JP2011239008A - Imaging apparatus, correction coefficient calculating method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus capable of setting a correction coefficient for distortion correction, simply and accurately.SOLUTION: An imaging apparatus 1 comprises: an image pickup device 10; an image processing unit 15 for processing an image signal obtained by imaging performed by the image pickup device 10; an image outputting unit 14 for displaying a picked-up image on the basis of the image signal processed by the image processing unit; an operating unit 13 for enabling a user to select an edge of an object which is to be a straight line, from the picked-up image; a correction coefficient calculating unit 17 for calculating a correction coefficient for correcting a lens distortion included in the picked-up image on the basis of a distortion amount with respect to the straight line of the edge and a distance to the edge from the center of the picked-up image; and an EEPROM 12 for storing therein the correction coefficient. In the imaging, the imaging apparatus 1 performs distortion correction on the picked-up image by using the correction coefficient stored in the EEPROM 12.

Description

  The present invention relates to an imaging apparatus, and more particularly to an imaging apparatus having a function of correcting lens distortion.

  Conventionally, in an imaging apparatus, a technique for correcting distortion of a captured image caused by aberration of an optical lens has been known. For example, Patent Document 1 discloses an invention in which a captured image is divided into a plurality of areas, and distortion correction is performed by applying a weighting coefficient that changes in accordance with the distortion correction amount for each divided area.

Japanese Patent No. 3333277

  The aberration of the optical lens varies depending on the individual imaging apparatus. In the above-described distortion correction, it is necessary to set in advance a correction coefficient to be used for distortion correction according to the optical lens used in the imaging apparatus. This correction coefficient is set by a user manually performing calibration while viewing the displayed captured image.

  However, it has been very troublesome to determine whether there is any distortion by looking at the captured image and finely adjust the correction coefficient. In addition, the determination of whether or not the captured image is distorted depends on factors such as the image used and the user's sense, and there are cases where accurate settings cannot be made.

  In view of the above background, an object of the present invention is to provide an imaging apparatus capable of setting a correction coefficient for distortion correction simply and accurately.

  An imaging apparatus according to the present invention includes an imaging element, an image processing unit that processes an image signal obtained by imaging with the imaging element, and a screen that displays a captured image based on the image signal processed by the image processing unit And an edge selection unit that allows a user to select an edge of an object that should be a straight line from the captured image, a distortion amount with respect to the straight line of the edge, and a distance from the center of the captured image to the edge, A correction coefficient calculation unit that calculates a correction coefficient for correcting lens distortion included in the captured image; and a storage unit that stores the correction coefficient, and uses the correction coefficient stored in the storage unit during imaging. It has a configuration for correcting distortion of a captured image.

  With this configuration, when the correction coefficient for correcting the distortion is calculated, the user only has to select the edge of the object shown in the captured image, so that the correction coefficient can be set easily. Further, in the conventional calibration, there is a possibility that the correction coefficient differs depending on the user who determines whether or not the captured image is distorted. Therefore, there is an advantage that it is not easily influenced by the user's sense. Note that the edge of an object that should be a straight line is an edge of an object that is expected to be straight in real space, such as a utility pole, a guardrail, or a building.

  In the imaging apparatus of the present invention, the edge selection unit displays a linear marker superimposed on the captured image at a position specified by a user, and when the confirmation of the position of the marker is input, Among the overlapping edges, an edge having a predetermined length is detected, and the detected edge is selected.

  According to the configuration of the present invention, a linear marker is displayed at a position specified by the user, and therefore it is possible to easily select an object suitable for obtaining a correction coefficient by comparing the marker with a captured image. it can.

  In the imaging apparatus according to the aspect of the invention, the edge selection unit may be configured to designate the marker only around the captured image.

  Since the amount of distortion is larger at the periphery of the image, the configuration of the present invention makes it possible to select an object edge suitable for calculating the correction coefficient. The “periphery of the captured image” can be appropriately set by the designer. For example, it can be determined such that (1) the outer side from the intermediate point from the center to the periphery of the captured image, (2) a portion that is 1/3 of the distance between the center and the periphery, from the side closer to the periphery.

  An imaging apparatus according to the present invention includes a zoom lens that forms an image of a subject on the imaging element, and a zoom magnification storage unit that stores data of a zoom magnification of the captured image, and the correction coefficient calculation unit includes the edge coefficient A correction coefficient for correcting lens distortion included in the captured image based on the amount of distortion with respect to the straight line, the distance from the center of the captured image to the edge, and the zoom magnification data stored in the zoom magnification storage unit Is calculated.

  With this configuration, since the correction coefficient is obtained in consideration of the zoom magnification of the zoom lens, the correction coefficient can be appropriately obtained even in an imaging apparatus with a zoom lens.

