JP5747474B2 - Imaging apparatus, imaging processing method, and program - Google Patents

Description

  The present invention relates to an imaging apparatus, an imaging processing method, and a program.

  2. Description of the Related Art Conventionally, there is a camera equipped with a function of capturing a white board with a digital camera and storing it as image data in order to record characters and figures written on the white board. By the way, if the whiteboard is photographed from an oblique direction, the image is captured in a state where the whiteboard is obliquely distorted. For example, a process of converting the captured image into a rectangular image by performing a trapezoid correction process or the like is performed. Some are performed (see, for example, Patent Document 1).

JP 2005-115711 A

  However, if trapezoidal correction processing is performed on an image shot from an oblique direction with respect to the whiteboard, the image area corresponding to the farther than the center of the whiteboard is relatively enlarged, and characters and figures are relatively enlarged. There is a problem that the resolution of information such as the image quality deteriorates compared to the image area closer to the image.

  An object of the present invention is to provide an imaging apparatus, an imaging processing method, and a program that can improve the balance of the resolution of an image generated by distortion correction processing.

In order to solve the above-described problem, an imaging apparatus according to a first aspect of the present invention includes an imaging unit, a processing unit that performs distortion correction processing for correcting distortion of a subject in the image, and an image obtained by imaging by the imaging unit. When performing distortion correction processing by the processing means, focusing means for controlling to perform a predetermined focus adjustment process for focusing at a position where the imaging distance is farther than the center of the subject, and the imaging means A region setting unit that sets a plurality of evaluation regions in which an in-focus evaluation value is to be calculated in the image captured by the method, and a calculation that calculates a focus evaluation value for each of the plurality of evaluation regions set by the region setting unit The focusing means is sequentially calculated by the calculating means when the focusing distance of the imaging means is moved from the infinite area side to the closest area side as the predetermined focus adjustment processing. Based on at least the farthest focus distance among the focus distances for detecting the peak focus evaluation value in the evaluation area, the focus is adjusted to focus on a position farther than the center of the subject. It is characterized by adjusting .

The invention according to claim 2 is characterized in that the region setting means sets a plurality of evaluation regions in which a focus evaluation value is to be calculated along a predetermined direction in an image captured by the imaging device. To do.
According to a third aspect of the present invention, the focusing unit further includes the evaluation region as one of the evaluation regions in the middle of moving the focusing distance of the imaging unit from the infinite region side to the closest region side as the predetermined focus adjustment processing. When the peak of the in-focus evaluation value is detected, the movement of the in-focus distance from that position is interrupted, and the in-focus distance at which the peak is detected or a predetermined distance from the in-focus distance is detected. It is characterized by adjusting the focus so as to focus on the in-focus distance .
According to a fourth aspect of the present invention, the focusing means includes a plurality of in-focus distance ranges for detecting peaks of in-focus evaluation values in the plurality of evaluation regions as the predetermined focus adjustment processing. It is characterized in that the focus is adjusted so that the in-focus distance is farther than the center of the subject .

According to a fifth aspect of the present invention, the processing means relatively expands the subject portion on the side where the imaging distance is farther than the image obtained by imaging with different imaging distances at each part of the subject. It is characterized by performing distortion correction processing .

The invention according to claim 6 further includes a determination unit that determines whether or not to perform distortion correction processing by the processing unit on an image obtained by imaging by the imaging unit, and the focusing unit includes: Control is performed so as to perform the predetermined focus adjustment process on condition that the determination unit determines that the distortion correction process is performed .

According to a seventh aspect of the present invention, the processing means further includes: a subject portion on the far side of the imaging distance according to a ratio of an imaging distance between the subject portion on the far side of the imaging distance and the subject portion on the side of the near side of the imaging distance. It is characterized by determining the relative enlargement ratio .

According to an eighth aspect of the present invention , when the contour of the subject is a right-angled quadrilateral, the processing means deforms the extracted contour shape according to the contour shape of the subject extracted from the captured image. It is characterized in that the relative magnification of the subject part on the far side of the imaging distance is determined so as to return to a right-angled quadrilateral by correction processing .

According to a ninth aspect of the present invention, the processing means further includes an image generation process for generating a right-angled quadrilateral image by performing a right-angled quadrangle conversion process on a predetermined subject in the image as the distortion correction process. It is a feature.

The invention according to claim 10 is further characterized in that when the image is picked up by the image pickup means, the plurality of evaluation areas set by the area setting means are located at positions closer to a position farther than the center of the predetermined subject. Further, it is characterized by further including guide means for guiding imaging so as to correspond to each.

According to an eleventh aspect of the present invention , the processing means further includes a subject portion on the far side of the imaging distance and an imaging distance based on a plurality of focusing distances at which peaks of focus evaluation values are detected in the plurality of evaluation regions. The relative enlargement ratio is determined by specifying the ratio of the imaging distance with the subject portion on the near side.

Furthermore the invention according to claim 12, further comprising setting means for setting the imaging mode for imaging a whiteboard, the determination unit, when the imaging mode is set by said setting means, distortion due to the processing means It is characterized in that it is determined that correction processing is performed.

An image pickup processing method according to a thirteenth aspect of the present invention is an image pickup processing method using an image pickup apparatus including an image pickup means, which is obtained by distortion correction processing for correcting distortion of a subject in an image and image pickup by the image pickup means. When the distortion correction process is performed on an image to be captured, a predetermined focus adjustment process for focusing at a position where the imaging distance is farther than the center of the subject , and an in-focus image within the image captured by the imaging unit An area setting process for setting a plurality of evaluation areas for which evaluation values are to be calculated; and a calculation process for calculating an in-focus evaluation value for each of the plurality of evaluation areas set by the area setting process. In the adjustment process, when the focus distance of the imaging unit is moved from the infinite range side to the close range side, the focus for detecting the peak of the focus evaluation value in any of the evaluation areas sequentially calculated by the calculation process is detected. Among away, is characterized by adjusting based on at least the farthest focus distance, the focus to focus on a distance farther than the center portion of the object.

According to a fourteenth aspect of the present invention, there is provided a program for an imaging apparatus including an imaging unit, a processing unit for performing distortion correction processing for correcting distortion of a subject in an image, and an image obtained by imaging by the imaging unit. When the distortion correction process is performed by the processing unit, the image is captured by the focusing unit and the imaging unit that are controlled to perform a predetermined focus adjustment process for focusing at a position where the imaging distance is farther than the center of the subject. In the image, function as area setting means for setting a plurality of evaluation areas for which focus evaluation values should be calculated, and calculation means for calculating focus evaluation values for the plurality of evaluation areas set by the area setting means. The focusing means sequentially performs the calculation by the calculation means when moving the focusing distance of the imaging means from the infinity side to the closest side as the predetermined focus adjustment processing. Focus at a position farther than the center of the subject based on at least the farthest focus distance among the focus distances that detect the peak focus evaluation value in any evaluation area It is characterized by adjusting the focus .

  According to the present invention, it is possible to improve the balance of the resolution of an image generated by distortion correction processing such as trapezoid correction.

It is a block diagram which shows schematic structure of the imaging device of one Embodiment to which this invention is applied. 3 is a flowchart illustrating an example of an operation related to an imaging process by the imaging apparatus of FIG. 1. 3 is a flowchart illustrating an example of an operation related to a focus adjustment process in the imaging process of FIG. 2. It is a figure which shows typically an example of the image which concerns on the imaging process of FIG. It is a block diagram which shows schematic structure of the imaging device of the modification 1. It is a figure for demonstrating the imaging process by the imaging device of FIG. 6 is a flowchart illustrating an example of an operation related to a focus adjustment process in an imaging process performed by the imaging apparatus in FIG. 5. It is a block diagram which shows schematic structure of the imaging device of the modification 2. It is a flowchart which shows an example of the operation | movement which concerns on the imaging process by the imaging device of FIG.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.
FIG. 1 is a block diagram illustrating a schematic configuration of an imaging apparatus 100 according to an embodiment to which the present invention is applied.

