JP2002077707A - Image pickup device and image pickup method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid wasteful image pickup due to the shape of an object or a positional relation between the object and the image pickup device. SOLUTION: This image pickup method comprises a first image pickup means (a step S1) for image picking up an object at an angle of view including the whole object, a shape detecting means (a step S2) for detecting the shape of a subject from the imaged picture, a deciding means (a step S3) for deciding the number and/or positions of partial pictures for picking-up the subject based on the detected shape, and a divided image pickup means (a step S4) for picking-up the partial pictures corresponding to the decided number and/or positions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image pickup apparatus and an image pickup method, and more particularly to an image pickup apparatus and an image pickup method for picking up an image of a rectangular document in a tilted state.

[0002]

2. Description of the Related Art Using a digital camera or the like, an image of a document showing a document or the like is taken. If the optical axis of the lens of the digital camera is not perpendicular to the document surface, the digital camera is located at a position where the document is raised, and the document is distorted in a captured image. Here, the angle between the optical axis of the lens of the digital camera and the normal to the document surface is called the tilt angle.

[0003] On the other hand, the resolution of an area sensor used in a digital camera has been dramatically improved in recent years, but is still at an insufficient level for a purpose of inputting a document image. Therefore, conventionally, in order to compensate for the lack of resolution and achieve relatively high resolution relatively easily, a technique has been proposed in which a document image is divided into a plurality of images and taken, and the obtained divided images are combined to generate a composite image. Proposed. In addition, the divisional imaging has an advantage of complementing the limitation on the angle of view of the digital camera for imaging.

[0004]

FIG. 11 is a diagram showing an example of an image obtained by imaging a document in a state where the digital camera is raised with respect to the document. Referring to FIG.
Although the subject image 101 of the document included in the image 100 is originally rectangular, it is distorted and trapezoidal due to tilt. The region 140 and the region 141 in the image 100 are backgrounds of the document and are unnecessary regions.

When image processing such as smoothing is performed on the image 100 as an image of a document, image processing is also performed on unnecessary areas 140 and 141. For this reason, there is a problem that useless processing is executed and the processing time is delayed. Also, image 1 from CCD
When outputting 00, there is a problem that useless integration time is wasted due to the area 140 and the area 141.

[0006] These problems also occur in an image obtained by imaging a subject having a non-rectangular shape, or a composite image obtained by dividing and imaging an object.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to eliminate wasteful imaging caused by the shape of a subject and the positional relationship between the subject and the apparatus. It is to provide a possible imaging device and imaging method.

It is still another object of the present invention to provide an image pickup apparatus and an image pickup method capable of obtaining an image having a different resolution according to a distance to a subject.

Another object of the present invention is to provide an image pickup apparatus capable of effectively utilizing an image pickup element according to the shape of a subject image distorted by a tilt angle.

[0010]

According to one aspect of the present invention, there is provided an image pickup apparatus comprising: first image pickup means for picking up an image of an object at an angle of view including the entire object; Shape detecting means for detecting the shape of the subject image from the image; determining means for determining the number and / or position of partial images for dividing and capturing the subject image based on the detected shape; Alternatively, the image processing apparatus further includes a divisional imaging unit that performs divisional imaging of the partial image corresponding to the position.

According to the present invention, the shape of a subject image is detected from an image captured at an angle of view including the entire subject, and the number and / or number of partial images for dividing and capturing the subject image based on the detected shape. The position is determined, and a partial image corresponding to the determined number and / or position is divided and captured. Therefore, the proportion of the subject included in the captured image increases. As a result, it is possible to provide an imaging device capable of eliminating unnecessary imaging caused by the shape of the subject and the positional relationship between the subject and the device.

Preferably, the determining means of the image pickup apparatus determines the number and / or position of partial images having different sizes according to the position of the partial image.

