JP2010041300A - Photographic apparatus and photographic control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photographic apparatus and an photographic control method, which can appropriately make focusing on an original document, even when photographing the original document, from a direction other than the frontal direction, and prevent image deterioration produced when distortions of an original document image obtained by photographic the original document are corrected. <P>SOLUTION: The photographic apparatus 10 extracts an original document area A100, where an original document 100 is imaged from an image P100, obtained by photographing the original document 100 that is rectangular. The photographic apparatus 10 performs AF and AE so as to appropriately set focusing on the document area A100, and subsequently photographs the original document 100; then the photographic apparatus 10 extracts the original document area A100 from the image captured after AF, and corrects the distortions of the original document area A100 and reproduce a shape of the original document 100, as well as, corrects an orientation of the original document area A100, to produce an original document image to be outputted. A projector 200 receives an original document image 100' from the photographic apparatus 10 and projects it onto a screen 300. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image capturing apparatus and an image capturing control method, and more particularly to an image capturing apparatus, an image capturing system, and an image capturing control method for capturing an image of a document and creating an output document image.

  In Patent Document 1, the front and back surfaces of a postcard are photographed to obtain the outline of the postcard image, the front image and the back image of the postcard are cut out from the photographed image, and the image of the cut out postcard is subjected to projective transformation to correct image distortion. An image processing apparatus for correction is disclosed.

Patent Document 2 discloses an image reading apparatus that images a document by forming an image of light from the rotating mirror on a one-dimensional solid-state imaging element while controlling the rotational position of the rotating mirror according to the reading position of the document. Yes.
JP 2007-180872 A Japanese Patent Laid-Open No. 2007-82005

  In Patent Document 1, it is difficult to focus on the entire postcard when the postcard is photographed from an oblique direction. In addition, when projective conversion is performed on an image captured obliquely and distorted, the image quality of an out-of-focus portion (for example, a hollow portion) deteriorates.

  In Patent Document 2, since a one-dimensional solid-state imaging element is used, it takes time to read a document image. Patent Document 2 relates to a dedicated image reading apparatus, and the apparatus becomes large and expensive.

  The present invention has been made in view of such circumstances, and even when a document is photographed from a direction other than the front, the document can be properly focused and obtained by photographing the document. It is an object of the present invention to provide a photographing apparatus and a photographing control method capable of preventing image deterioration that occurs when a distortion of a document image is corrected.

  The photographing apparatus according to the first aspect of the present invention includes photographing means for photographing an image of a substantially rectangular document, document recognition means for recognizing a document area in which the document is shown from the document image, and the document area. A center position calculating means for calculating the center position of the camera, a focus control means for controlling the photographing means to focus on the center position, and a photographed by the photographing means after focusing by the focus control means. Document image correcting means for creating an image obtained by correcting distortion of the document area recognized by the document recognition means.

  According to the first aspect, since the focus is set at the center position of the rectangular document, the focus can be appropriately adjusted even when the document is photographed from a direction other than the front. As a result, it is possible to prevent image deterioration that occurs when distortion in the document area in which the document is captured is corrected.

  The photographing apparatus according to a second aspect of the present invention is the photographing apparatus according to the first aspect, wherein the center position calculation unit detects the positions of the four vertices of the document area and connects the four vertices. The intersection of the diagonal lines of the document area is calculated as the center position.

  The photographing apparatus according to a third aspect of the present invention is the photographing apparatus according to the first or second aspect, wherein the focus control means includes a center including the center position among a plurality of areas obtained by dividing the document area. It is configured to focus on the area.

  According to a fourth aspect of the present invention, in the first to third aspects, a photographing apparatus according to the fourth aspect of the present invention acquires a focus evaluation value when focusing on the central area, and the focusing accuracy is based on the focus evaluation value. A focus accuracy evaluation means for evaluating the focus area, and when the focus control means evaluates that the focus accuracy of the center area is low, the focus accuracy of the area in the vicinity of the center area. It is configured to focus on the area evaluated as high.

  An imaging device according to a fifth aspect of the present invention is the imaging apparatus according to the fourth aspect, in which the focusing accuracy evaluation unit evaluates the center area when the focusing accuracy of the center area is low. The focusing accuracy of the adjacent area adjacent in the horizontal direction of the image of the document is evaluated, and the focusing control unit determines that the accuracy of focusing of the adjacent area is high. It is configured to focus.

  The imaging device according to a sixth aspect of the present invention is the imaging device according to the fifth aspect, wherein the focusing accuracy evaluation unit evaluates that the accuracy of focusing is low in both the central area and the adjacent area. The near side area closer to the photographing apparatus than the central area is evaluated, and the focus control unit evaluates that the near side area is high in focus accuracy. Is configured to focus on.

  According to a seventh aspect of the present invention, there is provided a photographing device for photographing a substantially rectangular document image, a document recognizing unit for recognizing a document area in which the document is reflected from the photographed image, and the document area. The vertex detection means for detecting the positions of the four vertices of the document and the photographing means are controlled to detect the focus position when the vertex area including the four vertices of the document area is focused. Focus control means for moving the focus to the average focus position of the focus position, and an image of the original area recognized by the original recognition means from an image photographed by the photographing means after focusing by the focus control means Original image correcting means for creating an image with corrected distortion.

  According to the seventh aspect, by moving the focus position to the average focus position of the focus position of the divided area including the four vertices of the document area, the document can be displayed in a state where the distance between each vertex and the photographing device is different. Even when shooting, it is possible to properly focus.

  An imaging device according to an eighth aspect of the present invention is the imaging device according to the seventh aspect, wherein the aperture value is adjusted so that the vertex area is within the depth of field after focusing on the average focus position. Value adjustment means is further provided.

  According to the eighth aspect, by adjusting the aperture value, it is possible to appropriately focus on the divided area including the four vertices.

  An image capturing apparatus according to a ninth aspect of the present invention includes an image capturing unit that captures an image of a substantially rectangular document, a first document recognition unit that recognizes a document area in which the document is captured from the captured image, A photographing control means for controlling the photographing means to zoom into a plurality of areas obtained by dividing the original area and photographing an image of each area, and the original from the image of each area photographed by the photographing means. Detected by a second document recognizing unit for recognizing an existing document area, a document image correcting unit for creating an image in which distortion of the document area detected from the image of each area is corrected, and the second document recognizing unit And image combining means for combining the images of the respective areas whose distortion has been corrected to create an image of the entire original.

  According to the ninth aspect, it is possible to improve the focusing accuracy for a document by dividing and photographing the document area.

