Method, device, and program for evaluating image stabilization effect of an imaging device

Abstract

To provide an evaluation method that can accurately measure a shake correction effect for an imaging apparatus.SOLUTION: An evaluation method for a shake correction effect for an imaging apparatus has: an evaluation step of calculating an evaluation value of a shake correction effect based on a shutter speed value when a reference blur amount theoretically calculated based on a blur waveform added to the imaging apparatus and an actually measured blur amount calculated by using an image picked up while the imaging apparatus is vibrated become specific blur amount; and a setting step of setting the specific blur amount. The setting step includes a first calculation step of calculating the amount of deterioration of an image picked up by the imaging apparatus caused by a factor other than a shake from the outside, and a selection step of selecting a determination level for defining the specific blur amount from a plurality of determination levels different in blur amount based on the image deterioration amount.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method, an evaluation device, and a program for evaluating the effect of image stabilization in an imaging device. [Background technology]

[0002] As a method for evaluating the shake correction effect of an imaging device, a method for calculating an evaluation value of the shake correction effect by taking into account the influence of the blur offset amount is disclosed in Patent Document 1. The blur offset amount is the amount of blur in a captured image caused by factors other than camera shake, and is a value specific to the device under test that is affected by the optical performance, number of effective pixels, image processing, etc. of the imaging device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5909686 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method of Patent Document 1, if the error in the blur offset amount is large compared with the determination level of the shake correction effect, there is a risk that the accuracy of the evaluation value of the shake correction effect will decrease. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an evaluation method for accurately measuring the shake correction effect of an imaging device. [Means for solving the problem]

[0005] A method for evaluating the image stabilization effect of an imaging device according to an embodiment of the present invention includes: the image capturing apparatus includes an evaluation step of calculating an evaluation value of the shake correction effect based on a shutter speed value at which a reference shake amount theoretically calculated based on a shake waveform applied to the image capturing apparatus and an actual measured shake amount calculated using an image captured while the image capturing apparatus is vibrated each reach a specific shake amount; and a setting step of setting the specific shake amount, wherein the setting step includes a first calculation step of calculating an image degradation amount of the image capturing apparatus caused by factors other than external shake, and a selection step of selecting, based on the image degradation amount, a determination level that defines the specific shake amount from among a plurality of determination levels having different shake amounts, the plurality of determination levels including a first determination level and a second determination level that defines a smaller amount of shake than the first determination level, and wherein, in the selection step, when the image degradation amount is a first amount, the first determination level is selected as the determination level that defines the specific shake amount, and when the image degradation amount is a second amount that is smaller than the first amount, the second determination level is selected as the determination level that defines the specific shake amount. It is characterized by: [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an evaluation method that can accurately measure the shake correction effect of an imaging device. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating a configuration example of an evaluation system according to a first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a hardware configuration of an image evaluation device. [Figure 3] 4 is a flowchart showing a method for evaluating the shake correction effect of the imaging device in the first embodiment. [Figure 4] 4 is a flowchart showing details of the determination level setting in FIG. 3. [Figure 5] 4 is a flowchart showing the details of the evaluation value calculation in FIG. 3. [Figure 6] Graph (A) is a graph showing an example of an estimated total amount of blur, graph (B) is a graph showing an example of a reference amount of blur and an actually measured amount of blur, and graph (C) is a graph showing an example of an evaluation value. [Figure 7] 10 is a flowchart showing details of evaluation value calculation in the second embodiment. [Figure 8] 10 is a graph showing an example of a blur offset amount. [Figure 9] 10 is a flowchart showing details of determination level setting in the third embodiment. [Figure 10] 10 is a flowchart showing details of determination level setting in the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, etc. However, the following embodiments do not limit the invention according to the claims, and not all of the features described in the following embodiments are necessarily essential to the present invention.

[0009] (First embodiment) FIG. 1 is a schematic diagram showing an example of the configuration of an evaluation system according to the first embodiment. The evaluation system 10 is a system for measuring the shake correction effect of an imaging device 11. The imaging device 11, which is the device under test, is fixed to a vibration table 12. The vibration table 12 mechanically generates vibrations that mimic human hand shake based on input vibration waveform data 13, and vibrates the imaging device 11. The vibration table 12 applies vibrations in the pitch direction (around an axis perpendicular to the plane of the paper in FIG. 1) indicated by arrow 12a, and in the yaw direction (around an axis in the up-down direction in FIG. 1) indicated by arrow 12b. The vibration table 12 can also be controlled to switch between a vibration state and a stationary state.

[0010] An imaging device 11 fixed to a vibration table 12 captures an image of a chart 14 placed directly opposite the imaging device 11. As an example, the chart 14 includes a plurality of black and white stripes having a certain width in the horizontal and vertical directions, and a color natural image portion.

[0011] The image of the chart captured by the imaging device 11 during vibration application is input to the image evaluation device 15. The image evaluation device 15 is, for example, a computer that executes image analysis software. The image evaluation device 15 detects the contrast of the image of the chart captured by the imaging device 11 and measures the deterioration of the image due to vibration application.