According to the present invention, the number and / or position of partial images having different sizes according to the positions of the partial images are determined. When the relative positions of the subject and the imaging device are in a predetermined relationship, tilt occurs. Changing the size of the partial image changes the resolution of the image. An image with a higher resolution of the subject image can be obtained as the portion of the subject is farther from the imaging device. As a result, it is possible to provide an imaging device capable of obtaining an image having a different resolution according to the distance to the subject.

[0014] Preferably, the imaging apparatus further includes a synthesizing means for synthesizing the partial images obtained by divisional imaging.

According to the present invention, since the divided partial images are combined, it is possible to obtain an image with a high resolution of the subject image.

According to another aspect of the present invention, an image pickup apparatus is an image pickup apparatus having a document table on which a subject is placed, and a camera installed above the document table and capturing an image of the subject. The camera includes an image sensor in which pixels are arranged according to a tilt angle or a readout area is set.

According to the present invention, there is provided an image pickup device in which pixels are arranged according to the tilt angle or a readout area is set. When the subject and the imaging device are in a positional relationship having a tilt angle, the shape of the subject image is distorted. The pixels of the image sensor are arranged according to the shape of the distorted subject image, or the readout area of the image sensor is set. In addition, since the distance to the subject is partially different depending on the tilt angle, the image sensor is arranged or the readout area of the image sensor is set according to the distance to the subject. For this reason, it is possible to provide an imaging device that can effectively use the imaging device according to the shape of the subject distorted by the tilt angle.
Further, it is possible to provide an imaging device capable of obtaining an image having a different resolution according to a distance to a subject.

According to still another aspect of the present invention, an imaging method includes the steps of imaging a subject at an angle of view including the entire subject, detecting the shape of the subject image from the captured image. The method includes a step of determining the number and / or position of partial images for dividing and capturing the subject image based on the shape, and a step of dividing and capturing partial images corresponding to the determined number and / or position.

According to the present invention, the shape of the subject image is detected from the image captured at the angle of view including the entire subject, and the number and / or the number of partial images for dividing and capturing the subject image are determined based on the detected shape. The position is determined, and a partial image corresponding to the determined number and / or position is divided and captured. Therefore, it is possible to provide an imaging method capable of eliminating unnecessary imaging caused by the shape of a subject and the positional relationship between the subject and the apparatus.

Preferably, the step of determining the imaging method includes:
The number and / or position of partial images having different sizes according to the position of the partial image are determined.

According to the present invention, the number and / or position of partial images having different sizes according to the position of the partial image is determined. For this reason, it is possible to provide an imaging method capable of obtaining images with different resolutions according to the distance to the subject.

Preferably, the imaging method further comprises a step of synthesizing the divided and imaged partial images.

According to the present invention, since the divided partial images are combined, it is possible to obtain an image with a high resolution of the subject image.

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. The same reference numerals in the drawings denote the same or corresponding members, and description thereof will not be repeated.

[First Embodiment] FIG. 1 is a diagram showing a state in which an original 1 is imaged by a digital camera 10 according to a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing the digital camera 10 according to the first embodiment. Referring to FIG. 2, a digital camera 10 has a release switch 12 for starting imaging by a user operation.
Multi-point distance measuring device 1 for measuring the distance to a subject
3 and a display unit 14 provided on the back surface of the camera body 11
And an image pickup unit 15 that simulates an eyeball, and a scan drive unit 16 for causing the image pickup unit 15 to scan.

The display unit 14 includes a liquid crystal panel, and is capable of displaying a warning and displaying a captured image. In addition, on the back of the camera body 11, in addition to the display unit 14, a mode switch for switching between a document / landscape mode (not shown), a power switch, and the like are provided.

FIG. 3 is a perspective view for explaining details of the image pickup unit 15 and the scan drive unit 16 of the digital camera according to the present embodiment. Referring to FIG. 3, imaging unit 15 includes a zoom lens 21 for changing the imaging magnification of a subject image, a zoom motor 23 for driving zoom lens 21, and converts an optical signal of the subject image into an electric signal. And a charge-coupled device (CCD) 22 as a photoelectric conversion device.