  The photographing apparatus according to a tenth aspect of the present invention is the photographing apparatus according to the ninth aspect, wherein the vertex detecting means for detecting the positions of the four vertices of the document area detected by the first document recognition means, Center position calculating means for calculating the center position of the document area detected by one document recognizing means, and the shooting control means sets the two vertices on the near side close to the shooting apparatus among the four vertices. Zooming is performed so that the horizontal interval between the images of the original is substantially coincident with the horizontal width of the field of view of the photographing means, and the near side area of the original area close to the photographing device is photographed, and the center Zoom control is performed so that the length of a line segment in the document area that passes through the position and extends in the horizontal direction substantially coincides with the horizontal width of the field of view of the photographing means, and the photographing device in the document area is controlled. From those configured to photograph the farther rear side area.

  The photographing apparatus according to an eleventh aspect of the present invention is the focusing control means according to the tenth aspect, wherein the document area is divided into a plurality of areas and the photographing means is controlled to perform focusing. When photographing the near side area, the focus position when the near side vertex area including the two near top vertices is focused is detected, and the focus is moved to the average focus position of the focus position of the near side vertex area. On the other hand, when shooting the back side area, the focus position when the focus is adjusted to the back side vertex area including the two vertices far from the imaging device is detected, and the average focus position of the back side vertex area is detected. Focus control means for moving the focus to the focus position is further provided.

  A photographing apparatus according to a twelfth aspect of the present invention is the photographing apparatus according to any one of the first to eleventh aspects, further comprising an image processing means for binarizing an image photographed by the photographing means, wherein the document recognition means comprises the 2 The document area is detected from the digitized image.

  A photographing apparatus according to a thirteenth aspect of the present invention is the photographing apparatus according to any one of the first to eleventh aspects, further comprising marker detection means for detecting markers printed at at least four corners of the original, wherein the original recognition means A marker is detected to recognize the document area.

  The photographing apparatus according to a fourteenth aspect of the present invention is the photographing apparatus according to any one of the first to thirteenth aspects, further comprising marker detecting means for detecting a marker formed on the original, wherein the original image correcting means includes the marker. And detecting the orientation of the document based on the shape of the marker.

  According to a fifteenth aspect of the present invention, in the first to fourteenth aspects, the photographing apparatus further includes exposure control means for performing exposure control based on the image in the document area.

  According to the fifteenth aspect, it is possible to appropriately perform focusing and AE control with respect to the document area.

  According to a sixteenth aspect of the present invention, in the fifteenth aspect, the exposure control unit performs average photometry, peak photometry, or multi-pattern photometry on the image in the document area. The exposure control is performed based on the photometric result.

  According to a seventeenth aspect of the present invention, there is provided a photographing control method comprising: (1a) photographing a substantially rectangular document image by photographing means; (1b) recognizing a document area in which the document is photographed from the document image; (1c) calculating the center position of the document area; (1d) controlling the photographing means to focus on the center position; and (1e) focusing on the center position and then the document by the photographing means. (1f) The document area is recognized from the image photographed in (1e), and (1g) an image in which the distortion of the document area recognized in (1f) is corrected is created. It is a thing.

  In the photographing control method according to the eighteenth aspect of the present invention, in (1d), a focus evaluation value when the center area is focused is acquired, and the accuracy of focusing is evaluated based on the focus evaluation value. And, when it is evaluated that the focus accuracy of the center area is low, it is configured to focus on the area evaluated as having high focus accuracy among the areas near the center area. is there.

  In a photographing control method according to a nineteenth aspect of the present invention, (2a) an image of a substantially rectangular document is photographed by photographing means, (2b) a document area where the document is photographed is recognized from the photographed image, (2c) detecting the positions of the four vertices of the document area; and (2d) controlling the photographing means to detect the focus position when focusing on the vertex area including the four vertices of the document area. Then, the focus is moved to the average focus position of the focus position of the vertex area, (2e) after focusing in (2d), the document is photographed by the photographing means, (2f) photographed in (2e) The document area is recognized from the captured image, and (2g) an image in which the distortion of the document area recognized in (2f) is corrected is created.

  The shooting control method according to a twentieth aspect of the present invention is the shooting control method according to the nineteenth aspect, wherein the aperture value is adjusted so that the vertex area is within the depth of field after focusing on the average focus position. It is comprised as follows.

  In the shooting control method according to the twenty-first aspect of the present invention, (3a) an image of a substantially rectangular document is shot by the shooting means, and (3b) a document area in which the document is shown is recognized from the shot image. , (3c) controlling the photographing means to zoom into a plurality of areas obtained by dividing the document area to photograph images of each area, and (3d) from the images of each area photographed in (3c) An original area in which the original is reflected is detected, (3e) an image in which the distortion of the original area detected from the image in each area is corrected is created, and (3f) each of the distortion corrected in (3e) The image of the area is synthesized to create the entire image of the original.

  In the shooting control method according to the twenty-second aspect of the present invention, in (3c), the positions of the four vertices of the document area are detected, the center position of the document area is calculated, and the four vertices out of the four vertices are calculated. Zooming control is performed so that the horizontal interval of the image of the document at the two apexes on the near side close to the imaging unit is substantially equal to the horizontal width of the field of view of the imaging unit, and the imaging device in the document area Zooming is performed so that the length of the line segment in the document area extending in the horizontal direction passing through the center position substantially matches the horizontal width of the field of view of the imaging means. Then, it is configured to photograph the back side area far from the photographing apparatus in the document area.

  The shooting control method according to a twenty-third aspect of the present invention is the shooting control method according to the twenty-second aspect, in which the focus is adjusted when the near-side vertex area including the two near-side vertices is focused during shooting of the near-side area. The position is detected, the focus is moved to the average focus position of the focus position of the front side vertex area, and when the back side area is shot, the focus is set on the back side vertex area including the two vertices far from the imaging device. The focus position in the case of being matched is detected, and the focus is moved to the average focus position of the focus position of the back vertex area.

  According to a twenty-fourth aspect of the present invention, in the seventeenth to twenty-fourth aspects, exposure control is performed based on an image in the document area.

  According to the present invention, it is possible to properly focus even when a document is photographed from a direction other than the front. As a result, it is possible to prevent image deterioration that occurs when distortion in the document area in which the document is captured is corrected.

  Hereinafter, preferred embodiments of a photographing apparatus and a photographing control method according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating the operation of the photographing apparatus according to the first embodiment of the present invention. FIG. 2 is a diagram illustrating an image of a document photographed by the photographing apparatus 10.

  As shown in FIG. 1, the photographing apparatus 10 according to the present embodiment extracts a document area A100 in which a document 100 is captured from an image P100 obtained by photographing a rectangular document 100. The photographing apparatus 10 photographs the document 100 after performing automatic focus adjustment (AF) so as to focus on the center position of the document area A100. The photographing apparatus 10 extracts the document area A100 from the image photographed after AF, corrects the distortion of the document area A100 to reproduce the shape of the document 100, corrects the orientation of the document area A100, and outputs it. Create an original image.

  The projector 200 receives the document image 100 ′ from the photographing apparatus 10 and projects it on the screen 300.

  FIG. 3 is a block diagram showing the photographing apparatus according to the first embodiment of the present invention.

