step SE-8).

The image control unit 102a controls the area light source 21b (uniform light source) to turn off the area light source 21b (uniform light source) (step SE-9).

Then, the front / rear determination unit 102e determines whether the image and the depth information are valid (step SE-10).

Then, when the alarm notification unit 102c determines that the image and depth information are not valid (detection of the movement of the medium) by the front / rear determination unit 102e (step SE-10: No), the user is again prompted to read the image. An alarm for prompting is notified (step SE-11), and the process proceeds to step SE-1.

On the other hand, when the three-dimensional information acquisition unit 102f determines that the image and depth information are valid (the subject is not moving) by the back-and-forth determination unit 102e (step SE-10: Yes), a plurality of different pattern images Based on the above, the three-dimensional information of the medium is acquired (the three-dimensional shape of the medium is restored) (step SE-12).

Here, an example of the three-dimensional shape restoration processing in the present embodiment will be described with reference to FIGS. FIG. 16 is a diagram illustrating an example of phase information calculation processing in the present embodiment. FIG. 17 is a diagram illustrating an example of an absolute phase calculation process in the present embodiment. FIG. 18 is a diagram illustrating an example of a three-dimensional shape restoration process in the present embodiment.

As illustrated in FIG. 16, the three-dimensional information acquisition unit 102 f may calculate the phase information of the medium using Equation 1 below based on a plurality of pattern irradiation images as illustrated in FIG. 15.

And as shown in FIG. 17, the three-dimensional information acquisition part 102f may calculate the absolute phase of a medium based on the calculated phase information.

Then, as illustrated in FIG. 18, the three-dimensional information acquisition unit 102 f may perform depth estimation using the following formula 2 based on the calculated absolute phase, and perform a three-dimensional shape restoration process of the medium. As described above, in the present embodiment, even when a dense three-dimensional shape is acquired by using an image in which the phase pattern is changed, it does not take time to read an image necessary for the three-dimensional shape restoration process. I'm sorry.

14, the distortion correction unit 102g corrects the distortion of the read image (medium image) based on the three-dimensional information (step SE-13), and ends the process.

Here, with reference to FIG. 19, an example of distortion correction processing in the present embodiment will be described. FIG. 19 is a flowchart illustrating an example of distortion correction processing according to the present embodiment.

As shown in FIG. 19, the distortion correction unit 102g flattens the distortion shape of the medium based on the three-dimensional information (step SF-1).

The distortion correction unit 102g maps the color information using the two-dimensional image (the previous image and the subsequent image) read by the area sensor 22b and used for the validity determination process, thereby reading the read image (medium image). Is corrected (step SF-2), and the process is terminated.

As described above, in this embodiment, in order to perform the three-dimensional shape restoration process, the object may be imaged by irradiating the phase pattern. In the present embodiment, generally, since three or more images having a phase shift are prepared, the image reading may be performed as many times as necessary. In the present embodiment, phase pattern irradiation and image reading may be performed in synchronization.

In this embodiment, texture image reading may be performed after the number of images necessary for three-dimensional shape restoration is captured. In the present embodiment, the three-dimensional shape may be restored from the pattern irradiation image acquired for the three-dimensional shape restoration. In the present embodiment, an image obtained by correcting three-dimensional distortion using a three-dimensional shape and texture image may be acquired.

In this embodiment, since the two-dimensional image used in the three-dimensional shape restoration process is affected by pattern irradiation, color information mapping may be performed using a two-dimensional image irradiated with a uniform light source. In the present embodiment, the mapping image can also be used for specifying a medium region using the difference of the medium edge information. In the present embodiment, by using the image used in the movement detection process for mapping color information, the entire process can be performed efficiently and the corrected image may be affected by pattern irradiation. Absent.

As described above, in the present embodiment, an image distorted based on three-dimensional information is obtained by restoring an accurate three-dimensional shape using a light source that irradiates a phase pattern and an image sensor that acquires the image. Can be corrected. In this embodiment, since the conventional method of irradiating grid light cannot acquire a steep change in the medium, three-dimensional information of the entire imaging area is acquired by using pattern light whose phase has been changed. It is possible to do.

Thereby, in this embodiment, even a distortion with respect to a steep change such as a fold can be corrected. Further, in the present embodiment, when imaging by irradiating the pattern light with the phase changed a plurality of times, it is assumed that the subject is not moving, so the entire subject is photographed before and after obtaining the three-dimensional information, It may be determined that the subject is not moving by comparing the images.

In the present embodiment, the movement determination of the subject may be performed based on the edge detection coordinates of the medium. In the present embodiment, if there is no movement of the subject after the movement of the subject is determined, an image without distortion may be generated from the captured image and the stereoscopic information. On the other hand, in the present embodiment, when the movement of the subject is detected, an alarm may be notified to the user, and the acquisition of the three-dimensional information may be performed again.

