JP2004086747A - Method for measuring distortion aberration and image processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate distortion aberration from picture data and to correct the distortion aberration. <P>SOLUTION: Photographed picture data are processed by edge extraction processing and thinning processing to obtain many segments. Respective segments are identified and the distortion aberration coefficient of each segment is calculated while supposing that a part of a straight line of each segment is distorted. These distortion aberration coefficients are statistically processed to estimate a distortion correction coefficient. Projection conversion processing is applied to the picture data by using the distortion correction coefficient to obtain corrected picture data. Even in the case of the picture data of a general natural image in which the characteristics of a photographing lens 21 are unknown, the distortion aberration of the picture data can be corrected. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a distortion aberration measuring method and an image processing apparatus capable of measuring and correcting distortion of image data.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known a method of electrically correcting image data with respect to a distortion of a photographing lens having an aberration in which a square object photographed by a photographing lens is deformed into a pin shape or a barrel shape.
[0003]
For example, there is known a method of electrically correcting an image based on data recorded in advance with respect to distortion of a photographing lens of an electronic still camera (for example, see Patent Document 1).
[0004]
The configuration described in Patent Document 1 includes a memory (RAM) for recording image data, a microcomputer for performing correction processing during reproduction, and a ROM in which data for lens distortion processing is recorded in advance. In this configuration, distortion information of the photographing lens is recorded together with each image data, and correction is performed based on the distortion information when reproducing the image data.
[0005]
However, in this configuration, it is necessary to measure and record distortion information of the photographing lens in advance, and it is applicable only to a specific photographing lens, and has a problem of low versatility.
[0006]
In this regard, a television camera that measures a lens distortion correction process in advance and does not record the data in a ROM or the like, shoots a specific reference target object, calculates a distortion coefficient from this image data, and performs correction. A configuration of a data processing device is known (for example, refer to Patent Document 2).
[0007]
In the configuration described in Patent Document 2, an object called a master work is photographed, the center coordinates of the photographing lens are calculated from the photographed image data, and the distortion rate of the photographing lens is corrected based on the center coordinates. A distortion correction coefficient is calculated.
[0008]
However, in this configuration, it is necessary to perform a complicated operation of photographing a specific target object as a reference and calculating a distortion correction coefficient, and has a problem of low versatility.
[0009]
[Patent Document 1]
Japanese Patent Publication No. 5-15111 (Table 1-3, Fig. 5)
[0010]
[Patent Document 2]
JP-A-7-15647 (FIGS. 1 to 5)
[0011]
[Problems to be solved by the invention]
In the configuration using the data for the lens distortion processing as in the conventional case, it is necessary to measure and record the distortion information of the photographing lens in advance, and there is a problem of low versatility. In addition, in a configuration in which a specific reference object is photographed and a distortion coefficient is calculated from the image data to perform correction, it is necessary to photograph the specific reference object, which has a problem of low versatility. are doing.
[0012]
The present invention has been made in view of such a point, and an object of the present invention is to provide a distortion aberration measuring method and an image processing apparatus capable of easily correcting distortion.
[0013]
[Means for Solving the Problems]
2. The distortion aberration measuring method according to claim 1, wherein: a boundary extraction step of extracting a boundary component of the image data as a line segment; a line segment identification step of individually identifying the plurality of extracted line segments; A distortion coefficient calculating step of calculating a distortion aberration coefficient assuming that a part of a straight line is distorted, and statistically processing the calculated distortion aberration coefficients to calculate a distortion of the image data. And a correction coefficient estimating step of estimating a distortion correction coefficient to be corrected.
[0014]
In this configuration, a distortion correction coefficient for correcting the distortion of the image data is estimated from the image data. The distortion can be corrected automatically or manually using the distortion correction coefficient. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion is easily corrected.
[0015]
According to a second aspect of the present invention, in the distortion aberration measuring method of the first aspect, the statistical processing in the correction coefficient estimation step uses at least one of average value calculation, variance calculation, and histogram creation. is there.