  The photographing apparatus 10 according to the present embodiment is an electronic camera that takes an image and records it as electronic data.

  A central processing unit (CPU) 12 controls the overall operation of the photographing apparatus 10 according to a predetermined program, and performs various calculations including an automatic focus adjustment (AF) calculation, an automatic exposure (AE) calculation, and a white balance (WB) adjustment calculation. carry out.

  The power supply unit 14 includes a battery and a power supply control circuit, and supplies power to each unit in the photographing apparatus 10.

  The operation unit 16 is an operation member that receives an operation input from a user, and includes a power switch and a shutter switch. The power switch is an operation member for switching on / off the power of the photographing apparatus 10. The shutter switch is an operation member that inputs an instruction to start shooting.

  A signal from the operation unit 16 is input to the CPU 12. The CPU 12 controls each circuit of the photographing apparatus 10 based on an input signal from the operation unit 16 and performs, for example, lens driving control, photographing operation control, image processing control, and image data recording / reproduction control.

  The mode setting unit 18 is an operation member that receives an operation for switching the operation mode of the photographing apparatus 10. The operation mode of the photographing apparatus 10 is switched between a normal photographing mode (a still image photographing mode and a moving image photographing mode), a document photographing mode, and a reproduction mode for reproducing an image in response to an operation input from the mode setting unit 18. .

  The photographing unit 20 includes a lens unit 22 including a focus lens, a zoom lens, and a diaphragm, a lens control unit 24 that drives and controls the lens unit, and an imaging device (CCD or CMOS).

  The AF unit 26 is a high-pass filter that passes only the high-frequency component of the G signal obtained from the image sensor, an absolute value processing unit that takes the absolute value of the output signal from the high-pass filter, and a focus target that is preset in the screen An AF area extracting unit that extracts a signal in an area (hereinafter referred to as an AF area) and an integrating unit that integrates absolute values in the AF area to obtain an integrated value (focus evaluation value (AF evaluation value)) are included. The CPU 12 moves the focus lens to acquire AF evaluation values at a plurality of focus positions, determines a lens position where the AF evaluation value is maximized as a focus position, and moves the focus lens to the focus position. Note that the AF evaluation value may be obtained from a luminance signal (Y signal).

  The AE unit 28 divides one image screen output from the image sensor into a plurality of divided areas (for example, 8 × 8 or 16 × 16), and accumulates R, G, and B signals for each divided area. The CPU 12 detects the brightness of the subject (subject brightness) based on the integrated value acquired from the AE unit 28, and calculates an exposure value (shooting EV value) suitable for shooting. The CPU 12 determines the aperture value and shutter speed according to the obtained exposure value and a predetermined program diagram, and controls the electronic shutter function and aperture of the image sensor to adjust the exposure amount.

  The memory unit 30 includes a recording medium (for example, xD picture card (registered trademark) or SD card (registered trademark)) and a socket in which the recording medium is detachably mounted. Is recorded on the recording medium as an image file of the format.

  In the normal shooting mode, when the CPU 12 detects half-press of the shutter switch, the CPU 12 acquires the AF evaluation value and the integrated value from the AF unit 26 and the AE unit 28, respectively, and performs AF control and AE control. When the CPU 12 detects that the shutter switch is fully pressed, it captures an image. Then, the CPU 12 converts the captured image into an image data file of a predetermined format and outputs it to the memory unit 30.

[Original mode]
Next, the operation of the photographing apparatus 10 in the document photographing mode will be described.

  In the document shooting mode, as shown in FIG. 1, shooting is performed by placing on the desk 400 so that the relative position of the shooting device 10 and the document 100 does not change during shooting.

  When the CPU 12 detects that the shutter switch is fully pressed in the document photographing mode, the CPU 12 controls the photographing unit 20 to photograph the document 100. In the document shooting mode, shooting of the document 100 is automatically performed at predetermined time intervals in addition to being performed at the timing of pressing the shutter switch.

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary edge image.

  The document recognition unit 32 detects a contour B100 of the document 100 from the binary edge image, and extracts a document area A100 surrounded by the contour B100.

The document four-corner recognition unit 34 detects vertices D ₁ , D ₂ , D ₃ , and D ₄ at the four corners of the document 100 from the contour B 100 and indicates the positions of the four vertices D ₁ , D ₂ , D ₃ , and D _4. Get the coordinates.

The document center calculation unit 36 calculates the coordinates of the intersection D _C of the diagonal lines D ₁ D ₄ and D ₂ D ₃ connecting the opposite vertices of the document 100 as the center position of the document area A100. Instead of the intersection of diagonal lines D _C, for example, the centroid of the original area A100, the center of the inscribed circle or the circumscribed circle may be used as the center position of the document area A100.

CPU12 divides the document area A100 in a predetermined splitting area, sets the area _{A C} around the intersection _{D C} shown in FIG. 4 in the AF area. Then, CPU 12 controls the imaging unit 20 and the AF unit 26 obtains the AF evaluation value of the AF area _{A C} at a plurality of focus positions, performs the AF control so focus is the AF area _{A C.}

  The CPU 12 captures the original 100 again after the AF control is completed. The document recognition unit 32 detects a contour B100 from the recaptured document image, and cuts out a document area A100 surrounded by the contour B100.

  The distortion processing unit 38 performs projection conversion (projection conversion (for example, affine conversion)) on the document area A100 cut out from the re-captured image to correct the distortion of the document area A100, thereby creating a rectangular document image. .

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38, and creates an output document image 100 '. The output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300 as shown in FIG.

  In the present embodiment, an up / down detection marker UP is printed on the document 100. The CPU 12 detects the vertical direction of the document area A100 by detecting this marker from the document area in the image. Note that a member on which the marker UP is formed may be placed on the document 100 or in the vicinity of the document 100. Further, the vertical direction of the document area A100 may be detected by recognizing characters or images printed on the document 100, for example.

  Next, the photographing control method according to the first embodiment of the present invention will be described with reference to the flowchart of FIG.

  First, when the operation mode is switched to the document photographing mode (Yes in step S10), the CPU 12 controls the photographing unit 20 to capture an image of the document 100 at a predetermined photographing timing (step S14).

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary edge image (step S16). The document recognition unit 32 extracts the document area A100 (step S18).

Document 4 corners recognition unit 34 detects the four vertexes _{D 1, D 2, D 3} , D 4 of the document 100, four vertices _{D 1, D 2, D 3} , and acquires the coordinates of _{D 4} (step S20) .

Original center calculation section 36 calculates an intersection _{D C} coordinates of the diagonal _D 1 _{D 4} and _D 2 _{D 3} which connects the vertex facing the document 100 (step S22).

CPU12 is the intersection _{D C} was subjected to the AF control so focus is the AF area _{A C} centered (step S24, S26), captures the image of the document again after AF control ends (step S28).