As shown in FIG. 1, the imaging apparatus 100 according to the present embodiment includes a focus lens 1, a lens driving unit 2, an electronic imaging unit 3, a unit circuit 4, an imaging control unit 5, an image generation unit 6, an AF processing unit 7, and an image. A processing unit 8, a display unit 9, an image recording unit 10, an operation input unit 11, a buffer memory 12, a program memory 13, a central control unit 14 and the like are provided.
The lens driving unit 2, the imaging control unit 5, the image generation unit 6, the AF processing unit 7, the image processing unit 8, the display unit 9, the image recording unit 10, the buffer memory 12, the program memory 13, and the central control unit 14 are They are connected via a bus line 15.

  The lens driving unit 2 drives the focus lens 1 in the optical axis direction. Specifically, the lens driving unit 2 includes a driving source such as a focus motor and a driver that drives the driving source in accordance with control signals from the AF processing unit 7 and the central control unit 14 (none of which is shown). .

  The electronic imaging unit 3 is disposed on the optical axis of the focus lens 1. The electronic imaging unit 3 is composed of, for example, an image sensor such as a charge coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), and an optical image that has passed through various lenses such as the focus lens 1 is a two-dimensional image. Convert to signal.

The unit circuit 4 receives an analog imaging signal corresponding to the optical image of the subject output from the electronic imaging unit 3, receives a CDS that holds the input imaging signal, and a gain adjustment amplifier (AGC) that amplifies the imaging signal. ), An A / D converter (ADC) for converting the amplified imaging signal into a digital imaging signal, and the like.
Then, the unit circuit 4 transmits a digital imaging signal to the image generation unit 6.

  The imaging control unit 5 performs control to drive the electronic imaging unit 3 and the unit circuit 4 at a timing according to the frame rate set by the central control unit 14. Specifically, the imaging control unit 5 includes a TG (Timing Generator), a driver for driving the electronic imaging unit 3, and the like (both not shown), and controls the operation timing of the driver and the unit circuit 4 via the TG. . That is, when the central control unit 14 sets the shutter speed according to the program diagram read from the program memory 13, the TG of the imaging control unit 5 outputs the charge accumulation time corresponding to the shutter speed to the driver as a shutter pulse, The electronic image pickup unit 3 is operated in accordance with the drive pulse signal from the driver to control the charge accumulation time (exposure time).

  The focus lens 1, the electronic imaging unit 3, the unit circuit 4, and the imaging control unit 5 configured in this way constitute imaging means for imaging a subject.

  The image generation unit 6 performs processing such as γ correction processing and white balance processing on the image data sent from the unit circuit 4 and generates a luminance color difference signal (YUV data). Then, the image generation unit 6 outputs the generated image data of the luminance / color difference signal to the AF processing unit 7 and the image processing unit 8.

  The AF processing unit 7 includes an area setting unit 7a, an evaluation value calculation unit 7b, and a focus control unit 7c.

The area setting unit 7a sets an AF evaluation area A that is an evaluation area of the focus lens 1 in the live view image P1.
That is, for example, each time image data of the live view image P1 is sent from the image generation unit 6, the region setting unit 7a evaluates the focus state of the focus lens 1 in the live view image P1 with respect to the image data. Accordingly, the AF evaluation area A (see FIG. 4A, etc.) in which the AF evaluation value is calculated by the evaluation value calculation unit 7b is set. Specifically, when the imaging mode for imaging the whiteboard is set by the central control unit 14, the area setting unit 7 a switches the distance measurement method to “multi AF” and within a predetermined angle (for example, A plurality (for example, three) of AF evaluation areas A are set along the horizontal direction.
At this time, the display unit 9 superimposes on the live view image P1 and displays the AF frame W in association with each AF evaluation area A (see FIG. 4A and the like). The AF frame W may be displayed only in the AF evaluation area A that is in focus among the plurality of AF evaluation areas A,.

  As described above, the area setting unit 7a constitutes an area setting unit that sets a plurality of AF evaluation areas A in which an AF evaluation value is to be calculated along a predetermined direction in an image captured by the imaging unit.

The evaluation value calculation unit 7 b calculates an AF evaluation value related to the evaluation of the focus state of the focus lens 1.
Based on the image data of the images of the plurality of AF evaluation areas A,... Set by the area setting unit 7a, the evaluation value calculation unit 7b, for example, an AF evaluation value indicating the contrast level of the image of each AF evaluation area A Is calculated. Specifically, when the focus driving unit 7c moves the focus lens 1 from the infinity region side to the closest region side along the optical axis direction under the control of the focus control unit 7c, the evaluation value calculation unit 7b , Among a plurality of focus lens addresses that define the position of the focus lens 1 in the optical axis direction, at a distance measurement position corresponding to a predetermined number of addresses set at predetermined intervals, a plurality of AF evaluation areas A,. An AF evaluation value is sequentially calculated for each.
As described above, the evaluation value calculation unit 7b constitutes a calculation unit that calculates the AF evaluation values (focus evaluation values) for the plurality of AF evaluation areas A,... Set by the area setting unit 7a.

The focus control unit 7 c performs a focus adjustment process for adjusting the focus position of the focus lens 1.
That is, the focus control unit 7c sends a predetermined control signal corresponding to the focus lens address to the lens driving unit 2 so as to focus on a position that is farther than the center of the predetermined subject S in the live view image P1. And the focus motor is driven to adjust the focus position (focus distance) of the focus lens 1. Specifically, the focus control unit 7c outputs a predetermined control signal to the lens driving unit 2 to move the focus lens 1 from the infinite region side to the closest region side along the optical axis direction. The focus position of the focus lens 1 is adjusted based on the AF evaluation values of the plurality of AF evaluation areas A,... Sequentially calculated by the evaluation value calculation unit 7b (focus adjustment processing). More specifically, the focus control unit 7c calculates the evaluation value when moving the focus lens 1 to infinity along the optical axis direction after moving the focus lens 1 to infinity. The distance is longer than the central portion of the predetermined subject S based on at least the farthest focus distance among the focus distances for detecting the contrast peak of any AF evaluation area A sequentially calculated by the unit 7b. The focus position of the focus lens 1 is adjusted so as to focus on the position. For example, the focus control unit 7c determines changes in contrast corresponding to a plurality of AF evaluation areas A,... Sequentially calculated by the evaluation value calculation unit 7b, and corresponds to any AF evaluation area A. A control signal is output to the lens drive unit 2 that sets the distance measurement position where the contrast peak is detected as the focus position of the focus lens 1. At this time, when the focus control unit 7c detects the peak of the AF evaluation value in any of the AF evaluation areas A, the focus control unit 7c moves the focus lens 1 closer to that side, that is, moves the focus distance. It may be interrupted.

Further, the focus control unit 7c converts the right-angled quadrilateral conversion by the quadrilateral conversion processing unit 8b to the image data (YUV data) of the captured image P2 (see FIG. 4B) generated by the image generation unit 6. A determination unit c1 for determining whether to perform distortion correction processing such as processing.
Specifically, the determination unit c1 determines whether the imaging mode for imaging the whiteboard is set based on a predetermined operation of the selection determination button 11b of the operation input unit 11 by the user. It is determined whether or not to perform distortion correction processing by the quadrilateral conversion processing unit 8b on the image data (YUV data) (see FIG. 4B).
Then, when it is determined by the determination unit c1 that the distortion correction process is to be performed, the focusing control unit 7c focuses on a position where the imaging distance is farther than the central portion of the predetermined subject S as described above. A predetermined focus adjustment process is performed. On the other hand, when the determination unit c1 determines that the distortion correction process is not performed, the focus control unit 7c performs control so that the predetermined focus adjustment process is not performed.
The determination unit c1 is configured by the focus control unit 7c. However, the determination unit c1 is an example, and the present invention is not limited thereto. Whether the determination unit c1 is configured by the focus control unit 7c is arbitrarily determined. For example, it may be configured by other units such as the central control unit 14 or the determination unit c1 may be provided independently of the other configurations.