As described above, the present embodiment solves the problem that occurs in the conventional overhead scanner that the image is distorted due to the influence of floating paper or three-dimensional folds. Conventionally, a method for correcting the distortion by estimating the three-dimensional shape from the contour of the medium has been proposed. However, the estimation of the three-dimensional shape is based on the assumption that the medium has a fixed pattern (fixed shape). It was. Therefore, the present embodiment solves the conventional problem that an irregularly shaped and distorted medium cannot be corrected.

Conventionally, a method for correcting a distortion by acquiring a three-dimensional shape by irradiating grid light has been proposed. However, while a gentle distortion of a medium can be corrected, Could not acquire the three-dimensional information correctly and the distortion was not corrected. Therefore, in the present embodiment, the conventional problem that the steep distortion of the medium cannot be corrected is solved.

Conventionally, as a method for acquiring a dense three-dimensional shape, a method of irradiating pattern light with a changed phase is known. However, it takes time to perform irradiation and reading by switching pattern light. If the medium moves during that time, the distortion cannot be corrected correctly. Therefore, in the present embodiment, the conventional problem that the distortion cannot be corrected correctly by combining the movement detection of the medium is solved.

[3. Other Embodiments]
Although the embodiments of the present invention have been described so far, the present invention can be implemented in various different embodiments within the scope of the technical idea described in the claims other than the above-described embodiments. It ’s good.

For example, the overhead image reading apparatus 100 may perform processing in a stand-alone form, and performs processing in response to a request from a client terminal (which is a separate housing from the overhead image reading apparatus 100). The processing result may be returned to the client terminal.

In addition, among the processes described in the embodiment, all or a part of the processes described as being automatically performed can be manually performed, or all of the processes described as being manually performed can be performed. Alternatively, a part can be automatically performed by a known method.

In addition, the processing procedure, control procedure, specific name, information including parameters such as registration data or search conditions for each processing, screen examples, or database configuration shown in the description and drawings are specially noted. It can be changed arbitrarily except for.

Further, regarding the overhead image reading apparatus 100, each illustrated component is functionally conceptual and does not necessarily need to be physically configured as illustrated.

For example, all or some of the processing functions provided in each apparatus of the overhead image reading apparatus 100, particularly the processing functions performed by the control unit 102, are performed by a CPU (Central Processing Unit) and the CPU. It may be realized by a program to be interpreted and executed as hardware by wired logic. The program is recorded on a non-transitory computer-readable recording medium including a programmed instruction for causing a computer to execute the method according to the present invention, which will be described later, and an overhead image as necessary. It is mechanically read by the reading device 100. That is, in the storage unit 106 such as a ROM or an HDD (Hard Disk Drive), a computer program for giving instructions to the CPU in cooperation with an OS (Operating System) and performing various processes is recorded. This computer program is executed by being loaded into the RAM, and constitutes a control unit in cooperation with the CPU.

The computer program may be stored in an application program server connected to the overhead image reading apparatus 100 via an arbitrary network, and may be downloaded in whole or in part as necessary. Is possible.

Further, the program according to the present invention may be stored in a computer-readable recording medium, or may be configured as a program product. Here, the “recording medium” includes a memory card, USB memory, SD card, flexible disk, magneto-optical disk, ROM, EPROM, EEPROM, CD-ROM, MO, DVD, and Blu-ray (registered trademark). It includes any “portable physical medium” such as Disc.

In addition, “program” is a data processing method described in an arbitrary language or description method, and may be in any form such as source code or binary code. Note that the “program” is not necessarily limited to a single configuration, but is distributed in the form of a plurality of modules and libraries, or in cooperation with a separate program typified by an OS (Operating System). Including those that achieve the function. In addition, a well-known structure and procedure can be used about the specific structure for reading a recording medium in each apparatus shown in embodiment, a reading procedure, or the installation procedure after reading.

Various databases and the like stored in the storage unit 106 are storage means such as a memory device such as a RAM or a ROM, a fixed disk device such as a hard disk, a flexible disk, and / or an optical disk. Various programs, tables, databases, and / or web page files used may be stored.

The overhead image reading apparatus 100 may be configured as an information processing apparatus such as a known personal computer or workstation, or may be configured by connecting an arbitrary peripheral device to the information processing apparatus. The overhead image reading apparatus 100 may be realized by installing software (including programs, data, and the like) that realizes the method of the present invention in the information processing apparatus.

Furthermore, the specific form of distribution / integration of the devices is not limited to that shown in the figure, and all or a part of them may be functional or physical in arbitrary units according to various additions or according to functional loads. Can be distributed and integrated. That is, the above-described embodiments may be arbitrarily combined and may be selectively implemented.