[0016]
In this configuration, the distortion correction coefficient is estimated by using one or a combination of the average value calculation, the variance calculation, and the histogram creation.
[0017]
According to a third aspect of the present invention, in the distortion aberration measuring method according to the first or second aspect, among the plurality of line segments individually identified in the line segment identifying step, a relatively short line segment has a distortion coefficient. The method includes a filter step of excluding from the calculation target of the distortion aberration coefficient in the calculation step.
[0018]
In this configuration, a relatively short line segment, which is likely to have no valid information or a line segment in which a calculation error becomes large, is excluded from the calculation of the distortion aberration coefficient. The correction coefficient is accurately estimated.
[0019]
5. The image processing apparatus according to claim 4, wherein: a boundary extracting unit that extracts a boundary component of the image data as a line segment; a line segment identifying unit that individually identifies the plurality of extracted line segments; Distortion coefficient calculating means for respectively calculating a distortion coefficient assuming that a part of the straight line is distorted, and statistically processing the calculated distortion coefficients to correct the distortion of the image data Correction coefficient estimating means for estimating the distortion correction coefficient to be performed.
[0020]
In this configuration, a distortion correction coefficient for correcting the distortion of the image data is estimated from the image data. The distortion can be corrected automatically or manually using the distortion correction coefficient. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion is easily corrected.
[0021]
An image processing apparatus according to a fifth aspect of the present invention is the image processing apparatus according to the fourth aspect, further comprising a projection conversion unit that corrects distortion of image data based on the estimated distortion correction coefficient.
[0022]
In this configuration, the distortion of the image data is automatically corrected by the projective transformation means.
[0023]
According to a sixth aspect of the present invention, in the image processing apparatus of the fourth aspect, a correction coefficient display means for displaying an estimated distortion correction coefficient and a distortion correction coefficient for correcting distortion of image data are arbitrarily set. It comprises a possible correction coefficient setting means and a projection conversion means for correcting distortion of image data based on the set distortion correction coefficient.
[0024]
In this configuration, the distortion is corrected to an arbitrary degree with reference to the displayed distortion correction coefficient.
[0025]
According to a seventh aspect of the present invention, in the image processing apparatus according to any one of the fourth to sixth aspects, the correction coefficient estimating means can execute a plurality of statistical processes, and any of the statistical processes can be selected. It is provided with possible statistical processing selection means.
[0026]
In this configuration, the distortion correction coefficient can be accurately estimated or high-speed processing can be performed by arbitrarily selecting the statistical processing based on the properties of the image data.
[0027]
An image processing apparatus according to an eighth aspect is the image processing apparatus according to any one of the fourth to seventh aspects, further comprising an output unit including at least one of a display unit that displays image data and a printing unit that prints the image data. It was done.
[0028]
In this configuration, the distortion correction coefficient is estimated for the image data output by the output unit, and the distortion can be corrected. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion is easily corrected.
[0029]
An image processing apparatus according to a ninth aspect is the image processing apparatus according to any one of the fourth to eighth aspects, further comprising an optical system having a photographing lens, and an imaging mechanism capable of capturing and outputting image data. is there.
[0030]
In this configuration, the distortion correction coefficient is estimated for the image data captured by the imaging lens, and the distortion can be corrected. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion is easily corrected.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an image processing apparatus according to the present invention will be described with reference to the drawings.
[0032]
In addition, in this specification, a line segment is described as including not only a part of a straight line but also a curve.
[0033]
1 and 2, reference numeral 10 denotes an image processing apparatus. The image processing apparatus 10 includes an imaging mechanism 11, which is a camera, a data processing apparatus 12, a display device 13 that forms output means, and a printing apparatus 14 that forms output means. A digital still camera is configured by combining recording means, operating means, and the like (not shown) integrally or separately.
[0034]
Then, as shown in FIG. 1, the image processing apparatus 10 captures an imaging target S such as a landscape with an imaging mechanism 11, and inputs digital image data as a general natural image to a data processing apparatus 12. Then, the data processing device 12 temporarily stores the data, makes an appropriate correction, displays the data on the display device 13, prints the data with the printing device 14, and stores the data in the recording means.
