JPH1196346A - Image processing method and image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor provided with the function for correcting trapezoidal distortion through simple operation. SOLUTION: This processor corrects the distortion caused in an image when there is inclination between the optical axis of a lens and an object. In this case, the processor is provided with a correcting means 10 for calculating the respective correction parameters of a correction parameter for correcting a horizontal expansion magnification corresponding to the horizontal distortion amount of the image, a correction parameter for correcting a vertical expansion magnification corresponding to the vertical distortion amount of the image, a correction parameter for correcting the vertical central axis of the image and a correction parameter for correcting the angle of the image in rotating direction and executing the correction of image data based on these correction parameters.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing method and an image processing apparatus for correcting distortion generated in an image when an optical axis of a lens of an image receiving means and a subject have an inclination.

[0002]

2. Description of the Related Art When an axis perpendicular to a subject and the optical axis of a camera lens do not coincide with each other, that is, when the optical axis of the lens of the image receiving means and the subject have an inclination, an obtained image (captured image) is obtained. ) Causes a trapezoidal distortion (hereinafter referred to as “movement”).

For example, when photographing a tall building or tower,
Such a phenomenon occurs when photographing a timetable installed at a high position.

[0004]

In order to prevent the occurrence of such a tilt, a dedicated lens or camera having a tilt mechanism is required.

However, an apparatus having such a tilting mechanism is not common. In addition, digital cameras that have become widespread in recent years are indispensable for their small size and light weight, and it is difficult to provide such a mechanism.

In a digital camera, the obtained image data can be corrected by image processing.
For example, some image processing software has a function of generating a pseudo perspective by correcting the horizontal direction of an image. However, since this function does not perform vertical correction, only an unnatural image can be obtained. Further, in order to use this function, the pointing device must be operated a plurality of times, which is very troublesome.

Further, Japanese Patent Application Laid-Open No. 6-189236 discloses a technique for correcting either the horizontal direction or the vertical direction of trapezoidal distortion.
JP-A-6-164966 and JP-A-6-38152, all of which are improvements on video output devices such as projectors. Therefore, it cannot be used for image processing of image data of a digital camera or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to realize an image processing method and an image processing apparatus having a function of correcting trapezoidal distortion with a simple operation. .

[0009]

Accordingly, the invention as a means for solving the problem is described below. (1) The invention according to claim 1 is an image processing method for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein the image processing method corrects a horizontal direction according to a horizontal distortion amount of the image. The image processing method is characterized in that the magnification of the image is changed.

In this image processing method, by changing the horizontal magnification in accordance with the amount of horizontal distortion of the image, the compressed and shortened portion of the trapezoidal distortion is extended, and the distortion is corrected to be inconspicuous. can do.

(2) The invention according to claim 2 is an image processing method for correcting distortion occurring in an image when the optical axis of a lens and a subject have an inclination, wherein the method is based on a vertical distortion amount of the image. The image processing method is characterized in that the enlargement magnification in the vertical direction is changed by changing the magnification.

In this image processing method, by changing the vertical magnification in accordance with the amount of vertical distortion of the image, the compressed and shortened portion of the trapezoidal distortion is extended, and the distortion is corrected to be less noticeable. can do.

(3) The invention according to claim 3 is an image processing method for correcting distortion occurring in an image when the optical axis of the lens and the subject have an inclination, wherein the inclination of the central axis in the vertical direction of the image is corrected. This is an image processing method characterized by correcting.

In this image processing method, by correcting the inclination of the central axis in the vertical direction of the image, the central axis inclined in the trapezoidal distortion can be corrected to be vertical, and the distortion can be corrected so as to be inconspicuous. .

(4) The invention according to claim 4 is an image processing method for correcting distortion occurring in an image when an optical axis of a lens and a subject have an inclination, and correcting an angle in a rotation direction of the image. An image processing method characterized in that:

In this image processing method, by correcting the angle in the rotation direction of the image, the rotation state accompanying the trapezoidal distortion can be restored, and the distortion can be corrected to a state in which the distortion is inconspicuous.