  The correction coefficient calculation method of the present invention is a method for obtaining a correction coefficient for performing distortion correction of a captured image at the time of imaging, and the imaging apparatus processes the image signal obtained by imaging and displays the captured image. A step in which the imaging device causes a user to select an edge of an object that should be a straight line from the captured image; and the imaging device is configured to detect the distortion amount of the edge along the straight line and the edge from the center of the captured image. And a step of calculating a correction coefficient for correcting lens distortion included in the captured image, and a step of storing the correction coefficient in a storage unit. .

  With this configuration, the correction coefficient can be determined simply and accurately as in the above-described imaging apparatus. Note that various configurations of the above-described imaging apparatus can be applied to the correction coefficient calculation method of the present invention.

  The program of the present invention is a program for obtaining a correction coefficient for correcting distortion of a captured image at the time of imaging, and processing the image signal obtained by imaging on a computer to display the captured image , Including the step of causing the user to select an edge of an object that should be a straight line from the captured image, the amount of distortion with respect to the straight line of the edge, and the distance from the center of the captured image to the edge. And a step of calculating a correction coefficient for correcting the lens distortion, and a step of storing the correction coefficient in a storage unit.

  With this configuration, the correction coefficient can be determined simply and accurately as in the above-described imaging apparatus. Various configurations of the above-described imaging apparatus can be applied to the program of the present invention.

  According to the present invention, the correction coefficient can be set simply and accurately simply by selecting the edge of the object shown in the captured image.

The figure which shows the structure of the imaging device of 1st Embodiment Figure showing a marker display example (A) The figure which shows the example of the distortion called "ball shape distortion", (b) The figure which shows the example of the distortion called "pin cushion distortion" Diagram showing the amount of distortion for the straight line of the selected edge The figure which shows the operation | movement of the correction coefficient setting by the imaging device of 1st Embodiment The figure which shows the structure of the imaging device of 2nd Embodiment The figure which shows the operation | movement of the correction coefficient setting by the imaging device of 1st Embodiment

An imaging apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an imaging apparatus 1 according to the first embodiment. The imaging device 1 includes an imaging device 10, a processor 11, an EEPROM 12 that is a storage unit, an operation unit 13, and an image output unit 14. In FIG. 1, one processor 11 is shown. However, in an actual apparatus, for example, the function of the processor 11 is achieved by a plurality of processors such as an FEP (Front End Processor), a DSP (Digital Signal Processor), and a camera CPU. It may be realized. The image sensor 10 has a function of imaging a subject and outputting an image signal. The image sensor 10 inputs an image signal to the processor 11.

  The processor 11 includes an image processing unit 15 that processes an image signal obtained by the image sensor 10, a marker display unit 16 that displays a linear marker superimposed on the captured image, and a correction coefficient for performing distortion correction. Each function of the correction coefficient calculation unit 17 for calculating? The marker display unit 16 moves the linear marker vertically and horizontally based on operation data from the operation unit 13. The marker may be controlled not to be displayed near the center of the captured image. This is because the vicinity of the center of the captured image has a small distortion and is not suitable for calculating a correction coefficient for distortion correction.

  FIG. 2 is a diagram illustrating a display example of markers superimposed on a captured image. In the example shown in FIG. 2, markers M1 and M2 extending vertically and horizontally are displayed. By the user's operation, the marker M1 extending in the vertical direction moves in the horizontal direction, and the marker M2 extending in the horizontal direction moves in the vertical direction. In the present embodiment, the two markers M1 and M2 are used, but one of the vertical and horizontal markers may be used.

  When the user inputs confirmation from the operation unit 13 with the markers M1 and M2 superimposed on the edges of the object, the correction coefficient calculation unit 17 calculates the correction coefficient from the portion of the captured image that overlaps the markers M1 and M2. Detect edges for. Here, the correction coefficient calculation unit 17 detects an edge having a predetermined length. By comparing an edge having a predetermined length with a straight line, the distortion amount of the edge can be obtained appropriately. The predetermined length can be set appropriately by design. For example, the length may be set to be half the screen length or 2/3 the screen length.

  FIG. 3A and FIG. 3B are diagrams showing examples of distortion. FIG. 3A shows an example of distortion called “barrel distortion”, and FIG. 3B shows an example of distortion called “pin cushion distortion”. As shown in FIGS. 3A and 3B, since the distortion pattern is known, if the distortion amount at a certain position in the image is known, the distortion amount at another position can be obtained by calculation.

  FIG. 4 is a diagram illustrating a distortion amount with respect to a straight line of a selected edge. The selected edge is a straight line in the real space, but appears to be distorted with respect to the straight line due to the distortion caused by the aberration of the optical lens. The correction coefficient calculation unit 17 calculates a distortion amount with respect to the straight line of the edge selected by the user, and calculates a correction coefficient for correcting the edge into a straight line based on the calculated distortion amount. Further, the correction coefficient calculation unit 17 calculates a correction coefficient at a position other than the position where the straight line exists based on the position of the edge and the amount of distortion.