The zoom lens 21 can change the imaging magnification by driving a zoom motor 23, and forms the light of the incident subject image on the CCD 22. Note that the imaging magnification has a range in which an image from the entire image of the imaging area to the divided image of the smallest partial area can be formed on the CCD 22 in accordance with the number of divisions and the position of the imaging area.

The scanning drive unit 16 is a U-shaped guide 2
4, a rotating shaft 25 rotatably supporting a lower portion of the U-shaped guide 24, a rotating shaft 26 rotatably supported on the upper portion of the U-shaped guide 24, and rotatably supporting the imaging unit 15. It comprises a motor and angle sensors 27 and 28 coupled to the respective rotating shafts 25 and 26, respectively.
Therefore, the imaging direction of the imaging unit 15 can be arbitrarily controlled in the X and Y directions.

FIG. 4 is a control block diagram showing the overall configuration of the digital camera 10 according to the first embodiment.
Referring to FIG. 4, digital camera 10 has a central processing unit (CPU) 31 that controls the entire digital camera 10.
A multi-point distance measuring device 13, an operation unit 32 for performing various operations by a user, a display unit 14 for displaying a preview image of a captured image, and a zoom motor 23 for changing an imaging magnification. A zoom control unit 33 for controlling the driving of the camera, a focus adjustment device 34 for performing focus adjustment,
An imaging direction control unit 35 for driving the scanning drive unit 16 to control the imaging direction.

Here, the operation unit 32 includes the release switch 12, a power switch, a mode changeover switch, and the like.

The imaging direction controller 35 drives the scanning drive unit 16 in accordance with an instruction from the CPU 31 to move the imaging direction of the imaging unit 15 in a predetermined direction. The imaging direction of the imaging unit 15 is the optical axis direction of the zoom lens 21.

The zoom controller 33 drives the zoom motor 23 according to an instruction from the CPU 31 to change the imaging magnification of the zoom lens 21.

The digital camera 10 further includes a CCD 22 serving as an image pickup device and a CCD 22 for driving the CCD 22.
A CD driving unit 36, a memory 37 for storing image data obtained by the CCD 22, and an image processing unit 3 for performing predetermined image processing on the image data stored in the memory 37
8 and a recording unit 40 for recording image data subjected to image processing by the image processing unit 38.

The image processing section 38 performs a skew correction process for performing skew correction on the image data stored in the memory 37, and a laying process for forming a composite image by bonding the skew-corrected divided image data. Do. In the inclination correction, the inclination of the document surface (subject surface) is obtained based on the distance between a plurality of points measured by the multipoint distance measuring device 13. Then, in accordance with the value and the inclination in the imaging direction set in advance according to the number of divisions of imaging, the inclination of each of the captured divided image data is corrected.

As described above, in the digital camera 10 according to the first embodiment, the imaging direction and the imaging magnification can be arbitrarily changed while the camera body 11 is fixed, and the imaging is performed at a desired imaging magnification in a desired imaging direction. Is possible.

FIG. 5 is a first diagram showing the number and positions of images obtained by pre-scanning and divided images. Referring to FIG. 5, image 100 is obtained by digital camera 10.
This is an image obtained by capturing an image so that the entire original 1 serving as a subject falls within the image. The subject image 101 of the document in the image 100 has a trapezoidal shape due to the influence of the tilt and is distorted in shape.

When nine-division imaging is performed based on the image 100 obtained by the prescan, nine divided images 1
11 to 119 are shown. These divided images 111
119 are the same in size, and their positions are determined such that three divided images are arranged in each of the vertical direction and the horizontal direction. As apparent from the figure, the divided image 111
And the divided image 113 do not include the subject image 101 at all.