(5) The invention according to claim 5 is an image processing method for correcting distortion that occurs in an image when the optical axis of the lens and the subject have an inclination, wherein the method is based on the amount of horizontal distortion of the image. Correction of the horizontal magnification, vertical magnification according to the amount of vertical distortion of the image, correction of the inclination of the central axis of the image in the vertical direction, or correction of the angle in the rotation direction of the image. This is an image processing method characterized by performing correction in combination with the above.

In this image processing method, the above (1) to
By performing the correction in combination with any one of the plurality of (4), the correction can be made such that the influence of the distortion is less noticeable.

(6) The invention according to claim 6 is an image processing method for correcting distortion occurring in an image when the optical axis of a lens and a subject have an inclination, wherein the method is based on a horizontal distortion amount of the image. Correction of the horizontal magnification, vertical magnification according to the amount of vertical distortion of the image, correction of the inclination of the central axis of the image in the vertical direction, or correction of the angle in the rotation direction of the image. When performing the correction in which the corrections are combined, a correction parameter for each correction is obtained, and then a correction parameter obtained by adding the corrections is obtained, and the image data is corrected at one time.

In this image processing method, the above (1) to (1)
When performing the correction combining any of the above (4),
First, the correction parameters for each correction are obtained, a comprehensive correction parameter for each correction is obtained, and the correction is performed at once based on the comprehensive correction parameters. Can be corrected to a state in which the influence of distortion is not noticeable, without causing deterioration of.

(7) The invention according to claim 7 is an image processing apparatus for correcting distortion occurring in an image when an optical axis of a lens and a subject have an inclination, wherein the image processing apparatus adjusts the distortion in the horizontal direction of the image. And a horizontal direction correcting unit for correcting the horizontal magnification.

In this image processing apparatus, the horizontal magnification is changed in accordance with the amount of horizontal distortion of the image, so that the compressed and shortened portion of the trapezoidal distortion is extended, and the distortion is corrected to be inconspicuous. can do.

(8) An eighth aspect of the present invention is an image processing apparatus for correcting distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein the image processing apparatus corrects a distortion in an image in a vertical direction. And a vertical direction correcting means for correcting the vertical magnification.

In this image processing apparatus, by changing the magnification in the vertical direction in accordance with the amount of distortion in the vertical direction of the image, the compressed and shortened portion of the trapezoidal distortion is extended, and the distortion is corrected to be inconspicuous. can do.

According to a ninth aspect of the present invention, there is provided an image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein the inclination of a central axis in a vertical direction of the image is corrected. An image processing apparatus comprising a central axis inclination correction means for performing correction.

In this image processing apparatus, by correcting the inclination of the central axis in the vertical direction of the image, the central axis inclined in the trapezoidal distortion can be corrected so as to be vertical, and the distortion can be corrected so as to be inconspicuous. .

(10) An image processing apparatus for correcting distortion generated in an image when the optical axis of a lens and a subject have an inclination, wherein the angle of the image in the rotation direction is corrected. An image processing apparatus comprising a rotation angle correction unit for performing the rotation angle correction.

In this image processing apparatus, by correcting the angle of the image in the rotation direction, the rotation state accompanying the trapezoidal distortion can be restored, and the distortion can be corrected to a state in which the distortion is inconspicuous.

(11) The invention according to claim 11 is an image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination. Horizontal correction means for correcting the horizontal magnification according to the vertical magnification correction means for correcting the vertical magnification according to the amount of vertical distortion of the image; and An image processing apparatus comprising: a center axis tilt correction unit that corrects a tilt; and a rotation angle correction unit that corrects an angle in a rotation direction of an image.

This image processing apparatus can correct horizontal enlargement magnification, correct vertical enlargement magnification, correct the inclination of the central axis in the vertical direction, and correct the angle in the rotation direction of the image. Can be corrected to be inconspicuous.