Note that the focus control unit 7 c may adjust the focus position of the focus lens 1 by moving the electronic imaging unit 3 in the optical axis direction instead of the focus lens 1.
In this way, the focus control unit 7c performs the focus adjustment processing for adjusting the focus of the imaging unit so that the focus is at a position farther than the center of the predetermined subject S in the image captured by the imaging unit. The focusing means to perform is comprised.

  The image processing unit 8 includes an encoding unit (not shown) that compresses and encodes image data (YUV data) generated by the image generation unit 6 using a predetermined encoding method (for example, JPEG method), and image recording. The image processing apparatus includes a decoding unit (not shown) that decodes the encoded image data read from the unit 10 using a decoding method corresponding to the encoding method.

  The image processing unit 8 includes a contour extraction unit 8a and a quadrilateral conversion processing unit 8b.

The contour extracting unit 8a extracts the predetermined image region R by performing the contour extracting process on the captured image P2 (see FIG. 4B) picked up by the focus adjusting process performed by the focusing control unit 7c. .
That is, the contour extraction unit 8a acquires the luminance signal Y of the YUV data of the captured image P2 of the predetermined subject S (for example, white board) generated by the image generation unit 6, for example. Then, the contour extraction unit 8a performs a straight line detection process (for example, a Hough transform process) on the luminance signal Y to detect a straight line, and a quadrangle formed by four straight lines extending in a predetermined direction. Specify as contour. Thereafter, the contour extracting unit 8a extracts the image area within the specified quadrangle as a predetermined image area R (see FIG. 4B). When a plurality of quadrangles are specified, the contour extracting unit 8a extracts image regions in the plurality of quadrangles.
As a result, a substantially rectangular (rectangular quadrilateral) image or the like of the entry area in which whiteboard characters and figures (for example, “F, F, F”, etc.) are written is extracted as the predetermined image area R. .

In addition, although the thing using a straight line detection process was illustrated as an outline extraction process, it is an example and is not restricted to this, Arbitrary arbitrary as long as predetermined image area | region R (square area | region) can be extracted Can be changed.
In addition, although the Hough conversion process is illustrated as the straight line detection process, it is an example, and the present invention is not limited to this, and can be arbitrarily changed as appropriate, such as an edge detection process. The Hough transform process and the edge detection process are well-known techniques, and thus detailed description thereof is omitted here.

The quadrangle conversion processing unit 8b performs a right-angled quadrangle conversion process (distortion correction process) on the square area extracted by the contour extraction unit 8a to generate a right-angled quadrangle image P3 (see FIG. 4C).
That is, a distorted quadrangle that does not form a right-angled quadrilateral (each interior angle is not a right angle) by capturing an image in a state where the predetermined subject S (for example, a whiteboard) and the image capturing apparatus 100 are not exactly facing each other. The image area (whiteboard entry area) is extracted as the predetermined image area R by the contour extracting unit 8a. Therefore, the quadrangle conversion processing unit 8b performs a right-angled quadrangle conversion process (for example, a predetermined image region R) extracted from the luminance signal Y of the captured image P2 of the whiteboard by the contour extracting unit 8a (for example, the predetermined image region R). A trapezoidal correction process or the like is performed to generate a rectangular quadrilateral image P3 (for example, a rectangular image, a square image, etc.). That is, the quadrilateral conversion processing unit 8b uses the short side (the side farther from the center of the predetermined subject S) as the long side of the square region (predetermined image region R) extracted by the contour extraction unit 8a. A process of relatively enlarging to match the side (the side closer to the center of the predetermined subject S) is performed to generate a right-angled quadrilateral image P3. At this time, the quadrangle conversion processing unit 8b may perform processing for relatively reducing the long side of the square region (predetermined image region R) to the short side.
In this way, the quadrilateral conversion processing unit 8b, when the contour of the predetermined subject S is a right-angled quadrilateral, this extracted contour shape according to the contour shape of the predetermined subject S extracted from the captured image. The relative enlargement ratio of the subject portion on the far side of the imaging distance is determined so as to return to the right quadrilateral by the right quadrilateral conversion processing (distortion correction processing).
Here, when a plurality of square areas are extracted by the contour extraction unit 8a, the quadrilateral conversion processing unit 8b is based on a predetermined operation of the operation input unit 11 by the user among the plurality of square areas. The rectangular region selected and designated by the central control unit 14 is subjected to a right-angled quadrangle conversion process.

Note that the trapezoid correction process is exemplified as the right-angled quadrangle conversion process, but is not limited to this example, and can be arbitrarily changed as long as it is an oblique conversion process that converts a quadrangle into a right-angled quadrilateral shape. . Since the trapezoid correction process is a known technique, detailed description thereof is omitted here.
As described above, the quadrangle conversion processing unit 8b acquires the image captured by the imaging unit that has been subjected to the focus adjustment processing by the focus control unit 7c, and performs a right-angled quadrangle conversion process on a predetermined subject in the image. To form a right-angled quadrilateral image P3.
In the above embodiment, the quadrangle conversion processing unit 8b performs the right-angled quadrangle conversion processing on the quadrilateral region extracted by the contour extraction unit 8a to generate the right-angled quadrilateral image P3. Distortion correction processing that extends this right-angled quadrangle conversion processing may be performed not only on the square area that has been made, but also on the entire captured image including the surrounding area. In this case, the generated right-angled quadrilateral image may include a peripheral region of the square region extracted by the contour extraction unit 8a.

In addition, in order to determine the conversion parameter of the right-angled quadrilateral conversion process, the outline extraction by the outline extraction unit was performed, but when the conversion parameter of the right-angled quadrilateral conversion process is determined by another method, the outline extraction process is unnecessary.
In other words, the quadrilateral conversion processing unit 8b performs the subject portion on the far side of the imaging distance according to the ratio of the imaging distance between the subject portion on the far side of the predetermined subject S and the subject portion on the near side of the imaging distance. It is also possible to determine a relative enlargement ratio for the subject portion on the side where the imaging distance is near, and to determine a conversion parameter of the right-angled quadrangle conversion process according to this enlargement ratio.
For example, even when only a part of the whiteboard is imaged without including the outline of the whiteboard, if the ratio of the imaging distance between the left edge and the right edge of the whiteboard is known, the left edge of the whiteboard in the distortion correction process And the rightmost magnification factor can be determined.
Even if the ratio of the imaging distance between the left end and the right end of the whiteboard is not known, the enlargement ratio between the left end and the right end of the whiteboard can be determined if the imaging angle of the whiteboard is known.

The display unit 9 converts the YUV data for one frame stored in the buffer memory 12 into a video signal, and then displays it as a live view image P1 on the display screen. Specifically, the display unit 9 sequentially displays the live view image P1 based on a plurality of image frames generated by capturing the subject, or displays the REC view image captured as the actual captured image.
At the time of image reproduction, the display unit 9 displays an image based on the image data read from the image recording unit 10 and decoded by the image processing unit 8.

In addition, the display unit 9 provides guidance for imaging based on the plurality of AF evaluation areas A,... Set by the area setting unit 7a when the live view image P1 is captured as a guide unit. Specifically, the display unit 9 has a plurality of AF evaluation areas A,..., In particular, the AF evaluation areas A and A at both left and right ends are farther from the center of the predetermined subject S (for example, the left end in FIG. 4). ) Is superimposed on the live view image P1 so as to be captured in a state corresponding to each of the positions close to (for example, the right end in FIG. 4), and OSD display is performed.
Here, as the guide display G, for example, as shown in FIG. 4A, a bar display for instructing an angle of view corresponding to the AF evaluation areas A at the left and right ends, or a display for instructing an adjustment of the angle of view by characters. (For example, “Please adjust the angle of view so that both ends of the whiteboard enter”).