  Next, the document recognizing unit 32 cuts out the document area A100 from the recaptured document image. The distortion processing unit 38 performs projective transformation (for example, affine transformation) on the document area A100 cut out by the document recognition unit 32 to correct the distortion of the document area A100, and creates a rectangular document image (step S30).

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38 to create an output document image 100 ′ and outputs it to the projector 200 (step S32). As a result, the output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

According to the present embodiment. Thus focus on AF area A _C around the intersection D _C of the diagonal lines of the rectangle of the original 100, even when the captured document 100 from a direction other than the front, focusing Can be performed appropriately. Thereby, it is possible to prevent image degradation that occurs when the distortion of the document area A100 in which the document 100 is captured is corrected.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. This embodiment is one in which the AF evaluation value among the divided areas in the diagonal of the vicinity of the intersection A _C of the original area A100 is to match the higher division area focus. Note that the configuration of the photographing apparatus 10 is the same as that in the first embodiment.

  FIG. 6 is a flowchart showing a shooting control method according to the second embodiment of the present invention.

  First, when the operation mode is switched to the document photographing mode (Yes in Step S40), the CPU 12 controls the photographing unit 20 to capture an image of the document 100 at a predetermined photographing timing (Step S44).

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary edge image (step S46). The document recognition unit 32 extracts the document area A100 (step S48).

Original four corners recognition unit 34 detects the four vertexes _{D 1, D 2, D 3} , D 4 of the document 100, four vertices _{D 1, D 2, D 3} , and acquires the coordinates of _{D 4} (step S50) .

Original center calculation section 36 calculates an intersection _{D C} coordinates of the diagonal _D 1 _{D 4} and _D 2 _{D 3} which connects the vertex facing the document 100 (step S52).

CPU12 divides near the intersection _{D C} on the original area A100, and acquires the AF evaluation value for each divided area by performing an AF search (Step S54). Then, the CPU 12 performs AF control so as to focus on the divided area where the AF evaluation value is high when the focus is achieved (step S56), and captures the original image again after the AF control ends (step S58).

  Next, the document recognizing unit 32 cuts out the document area A100 from the recaptured document image. The distortion processing unit 38 performs projective transformation (for example, affine transformation) on the document area A100 cut out by the document recognition unit 32 to correct the distortion of the document area A100, thereby creating a rectangular document image (step S60).

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38, creates an output document image 100 ', and outputs it to the projector 200 (step S62). As a result, the output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  FIG. 7 is a flowchart showing the flow of AF processing.

First, as shown in FIG. 8, the CPU 12 divides the document area A100 extracted by the document recognition unit 32 (step S70). Then, the CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search, and acquires AF evaluation values in the divided areas A _1A , A _1B ,..., A _5E (step S72).

Then, CPU 12 determines whether the AF evaluation value when focus mainly area _{A 3C} including an intersection _{D C} of the diagonal lines _D 1 _{D 4} and _D 2 _{D 3} is a reliable value (step S74) . In the present embodiment, an AF evaluation value (maximum value) threshold is set in advance such that sufficient focusing accuracy (focusing accuracy) can be obtained. In step S74, the CPU 12 determines the reliability of the AF evaluation value based on whether or not the AF evaluation value of the center area A _3C is equal to or greater than this threshold value.

When it is determined that the AF evaluation value of the center area A _3C is reliable (Yes in step S74), the CPU 12 controls the photographing unit 20 to focus on the center area A _3C (a focus position where the AF evaluation value is maximized). The focus position is moved to (step S78).

On the other hand, when it is determined that the AF evaluation value of the center area A _3C is not reliable (No in step S74), the CPU 12 selects a divided area having the largest AF evaluation value in the vicinity of the center area A _3C (step S76). The focus position is moved to the focus position of the divided area (step S78).

  FIG. 9 is a flowchart showing another embodiment of the AF process.

First, the CPU 12 divides the document area A100 extracted by the document recognition unit 32 (step S80). Then, the CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search, and acquires AF evaluation values in the divided areas A _1A , A _1B ,..., A _5E (step S82).

Then, CPU 12 determines whether the AF evaluation value when focus mainly area _{A 3C} including an intersection _{D C} of the diagonal lines _D 1 _{D 4} and _D 2 _{D 3} is a reliable value (step S84) .

When it is determined that the AF evaluation value of the center area A _3C is reliable (Yes in step S84), the CPU 12 controls the photographing unit 20 to focus on the center area A _3C (a focus position where the AF evaluation value is maximized). The focus position is moved to (step S90).

On the other hand, when it is determined that the AF evaluation value of the central area A _3C is not reliable (No in step S84), the CPU 12 is adjacent to the horizontal direction of the central area A _3C in FIG. 8 (the horizontal direction of the field of view of the photographing apparatus 10). AF evaluation values (maximum values) of the divided areas A _3B and A _3D are acquired (step S86). Then, the CPU 12 moves the focus position to the focus position of the divided area with the larger AF evaluation value (maximum value) among the divided areas A _3B and A _3D (steps S88 and S90).

On the other hand, when the AF evaluation values of the divided areas A _3B and A _3D are both less than the threshold value, for example, A _4C , A for a divided area closer to the image capturing apparatus 10 than the divided area A _3C (front divided area). _The AF evaluation values are evaluated in the order of _4B , _A4D,. When the AF evaluation values of any of the divided areas are less than the threshold value, for example, A _2C , A _2B for the divided areas (the divided areas on the back side) farther from the imaging device 10 than the divided area A _3C. , A _2D ,... Are evaluated in the order of AF evaluation values.

According to the present embodiment, AF evaluation value of the center area A _3C when (maximum value) is equal to or less than a predetermined value, laterally adjacent to the central area A _3C, the distance is the center area A _3C from the imaging device 10 Since the AF control is performed in accordance with a divided area close to, focusing can be performed more appropriately.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, AF control is performed based on AF evaluation values of divided areas including four vertices. Note that the configuration of the photographing apparatus 10 is the same as that in the first embodiment.

  FIG. 10 is a flowchart showing a shooting control method according to the third embodiment of the present invention.

  First, when the operation mode is switched to the document photographing mode (Yes in step S100), the CPU 12 controls the photographing unit 20 to capture an image of the document 100 at a predetermined photographing timing (step S104).

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary edge image (step S106). The document recognition unit 32 extracts the document area A100 (step S108).

Original four corners recognition unit 34 detects the four vertexes _{D 1, D 2, D 3} , D 4 of the document 100, four vertices _{D 1, D 2, D 3} , and acquires the coordinates of _{D 4} (step S110) .

The CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search (step S112). Then, the CPU 12 detects the focus positions of the divided areas A _1A , A _1E , A _5A , A _5E including the four vertices D ₁ , D ₂ , D ₃ , D ₄ (step S114).

Next, the CPU 12 calculates an average value of focus positions (hereinafter referred to as an average focus position) of the divided areas A _1A , A _1E , A _5A , A _5E (step S116). Then, the CPU 12 controls the photographing unit 20 to move the focus lens to the average focus position calculated in step S116 (step S118), and captures the original image again (step S120).