As described above, the overhead image reading apparatus, the image processing method, and the program according to the present invention can be implemented in many industrial fields, particularly in the image processing field that handles images read by a scanner. Useful.

DESCRIPTION OF SYMBOLS 2 Mounting surface 10 Main body 20 Optical unit 21 Light source part 21a Line light source 21b Area light source 22 Image reading part

22a Line sensor

22b Area sensor 100 Overhead type image reading apparatus 102 Control part 102a Image control part 102b Image acquisition part 102c Alarm notification part 102d Crop unit 102e Front / rear determination unit 102f Three-dimensional information acquisition unit 102g Distortion correction unit 106 Storage unit 112 Input / output unit

Claims

A read image obtained by causing the image reading unit to read the medium, and a pattern image obtained by causing the image reading unit to read the medium irradiated with the light whose irradiation position is changed from the light source unit, and changing the brightness. Image acquisition means for acquiring;
3D information acquisition means for acquiring 3D information of the medium based on a plurality of different pattern images;
Distortion correcting means for correcting distortion of the read image based on the three-dimensional information;
An overhead image reading apparatus comprising:
The light source unit is
Line light source and / or area light source,
The image reading unit
The overhead image reading apparatus according to claim 1, comprising a line sensor and / or an area sensor.
The pattern image is
The overhead image reading apparatus according to claim 1, wherein the brightness phase pattern is changed.
The light source unit is
Changing the irradiation position, irradiating the medium with a pattern light whose phase has changed,
The image acquisition means includes
The read image obtained by reading the medium by the image reading unit and the medium irradiated with the pattern light from the light source unit are read by the image reading unit, and the phase pattern of brightness is changed. The overhead image reading apparatus according to claim 1, wherein the pattern image is acquired.
The image acquisition means includes
Before and after acquisition of the pattern image, the medium is read by the image reading unit, and the two read images are acquired as a front image and a back image,
Before and after determination means for determining a change in position between the medium image in the previous image and the medium image in the subsequent image;
Further comprising
The three-dimensional information acquisition means
2. The overhead image reading apparatus according to claim 1, wherein the three-dimensional information of the medium is acquired based on a plurality of different pattern images when the front-rear determination unit determines that the position change does not occur.
An alarm notification means for notifying an alarm for prompting image reading again when it is determined by the front-rear determination means that the position change is present;
The overhead image reading apparatus according to claim 5, further comprising:
The front-rear determining means is
The overhead image reading apparatus according to claim 5, wherein the position change is determined based on an edge coordinate of the medium image in the previous image and an edge coordinate of the medium image in the subsequent image.
The front-rear determining means is
The overhead image according to claim 5, wherein the position change is determined based on a coordinate number indicating a difference between an edge coordinate of the medium image in the previous image and an edge coordinate of the medium image in the subsequent image. Reader.
The distortion correction means includes
The overhead type according to claim 1, wherein a three-dimensional shape of a medium is flattened based on the three-dimensional information, and color information is mapped using the read image to correct distortion of the read image. Image reading device.
The distortion correction means includes
The distortion of the read image is corrected by flattening a three-dimensional shape of a medium based on the three-dimensional information and mapping color information using the front image and / or the rear image. 5. An overhead image reading apparatus according to 5.
Cropping means for performing crop processing of the medium image in the read image;
Further comprising
The distortion correction means includes
The overhead image reading apparatus according to claim 1, wherein distortion of the medium image is corrected based on the three-dimensional information.
The light source unit is
Furthermore, the medium is irradiated with the uniform light,
The image acquisition means includes
The overhead image reading apparatus according to claim 1, wherein the read image obtained by causing the image reading unit to read the medium irradiated with the uniform light from the light source unit is acquired.
Executed by an overhead image reading apparatus;
A read image obtained by causing the image reading unit to read the medium, and a pattern image obtained by causing the image reading unit to read the medium irradiated with the light whose irradiation position is changed from the light source unit, and changing the brightness. An image acquisition step to acquire;
A three-dimensional information acquisition step of acquiring three-dimensional information of the medium based on a plurality of different pattern images;
A distortion correction step of correcting distortion of the read image based on the three-dimensional information;
An image processing method comprising:
To execute the overhead image reading apparatus,
A read image obtained by causing the image reading unit to read the medium, and a pattern image obtained by causing the image reading unit to read the medium irradiated with the light whose irradiation position is changed from the light source unit, and changing the brightness. An image acquisition step to acquire;
A three-dimensional information acquisition step of acquiring three-dimensional information of the medium based on a plurality of different pattern images;
A distortion correction step of correcting distortion of the read image based on the three-dimensional information;
The program characterized by including.