In this nine-division imaging, divided images 111 and 1
It is useless to image 13. That is, CC
Not only is the processing time required for integration of D22 wasted, but also the processing time required for predetermined image processing performed on the divided images 111 and 113 is wasted.

Therefore, the nine divided images 111 to 11
It is sufficient to capture seven of the nine divided images except the divided image 111 and the divided image 113. When capturing seven divided images, the pixel values corresponding to the positions of the divided image 111 and the divided image 113 may be set to, for example, white or black values according to the application.

Further, when performing a geometric deformation such as a tilt correction at the same time when creating a composite image by pasting the divided images, the divided image 111 and the divided image 113 are not required at all. This is because the combined image finally combined by the tilt correction does not include the divided image 111 and the divided image 113.

FIG. 6 is a second diagram showing the number and positions of the images obtained by the prescan and the divided images. Referring to FIG. 6, the upper three divided images 121 to 123, the middle three divided images 124 to 126, and the lower three divided images 127 to 129 have upper, middle, and lower sizes. Each is different. The upper row is the smallest and the lower row is the largest. The three divided images on the same level have the same size.

If the subject image 101 is deformed under the influence of the tilt and the tilt is corrected, there arises a problem that the resolution of the corrected image is partially different. By determining the size of the divided image so as to change the resolution according to the distance from the digital camera 10, the
It is possible to solve the problem that the resolution is different for each position of 01. In other words, the portion of the document 1 that is far from the digital camera 10 is imaged with a smaller divided image, in other words, with a higher resolution. For the portion of the document 1 that is short from the digital camera 10, the size of the divided image is increased, in other words, the resolution is reduced, and the image is captured.

In this embodiment, the divided image is shown when the digital camera 10 is tilted up and down. However, when the digital camera 10 is tilted up and down, the size of the divided image is Will be different depending on the horizontal position.

Further, in this embodiment, the divided images having the three sizes of the upper, middle, and lower stages are used, but the nine divided images may have different sizes. For example, the size of the divided image may be determined based on the distance measured by the multipoint distance measuring device 13.

FIG. 7 is a flowchart showing the flow of the imaging process performed by the digital camera 10 according to the first embodiment. Referring to FIG. 7, digital camera 10
First, a pre-scan is performed to capture the original 1 at a wide angle so as to include the entire original 1 as a subject (step S1). Thereby, the image 10 shown in FIG.
0 is stored in the memory 37. Image 100 at this time
May be a low resolution image.

In the next step S2, a subject is detected from the image 100 (step S2). The detection of the subject
The image 100 obtained in step S1 is subjected to edge extraction processing, and the contour of the subject image 101 is extracted from the extracted edges, thereby obtaining an image 10 of the subject image 101.
The position in zero is specified. The contour of the subject image may be extracted by using the detection result of the background luminance value.

The number of divided images and the position in the image 100 are determined from the position of the subject image 101 in the image 100 (step S3). When the number of divisions is determined in advance, the number and position of the divisional images are determined according to the finally required resolution of the composite image and the like. For example, as shown in FIG. 5, when the image 100 obtained by the pre-scan is divided into nine parts, the position of the image 100 is
The position and size of the divided image are determined so that each divided image includes a portion obtained by dividing the image into three in the vertical direction and three in the horizontal direction. Then, an actually necessary divided image is selected. For example, in the example shown in FIG.
Seven divided images excluding the divided image 111 and the divided image 113 are selected from 11 to 119.

In the image 100 shown in FIG. 6, the predetermined number of divisions is 9, and the size and position of the divided image are determined by the ratio of the size of the subject image 101 in the vertical and horizontal directions. .

If the required resolution is high, the number of divided images may be increased, and if the resolution is low, the number of divided images may be reduced.

Then, the divided images determined in step S3 are captured. The angle of view in imaging here is different from the angle of view captured in step S1, and is set to an angle of view corresponding to the size of each divided image.