(12) The invention according to claim 12 is an image processing apparatus for correcting distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein the amount of distortion in the horizontal direction of the image is reduced. Correction parameters relating to the correction of the magnification in the horizontal direction according to the correction, correction parameters relating to the correction of the magnification in the vertical direction according to the amount of distortion in the vertical direction of the image, and correction parameters relating to the correction of the angle in the rotation direction of the image , And correction means for obtaining a total correction parameter when correcting by combining the parameters, and performing correction of the image data based on the total correction parameter. Is an image processing apparatus.

In this image processing apparatus, it is possible to correct the magnification in the horizontal direction, to correct the magnification in the vertical direction, and to correct the angle in the rotation direction of the image. At this time, correction parameters for each correction are obtained first, and a total correction parameter (coordinate conversion correction parameter) for each correction is obtained, and correction is performed at once based on the total correction parameter. Thus, even when a plurality of corrections are performed, the correction can be made to a state in which the influence of the distortion is not noticeable, without deteriorating the image quality.

(13) An image processing apparatus for correcting distortion generated in an image when the optical axis of the lens and the subject have an inclination, wherein the distortion amount in the horizontal direction of the image is reduced. Correction parameters relating to the correction of the magnification in the horizontal direction according to the correction, correction parameters relating to the correction of the magnification in the vertical direction according to the amount of distortion in the vertical direction of the image, and correction parameters relating to the correction of the angle in the rotation direction of the image And an image processing unit for associating each of the parameters with image data.

In this image processing apparatus, the parameters of the correction of the magnification in the horizontal direction, the correction of the magnification in the vertical direction, and the correction of the angle in the rotation direction of the image are associated with the image data. If necessary, it is possible to make necessary corrections later.

[0035]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram including a configuration of each part around an image processing apparatus according to each embodiment of the present invention, and is also an example of an apparatus that performs an image processing method according to each embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes an image processing unit constituted by image processing hardware (image processing processor), image processing software and the like, and also constitutes a correction parameter calculating means and a correcting means according to the claims. And has a function of image processing described below.

A frame memory 11 stores image data to be processed and rewrites (coordinate conversion) the image. Reference numeral 12 denotes an operation unit into which various instructions and operations from the user are input, and is configured by a pointing device in addition to a key input device. Reference numeral 13 denotes an image display unit that displays an image to be processed and an image during and after processing as needed. A data storage unit 14 stores processed image data.

The image processing procedure will be described below with reference to the flowchart of FIG. 2 and the explanatory diagrams of FIG. 3 and subsequent figures.
It is assumed that the image having the trapezoidal distortion to be processed is as shown in FIG. Here, the side ab is in a reduced state due to distortion.

First, the image processing section 10 takes in input image data (FIG. 2) to be processed. Then, a coordinate reading process is performed to read the coordinates of the main subject excluding the background and the like.

The reading of the coordinates may be performed automatically by an edge emphasizing process and a clipping process, or may be performed by an operator giving an instruction from the operating unit 12.

Then, referring to the lengths of the short side (FIG. 3ab) and the long side (FIG. 3cd) in the horizontal direction, a correction parameter (horizontal direction) for making the short side the same length as the long side is set. An enlargement parameter) is calculated (S1 in FIG. 2). Note that this horizontal enlargement parameter changes according to the distance h from the long side cd. For example, assuming that the distance from cd to ab is h0, the horizontal enlargement parameter A is A = (h / h0) · (c
d / ab).

When such horizontal enlargement correction is performed, an image as shown in FIG. 4A is obtained as shown in FIG. 4B. Further, a vertical enlargement correction parameter (vertical enlargement parameter) is calculated so that the intervals between the respective parts in the vertical direction become equal (S2 in FIG. 2). Note that this vertical enlargement parameter is the same as the above-described horizontal enlargement parameter for each pixel. When such vertical enlargement correction is performed, an image as shown in FIG. 4C becomes as shown in FIG. 4D.