  Next, the document recognizing unit 32 cuts out the document area A100 from the recaptured document image. The distortion processing unit 38 performs projective transformation (for example, affine transformation) on the document area A100 cut out by the document recognition unit 32 to correct the distortion of the document area A100, and creates a rectangular document image (step S122).

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38, creates an output document image 100 ', and outputs it to the projector 200 (step S124). As a result, the output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  FIG. 11 is a flowchart showing a flow of AF control according to the third embodiment of the present invention.

First, the CPU 12 divides the document area A100 as shown in FIG. 8 (step S130). Then, the CPU 12 controls the photographing unit 20 and the AF unit 26 to execute the AF search, and the divided areas A _1A , A _1E , A _5A , A _5E including the four vertices D ₁ , D ₂ , D ₃ , D _4. Is detected (step S132).

Next, the CPU 12 calculates the average focus position of the focus positions of the divided areas A _1A , A _1E , A _5A , A _5E , controls the photographing unit 20, and sets the focus lens at the average focus position calculated in step S 116. Move (step S134).

According to the present embodiment, the four vertexes D ₁ , D ₂ , D ₃ , D ₄ , the photographing device 10, and the focus position are moved to the average focus position of the focus position of the four divided areas of the document area A 100. Even when the original 100 is photographed in a state where the distance between them is different, focusing can be performed appropriately. Thereby, it is possible to prevent image degradation that occurs when the distortion of the document area A100 in which the document 100 is captured is corrected.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. In the present embodiment, AF control is performed based on AF evaluation values of divided areas including four vertices, and the focus depth is controlled to improve the focusing accuracy. Note that the configuration of the photographing apparatus 10 is the same as that in the first embodiment.

  FIG. 12 is a flowchart showing an imaging control method according to the fourth embodiment of the present invention.

  First, when the operation mode is switched to the document photographing mode (Yes in step S140), the CPU 12 controls the photographing unit 20 to capture an image of the document 100 at a predetermined photographing timing (step S144).

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary edge image (step S146). The document recognition unit 32 extracts the document area A100 (step S148).

Original four corners recognition unit 34 detects the four vertexes _{D 1, D 2, D 3} , D 4 of the document 100, four vertices _{D 1, D 2, D 3} , and acquires the coordinates of _{D 4} (step S150) .

The CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search (step S152). Then, the CPU 12 detects the focus positions of the divided areas A _1A , A _1E , A _5A , A _5E including the four vertices D ₁ , D ₂ , D ₃ , D ₄ (step S154).

Next, the CPU 12 calculates an average value (hereinafter referred to as an average focus position) of the focus positions of the divided areas A _1A , A _1E , A _5A , and A _5E (step S156). Then, the CPU 12 controls the photographing unit 20 to move the focus lens to the average focus position calculated in step S156 (step S158). Then, the CPU 12 changes the aperture value of the photographing unit 20 so that the focal depths of the divided areas A _1A , A _1E , A _5A , A _5E are within the depth of field (step S160), and the image of the document is changed. It takes in again (step S162).

  Next, the document recognizing unit 32 cuts out the document area A100 from the recaptured document image. The distortion processing unit 38 performs projective transformation (for example, affine transformation) on the document area A100 cut out by the document recognition unit 32 to correct the distortion of the document area A100, and creates a rectangular document image (step S164).

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38, creates an output document image 100 ', and outputs it to the projector 200 (step S166). As a result, the output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  FIG. 13 is a flowchart showing a flow of AF control according to the fourth embodiment of the present invention.

First, the CPU 12 divides the document area A100 as shown in FIG. 8 (step S170). Then, the CPU 12 controls the photographing unit 20 and the AF unit 26 to execute the AF search, and the divided areas A _1A , A _1E , A _5A , A _5E including the four vertices D ₁ , D ₂ , D ₃ , D _4. Is detected (step S172).

Next, the CPU 12 calculates the average focus position of the focus positions of the divided areas A _1A , A _1E , A _5A , A _5E , controls the photographing unit 20, and sets the focus lens at the average focus position calculated in step S 116. Move (step S174). Then, the CPU 12 changes the aperture value of the photographing unit 20 so that the focal depths of the divided areas A _1A , A _1E , A _5A , A _5E are within the depth of field (step S176).

According to the present embodiment, the four vertexes D ₁ , D ₂ , D ₃ , D ₄ , the photographing device 10, and the focus position are moved to the average focus position of the focus position of the four divided areas of the document area A 100. Even when the original 100 is photographed in a state where the distance between them is different, focusing can be performed appropriately. Thereby, it is possible to prevent image degradation that occurs when the distortion of the document area A100 in which the document 100 is captured is corrected.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. In the present embodiment, exposure control is performed in accordance with the document area A100 in which the document 100 is shown.

  FIG. 14 is a block diagram showing an imaging apparatus according to the fifth embodiment of the present invention.

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the photographing unit 20 in the document photographing mode to generate a binary edge image.

  The document recognition unit 32 detects a contour B100 of the document 100 from the binary edge image, and extracts a document area A100 surrounded by the contour B100.

The document four-corner recognition unit 34 detects vertices D ₁ , D ₂ , D ₃ , and D ₄ at the four corners of the document 100 from the contour B 100 and indicates the positions of the four vertices D ₁ , D ₂ , D ₃ , and D _4. Get the coordinates.

The document center calculation unit 36 calculates the coordinates of the intersection D _C of the diagonal lines D ₁ D ₄ and D ₂ D ₃ connecting the opposite vertices of the document 100.

  The CPU 12 controls the photographing unit 20 and the AF unit 26 to perform AF control so that the document area A100 is focused. As the AF control method, the methods of the first to fourth embodiments can be applied.

  The AE unit 28 calculates an average photometric value of the entire document area A100 from the R, G, and B signals of the document area A100. The CPU 12 detects the brightness of the subject (subject brightness) based on the integrated value acquired from the AE unit 28, and calculates an exposure value (shooting EV value) suitable for shooting. The CPU 12 determines the aperture value and shutter speed according to the obtained exposure value and a predetermined program diagram, and controls the electronic shutter function and aperture of the image sensor to adjust the exposure amount.

  In addition to the above-mentioned average metering, for example, peak metering for calculating a metering value in accordance with a high-luminance area in the document area A100 or the document area A100 is divided into a plurality of divided areas. Thus, multi-pattern photometry for calculating a photometric value for each divided area can be applied.

  After completing the AF control and the AE control, the CPU 12 captures the document 100 again. The document recognition unit 32 detects a contour B100 from the recaptured document image, and cuts out a document area A100 surrounded by the contour B100.

  The distortion processing unit 38 performs projection conversion (projection conversion (for example, affine conversion)) on the document area A100 cut out from the re-captured image to correct the distortion of the document area A100, thereby creating a rectangular document image. .