In the last step S5, each of the divided images picked up in step S4 is pasted to form one composite image. The created composite image is stored in the recording unit 40.
Is output to

As described above, in the digital camera 10 according to the first embodiment, the number and position of the divided images are determined according to the shape of the subject imaged by the pre-scan. Thus, it is possible to eliminate a divided image that captures an appropriate area, and to speed up the processing.

Further, since the size of the divided image is made different depending on the shape of the subject image, it is possible to prevent the resolution of the image corrected by the tilt correction processing from being different for each part.

The size of the divided image may be determined based on the shape of the subject image 101 included in the image 100, or the distance to the subject may be separately measured by the multipoint distance measuring device 13. Alternatively, the distance may be determined based on the measured distance.

[Second Embodiment] Next, an image pickup apparatus according to a second embodiment will be described. FIG. 8 is a perspective view of an imaging device according to the second embodiment. Referring to FIG. 8, imaging apparatus 130 includes a document table 134 on which document 1 is placed, and a digital camera 131 supported by support bar 135 above document table 134.

The digital camera 131 has the same configuration as the digital camera 10 of the first embodiment except for the structure of the CCD 22. The description of the same configuration as digital camera 10 in the first embodiment will not be repeated here.

As shown in FIG. 8, the digital camera 1
Although the reference numeral 31 is installed above the document table 134, the normal line of the document table 134 and the imaging direction of the digital camera 131 are not parallel. Therefore, in the image obtained by imaging the document 1 placed on the document table 134 by the digital camera 131, the rectangular document 1 is distorted due to the tilt and appears as a trapezoid. For example, the image shown in FIG. 11 is obtained. Since the document 1 is rectangular, the shape of the subject image 101 appearing in an image 100 obtained by imaging the document 1 is a trapezoid. Thus, the document table 134 and the digital camera 13
In the case where the tilt angle with 1 is almost fixed, the image 1
The distortion of the subject image 101 during 00 is also fixed.

In the digital camera 131 according to the second embodiment, the shape of the CCD is adapted to the shape of the subject image 101 which is distorted by the influence of tilt.

FIG. 9 is a diagram showing a schematic configuration of an image pickup unit of a digital camera 131 according to the second embodiment. With reference to FIG.
132 is arranged. In the CCD 132, pixels having the same area are arranged in a convex shape including a trapezoidal subject image.

Thus, the subject image deformed by the tilt of the CCD 132 can be formed. And C
The portion of the CD 132 where the subject image 101 is not formed is CC
Since the area tightened to the entirety of D132 is reduced, the photoelectric conversion element can be effectively used.

The digital camera 131 has a CCD
Although the shape of 132 is convex, a signal may be read only from a convex region including the trapezoidal subject image 101 using a conventional rectangular CCD. This also allows CC
The same effect as when the shape of D is convex is obtained.

FIG. 10 is a view showing another CCD 133 of the digital camera 131 according to the second embodiment.
Referring to FIG. 10, pixels having a small area are arranged above CCD 133, and pixels having a large area are arranged below CCD 133. The overall shape is a convex shape including the trapezoidal subject image 101. By modifying the arrangement of the photoelectric conversion elements of the CCD 133 in this manner, the deformed subject image 101
Even when the tilt correction is performed, it is possible to prevent the resolution of the corrected image from being different for each part.

Since the CCD of the digital camera 131 according to the second embodiment is not rectangular, the image output from the CCD is not rectangular. Therefore, in order to finally obtain a rectangular image, the pixel value of a pixel without a CCD may be interpolated by “0” or “255”. Also,
When the tilt correction is performed before the image is output as a rectangular image, the image after the tilt correction becomes a rectangle, so that the image can be output as a rectangular image.

In practice, the subject light is divided into optical paths by a half mirror, a prism, or the like, and rectangular CCDs are arranged in each optical path so as to have the above-described shape equivalently.