[0035]
As shown in FIG. 2, the imaging mechanism 11 includes an imaging lens 21 that forms an optical system that is an optical imaging system, an aperture (not shown), an imaging device 22 such as a CCD that is an imaging unit, and an image signal processing circuit 23. And so on. Then, in the imaging mechanism 11, an image (a general natural image) of the imaging target S is formed on the imaging element 22 by the imaging lens 21. The analog image data output from the image sensor 22 is subjected to signal amplification processing, that is, gain adjustment, sampling processing, analog-digital (A / D) conversion processing, interpolation processing, color processing, and the like in an image signal processing circuit 23. Is performed, and the digitally converted image data is output.
[0036]
The data processing device 12 includes a CPU and the like, and includes an image buffer memory 31, a boundary extraction unit 32, a line segment identification unit 33, a distortion coefficient calculation unit 34, a correction coefficient estimation unit 35, a projection conversion unit 37, and the like. Have. Then, the image buffer memory 31 temporarily records the image data output from the imaging mechanism 11 as an uncorrected image, and stores the distortion-corrected image data in a recording unit, the display device 13, or the printing device 14. This is temporarily recorded before output. The boundary extracting means 32 extracts a boundary component of the image data as a line segment from the image data recorded in the image buffer memory 31, and performs edge extraction processing and thin line processing so that the subsequent processing proceeds smoothly. A line segment is obtained by performing a conversion process. The line segment identification unit 33 individually identifies a plurality of extracted line segments, and performs a labeling process on the line segment obtained by the boundary extraction unit 32 in order to prevent overlapping of the processes. It is. Further, the distortion coefficient calculating means 34 calculates a distortion aberration coefficient on the assumption that each of the identified (labeled) line segments is partially distorted. The correction coefficient estimating means 35 statistically processes the calculated distortion aberration coefficients to estimate a distortion correction coefficient for correcting the distortion of the image data. From the processing result, the tendency of each distortion aberration coefficient is grasped, and the distortion correction coefficient is estimated. Here, the statistical processing includes, for example, calculation of an average value or histogram creation processing. Further, the projection conversion means 37 corrects the distortion of the image data based on the estimated distortion correction coefficient. Further, although not shown, the operation means is provided with a selection switch or the like for selecting whether to automatically or manually correct the image data of the data processing device 12.
[0037]
The display device 13 includes, for example, a liquid crystal display panel, and the printing device 14 includes, for example, a color inkjet printer.
[0038]
Next, the operation of the data processing device 12 will be described with reference to the flowcharts of FIGS.
[0039]
First, image data (original image data) B0, which is an uncorrected image, is fetched from the imaging mechanism 11 into the image buffer memory 31 (step 1). Next, automatic correction or manual correction is performed according to the state of a selection switch as selection means for selecting whether to perform automatic correction or manual correction (step 2).
[0040]
Then, when the selection switch is an automatic correction, the image data of the photographed general natural image is subjected to a boundary extraction step, that is, an edge extraction processing, a thinning processing using a generally performed method, Obtain a number of line segments (step 3). This is because an uncorrected image captured by the imaging lens 21 includes a lot of information in addition to the information of interest and is difficult to handle as it is. Therefore, in order to smoothly perform the subsequent calculation processing, the uncorrected image data B0 recorded in the image buffer memory 31 is subjected to differential filter processing, binarization filter processing, isolated point removal filter processing, and connection point search. An edge extraction thinning process for extracting a boundary component of the image data B0 as a line segment is performed using a general image processing technique such as a process.
[0041]
Next, a line segment identification process, that is, a labeling process is performed on the line segment in the extracted image data in order to prevent the distortion coefficient calculation process from being applied to the same line segment redundantly (step 4). In the labeling process or the like, a relatively short line segment may be excluded from the labeling, and a filtering process may be performed to exclude the line segment from the target of the subsequent processes (step 5). Here, a relatively short line segment refers to a line segment that has a high possibility that it does not have valid information or that has a large calculation error. By performing this filtering step, it is possible to improve the accuracy of estimating the distortion correction coefficient and to speed up the processing.