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38, and creates an output document image 100 '. The output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  FIG. 15 is a flowchart showing an imaging control method according to the fifth embodiment of the present invention.

  First, when the operation mode is switched to the document photographing mode (Yes in step S180), the CPU 12 controls the photographing unit 20 to capture an image of the document 100 at a predetermined photographing timing (step S184).

  The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary edge image (step S186). The document recognition unit 32 extracts the document area A100 (step S188).

Original four corners recognition unit 34 detects the four vertexes _{D 1, D 2, D 3} , D 4 of the document 100, four vertices _{D 1, D 2, D 3} , and acquires the coordinates of _{D 4} (step S190) .

Original center calculation section 36 calculates an intersection _{D C} coordinates of the diagonal _D 1 _{D 4} and _D 2 _{D 3} which connects the vertex facing the document 100 (step S192).

  The CPU 12 performs AF control so that the document area A100 is in focus (step S194).

  The AE unit 28 calculates a photometric value from the document area A100. The CPU 12 calculates an exposure value from the photometric value calculated from the document area A100, and performs AE control (step S196).

  Next, after the AF control and AE control are completed, the original image is captured again (step S198). The document recognition unit 32 cuts out the document area A100 from the recaptured document image. The distortion processing unit 38 performs projective transformation (for example, affine transformation) on the document area A100 cut by the document recognition unit 32 to correct the distortion of the document area A100, and creates a rectangular document image (step S200).

  The CPU 12 detects and corrects the vertical direction of the document area A100 whose distortion has been corrected by the distortion processing unit 38 to create an output document image 100 ′ and outputs it to the projector 200 (step S202). As a result, the output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  According to this embodiment, focusing and AE control can be appropriately performed on the document area A100. Thereby, it is possible to prevent image degradation that occurs when the distortion of the document area A100 in which the document 100 is captured is corrected.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. In the present embodiment, the document 100 is photographed separately into a portion that is far from the photographing device 10 and a portion that is close to the image capturing device 10 to obtain an image of the entire document. Note that the configuration of the photographing apparatus 10 is the same as that in the first embodiment.

  FIG. 16 is a block diagram showing a photographing apparatus according to the sixth embodiment of the present invention, and FIG. 17 is a diagram for explaining the flow of photographing control according to the present embodiment.

  As shown in FIG. 16, the photographing apparatus 10 according to the present embodiment further includes an image composition unit 42.

As shown in FIG. 17A, markers M ₁ , M ₂ , M ₃ , and M ₄ are printed at the four corners of the document 100.

  The CPU 12 generates a binary image by binarizing the image signal for each pixel imaged in the imaging mode.

Document recognition unit 32, the marker _{M 1,} M _2, M 3, stores a shape pattern of _{M 4,} with respect to the binary image, the shape pattern of the marker _{M 1, M 2, M 3} , M 4 Pattern matching. Then, the document recognition unit 32 extracts a document area A100 surrounded by the markers M ₁ , M ₂ , M ₃ , and M ₄ (FIG. 17 (a)). Further, the document recognition unit 32 detects the vertical direction of the document 100 from the direction of the marker.

The document four-corner recognition unit 34 acquires coordinates indicating the positions of the markers M ₁ , M ₂ , M ₃ , and M ₄ on the document 100.

Original center calculation section 36 calculates the coordinates of the markers _{M 1, M 2, M 3} , the intersection of the line segment _M 1 _{M 4} and _M 2 _{M 3} connecting _{M 4 D C.}

The CPU 12 controls the photographing unit 20 to zoom so that two markers M ₃ and M ₄ on the side close to the photographing device 10 (hereinafter referred to as the near side) substantially coincide with the width W of the field of view F 10 of the photographing device 10. (FIG. 17B). In the step of FIG. 17 (b), CPU 12 has a document area A100 (intersection _{D C} than the lower area A1 of at least the original area A100 ') controls the zoom and angle to fit within the field of view F10.

The CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search, and performs AF control so that the area A1 ′ is in focus. Specifically, CPU 12 divides the original area A100 into a plurality of divided areas, and detect the focus position when the focus in the divided area including the marker M ₃ and M ₄ in the near side, the marker M ₃ and intermediate focal position of the divided area including the M ₄ moves the focus lens to the focus position of the (average).

The CPU 12 captures the original 100 again after the AF control is completed. Document recognition unit 32, a document image of the re-photographed original binarized to detect the marker _{M 1, M 2, M 3} , M 4 and is surrounded by the marker _{M 1, M 2, M 3} , M 4 Cut out area A100.

The distortion processing unit 38 performs projection conversion (projection conversion (for example, affine conversion)) on the document area A100 cut out from the re-captured image to correct the distortion of the document area A100, and generates a rectangular document image A100 ′. It is created (FIG. 17C). 'Although the area A1 below the intersection D _C of are in focus, the intersection point D _C than above the area A2' document image A100 becomes focus rough image.

Further, the CPU 12 controls the photographing unit 20 to obtain a straight line extending through the intersection D _C and extending in the lateral direction of the visual field F10 and the outline of the document area A100 (markers M ₁ , M ₂ , M ₃ , and M _4). Zooming is performed so that the line segment L connecting the intersection with the quadrangular shape substantially coincides with the width W of the field of view F10 of the photographing apparatus 10 (FIG. 17D). In the step of FIG. 17 (d), CPU 12 includes an area above the intersection _{D C} of the original area A100 controls the zoom and angle to fit within the field of view F10.

CPU12 performs an AF search by controlling the imaging unit 20 and the AF unit 26 performs the AF control so focus is in the area above the intersection _{D C} of the original area A100. If Specifically, CPU 12 is to divide the original area A100 into a plurality of divided areas, far side (hereinafter, referred to as rear side) from the imaging device 10 in focus on splitting area including the marker M ₁ and M ₂ of The focus lens is detected, and the focus lens is moved to an intermediate (average) focus position between the focus positions of the divided areas including the markers M ₁ and M ₂ .

The CPU 12 captures the original 100 again after the AF control is completed. The document recognition unit 32 binarizes the re-captured document image, detects the markers M ₁ and M ₂ and the outline of the document area A100, and cuts out the document area A100. For detecting the contour of the document area A100, the position information of the contour of the document area A100 at the end of the AF control may be stored, and the document area A100 may be determined based on this position information.

  The distortion processing unit 38 performs projection conversion (projection conversion (for example, affine conversion)) on the document area A100 cut out from the re-captured image to correct the distortion of the document area A100, and generates a rectangular document image A100 ″. Create (FIG. 17E).

Image synthesizing unit 42 synthesizes the area A2 above the intersection _{D C} of intersection _{D C} than the area A1 of the lower 17 of FIG. 17 (c) (e), to create the output document image 100 '(FIG. 17 (f)). The output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  FIG. 18 is a flowchart showing an imaging control method according to the sixth embodiment of the present invention.