As described above, in the image pickup apparatus 130 according to the second embodiment, the shape of the CCD or the shape of the area for reading out signals from the CCD is matched to the shape of the subject image, so that the waste of the CCD is reduced. Can be omitted.

Further, since the area of the pixel of the CCD is changed according to the distance from the subject, the resolution of the image after the tilt correction processing can be unified for the entire image.

Although the present embodiment has been described with respect to the case where there is a tilt at the time of imaging, the present invention can be applied to the case where the shape of the subject is not rectangular or the lens distortion is extremely large. Waste can be eliminated.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state in which a document 1 is imaged by a digital camera according to a first embodiment of the present invention.

FIG. 2 is a perspective view schematically showing the digital camera according to the first embodiment.

FIG. 3 is a perspective view for explaining details of an image pickup unit and a scan drive unit of the digital camera according to the present embodiment.

FIG. 4 is a control block diagram illustrating an overall configuration of the digital camera according to the first embodiment.

FIG. 5 is a first diagram illustrating an image obtained by pre-scanning and the number and positions of divided images.

FIG. 6 is a second diagram illustrating an image obtained by pre-scanning and the number and positions of divided images.

FIG. 7 is a flowchart illustrating a flow of an imaging process performed by the digital camera according to the first embodiment.

FIG. 8 is a perspective view of an imaging device according to a second embodiment.

FIG. 9 is a diagram illustrating a schematic configuration of an imaging unit of a digital camera according to a second embodiment.

FIG. 10 is a diagram illustrating another CCD of the digital camera according to the second embodiment.

FIG. 11 is a diagram illustrating an example of an image obtained by imaging a document in a state where the digital camera is raised with respect to the document.

[Explanation of symbols]

1 original, 10 digital camera, 11 camera body,
12 Release switch, 13 Multi-point distance measuring device, 14
Display unit, 15 imaging unit, 16 scanning drive unit, 21 zoom lens, 23 zoom motor, 24
Character guide, 25, 26 rotation axis, 27 angle sensor,
32 operation unit, 33 zoom control unit, 34 focus adjustment device, 35 imaging direction control unit, 36 drive unit, 37 memory, 38 image processing unit, 40 recording unit, 100 images, 1
01 subject image, 111 to 119, 121 to 129 divided images, 130 imaging device, 131 digital camera,
134 platen, 135 support bar.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H04N 101: 00 H04N 101: 00 F term (Reference) 5B047 BB04 BC05 BC15 CA14 CA17 CA23 CB09 CB23 DC07 5C022 AA00 AA13 AB51 AB68 AC01 AC27 AC69 CA07 5C023 AA11 AA37 BA02 BA11 CA02 DA04 DA08

Claims (7)

[Claims] A first imaging unit configured to image the subject at an angle of view including the entire subject; a shape detection unit configured to detect a shape of the subject image from the captured image; Determining means for determining the number and / or position of partial images for dividing and capturing the subject image; and divided image capturing means for dividing and capturing partial images according to the determined number and / or position. Imaging device. 2. The imaging apparatus according to claim 1, wherein the determination unit determines the number and / or position of partial images having different sizes according to the position of the partial image. 3. The image capturing apparatus according to claim 1, further comprising a combining unit that combines the divided partial images. 4. An image pickup apparatus comprising: a document table on which a subject is placed; and a camera which is installed above the document table and captures the image of the subject, wherein the camera has a pixel corresponding to a tilt angle. An image pickup apparatus, comprising: an image pickup element in which is arranged or a readout area is set. 5. A step of imaging the subject at an angle of view including the entire subject, a step of detecting a shape of the subject image from the captured image, and dividing the subject image based on the detected shape. An imaging method, comprising: determining the number and / or position of partial images to be imaged; and dividing and imaging partial images according to the determined number and / or position. 6. The imaging method according to claim 5, wherein the determining step determines the number and / or position of partial images having different sizes according to the position of the partial image. 7. The imaging method according to claim 5, further comprising the step of combining the divided partial images.