[0042]
Then, a distortion coefficient calculating step of calculating a distortion coefficient is performed on the line segment on which the labeling process has been performed (step 6), and it is confirmed whether the distortion coefficient has been calculated on all the labeled line segments (step 6). 7). In the distortion coefficient calculation step and the following steps, it is assumed that a part of the straight line is distorted for each of the identified line segments, that is, all the line segments of the image data are part of the straight line in the photographing target S. , And the third-order or third-order or higher order distortion aberration coefficient is calculated. The method of calculating the distortion coefficient is based on a conventionally known method. For example, a state in which the imaging lens has distortion is an actual state, a state in which the imaging lens is free from distortion is an ideal state, and a method in which image data is specified. If the position of the image is called an image point, the amount of distortion, which is the distance between the image point in the actual state and the image point in the ideal state, is the cube of the distance from the optical axis center of the taking lens to the image point in the ideal state. (The third order), and this proportionality constant is used as a distortion aberration coefficient (distortion correction coefficient).
[0043]
When calculating the distortion aberration coefficient, since the position of the center of the optical axis of the taking lens must be known with respect to the image, it is assumed that the center of the image is the center of the optical axis of the taking lens. Perform the calculation. Also, when the optical axis center position can be calculated with high accuracy from the image data, such as when there are a plurality of pairs of parallel lines in the image data, or when the optical axis center of the photographing lens is clearly shifted from the center of the image, Alternatively, the center position of the optical axis of the photographing lens can be calculated and used from image data by some method.
[0044]
Here, when the distortion coefficient is calculated by the above method when a general natural image is captured, a plurality of distortion coefficients corresponding to each line segment are obtained. That is, it is assumed that the line segment is a part of a straight line in the photographing target S, but the general natural image includes a line segment that is not a straight line.
[0045]
Therefore, in order to estimate the distortion correction coefficient for the photographing lens 21 that has photographed the general natural image, the characteristics of the general natural image and the characteristics of the photographing lens 21 are calculated for a plurality of distortion aberration coefficient groups calculated in the distortion coefficient calculating step. , A statistical process (statistical process) using a statistical method is performed, and a correction coefficient estimation process of a distortion correction coefficient for a general natural image is performed. Here, the statistical processing is necessary for estimating a distortion correction coefficient from a plurality of distortion aberration coefficient groups by a processing of calculating an average value, calculating a variance, and creating a histogram, singly or in combination. Processing.
[0046]
Here, it is expected that the following properties of general natural images can be used by statistical processing. That is, in general natural images, it is generally considered that a subject often has a line segment that is a part of a straight line. For example, when an artificial object such as an outer shape of a building or a window frame is selected as a subject, it can be assumed that the subject often includes a straight line. In addition, for a subject including such a straight line, distortion is more easily recognized by a human, and therefore, it is effective to correct the distortion. If the tendency of the distortion aberration coefficient group cannot be obtained, it is considered that the subject has few linear portions. Since it is considered that the image data of the subject having a small number of straight lines is unlikely to be distorted by humans, it is possible not to perform the correction.
[0047]
Then, using the result of such statistical processing, a correction coefficient estimation step of estimating the distortion correction coefficient, that is, a correction coefficient estimation processing is performed, that is, it is determined that the distortion correction coefficient is appropriate according to the result of the statistical processing on a large number of distortion aberration coefficients. Is used as a distortion correction coefficient for the photographing lens 21 that has photographed the image data. In the present embodiment, as the correction coefficient estimation processing, the following three processings are performed, and three distortion correction coefficients a, b, and c can be obtained.