  First, when the operation mode is switched to the document photographing mode (Yes in Step S210), the CPU 12 controls the photographing unit 20 to capture an image of the document 100 at a predetermined photographing timing (Step S214).

The CPU 12 binarizes the image signal for each pixel output from the image sensor of the imaging unit 20 to generate a binary image (step S216). The document recognition unit 32 performs template matching on the binary image (step S218), detects the markers M ₁ , M ₂ , M ₃ , and M ₄ printed at the four corners of the document 100, and the document area. A100 is extracted (step S220).

The document recognition unit 32 recognizes the vertical direction of the document 100 from the directions of the markers M ₁ , M ₂ , M ₃ , and M _{4 at} the four corners (step S222).

The document four corner recognition unit 34 acquires the coordinates of the markers M ₁ , M ₂ , M ₃ , and M _{4 at} the four corners (step S 224). Original center calculation section 36 calculates an intersection _{D C} coordinates of the line segment _(diagonal) M 1 _{M 4} and _M 2 _{M 3} connecting the marker facing the document 100 (step S226).

CPU12 is the intersection _{D C} was subjected to the AF control so focus is the AF area _{A C} of the center (step S228, S230), captures the image of the document again after AF control ends.

The CPU 12 controls the photographing unit 20 to perform zooming so that the two front markers M ₃ and M ₄ substantially coincide with the width W of the field of view F10 of the photographing apparatus 10 (step S232).

Next, the CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search (step S234). CPU12 divides the document area A100 into a plurality of divided areas, and detect the focus position when the focus in the divided area including the marker M ₃ and M ₄ in the near side, a marker M ₃ and M ₄ divided The focus lens is moved to an intermediate (average) focus position in the area focus position (step S236).

  The CPU 12 captures the original image again after the AF control and AE control in step S236 are completed (step S238).

Further, CPU 12 controls the imaging unit 20, intersection _{D C} extending in the lateral direction of the street field F10 straight and width W of the field F10 of the line segment L is imaging apparatus 10 that connects the intersection of the contour of the original area A100 Zooming is performed so as to substantially match (step S240).

Next, the CPU 12 controls the photographing unit 20 and the AF unit 26 to execute an AF search (step S242). CPU12 divides the document area A100 into a plurality of divided areas, and detect the focus position when the focus in the divided area including the marker M ₁ and M ₂ on the rear side, a marker M ₁ and M ₂ divided The focus lens is moved to an intermediate (average) focus position in the area focus position (step S244).

  The CPU 12 captures the original image again after the AF control and AE control in step S244 are completed (step S246).

  The document recognizing unit 32 cuts out the document area A100 from the images taken in steps S238 and S246. The distortion processing unit 38 performs projection conversion (projection conversion (for example, affine conversion)) on the document area A100 cut out from the images photographed in steps S238 and S246 to correct the distortion of the document area A100 (step S248). .

Image synthesis unit 42, combined with the intersection _{D C} than the lower area A1 in the image A100 'of the step S238 after the distortion correction, the area A2 above the intersection _{D C} in the image A100 "in step S246 after distortion correction Then, an output document image 100 ′ is created (step S250), and the output document image 100 ′ is output to the projector 200 via the external output unit 40 and projected onto the screen 300.

  According to the present embodiment, focusing accuracy with respect to the document 100 can be improved by dividing the document area A100 into the front side and the back side and shooting. Thereby, it is possible to prevent image degradation that occurs when the distortion of the document area A100 in which the document 100 is captured is corrected.

  Note that the shape and arrangement of the markers on the document 100 are not limited to the above. For example, the marker may be printed along the outline of the document 100.

  Further, the way of division when the original 100 is divided and photographed is not limited to the above. For example, the document area A100 may be divided into three or more areas in the vertical direction and photographed to create a composite image. Further, the document area A100 may be divided into a plurality of vertical and horizontal areas for shooting.

The figure which shows operation | movement of the imaging device which concerns on the 1st Embodiment of this invention. The figure which shows the image of the original image | photographed with the imaging device 10. 1 is a block diagram showing a photographing apparatus according to a first embodiment of the present invention. It shows the original area A100 and AF area _{A C} schematically 1 is a flowchart illustrating a shooting control method according to a first embodiment of the present invention. 7 is a flowchart showing a shooting control method according to the second embodiment of the present invention. The flowchart which shows the flow of the AF process which concerns on the 2nd Embodiment of this invention. The figure which shows the example which divided | segmented original area A100 Flowchart showing another embodiment of AF processing 7 is a flowchart showing a shooting control method according to the third embodiment of the present invention. The flowchart which shows the flow of AF control which concerns on the 3rd Embodiment of this invention. 7 is a flowchart showing a shooting control method according to the fourth embodiment of the present invention. The flowchart which shows the flow of AF control concerning the 4th Embodiment of this invention. The block diagram which shows the imaging device which concerns on the 5th Embodiment of this invention. 9 is a flowchart showing a shooting control method according to the fifth embodiment of the present invention. The block diagram which shows the imaging device which concerns on the 6th Embodiment of this invention. The figure for demonstrating the flow of imaging | photography control which concerns on the 6th Embodiment of this invention. 9 is a flowchart showing a shooting control method according to the sixth embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Imaging device, 12 ... CPU, 14 ... Power supply part, 16 ... Operation part, 18 ... Mode setting part, 20 ... Shooting part, 22 ... Lens part, 24 ... Lens control part, 26 ... AF part, 28 ... AE part , 30 ... Memory section, 32 ... Document recognition section, 34 ... Document four corner recognition section, 36 ... Document center calculation section, 38 ... Distortion processing section, 40 ... External output section, 42 ... Image composition section, 100 ... Document, 200 …projector

Claims (24)