  The guide display G by the display unit 9 is an example of an imaging guide method by the guide unit, and is not limited thereto, and can be arbitrarily changed as appropriate. For example, the imaging may be guided by human senses, in particular, hearing, touch, etc. For example, a plurality of AF evaluation areas A,... Are positions closer to a position farther than the center of the predetermined subject S. It may be possible to guide whether or not it corresponds to each by sound (voice etc.) or vibration.

  The image recording unit 10 is configured by, for example, a nonvolatile memory (flash memory). The image recording unit 10 also includes still image data and moving image data that have been compressed and encoded by a coding unit (not shown) of the image processing unit 8 using a predetermined coding method (for example, JPEG method, MPEG method, etc.). Record.

  The operation input unit 11 is for performing a predetermined operation of the imaging apparatus 100. Specifically, the operation input unit 11 is related to a subject shooting instruction, a shutter button 11a that can be half-pressed and fully pressed, a selection determination button 11b that is related to a selection instruction such as an imaging mode or a function, and a zoom amount adjustment. A zoom button (not shown) or the like according to instructions is provided, and a predetermined operation signal is output to the central control unit 14 in response to the operation of these buttons.

The operation input unit 11 outputs a designation signal for a predetermined imaging mode among a plurality of imaging modes based on a predetermined operation by the user. Specifically, the operation input unit 11 is an imaging mode for imaging a whiteboard selected based on a predetermined operation of the selection determination button 11b by the user among a plurality of imaging modes displayed on the display unit 9. A designation signal is output to the central control unit 14. When the designation signal output from the operation input unit 11 is input, the central control unit 14 sets an imaging mode for imaging the whiteboard as an imaging mode in accordance with the designation signal.
Here, the central control unit 14 and the operation input unit 11 constitute setting means for setting an imaging mode for imaging the whiteboard.

The buffer memory 12 is a buffer for temporarily storing image data and the like, and is also used as a working memory for the central control unit 14.
The program memory 13 stores various programs and data related to the functions of the imaging apparatus 100.

The central control unit 14 includes a CPU (not shown) that controls each unit of the imaging apparatus 100.
The central control unit 14 controls each unit of the imaging apparatus 100 based on the operation signal output from the operation input unit 11 and input. Specifically, when an imaging signal output according to a predetermined operation of the shutter button 11a of the operation input unit 11 is input, the central control unit 14 performs electronic control using a TG according to a predetermined program stored in the program memory 13. A process of taking a still image by controlling the drive timing of the imaging unit 3 and the unit circuit 4 is executed. One frame of YUV data stored in the buffer memory 12 by shooting this still image is compressed and encoded by the image processing unit 8 by the JPEG method or the like, and recorded as still image data in the image recording unit 10. .

Next, imaging processing by the imaging apparatus 100 will be described with reference to FIGS.
FIG. 2 is a flowchart illustrating an example of an operation related to the imaging process. FIG. 3 is a flowchart illustrating an example of an operation related to the focus adjustment process in the imaging process.
The following imaging process is a process of capturing a still image under the control of the central control unit 14, and images a whiteboard based on a predetermined operation of the selection determination button 11b of the operation input unit 11 by the user in advance. It is assumed that a desired imaging mode is selected from a plurality of imaging modes including the imaging mode to be selected.

As shown in FIG. 2, first, the central control unit 14 displays the live view image P1 on the display screen of the display unit 9 based on a plurality of image frames generated by imaging the subject (step S0).
Next, the central control unit 14 determines whether or not the set shooting mode is an imaging mode for imaging a whiteboard (step S1).
Here, if it is determined that the imaging mode is not for imaging the whiteboard (step S1; NO), that is, if it is determined that the imaging mode is other than the imaging mode for imaging the whiteboard, the central control unit 14 Controls execution of normal imaging processing (step S10).
On the other hand, when it is determined that the imaging mode is for imaging the whiteboard (step S1; YES), the central control unit 14 controls execution of the following imaging processing dedicated to the whiteboard. Accordingly, the determination unit c1 of the focusing control unit 7c determines that the distortion correction processing by the quadrilateral conversion processing unit 8b is performed on the image data (YUV data) of the captured image P2 of the whiteboard.
Then, the display unit 9 superimposes on the live view image P1, and the AF evaluation areas A at the left and right ends set by the area setting unit 7a are respectively positioned at positions closer to the position farther than the center of the predetermined subject S. A guide display G (see FIG. 4A) is performed so that imaging is performed in a corresponding state. That is, when the whiteboard is photographed at an appropriate size from an oblique direction, the AF evaluation area A is provided at each position corresponding to the left end and the right end of the whiteboard.
In the normal imaging process (step S10), the AF evaluation area is provided at a normal position that does not consider the positions of the left and right ends of the whiteboard. For example, AF evaluation areas are provided only at the central portion, or at a plurality of locations in the vertical direction, left and right, or diagonal directions slightly apart from the central portion.

Subsequently, the central control unit 14 determines whether an imaging instruction output from the operation input unit 11 is input based on a predetermined operation (for example, full pressing operation) of the shutter button 11a of the operation input unit 11 by the user. Is determined (step S2).
If it is determined that an imaging instruction has been input (step S2; YES), the AF processing unit 7 performs a focus adjustment process (see FIG. 3) for adjusting the in-focus position of the focus lens 1 (step S3). .
The focus adjustment process will be described in detail below with reference to FIG.

As illustrated in FIG. 3, the central control unit 14 outputs a predetermined control signal to the imaging control unit 5, and the imaging control unit 5 performs the electronic imaging unit 3 and the unit circuit 4 according to the predetermined control signal. Is switched so as to correspond to the driving for the automatic focusing process (AF) (step S31).
Thereafter, the focusing control unit 7c outputs a predetermined control signal to the lens driving unit 2 to move the focus lens 1 to infinity along the optical axis direction (step S32).

  Subsequently, each time the image data of the live view image P1 is sent from the image generation unit 6, the evaluation value calculation unit 7b receives a plurality of (for example, three) values set by the region setting unit 7a for the image data. ) In the AF evaluation area A,..., For example, an AF evaluation value indicating the contrast level of the image in each AF evaluation area A is calculated and acquired (step S33). The calculated AF evaluation value of each AF evaluation area A is stored in the buffer memory 12 in association with the focus lens address.

Next, the focus control unit 7c detects a contrast peak in one of the AF evaluation regions A based on the contrasts corresponding to the plurality of AF evaluation regions A calculated by the evaluation value calculation unit 7b. It is determined whether or not (step S34). If it is determined that no contrast peak is detected in any AF evaluation area A (step S34; NO), the focus control unit 7c outputs a predetermined control signal corresponding to the focus lens address. The focus lens 1 is moved to the close side along the optical axis direction by outputting to the lens driving unit 2 and driving the focus motor (step S35). Specifically, the focus control unit 7c, among a predetermined number of focus lens addresses corresponding to the ranging positions, has a predetermined lens lens corresponding to a focus lens address that causes the focal length of the focus lens 1 to be shortened by a predetermined step from infinity. A control signal is output to the lens driving unit 2. As a result, the lens driving unit 2 drives the focus motor to move the focus lens 1 toward the closest region along the optical axis direction so as to correspond to the focus lens address.
Thereafter, the central control unit 14 proceeds to step S33, and the evaluation value calculation unit 7b is set by the region setting unit 7a for the image data of the live view image P1 sent from the image generation unit 6. AF evaluation values are calculated based on the image data of a plurality of (for example, three) AF evaluation areas A,.
The above processing is executed until it is determined in step S34 that a contrast peak has been detected in any AF evaluation area A (step S34; YES).