[0048]
First, as the distortion correction coefficient a, an average value of a plurality of distortion aberration coefficients obtained in the distortion coefficient calculation step is adopted (steps 8 and 9). In addition, the distortion correction coefficient b is determined by calculating the method of the distortion correction coefficient a, that is, when calculating the average value, by creating a histogram showing the relationship between the distortion aberration coefficient value and the frequency shown in FIG. The distortion coefficient which does not exceed the threshold value f, that is, the infrequent distortion coefficient is excluded from the statistical calculation, that is, the calculation of the average (steps 12 to 15). Further, as the distortion correction coefficient c, a histogram showing the relationship between the value of the distortion aberration coefficient and the frequency shown in FIG. 7 is created, and the distortion aberration coefficient having the maximum frequency is adopted as the distortion correction coefficient (step 18). -20).
[0049]
Then, using the distortion correction coefficients a, b, and c estimated in the correction coefficient estimation processing, the projection conversion processing is performed on the image data (original image data) B0 in the projection conversion step (steps 10, 16, 21). ), And writes the corrected image data Ba, Bb, and Bc into the image buffer memory 31 (steps 11, 17, and 22).
[0050]
Next, the user operates the operation means as the selection means to select the image data B0 before correction and the corrected image data Ba, Bb, Bc (step 23), and the image data is displayed on the display device 13. (Step 24). Further, the distortion correction coefficients a, b, and c are displayed on the display device 13 (step 25).
[0051]
On the other hand, if the selection switch is set to manual correction in step 2, the user operates the operating means to input an arbitrary distortion correction coefficient (step 26), and project based on the input distortion correction coefficient. The conversion processing is performed (Step 27), the image data subjected to the projection conversion processing is written in the image buffer memory 31 (Step 28), and the image data is displayed on the display device 13 (Step 24).
[0052]
Also, in the case of manual correction, prior to this manual correction, the automatic correction processing shown in steps 3 to 22 is performed to obtain the distortion correction coefficients a, b, and c. The coefficients a, b, and c are displayed (step 25) and can be used as reference values at the time of manual correction.
[0053]
Then, the image data displayed on the display device 13 is recorded in the recording device by the user's operation of the operation device, and is printed from the printing device 14.
[0054]
As described above, according to the distortion correction method of the captured image of the present embodiment, image data of an arbitrary general natural image captured by the optical imaging system is image-processed to correct the distortion of the imaging lens 21. The coefficient is estimated, the distortion of the photographing lens 21 is electrically corrected using the distortion aberration correction coefficient, and a reproduced image (corrected image) similar to the original image can be obtained. Therefore, even when the characteristics of the photographing lens 21 used for photographing an arbitrary general natural image are unknown, it is possible to estimate the characteristics of the photographing lens 21 used for photographing, and a coefficient for correcting distortion. Does not need to be measured in advance, automatic correction is also possible, and distortion correction can be greatly facilitated.
[0055]
That is, by performing edge extraction thinning processing, labeling processing, distortion coefficient calculation processing, and correction coefficient estimation processing using statistical processing using image data recorded in the image buffer memory 31, the distortion correction coefficient is automatically determined. By performing the projection conversion process, it is possible to automatically obtain distortion-corrected image data for reproduction.
[0056]
In addition, since there is provided a selection unit for selecting automatic correction or manual correction for distortion, it is possible to widely meet the needs of the user.
[0057]
Also, when the distortion is manually corrected, the distortion correction coefficient is calculated and displayed in the automatic correction process, so that it can be used as a reference in the manual correction.
[0058]
In addition, in the correction coefficient estimation processing, since a selection unit that can select a plurality of processing methods is provided, the distortion correction coefficient can be accurately estimated, or high-speed processing can be performed, and the demands of users can be widely met. Can be.
[0059]
In the above-described first embodiment, in the correction coefficient estimation processing, a plurality of processing methods are sequentially executed to record the image data, respectively. By executing only the processing method of (1), the processing time can be reduced.
[0060]
In the correction coefficient estimation processing, it is automatically determined whether or not each statistical processing is successful. If it is not determined that the statistical processing is successful, the projection transformation processing may not be performed.