Photographing means for photographing an image of a substantially rectangular document;
Document recognition means for recognizing a document area in which the document is shown from an image of the document;
Center position calculating means for calculating the center position of the document area;
Focus control means for controlling the photographing means to focus on the center position;
A document image correcting unit that creates an image in which distortion of the document area recognized by the document recognition unit is corrected from an image shot by the shooting unit after focusing by the focusing control unit;
An imaging device comprising:   2. The photographing according to claim 1, wherein the center position calculating unit detects positions of four vertices of the document area and calculates an intersection of diagonal lines of the document area obtained by connecting the four vertices as the center position. apparatus.   The photographing apparatus according to claim 1, wherein the focusing control unit focuses on a central area including the central position among a plurality of areas obtained by dividing the document area. A focus accuracy evaluation unit that obtains a focus evaluation value when focusing on the center area and evaluates the accuracy of focusing based on the focus evaluation value is further provided.
When the focus control unit evaluates that the accuracy of focusing in the center area is low, out of the areas near the center area, focus on the area evaluated as having high accuracy in focusing, The imaging device according to any one of claims 1 to 3. The focusing accuracy evaluation means evaluates the focusing accuracy of an adjacent area adjacent to the central area in the horizontal direction of the image of the original when the focusing accuracy of the central area is evaluated to be low. ,
The imaging apparatus according to claim 4, wherein the focusing control unit focuses on the adjacent area when it is evaluated that the accuracy of focusing on the adjacent area is high. The focusing accuracy evaluation unit evaluates the focusing accuracy of the near side area closer to the photographing apparatus than the central area when the focusing accuracy is evaluated to be low in both the central area and the adjacent area. And
The photographing apparatus according to claim 5, wherein the focusing control unit focuses on the near side area when it is evaluated that the near side area has high focusing accuracy. Photographing means for photographing an image of a substantially rectangular document;
Document recognition means for recognizing a document area in which the document is shown from the photographed image;
Vertex detection means for detecting the positions of the four vertices of the document area;
Focus control for controlling the photographing means to detect a focus position when a focus area including the four vertices of the document area is focused, and to move the focus to an average focus position of the focus position of the vertex area Means,
A document image correcting unit that creates an image in which distortion of the document area recognized by the document recognition unit is corrected from an image captured by the imaging unit after focusing by the focusing control unit;
An imaging device comprising:   The photographing apparatus according to claim 7, further comprising an aperture value adjusting unit that adjusts an aperture value so that the vertex area falls within a depth of field after focusing on the average focus position. Photographing means for photographing an image of a substantially rectangular document;
First document recognition means for recognizing a document area in which the document is shown from the photographed image;
Shooting control means for controlling the shooting means to zoom into a plurality of areas obtained by dividing the document area and shooting images of each area;
Second document recognition means for recognizing a document area in which the document is shown from images of each area photographed by the photographing means;
A document image correcting means for creating an image in which distortion of the document area detected from the image of each area is corrected;
Image composition means for composing an image of each area detected by the second document recognition means and corrected for distortion to create an image of the entire document;
An imaging device comprising: Vertex detection means for detecting positions of four vertices of the document area detected by the first document recognition means;
Center position calculation means for calculating the center position of the document area detected by the first document recognition means;
The photographing control unit is configured so that a horizontal interval of the image of the document at two vertices nearer to the photographing device among the four vertices substantially matches a horizontal width of the field of view of the photographing unit. Zoom control is performed to photograph the near side area of the document area close to the photographing device, and the length of a line segment in the document area passing through the center position and extending in the horizontal direction is the field of view of the photographing unit. The photographing apparatus according to claim 9, wherein zoom control is performed so as to substantially match a horizontal width, and a far side area far from the photographing apparatus is photographed in the document area.   A focus control unit that divides the document area into a plurality of areas and controls the photographing unit to perform focusing, and includes a front vertex including the two front vertices when photographing the front area The focus position when the area is in focus is detected, and the focus is moved to the average focus position of the focus position of the near-side vertex area. On the other hand, when photographing the back area, The photographing according to claim 10, further comprising a focus control unit that detects a focus position when focusing on a back vertex area including a vertex and moves a focus to an average focus position of a focus position of the back vertex area. apparatus. Image processing means for binarizing the image taken by the photographing means;
The photographing apparatus according to claim 1, wherein the document recognition unit detects the document area from the binarized image. Marker detection means for detecting markers printed at at least four corners of the document,
The photographing apparatus according to claim 1, wherein the document recognition unit recognizes the document area by detecting the marker. Marker detection means for detecting a marker formed on the document is further provided,
The photographing apparatus according to claim 1, wherein the document image correcting unit detects the marker and detects an orientation of the document based on a shape of the marker.   The photographing apparatus according to claim 1, further comprising an exposure control unit that performs exposure control based on an image in the document area.   The photographing apparatus according to claim 15, wherein the exposure control unit performs average photometry, peak photometry, or multi-pattern photometry on an image in the document area, and performs exposure control based on the photometry result. (1a) An image of a substantially rectangular document is photographed by photographing means,
(1b) Recognizing an original area where the original is shown from the image of the original;
(1c) The center position of the document area is calculated,
(1d) controlling the photographing means to focus on the center position;
(1e) The original is photographed by the photographing means after focusing on the center position,
(1f) Recognizing the original area from the image taken in (1e),
(1g) A shooting control method for creating an image in which the distortion of the document area recognized in (1f) is corrected. In (1d) above,
Obtain a focus evaluation value when focusing on the central area, evaluate the accuracy of focusing based on the focus evaluation value,
The photographing control method according to claim 17, wherein when it is evaluated that the accuracy of focusing in the center area is low, focusing is performed on an area that is evaluated as having high accuracy in focusing among areas near the center area. . (2a) An image of a substantially rectangular document is photographed by photographing means,
(2b) Recognizing a document area where the document is shown from the captured image,
(2c) detecting the positions of the four vertices of the document area;
(2d) The photographing unit is controlled to detect the focus position when the vertex area including the four vertices of the document area is focused, and the focus is moved to the average focus position of the focus area of the vertex area. ,
(2e) The original is photographed by the photographing means after focusing in (2d),
(2f) Recognizing the original area from the image taken in (2e),
(2g) A shooting control method for creating an image in which the distortion of the document area recognized in (2f) is corrected.   The imaging control method according to claim 19, wherein after the focus is adjusted to the average focus position, an aperture value is adjusted so that the vertex area is within the depth of field. (3a) An image of a substantially rectangular document is photographed by the photographing means,
(3b) Recognizing a document area where the document is shown from the captured image;
(3c) controlling the photographing means to zoom into a plurality of areas obtained by dividing the document area and photographing images of each area;
(3d) detecting a document area in which the document is captured from the image of each area photographed in (3c);
(3e) Create an image in which the distortion of the document area detected from the image of each area is corrected,
(3f) A shooting control method for creating an image of the entire original by combining the images of the respective areas whose distortion has been corrected in (3e). In (3c) above,
Detecting the positions of the four vertices of the document area;
Calculate the center position of the document area,
Zoom control is performed so that the horizontal interval of the image of the original of the two vertices nearer to the photographing unit among the four vertices substantially coincides with the horizontal width of the field of view of the photographing unit, Shoot the near side area of the document area close to the photographing device,
Zoom control is performed so that the length of a line segment in the document area extending in the horizontal direction passing through the center position substantially coincides with the horizontal width of the field of view of the photographing unit, The imaging control method according to claim 21, wherein an area on the far side far from the imaging apparatus is imaged. When photographing the near side area, the focus position when the near side vertex area including the two near top vertices is focused is detected, and the focus is moved to the average focus position of the focus position of the near side vertex area. And
At the time of shooting in the back area, the focus position when the focus is adjusted to the back vertex area including the two vertices on the side far from the imaging device is detected, and the average focus position of the focus position in the back vertex area is detected. The photographing control method according to claim 22, wherein the focus is moved.   25. The photographing control method according to claim 17, wherein exposure control is performed based on an image in the document area.

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