If it is determined in step S34 that a contrast peak has been detected in any AF evaluation area A (for example, the leftmost AF evaluation area A) (step S34; YES), the focus control unit 7c A control signal is output to the lens drive unit 2 that sets the distance measurement position at which the contrast peak corresponding to any AF evaluation area A is detected as the focus position of the focus lens 1. As a result, the lens driving unit 2 stops the operation of moving the focus lens 1 closer to the closest side than the position where the contrast peak is first detected. At this time, the focus lens 1 moves slightly beyond the peak position in order to detect the peak. Therefore, in order to return the focus lens 1 to the peak position, the focus motor is driven reversely, It is moved along the axial direction to return to the distance measuring position where the peak of contrast is detected (step S36).
As described above, the focus control unit 7c adjusts the focus position of the focus lens 1 from the infinity side, and the movement of the focus lens from the position where the peak is detected to the closest side is limited. It is possible to focus in a shorter time to a position farther than the center of the predetermined subject S in the view image P1.

Thereafter, the central control unit 14 outputs a predetermined control signal to the imaging control unit 5, and the imaging control unit 5 displays the operation timing of the electronic imaging unit 3 and the unit circuit 4 according to the predetermined control signal. Switching is made so as to correspond to the drive for view display (step S37).
Thus, the focus adjustment process is finished.
The above is the focus adjustment process in the imaging process dedicated to the whiteboard, but in the focus adjustment process in the normal imaging process, control that shifts the focus to a position farther than the center portion of the predetermined subject S is particularly performed. Not done. In other words, in the normal focus adjustment process, the focus is adjusted to a position suitable for shooting a normal subject, such as the center of the subject, but in the focus adjustment process dedicated to the whiteboard, the focus position to be adjusted in the normal focus adjustment process In contrast, control is performed to shift the focus to a position that is a predetermined distance away.

  As shown in FIG. 2, the central control unit 14 then causes the imaging control unit 5 to adjust the exposure conditions (shutter speed, aperture, amplification factor, etc.), white balance, and other conditions as a predetermined subject S. An optical image of the whiteboard is picked up by the electronic image pickup unit 3 under a predetermined condition (step S4).

Subsequently, the quadrangle conversion processing unit 8b of the image processing unit 8 performs a right-angled quadrangle conversion process on the quadrangular area extracted by the contour extraction unit 8a to generate a right-angled quadrangle image P3 (see FIG. 4C). An image generation process is performed (step S5).
Specifically, the contour extraction unit 8a of the image processing unit 8 acquires, for example, the luminance signal Y of the YUV data of the captured image P2 of the whiteboard generated by the image generation unit 6 and outputs the luminance signal Y to the luminance signal Y. A straight line is detected to detect a straight line, and a quadrangle formed by four straight lines extending in a predetermined direction is specified as an outline. Thereafter, the contour extracting unit 8a extracts the image area within the specified quadrangle as a predetermined image area R (see FIG. 4B).
Subsequently, the quadrilateral transformation processing unit 8b is a rectangular quadrangle that is relatively enlarged with respect to the square region (predetermined image region R) extracted by the contour extracting unit 8a so that the short side is aligned with the long side. A right-angled quadrilateral image P3 is generated by performing shape conversion processing.

Next, the image processing unit 8 performs predetermined image processing such as contrast adjustment and smoothing processing on the image data of the right-angled quadrilateral image P3 generated by the quadrangle conversion processing unit 8b. The encoding unit (not shown) compresses and encodes the data using a predetermined encoding method (for example, JPEG method) (step S6). Thereafter, the central control unit 14 causes the image recording unit 10 to record the image data of the rectangular quadrilateral image P3 compressed and encoded by a predetermined encoding method (for example, JPEG method) (step S7).
Thereby, the imaging process is terminated.

As described above, according to the imaging apparatus 100 of the present embodiment, when the imaging mode for imaging the whiteboard is set, the distance is greater than the central portion of the predetermined subject S in the live view image P1. After the focus of the focus lens 1 is adjusted so as to be in focus, a right-angled quadrilateral image P3 is generated by performing a right-angled quadrangle conversion process (distortion correction process) on a predetermined subject S in the captured image P2. Even if the process of relatively enlarging the side farther than the center part of the predetermined subject S in the right-angled quadrangle conversion process is performed, the side farther than the center part of the predetermined subject S as in the prior art Thus, it is possible to prevent the degradation of the relative resolution with respect to other subject portions. Therefore, the balance of the resolution of the right-angled quadrilateral image P3 generated by the right-angled quadrangle conversion process can be improved in the entire range from the back side to the near side of the predetermined subject S.
In particular, for example, when the environment for imaging a predetermined subject S such as a white board is dark, it is necessary to open the aperture (small aperture value) in order to ensure proper exposure, and imaging cannot be performed with pan focus. Under such conditions, the balance of the resolution of the right-angled quadrilateral image P3 generated by the right-angled quadrangle conversion process can be improved.

  Specifically, when the focus lens 1 is moved from the infinite region side to the closest region side, the focus lens 1 is based on the AF evaluation values of the plurality of AF evaluation regions A,... Sequentially calculated by the evaluation value calculation unit. Since the focus of the subject is adjusted, the image can be picked up when the subject is focused on the side farther than the center of the predetermined subject S to which the right-angled quadrilateral transformation processing is applied. However, it is possible to save time for moving the focus lens 1 to the side closer to the distance and to speed up the focus adjustment processing.

  Further, when the live view image P1 is captured, the plurality of AF evaluation areas A,... Set by the area setting unit 7a are made to correspond to the positions that are closer to the position farther than the center of the predetermined subject S, respectively. Therefore, the user can easily adjust the AF evaluation area A to both the back side and the near side of the predetermined subject S to which the right-angled quadrangle conversion processing is performed according to the imaging guide.

The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.
Below, the modification of the imaging device 100 is demonstrated.

<Modification 1>
The imaging apparatus 200 according to the first modification takes into account the focus position of the focus lens 1 in consideration of the depth of field according to various imaging conditions (for example, focal length, imaging distance, aperture value, allowable confusion circle diameter, and the like). Adjust.
Note that the imaging apparatus 200 according to the first modification has substantially the same configuration as the imaging apparatus 100 according to the above-described embodiment except for the points described above, and a description thereof will be omitted.

That is, for example, when the focal length is long, the shooting distance (distance to the subject) is short (see FIGS. 6A and 6B), the aperture value is small, or the allowable circle of confusion is small. Since the depth of field becomes shallow, an image in front of the near point of the depth of field in the predetermined subject S in a state where the distance is farther than the center of the predetermined subject S. May become out of focus. Thereafter, the quadrilateral conversion processing unit 8b sets the short side (the side farther from the center of the predetermined subject S) of the square area extracted by the contour extracting unit 8a to the long side (the center of the predetermined subject S). If the distance is relatively large, the degree of blur is different between the side farther than the center of the predetermined subject S of the generated right-angled quadrilateral image P3 and the side closer to the distance. Even if smoothing is performed in the subsequent image processing, there may be a difference in the resolution of information such as characters and graphics.
Therefore, the focus control unit 7c moves the in-focus position of the focus lens 1 adjusted to a position farther from the center of the predetermined subject S by an amount allowed on the far point side of the depth of field. To correct.

As shown in FIG. 5, the AF processing unit 7 includes a correction condition determination unit 7d in addition to an area setting unit 7a, an evaluation value calculation unit 7b, and a focus control unit 7c.
The correction condition determination unit 7d uses the various imaging conditions (for example, focal length, shooting distance, aperture value, allowable confusion circle diameter, etc.) when capturing the live view image P1 as a reference, and the depth of front field and the rear field of view. The depth of field is calculated, and it is determined whether or not the depth of field obtained by adding the calculated forward depth of field and backward depth of field is shallower than a predetermined reference value. Note that the predetermined reference value is arbitrarily set as appropriate in consideration of, for example, the enlargement ratio on the short side of the square region by the quadrilateral conversion processing unit 8b.