  The processor 11 has various functions necessary for the imaging apparatus 1 in addition to the functions described above, but is not illustrated in FIG. Each function of the processor 11 is realized by reading and executing a program. Such a program is also included in the scope of the present invention.

  The EEPROM 12 stores the correction coefficient calculated by the correction coefficient calculation unit 17. The EEPROM 12 stores various setting values for performing image processing in addition to the correction coefficient for distortion correction.

  The operation unit 13 is configured by a switch, a dial, or the like that receives a user operation. The operation unit 13 accepts operations such as a release operation at the time of image capturing, image switching at the time of preview of a captured image, enlargement, reduction, and the like. In addition, the operation unit 13 receives a correction coefficient setting operation for distortion correction. The image output unit 14 has a function of displaying a preview of the captured image and various setting values of the imaging device 1.

  When selecting an edge to be used for setting a correction coefficient for distortion correction, the marker is displayed on the screen 14 by the marker display unit 16, the marker displayed by the operation by the operation unit 13 is moved, and the position is determined. Therefore, the marker display unit 16 and the operation unit 13 correspond to an edge selection unit that receives selection of an edge.

  The correction coefficient for distortion correction may be set once when the use of the imaging apparatus 1 is started. When performing imaging, the imaging apparatus 1 performs distortion correction of the captured image in the image processing unit 15. The image processing unit 15 reads the correction coefficient stored in the EEPROM 12 and performs distortion correction by multiplying the captured image by the correction coefficient.

  FIG. 5 is a diagram illustrating an operation for calculating the correction coefficient by the imaging apparatus 1. The imaging device 1 first performs imaging (S10), and displays a captured image obtained by imaging on a display device (not shown) via the image output unit 14 (S12). Next, the imaging apparatus 1 displays a marker superimposed on the captured image in accordance with a user instruction input from the operation unit 13 (S14). When the imaging device 1 receives an input for determining the marker position from the operation unit 13 (S16), the imaging device 1 detects an edge from a portion overlapping the marker (S18). The detected edge is an edge of an object that is expected to be a straight line in the real space, and is an edge that is displayed in a straight line in a captured image if there is no distortion. The imaging apparatus 1 calculates a correction coefficient for correcting the distortion based on the detected distortion amount with respect to the straight line of the edge (S20), and stores the calculated correction coefficient in the EEPROM 12 (S22). The configuration and operation of the imaging device 1 according to the first embodiment have been described above.

  The imaging apparatus 1 according to the first embodiment accepts selection of an edge of an object used for correction coefficient calculation using a marker superimposed and displayed on a captured image, and corrects the received edge of the object to a straight line. Find the correct correction factor. Thus, the user can easily set the correction coefficient for distortion correction only by selecting an edge that should be a straight line. In addition, according to this method, if an edge of an object that is known to be “straight” is selected, a correction coefficient is set using the edge of the object, so that the correction coefficient can be sensed by the user. Hard to be influenced.

(Second Embodiment)
FIG. 6 is a diagram illustrating a configuration of the imaging device 2 according to the second embodiment. The basic configuration of the imaging apparatus 2 of the second embodiment is the same as that of the first embodiment, but the imaging apparatus 2 has a zoom lens 18 in the second embodiment. Is different. The processor 11 also has a zoom magnification control unit 19 that changes the zoom magnification in accordance with an operation from the operation unit 13. The zoom magnification control unit 19 stores the current zoom magnification data in a register in the processor 11.

  The amount of distortion caused by the aberration of the optical lens varies depending on the zoom magnification. That is, if the zoom magnification is increased, the field of view to be captured is narrowed, so that distortion is less likely to occur. If the zoom magnification is low, the field of view to be imaged is widened and distortion is likely to occur. In the second embodiment, the correction coefficient for distortion correction is calculated also using the zoom magnification. In the imaging device 2 according to the second embodiment, the image processing unit 15 corrects the distortion of the captured image when performing imaging. The image processing unit 15 reads a correction coefficient corresponding to the zoom magnification of the captured image from the EEPROM 12 and performs distortion correction by multiplying the captured image by the correction coefficient.