With respect to the image (FIG. 4E) thus corrected for the horizontal enlargement and the vertical enlargement, the inclination of the entire image (the inclination of the left and right vertical contours: the inclination of the center axis of the tilt). Is calculated (S3 in FIG. 2). When such inclination correction is performed, an image as shown in FIG.
(F).

Further, even an image which has been subjected to the horizontal enlargement, the vertical enlargement, and the inclination correction as described above may have an angle in the rotation direction (FIG. 5A). In such a case, a correction parameter (rotational inclination correction parameter) for the inclination in the rotational direction of the entire image is calculated (FIG. 2S).
4). When such a tilt correction is performed, FIG.
The image as shown in FIG. 5A is as shown in FIG.

After the correction parameters for each correction are obtained as described above, a total correction parameter for performing correction (coordinate conversion) at a time by combining the correction parameters is obtained. Correction (coordinate transformation) of the image data based on the image data (FIG. 2S)
5).

As described above, by performing the correction at once based on the comprehensive correction parameters, even when performing a plurality of corrections, the correction can be made to a state in which the influence of distortion is not noticeable, without deteriorating the image quality. .

When the correction is performed at one time, the order in which the above-described correction parameters of S1 to S4 are obtained does not matter. Therefore, the correction parameters may be obtained in another order than that shown in FIG.

Further, without obtaining all the correction parameters of S1 to S4, any one or any two
The trapezoidal distortion may be corrected by obtaining only one or three correction parameters.

Also, without performing the correction, the parameters of the correction of the magnification in the horizontal direction, the correction of the magnification in the vertical direction, and the correction of the angle in the rotation direction of the image are associated with the image data, so that the original data can be obtained. Necessary correction can be performed later while the image data is left.

By the way, when the above-described correction is performed on an image as shown in FIG. 5C, since the enlargement has been corrected, the image extends out of the original image area (FIG. 5).
((D) broken line portion) There is a possibility. In such a case,
At the stage of obtaining the correction parameters, as shown in FIG. 5E, the area of the outer frame may be enlarged so as to cover the expected size of the subject with a predetermined margin.

In the above description of the embodiment, the enlargement parameter is obtained from the difference between the short side and the long side. Alternatively, the distance from the imaging means (camera) to each part of the subject may be obtained at the time of shooting and stored together with the image data, and the distortion correction processing may be executed with reference to the distance of each part.

For example, the digital camera 100 shown in FIG. 6 uses an AF mechanism to determine a distance d1 to the upper end of the subject 200 and a distance d2 to the lower end. In this case, the horizontal (vertical) enlargement parameter A can be calculated using d1 and d2 instead of the short side ab and the long side cd.

In this case, if da, db, dc, and dd are obtained in correspondence with the four corners a to d of the subject, more accurate correction can be performed. In order to realize such a function, an existing AF mechanism may be improved, a function for measuring a distance to a corner of a subject may be provided, and distance information may be stored together with image data.

In addition to the above-mentioned AF mechanism,
A similar function can be realized by the data of the angle between the lens optical axis and the subject and the angle of view of the lens. Here, as shown in FIG. 7, when the vertical angle of view of the camera lens is α and the elevation angle of the camera is β, the distance L1 to the upper end of the subject 200 and the distance L2 to the lower end of the object 200 are represented by the following equations. Is determined by

L1: L2 = 1 / cos (β + α / 2): 1
/ Cos (β-α / 2) That is, L1 / L2 = {cos (β-α / 2)} / ｛cos (β + α /
2)｝ Therefore, by using L1 / L2, the above-described horizontal enlargement parameter and vertical enlargement parameter can be obtained.

It is also conceivable that a tilt sensor is built in the digital camera 100 and output data of the tilt sensor is stored together with image data. The tilt sensor is a sensor that includes a level and detects tilts in the vertical direction and the rotation direction. Note that an effect is obtained even with a sensor that detects any one of the inclinations.

In this case, when the object is perpendicular to the ground, the angle between the optical axis of the camera and the object can be detected using the detection result of the inclination, and the above-described parameters can be obtained. Become. Since most subjects are perpendicular to the ground, a method using this tilt sensor is also effective.