[0061]
Next, a second embodiment will be described with reference to the flowcharts shown in FIGS.
[0062]
In the flowcharts shown in FIGS. 5 and 6, steps 1 to 7 and steps 26 to 28 assigned the same step numbers as those in the flowcharts shown in FIGS. 3 and 4 carry out the same processing as in the first embodiment. Is what you do.
[0063]
In the present embodiment, the user can select the method (statistical processing mode) of the correction coefficient estimation processing for estimating the distortion correction coefficient by the operation means. Therefore, following the distortion coefficient calculating step (steps 6 and 7), according to the selection of the statistical processing mode (step 50), the average value of the plurality of distortion aberration coefficients obtained in the distortion coefficient calculating step is calculated in the same manner as in step 8. (Step 51) or, similarly to Steps 12 to 14, when calculating the average value, create a histogram showing the relationship between the value of the distortion coefficient and the frequency shown in FIG. It is determined that the distortion coefficient does not exceed the threshold value f, that is, the infrequently used distortion aberration coefficient adopts a value excluded from the statistical calculation, that is, the calculation of the average (steps 52 to 54). A histogram showing the relationship between the value of the distortion aberration coefficient and the frequency shown in (1) is created, and the distortion aberration coefficient with the highest frequency is adopted as the distortion correction coefficient (steps 55 and 56). The values and the distortion correction coefficient e (step 57). Then, similarly to steps 21 to 25, the image data is subjected to the projection conversion processing based on the distortion correction coefficient e (step 59), and the corrected image data Be is written to the image buffer memory 31 (step 60), and the image data is displayed. The information is displayed on the device 13 (step 61), and the distortion correction coefficient e is displayed on the display device 13 (step 62).
[0064]
Further, in the second embodiment, following step 57, whether or not the selected correction coefficient estimating method is successful is determined by using, for example, a variance value of the distortion correction coefficient e or the like. Judgment is made based on whether or not a peak is found in the frequency. If no peak is found in the frequency of the distortion correction coefficient e, it is determined that the selected correction coefficient estimating method is not effective, and the projection conversion processing is performed. (Step 58).
[0065]
In the above embodiment, a digital still camera has been described. However, the present invention is not limited to this configuration, and the present invention can be applied to a device such as a camera or a scanner that handles images electronically captured using a capturing lens. . For example, a similar effect can be realized even in a configuration in which an imaging device is not directly provided, such as when a printed image having distortion is read by a scanner.
[0066]
In addition, although both the display device 13 and the printing device 14 are provided as output means of image data for reproduction, either one of them may be provided, or neither may be provided.
[0067]
In addition, the image pickup mechanism 11 as a camera unit may be integrally provided or may not be provided.
[0068]
【The invention's effect】
According to the distortion aberration measuring method of the first aspect, a distortion correction coefficient for correcting distortion of the image data can be estimated from the image data. The distortion can be corrected automatically or manually using the distortion correction coefficient. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion can be easily corrected.
[0069]
According to the distortion aberration measuring method of the second aspect, in addition to the effect of the first aspect, the distortion correction coefficient is estimated by using one or a combination of the average value calculation, the variance calculation, and the histogram creation. it can.
[0070]
According to the distortion aberration measuring method of the third aspect, in addition to the effect of the first or second aspect, a line segment which is more likely to have no valid information or has a relatively large calculation error. By excluding short line segments from the object of calculating the distortion coefficient, the distortion correction coefficient can be estimated with high accuracy.
[0071]
According to the image processing device of the fourth aspect, a distortion correction coefficient for correcting distortion of the image data can be estimated from the image data. The distortion can be corrected automatically or manually using the distortion correction coefficient. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion can be easily corrected.
[0072]
According to the image processing apparatus of the fifth aspect, in addition to the effect of the fourth aspect, the distortion of the image data can be automatically corrected by the projective transformation means.