  When the correction condition determination unit 7d determines that the depth of field is shallower than a predetermined reference value, the focusing control unit 7c adjusts the focus position of the focus lens 1 adjusted in the same manner as in the above embodiment. That is, the focus position of the focus lens 1 adjusted to a position farther from the center of the predetermined subject S is adjusted. Specifically, the focus control unit 7c sets the position in the optical axis direction of the focus lens 1 on the far point side of the depth of field based on the rear depth of field calculated by the correction condition determination unit 7d. The in-focus position of the focus lens 1 is corrected by moving it to the closest side (near point side) by an allowable amount.

Next, focus adjustment processing by the imaging apparatus 200 according to Modification 1 will be described in detail with reference to FIG.
Among the focus adjustment processes performed by the imaging apparatus 200 according to the first modification, the processes in steps S31 to S35 are the same as the focus adjustment processes in the above-described embodiment, and a detailed description thereof is omitted.

As shown in FIG. 7, when it is determined in step S34 that a contrast peak has been detected in any AF evaluation area A (step S34; YES), the correction condition determination unit 7d of the AF processing unit 7 Then, it is determined whether or not the depth of field when capturing the live view image P1 is shallower than a predetermined reference value (step S41). Specifically, the correction condition determination unit 7d calculates the front depth of field and the rear depth of field based on various imaging conditions (for example, focal length, shooting distance, aperture value, allowable confusion circle diameter, etc.). Then, it is determined whether or not the depth of field obtained by adding the front depth of field and the rear depth of field is shallower than a predetermined reference value.
When it is determined that the depth of field is shallower than the predetermined reference value (step S41; YES), the focus control unit 7c detects a contrast peak corresponding to any AF evaluation area A. The focus position of the focus lens 1 corresponding to the distance measurement position is corrected (step S42). Specifically, the focus control unit 7c sets the position in the optical axis direction of the focus lens 1 on the far point side of the depth of field based on the rear depth of field calculated by the correction condition determination unit 7d. The in-focus position of the focus lens 1 is corrected by moving it to the closest side (near point side) by an allowable amount.

Thereafter, the focus control unit 7 c outputs a predetermined control signal related to the focus lens address corresponding to the focus position of the corrected focus lens 1 to the lens driving unit 2. Thereby, the lens driving unit 2 drives the focus motor to move the focus lens 1 along the optical axis direction to the in-focus position of the corrected focus lens 1 (step S43).
Thereafter, the central control unit 14 shifts the processing to step S37, and the imaging control unit 5 switches the operation timing of the electronic imaging unit 3 and the unit circuit 4 so as to correspond to the driving for live view display. The focus adjustment process ends.

  When it is determined in step S41 that the depth of field is not shallower than the predetermined reference value (step S41; NO), the focus control unit 7c moves the process to step S36, and The same process as step S36 of the focus adjustment process of the embodiment is performed.

  Therefore, according to the imaging device 200 of the first modification, the focus position of the focus lens 1 is adjusted in consideration of the depth of field according to various imaging conditions. The image on the near side from the near point is in a blurred state, and the side farther than the center of the predetermined subject S of the right-angled quadrilateral image P3 generated by the right-angled quadrangle conversion process is closer to the side. The right-angled quadrangle generated by the right-angled quadrangle conversion processing in the entire range from the back side to the near side of the predetermined subject S, regardless of whether the degree of blur occurs or not The balance of the resolution of the shape image P3 can be improved.

<Modification 2>
The imaging apparatus 300 according to Modification 2 changes the content of the imaging process according to the perspective difference between the position far from the center of the predetermined subject S and the position near the distance.
Note that the imaging apparatus 300 of Modification 2 has substantially the same configuration as the imaging apparatus 100 of the above-described embodiment except for the points described above, and a description thereof is omitted.

  As shown in FIG. 8, the AF processing unit 7 includes a perspective difference determination unit 7e in addition to an area setting unit 7a, an evaluation value calculation unit 7b, and a focus control unit 7c.

The focusing control unit 7c corresponds to each AF evaluation region A based on the AF evaluation value calculated by the evaluation value calculation unit 7b for each of the plurality of AF evaluation regions A,... Set by the region setting unit 7a. The contrast peak, that is, the focus position of the focus lens 1 corresponding to each AF evaluation area A is detected.
The perspective difference determination unit 7e corresponds to a focus position of the focus lens 1 in each AF evaluation area A detected by the focus control unit 7c, specifically, a position far from the center of the predetermined subject S. Based on the in-focus position of the focus lens 1 related to the AF evaluation area A and the in-focus position of the focus lens 1 related to the AF evaluation area A corresponding to a position close to the center of the predetermined subject S. A perspective difference between a position far from the center of the subject S and a position near the distance is calculated. Then, the perspective difference determination unit 7e determines whether or not the calculated perspective difference is within a predetermined distance range defined by the first determination value and the second determination value that is larger than the first determination value. .
When the perspective difference determination unit 7e determines that the perspective difference in the predetermined subject S is within the predetermined distance range, the determination unit c1 converts the image data (YUV data) of the captured image P2 into a quadrangle. It is determined that the distortion correction process is performed by the processing unit 8b, and the focus adjustment process similar to that in the above embodiment is performed in the imaging process.

The image processing unit 8 includes a composite image generation unit 8c in addition to the contour extraction unit 8a and the quadrilateral conversion processing unit 8b.
When the perspective difference determination unit 7e determines that the perspective difference in the predetermined subject S is not within the predetermined distance range and is greater than the second determination value, the composite image generation unit 8c focuses the focus control unit 7c. Are obtained from the image generator 6 while the focus lens 1 is moved to the in-focus position of the focus lens 1 corresponding to each of the plurality of AF evaluation areas A,. Then, the composite image generation unit 8c includes an image area including the AF evaluation area A having the highest AF evaluation value from each of the plurality of images (for example, a substantially rectangular shape divided along the vertical direction at substantially equal intervals in the horizontal direction). Each of the shape image areas) is trimmed and extracted.
That is, the composite image generation unit 8c, for example, has a predetermined trimmed from an image captured by performing focus adjustment of the focus lens 1 with reference to the central AF evaluation area A among the three AF evaluation areas A,. The image is focused on the center of the subject S, and the focus evaluation of the focus lens 1 is performed with the leftmost AF evaluation area A as a reference. The focus is acquired at a position far from the center portion obtained by adjusting the focus of the focus lens 1 on the basis of the matched image area and the rightmost AF evaluation area A as a reference and trimming from the captured image.
Then, the composite image generation unit 8c generates a single composite image by combining a plurality of image regions extracted according to each AF evaluation region A.

  After that, the contour extraction unit 8a performs a contour extraction process on the composite image generated by the composite image generation unit 8c to extract a predetermined image region R.

Next, imaging processing performed by the imaging apparatus 300 according to Modification 2 will be described with reference to FIG.
Among the focus adjustment processes performed by the imaging apparatus 300 according to the second modification, the processes in steps S0 to S7 are the same as the focus adjustment processes in the above embodiment, and a detailed description thereof is omitted.

As shown in FIG. 9, when it is determined in step S2 that an imaging instruction has been input (step S2; YES), the perspective difference determination unit 7e of the AF processing unit 7 is distanced from the center of the predetermined subject S. The distance difference between the far position and the near position is detected (step S51).
Specifically, the focus control unit 7c determines the contrast peak corresponding to each AF evaluation region A based on the AF evaluation value calculated by the evaluation value calculation unit 7b for each of the plurality of AF evaluation regions A,. (Focus position of the focus lens 1 corresponding to each AF evaluation area A) is detected. Then, the perspective difference determination unit 7e is located at a focus position of the focus lens 1 in each AF evaluation area A detected by the focus control unit 7c, specifically, at a position far from the center of the predetermined subject S. Based on the in-focus position of the focus lens 1 related to the corresponding AF evaluation area A and the in-focus position of the focus lens 1 related to the AF evaluation area A corresponding to a position close to the center of the predetermined subject S, A perspective difference between a position far from the center of the predetermined subject S and a position near the distance is calculated.