[0058]

As described in detail above, according to the inventions described in this specification, the following effects can be obtained.

(1) In the image processing method according to the first aspect, by changing the horizontal magnification in accordance with the horizontal distortion amount of the image, a portion shortened by compression in the trapezoidal distortion can be reduced. It can be stretched and corrected so that distortion is not noticeable.

(2) In the image processing method according to the second aspect, by changing the vertical magnification in accordance with the vertical distortion amount of the image, the portion shortened by compression in the trapezoidal distortion can be reduced. It can be stretched and corrected so that distortion is not noticeable.

(3) In the image processing method according to the third aspect, by correcting the inclination of the central axis in the vertical direction of the image, the inclined central axis in the trapezoidal distortion is corrected to be vertical, and the distortion is reduced. It can be corrected to be inconspicuous.

(4) In the image processing method according to the fourth aspect, by correcting the angle of the image in the rotation direction, the rotation state accompanying the trapezoidal distortion is restored, and the distortion is not noticeable. It can be corrected to the state.

(5) In the image processing method according to the fifth aspect of the present invention, by performing the correction in combination with any one of the above (1) to (4), the influence of the distortion is less noticeable. Can be corrected.

(6) In the image processing method according to the sixth aspect of the invention, when performing correction by combining any one of the above (1) to (4), a correction parameter relating to each correction is first set. In advance, a comprehensive correction parameter obtained by combining the corrections is obtained, and the correction is performed at once based on the comprehensive correction parameter. Can be corrected to a state in which the influence of is not conspicuous.

(7) In the image processing apparatus according to the seventh aspect, by changing the horizontal enlargement magnification in accordance with the horizontal distortion amount of the image, the portion compressed and shortened in the trapezoidal distortion can be reduced. It can be stretched and corrected so that distortion is not noticeable.

(8) In the image processing apparatus according to the eighth aspect, by changing the vertical enlargement magnification in accordance with the vertical distortion amount of the image, the portion compressed and shortened in the trapezoidal distortion is reduced. It can be stretched and corrected so that distortion is not noticeable.

(9) In the image processing apparatus according to the ninth aspect, by correcting the inclination of the central axis in the vertical direction of the image, the inclined central axis in the trapezoidal distortion is corrected to be vertical, and the distortion is reduced. It can be corrected to be inconspicuous.

(10) In the image processing apparatus according to the tenth aspect, by correcting the angle of the rotation direction of the image, the rotational state accompanying the trapezoidal distortion is corrected to be returned, and the distortion is not noticeable. It can be corrected to the state.

(11) In the image processing apparatus according to the eleventh aspect, the correction of the magnification in the horizontal direction, the correction of the magnification in the vertical direction, the correction of the inclination of the center axis in the vertical direction, the angle in the rotation direction of the image. Can be corrected, and the distortion can be corrected so as to be less noticeable.

(12) According to the image processing apparatus of the twelfth aspect, it is possible to correct the magnification in the horizontal direction, the magnification in the vertical direction, and the angle in the rotation direction of the image. When performing any combination of corrections, a correction parameter for each correction is determined first, and a total correction parameter (coordinate conversion correction parameter) for each correction is determined. By performing the corrections at once based on the above, it is possible to correct the plurality of corrections to a state in which the influence of the distortion is inconspicuous, without deteriorating the image quality.

(13) In the image processing apparatus according to the thirteenth aspect, each of the parameters of the correction of the magnification in the horizontal direction, the correction of the magnification in the vertical direction, and the correction of the angle in the rotation direction of the image is associated with the image data. Therefore, it is possible to perform necessary correction later while leaving the original image data.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration including a periphery of an image processing apparatus used in an embodiment of the present invention.

FIG. 2 is a flowchart showing a state of reading a radiation image according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram showing an image used in the embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating an image obtained by the correction according to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing an image obtained by the correction according to the embodiment of the present invention.

FIG. 6 is a schematic diagram showing a state of photographing for performing correction according to the embodiment of the present invention.