  FIG. 7 is a diagram illustrating an operation for setting the correction coefficient by the imaging apparatus 2. First, the imaging device 2 performs imaging (S10). The imaging device 2 stores the zoom magnification data of the zoom lens 18 at the time of imaging in a register (S11). The imaging device 2 displays a captured image obtained by imaging on a display device (not shown) via the image output unit 14 (S12). Next, the imaging device 2 displays a marker superimposed on the captured image in accordance with a user instruction input from the operation unit 13 (S14). When the imaging device 2 receives an input for determining the marker position from the operation unit 13 (S16), the imaging device 2 detects an edge from a portion overlapping the marker (S18). The detected edge is a straight edge in the real space, and is an edge displayed in a straight line even in the captured image if there is no distortion. The imaging device 2 calculates a correction coefficient for correcting the distortion based on the detected distortion amount with respect to the straight line of the edge (S20). Here, the correction coefficient calculation unit 17 calculates the correction coefficient in consideration of the zoom magnification data obtained when the image stored in the register is captured. The correction coefficient calculation unit 17 stores the calculated correction coefficient in the EEPROM 12 (S22). The configuration and operation of the imaging device 2 according to the second embodiment have been described above.

  As in the first embodiment, the imaging apparatus 2 according to the second embodiment can easily set the correction coefficient for distortion correction only by the user selecting an edge that should be a straight line. At the same time, the correction coefficient can be set less susceptible to the user's sense.

  In addition, since the imaging apparatus 2 according to the second embodiment determines the correction coefficient in consideration of the zoom magnification, a simple correction coefficient setting can be realized even in the imaging apparatus 2 that can change the zoom magnification. Is possible.

  In the second embodiment, in the mode for setting the correction coefficient, the imaging apparatus 2 may perform imaging while minimizing the zoom magnification, that is, maximizing the imaging range. As the zoom magnification is smaller, the distortion included in the captured image becomes larger. With this configuration, an image suitable for obtaining a correction coefficient for distortion correction can be obtained.

  Although the imaging apparatus of the present invention has been described in detail with reference to the embodiment, the present invention is not limited to the above-described embodiment.

  In the above-described embodiment, the example in which the marker is displayed and the selection of the edge of the object that should be a straight line is received has been described. However, the user interface that receives the selection of the edge of the object that should be a straight line is not limited to the marker display. For example, an edge having a predetermined length may be detected from the captured image, the detected edges may be focused in order, and the user may select a desired edge. A display device may be provided in the imaging device. When the display device uses a touch panel, the user may instruct a desired edge on the screen.

  The present invention has an excellent effect that a correction coefficient can be set simply and accurately simply by selecting an object shown in a captured image, and has a function of correcting image distortion caused by distortion of an optical lens. It is useful as a device.

1, 2 Imaging device 10 Imaging element 11 Processor 12 EEPROM
13 Operation unit 14 Image output unit 15 Image processing unit 16 Marker display unit 17 Correction coefficient calculation unit 18 Zoom lens 19 Zoom magnification control unit

Claims (6)

An image sensor;
An image processing unit for processing an image signal obtained by imaging by the imaging device;
An image output unit for displaying a captured image based on the image signal processed by the image processing unit;
An edge selection unit that allows a user to select an edge of an object that should be a straight line from the captured image;
A correction coefficient calculation unit that calculates a correction coefficient for correcting lens distortion included in the captured image based on a distortion amount with respect to the straight line of the edge and a distance from the center of the captured image to the edge;
A storage unit for storing the correction coefficient;
With
An imaging apparatus that performs distortion correction of a captured image using a correction coefficient stored in the storage unit during imaging. The edge selector is
A linear marker is displayed in a position designated by the user so as to be superimposed on the captured image, and when the confirmation of the position of the marker is input, a predetermined length of the edge reflected on the marker is set. The imaging apparatus according to claim 1, wherein an edge having the detected edge is detected and the detected edge is selected.   The imaging apparatus according to claim 2, wherein the edge selection unit can designate the marker only in the periphery of the captured image. A zoom lens that forms an image of a subject on the image sensor;
A zoom magnification storage unit for storing zoom magnification data of the captured image,
The correction coefficient calculator is
In order to correct lens distortion included in the captured image based on the distortion amount of the edge with respect to the straight line, the distance from the center of the captured image to the edge, and the zoom magnification data stored in the zoom magnification storage unit The imaging apparatus according to claim 1, wherein the correction coefficient is calculated. A method for obtaining a correction coefficient for correcting distortion of a captured image at the time of imaging,
An imaging device processing an image signal obtained by imaging to display a captured image;
The imaging device causing a user to select an edge of an object that should be a straight line from the captured image; and
The imaging device calculating a correction coefficient for correcting lens distortion included in the captured image based on a distortion amount with respect to the straight line of the edge and a distance from the center of the captured image to the edge;
The imaging device storing the correction coefficient in a storage unit;
A correction coefficient calculation method comprising: A program for obtaining a correction coefficient for correcting distortion of a captured image at the time of imaging,
Processing an image signal obtained by imaging and displaying the captured image;
Causing the user to select an edge of an object that should be a straight line from the captured image;
Calculating a correction coefficient for correcting lens distortion included in the captured image based on a distortion amount with respect to the straight line of the edge and a distance from the center of the captured image to the edge;
Storing the correction coefficient in a storage unit;
A program that executes

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