Subsequently, the perspective difference determination unit 7e determines whether or not the calculated perspective difference in the predetermined subject S is within a predetermined distance range defined by the first determination value and the second determination value (step S1). S52), the process is branched according to the determination result.
Here, when it is determined that the perspective difference in the predetermined subject S is within the predetermined distance range (step S52; the perspective difference is within the predetermined distance range), the focus adjustment process similar to that in the above embodiment (step S3) is performed. In this case, since the focus position of the focus lens 1 corresponding to each of the plurality of AF evaluation areas A,... Has already been detected, the focus control unit 7c selects the focus among the plurality of AF evaluation areas A,. The focus lens 1 may be moved to a predetermined position, with the distance measurement position corresponding to the AF evaluation area A where the lens 1 is disposed on the most infinite region side as the focus position of the focus lens 1.
That is, the focus control unit 7c specifies a plurality of focus distances for detecting the peak of the AF evaluation value in the plurality of AF evaluation areas A,..., And a predetermined subject within the range of the plurality of focus distances. The focus position of the focus lens 1 is adjusted so that the focus distance is farther than the central portion of S.
Further, in the right-angled quadrangle conversion processing in the subsequent step S5, the quadrilateral conversion processing unit 8b is based on a plurality of in-focus distances in which peaks of AF evaluation values are detected in a plurality of AF evaluation areas A,. The ratio of the imaging distance between the subject part on the far side of the imaging distance and the subject part on the side of the near imaging distance is specified, and the relative part of the subject part on the far side of the imaging distance to the subject part on the near side of the imaging distance is specified. The enlargement rate may be determined.

On the other hand, when it is determined in step S52 that the perspective difference in the predetermined subject S is not within the predetermined distance range and is larger than the second determination value (step S52; the perspective difference is the second determination value). The focus control unit 7c controls the lens driving unit 2 to move the focus lens 1 to the focus position of the focus lens 1 corresponding to each of the plurality of AF evaluation areas A,. At the in-focus position of the focus lens 1, the imaging control unit 5 causes the electronic imaging unit 3 to capture an optical image of the whiteboard under predetermined imaging conditions (step S53). In other words, the optical position of the focus lens 1 is varied for each AF evaluation area A, and an optical image of the whiteboard is taken a plurality of times.
Then, after obtaining a plurality of captured images, the composite image generation unit 8c trims and extracts an image area including the AF evaluation area A having the highest AF evaluation value from each of the images, and extracts each AF. A plurality of image areas extracted according to the evaluation area A are combined to generate one combined image (step S54). That is, the composite image generation unit 8c, for example, among the three AF evaluation areas A,..., The image area focused on the center of the predetermined subject S with the center AF evaluation area A as a reference, the leftmost AF An image area that is in focus at a position far from the center with respect to the evaluation area A, and after the focus acquires an image area at a position far from the center with respect to the rightmost AF evaluation area A, these A composite image is generated by combining image regions.
Thereafter, the central control unit 14 shifts the processing to step S5, and the quadrangle conversion processing unit 8b performs a right-angled quadrangle conversion process on the quadrilateral region extracted from the composite image by the contour extraction unit 8a, thereby generating a right-angled quadrilateral. An image P3 is generated.

If it is determined in step S52 that the perspective difference in the predetermined subject S is not within the predetermined distance range and is smaller than the first determination value (step S52; the perspective difference is the first determination value). The focusing control unit 7c switches the distance measuring method to “spot AF” and controls the lens driving unit 2 to select the AF evaluation area A in the center among the plurality of AF evaluation areas A,. The focus lens 1 is moved to the focus position of the corresponding focus lens 1 (step S55).
Thereafter, the central control unit 14 shifts the processing to step S4, and the imaging control unit 5 causes the electronic imaging unit 3 to capture an optical image of the whiteboard under a predetermined imaging condition (step S4).

Therefore, according to the imaging apparatus 300 of the second modification, the perspective difference between the position far from the center of the predetermined subject S and the position near the distance, that is, the angle at which the imaging apparatus 300 captures the predetermined subject S Accordingly, the contents of the imaging process are changed, so that the right-angled quadrilateral image P3 in which deterioration of the balance of resolution is suppressed can be efficiently generated.
In particular, when it is determined that the perspective difference in the predetermined subject S is not within the predetermined distance range and is larger than the second determination value, an image area in which the center of the predetermined subject S is in focus, An image area focused at a position far from the center of the subject S, and a focus is obtained by trimming the image area from a corresponding captured image at a position far from the center of the predetermined subject S. Since a composite image is generated by combining these image areas, a composite image in focus can be generated in the entire range from the back side to the front side of the predetermined subject S. Thereafter, a right-angled quadrilateral transformation process is performed on the quadrilateral region extracted from the composite image to generate a right-angled quadrilateral image P3, whereby a right angle is obtained in the entire range from the back side to the near side of the predetermined subject S. It is possible to more suitably prevent deterioration in resolution of the right-angled quadrilateral image P3 generated by the quadrilateral conversion process.

  In the second modification, when it is determined that the perspective difference in the predetermined subject S is not within the predetermined distance range and is larger than the second determination value, the composite image is generated. Instead, a predetermined warning message indicating that the balance of resolution of the right-angled quadrilateral image P3 generated by the right-angled quadrangle conversion process is deteriorated may be displayed on the display screen of the display unit 9.

In the embodiment and each of the first and second modified examples 1 and 2, a plurality of AF evaluation areas A are considered in consideration of an enlargement ratio for each image block in distortion correction for correcting distortion of an optical image inherently generated in the lens. ,... May be specified as an AF evaluation area A to be focused.
That is, the contour extraction unit 8a performs a contour extraction process on the live view image P1 to identify a predetermined square. The quadrangle conversion processing unit 8b divides the specified predetermined rectangle into a plurality of image blocks, and calculates an enlargement ratio in the right-angled quadrangle conversion processing for each image block. In addition, the AF processing unit 7 calculates an enlargement ratio in the distortion correction processing for each image block of the predetermined quadrangle specified by the contour extraction processing, based on the distortion correction data defined for each optical zoom stage. The focus control unit 7c then calculates the AF evaluation area in the vicinity of the image block having the largest enlargement ratio based on the calculated enlargement ratio in the quadrangle quadrangle conversion process and the enlargement ratio in the distortion correction process for each image block. A is specified as the AF evaluation area A for adjusting the focus position of the focus lens 1.

Furthermore, in the above-described embodiment, the focus adjustment process is performed when the shutter button 11a of the operation input unit 11 is fully pressed. However, when the shutter button 11a is half-pressed, Regardless of whether the shutter button 11a is operated or not, it may be executed while the live view image P1 is being displayed.
Further, whether or not an imaging mode for imaging a whiteboard is provided as an imaging mode of the imaging devices 100, 200, and 300 can be arbitrarily changed as appropriate. In addition, the focus adjustment process and the image generation process are executed when the imaging mode for imaging the whiteboard is set. However, the present invention is not limited to this, and is executed in another imaging mode. May be.

  Furthermore, the configurations of the imaging devices 100, 200, and 300 are merely examples illustrated in the above-described embodiment, and are not limited thereto. Any configuration that includes at least an imaging unit, a focusing unit, and a processing unit may be used as appropriate. It can be changed arbitrarily. For example, the display unit 9 is provided as guide means for performing imaging guidance (guide display G). However, whether or not the guide means is provided can be arbitrarily changed as appropriate.