[0073]
According to the image processing apparatus of the sixth aspect, in addition to the effect of the fourth aspect, the distortion can be corrected to an arbitrary degree with reference to the displayed distortion correction coefficient.
[0074]
According to the image processing apparatus of the seventh aspect, in addition to the effect of any one of the fourth to sixth aspects, the distortion correction coefficient can be accurately determined by arbitrarily selecting a statistical process based on the properties of the image data. Estimation can be performed well or processing can be performed at high speed.
[0075]
According to the image processing apparatus of the eighth aspect, in addition to the effect of any one of the fourth to seventh aspects, it is possible to estimate a distortion correction coefficient for image data output by the output unit and correct the distortion. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion can be easily corrected.
[0076]
According to the image processing apparatus of the ninth aspect, in addition to the effects of any one of the fourth to eighth aspects, it is possible to estimate a distortion correction coefficient for image data captured by a photographic lens and correct the distortion. There is no need to measure the coefficient for correcting the distortion in advance, and the distortion can be easily corrected.
[Brief description of the drawings]
FIG. 1 is a partial block diagram illustrating an embodiment of an image processing apparatus according to the present invention.
FIG. 2 is a block diagram showing the image processing apparatus according to the first embodiment;
FIG. 3 is a flowchart showing the first embodiment.
FIG. 4 is a flowchart following FIG.
FIG. 5 is a flowchart showing a second embodiment of the present invention.
FIG. 6 is a flowchart following FIG. 5;
FIG. 7 is an explanatory diagram showing a histogram used in the first and second embodiments.
[Explanation of symbols]
10 Image processing device
11 Imaging mechanism
13. Display device as output means
14 Printing device as output means
21 Shooting lens
32 Boundary extraction means
33 line segment identification means
34 means for calculating distortion coefficient
35 Correction coefficient estimation means
37 Projection conversion means

Claims (9)

A boundary extraction step of extracting a boundary component of the image data as a line segment;
A line segment identification step of individually identifying the plurality of extracted line segments,
A distortion coefficient calculating step of calculating a distortion aberration coefficient assuming that a part of the straight line is distorted for each of the identified line segments,
A correction coefficient estimating step of statistically processing the calculated distortion aberration coefficients and estimating a distortion correction coefficient for correcting distortion of the image data. 2. The distortion aberration measuring method according to claim 1, wherein at least one of average value calculation, variance calculation, and histogram creation is used in the statistical processing in the correction coefficient estimation step. A filter step for excluding a relatively short line segment from a target of calculation of a distortion aberration coefficient in the distortion coefficient calculation step among a plurality of line segments individually identified in the line segment identification step. Item 3. The distortion aberration measuring method according to item 1 or 2. A boundary extracting means for extracting a boundary component of the image data as a line segment,
Line segment identification means for individually identifying the plurality of extracted line segments,
Distortion coefficient calculation means for calculating a distortion aberration coefficient, respectively, assuming that a part of a straight line is distorted for each of the identified line segments,
An image processing apparatus comprising: a correction coefficient estimating unit configured to statistically process the calculated distortion aberration coefficients and to estimate a distortion correction coefficient for correcting the distortion of the image data. 5. The image processing apparatus according to claim 4, further comprising a projection conversion unit that corrects distortion of the image data based on the estimated distortion correction coefficient. Correction coefficient display means for displaying the estimated distortion correction coefficient,
Correction coefficient setting means for arbitrarily setting a distortion correction coefficient for correcting distortion of image data,
5. The image processing apparatus according to claim 4, further comprising a projection conversion unit that corrects distortion of the image data based on the set distortion correction coefficient. 7. The correction coefficient estimating unit is capable of executing a plurality of statistical processes, and includes a statistical process selecting unit capable of arbitrarily selecting one of the statistical processes. Image processing device. The image processing apparatus according to claim 4, further comprising an output unit including at least one of a display unit that displays image data and a printing unit that prints the image data. 9. The image processing apparatus according to claim 4, further comprising an optical system having a photographing lens, and an image capturing mechanism capable of capturing and outputting image data.

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