FIG. 7 is a schematic diagram showing a state of photographing for performing correction according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Image processing unit 11 Frame memory 12 Operation unit 13 Image display unit 14 Data storage unit

Claims (13)

[Claims] 1. An image processing method for correcting distortion occurring in an image when an optical axis of a lens and a subject have an inclination, wherein a horizontal magnification is changed in accordance with a horizontal distortion amount of the image. An image processing method comprising: 2. An image processing method for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein a magnification in a vertical direction is changed according to an amount of distortion in an image in a vertical direction. An image processing method comprising: 3. An image processing method for correcting distortion occurring in an image when an optical axis of a lens and a subject have an inclination, wherein the inclination of a central axis in a vertical direction of the image is corrected. Processing method. 4. An image processing method for correcting distortion occurring in an image when an optical axis of a lens and a subject have an inclination, wherein the angle in the rotation direction of the image is corrected. 5. An image processing method for correcting distortion occurring in an image when an optical axis of a lens and a subject have an inclination, the method comprising: correcting a horizontal enlargement magnification according to a horizontal distortion amount of an image; To perform a correction that combines any of the following: correction of the vertical magnification according to the amount of distortion in the vertical direction of the image, correction of the inclination of the central axis of the image in the vertical direction, or correction of the angle in the rotation direction of the image. The image processing method according to claim 1, wherein: 6. An image processing method for correcting distortion that occurs in an image when an optical axis of a lens and a subject have an inclination, the method comprising: correcting a horizontal magnification according to a horizontal distortion amount of an image; When performing a correction that combines any of the following: vertical magnification magnification correction according to the amount of vertical distortion of the image, correction of the inclination of the central axis of the image in the vertical direction, or correction of the angle in the rotation direction of the image. 6. The image processing method according to claim 1, further comprising: obtaining a correction parameter for each correction, obtaining a correction parameter obtained by combining the corrections, and correcting the image data at a time. 7. An image processing apparatus for correcting a distortion occurring in an image when an optical axis of a lens and a subject have an inclination, wherein the apparatus corrects a horizontal magnification according to a horizontal distortion amount of the image. An image processing apparatus, comprising: a horizontal direction correcting unit for performing the correction. 8. An image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and an object have an inclination, the correction being performed on a vertical magnification according to a vertical distortion amount of the image. An image processing apparatus comprising: a vertical direction correcting unit for performing the correction. 9. An image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein a central axis inclination correcting means for correcting an inclination of a central axis in a vertical direction of the image. An image processing apparatus comprising: 10. An image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, comprising a rotation angle correction unit for correcting an angle in a rotation direction of the image. An image processing apparatus characterized by the above-mentioned. 11. An image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, and correcting a horizontal magnification according to a horizontal distortion amount of the image. Horizontal correction means for performing vertical magnification correction in accordance with the amount of vertical distortion of the image, and vertical axis correction means for correcting the inclination of the central axis in the vertical direction of the image. An image processing apparatus, comprising: a rotation angle correction unit that corrects an angle of a rotation direction of an image. 12. An image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, and correcting a horizontal magnification according to a horizontal distortion amount of the image. Parameter calculation means for calculating correction parameters for: a correction parameter relating to correction of an enlargement magnification in a vertical direction according to a vertical distortion amount of an image; and a correction parameter relating to correction of an angle in a rotation direction of an image. An image processing apparatus, comprising: a correction unit that obtains a total correction parameter when performing correction by combining each parameter, and executes correction of image data based on the total correction parameter. 13. An image processing apparatus for correcting a distortion generated in an image when an optical axis of a lens and a subject have an inclination, wherein a correction of a horizontal magnification according to a horizontal distortion amount of the image is performed. Parameter calculation means for calculating correction parameters for: a correction parameter relating to correction of an enlargement magnification in a vertical direction according to a vertical distortion amount of an image; and a correction parameter relating to correction of an angle in a rotation direction of an image. An image processing unit for associating each parameter with image data.