In addition, in the above-described embodiment, the functions as the processing unit, the determination unit, and the focusing unit are controlled under the control of the central control unit 14, and the quadrilateral conversion processing unit 8b and the AF processing unit of the image processing unit 8. However, the present invention is not limited to this, and may be realized by executing a predetermined program or the like by the CPU of the central control unit 14.
That is, a program including a generation processing routine, a determination processing routine, and a focusing processing routine is stored in the program memory 13 that stores the program. Then, the CPU of the central control unit 14 relatively enlarges the subject portion on the side where the imaging distance is farther than the image obtained by imaging the CPU of the central control unit 14 in a state where the imaging distance is different in each part of the subject by the generation processing routine. You may make it function as a process means which performs a distortion correction process. Further, the CPU of the central control unit 14 may function as a determination unit that determines whether to perform distortion correction processing by the processing unit on an image obtained by imaging by the imaging unit by a determination processing routine. Further, when it is determined by the focusing processing routine that the CPU of the central control unit 14 performs the distortion correction processing by the determining means, a predetermined focus adjustment processing for focusing at a position where the imaging distance is farther than the central portion of the subject. On the other hand, when it is determined by the determination means that the distortion correction process is not performed, the determination means may function as a focusing means for performing control so as not to perform the predetermined focus adjustment process.

  Similarly, the area setting unit, the calculation unit, the guidance unit, and the setting unit may be realized by executing a predetermined program or the like by the CPU of the central control unit 14.

  Furthermore, as a computer-readable medium storing a program for executing each of the above processes, a non-volatile memory such as a flash memory or a portable recording medium such as a CD-ROM is applied in addition to a ROM or a hard disk. Is also possible. A carrier wave is also used as a medium for providing program data via a predetermined communication line.

DESCRIPTION OF SYMBOLS 100 Imaging device 1 Focus lens 2 Lens drive part 3 Electronic imaging part 7 AF process part 7a Area setting part 7b Evaluation value calculation part 7c Focus control part c1 Judgment part 8 Image processing part 8b Quadrilateral conversion process part 9 Display part 11 Operation Input unit 14 Central control unit

Claims (14)

Imaging means;
Processing means for performing distortion correction processing for correcting distortion of a subject in the image;
When distortion correction processing by the processing means is performed on an image obtained by imaging by the imaging means, control is performed so as to perform predetermined focus adjustment processing for focusing on a position that is farther than the center of the subject. Focusing means to
An area setting means for setting a plurality of evaluation areas in which an in-focus evaluation value is to be calculated in an image captured by the imaging means;
Calculation means for calculating a focus evaluation value for each of the plurality of evaluation areas set by the area setting means;
With
As the predetermined focus adjustment process, the focusing unit adjusts the focus of any evaluation area sequentially calculated by the calculation unit when the focusing distance of the imaging unit is moved from the infinite region side to the closest region side. Based on at least the farthest focus distance for detecting the peak of the focus evaluation value, the focus is adjusted to focus on a position that is farther than the center of the subject. Imaging device.   The imaging apparatus according to claim 1, wherein the area setting unit sets a plurality of evaluation areas for calculating a focus evaluation value in a predetermined direction in an image captured by the imaging unit. The focusing means is
As the predetermined focus adjustment process, if the focus evaluation value peak of any one of the evaluation areas is detected while moving the focusing distance of the imaging unit from the infinite range side to the close range side, it is closer to that. The focus is adjusted so that the movement of the focusing distance to the area side is interrupted and the focusing distance at which this peak is detected or the focusing distance on the closest area side is focused by a predetermined distance from the focusing distance. The imaging apparatus according to claim 1 or 2. The focusing means is
As the predetermined focus adjustment processing, focus is adjusted to an in-focus distance that is farther from the center of the subject in a plurality of in-focus distance ranges in which peaks of in-focus evaluation values are detected in the plurality of evaluation areas. The imaging apparatus according to any one of claims 1 to 3, wherein the focus is adjusted as described above.   The processing means performs a distortion correction process for relatively enlarging a subject portion on a side with a longer imaging distance on an image obtained by imaging with different imaging distances at each part of the subject. The imaging device according to any one of claims 1 to 4. A judgment means for judging whether or not to perform distortion correction processing by the processing means on an image obtained by imaging by the imaging means;
6. The focusing device according to claim 1, wherein the focusing unit performs control so as to perform the predetermined focus adjustment process on condition that the determination unit determines to perform distortion correction processing. The imaging device according to item.   The processing means determines a relative enlargement ratio of the subject portion on the far side of the imaging distance according to a ratio of the subject distance on the far side of the subject portion and the subject portion on the near side of the imaging distance. The imaging device according to any one of claims 1 to 6, wherein   When the contour of the subject is a right-angled quadrilateral, the processing means returns the extracted contour shape to the right-angled quadrilateral by the distortion correction processing according to the contour shape of the subject extracted from the captured image. The image pickup apparatus according to claim 1, wherein a relative enlargement ratio of a subject part on a far side of the image pickup distance is determined.   9. The image processing according to claim 1, wherein the processing unit includes an image generation process for generating a right-angled quadrilateral image by performing a right-angled quadrangle conversion process on a predetermined subject in the image as the distortion correction process. The imaging device according to claim 1.   When the image is picked up by the image pickup means, a plurality of evaluation areas set by the area setting means are provided to guide the image pickup so as to correspond to positions that are far from the center of the predetermined subject. The image pickup apparatus according to claim 1, further comprising a guide unit that performs the operation. The processing means, based on a plurality of focus distances in which peaks of focus evaluation values are detected in the plurality of evaluation regions, an imaging distance between a subject part on the far side and a subject part on the near side. The image pickup apparatus according to claim 7, wherein the relative enlargement ratio is determined by specifying the ratio. It further comprises setting means for setting an imaging mode for imaging the whiteboard,
The imaging apparatus according to claim 6 , wherein the determination unit determines to perform distortion correction processing by the processing unit when the imaging mode is set by the setting unit. An imaging processing method using an imaging device including an imaging means,
Distortion correction processing for correcting distortion of the subject in the image;
When performing the distortion correction process on an image obtained by imaging by the imaging unit, a predetermined focus adjustment process for focusing on a position where the imaging distance is farther than the center of the subject;
An area setting process for setting a plurality of evaluation areas in which an in-focus evaluation value is to be calculated in an image captured by the imaging unit;
A calculation process for calculating a focus evaluation value for each of the plurality of evaluation areas set by the area setting process;
Including
In the predetermined focus adjustment process, when the focusing distance of the imaging unit is moved from the infinite region side to the closest region side, the peak of the focus evaluation value of any evaluation region sequentially calculated by the calculation processing is obtained. An imaging processing method comprising: adjusting a focal point so as to focus on a position farther than a center portion of a subject based on at least a farthest focusing distance among detected focusing distances. A computer of an imaging apparatus comprising imaging means;
Processing means for performing distortion correction processing for correcting distortion of a subject in the image;
When distortion correction processing by the processing means is performed on an image obtained by imaging by the imaging means, control is performed so as to perform predetermined focus adjustment processing for focusing on a position that is farther than the center of the subject. Focusing means,
A region setting unit for setting a plurality of evaluation regions in which an in-focus evaluation value is to be calculated in an image captured by the imaging unit;
Calculation means for calculating a focus evaluation value for each of the plurality of evaluation areas set by the area setting means;
Function as
As the predetermined focus adjustment process, the focusing unit adjusts the focus of any evaluation area sequentially calculated by the calculation unit when the focusing distance of the imaging unit is moved from the infinite region side to the closest region side. Based on at least the farthest focus distance for detecting the peak of the focus evaluation value, the focus is adjusted to focus on a position that is farther than the center of the subject. program.