[0012] FIG. 2 is a diagram showing an example of the hardware configuration of the image evaluation device 15. As shown in FIG. The image evaluation device 15 has a CPU 101, a ROM 102, a RAM 103, a storage unit 104, an operation I / F 105, a display I / F 106, and an external I / F 107. The elements of the image evaluation device 15 are connected to one another via a system bus 108. Note that CPU stands for Central Processing Unit, ROM stands for Read Only Memory, and RAM stands for Random Access Memory.

[0013] The CPU 101 starts the OS (Operating System) by a boot program stored in the ROM 102. The CPU 101 executes various processes, which will be described later, by running an image analysis software program stored in the storage unit 104 on the OS. The RAM 103 is used as a temporary area such as the main memory and work area of ​​the CPU 101.

[0014] The operation I / F 105 is an interface that connects the CPU 101 and the operation unit 109, and sends information input from the operation unit 109 to the CPU 101. The operation unit 109 is a device that accepts operator input to the image evaluation device 15, and is composed of, for example, a keyboard, a pointing device, etc.

[0015] The display I / F 106 is an interface that connects the CPU 101 and the display unit 110, and outputs image data to be displayed to the display unit 110. The display unit 110 is a device that outputs an operation screen of the image evaluation device 15, and is configured by a display device such as a liquid crystal display.

[0016] The external I / F 107 is an interface for acquiring image data and various information of the image capturing device 11, which is the device under test. The external I / F 107 may be configured to acquire information through wired or wireless communication, or may be configured to read information via a removable storage medium.

[0017] Next, a method for evaluating the shake correction effect of the imaging device in the first embodiment will be described with reference to FIG.

[0018] In S200, the vibration table 12 is placed in a stationary state and an image of the chart 14 is captured by the imaging device 11 of the device under test. This allows an evaluation image to be acquired when the imaging device 11 is in a stationary state. When capturing images in a stationary state, the shutter speed value of the imaging device 11 is changed so as to slow down by up to one step from a predetermined value to a value sufficient for calculating an evaluation value. Then, multiple images are captured at each shutter speed value.

[0019] In S300, the image evaluation device 15 selects and sets the determination level for the shake correction effect from a plurality of determination levels. S300 will be described in detail later.

[0020] In S400, the vibration table 12 is vibrated and an image of the chart 14 is captured by the imaging device 11 of the device under test. At this time, the shake correction function of the imaging device 11 is set to ON. As a result, an evaluation image is acquired in the vibrating state of the imaging device 11. In the vibrating state, as with the stationary state imaging, the shutter speed value of the imaging device 11 is changed so as to slow down by up to one step from a predetermined value to a value sufficient for calculating the evaluation value. Then, multiple images are captured at each shutter speed value.

[0021] In S500, the image evaluation device 15 calculates an evaluation value indicating the shake correction effect of the imaging device 11 based on the setting values ​​of the imaging device 11, the evaluation image in a stationary state, and the evaluation image in a vibrating state. S500 will be described in detail later. This completes the series of operations in the evaluation method shown in FIG.

[0022] FIG. 4 is a flowchart showing details of the determination level setting (S300) in FIG. Here, a program for realizing the operation of setting the judgment level in S300 (FIG. 4, or FIGS. 9 and 10 described later) is stored in the RAM 103, the storage unit 104, or the ROM 102, and is executed by the CPU 101.

[0023] In S302, the image evaluation device 15 acquires evaluation images in a stationary state of the imaging device 11. As described above, the evaluation images are a group of images obtained by capturing images of the chart 14 multiple times at the same shutter speed value while changing the shutter speed value multiple times.

[0024] In S303, the image evaluation device 15 calculates the blur offset amount Di from the evaluation images in a stationary state. For example, the image evaluation device 15 calculates the square root of the sum of the squares of the blur amounts at the boundaries between different color regions (for example, the boundaries between white and black stripes) in each evaluation image. Then, the image evaluation device 15 calculates the blur offset amount Di for each shutter speed value by averaging the sum of the calculated values ​​at the same shutter speed value by the number of images captured.

[0025] The blur offset amount Di is the amount of blur that occurs in an image when the image is still, and is a parameter that indicates the amount of image degradation caused by factors other than external shake. For example, image degradation can occur due to the optical performance of the image sensor and lens of the image capture device 11, so the blur offset amount Di is a value that is unique to each image capture device 11. Note that in this embodiment, the blur offset amount Di calculated for each shutter speed value indicates the relationship between the shutter speed value, which is the exposure time, and the amount of image degradation.

[0026] In S304, the image evaluation device 15 calculates a representative value Dim from the blur offset amount Di, which is a function of the shutter speed value. For example, the image evaluation device 15 calculates the blur offset amount Di corresponding to the fastest shutter speed value, that is, the shutter speed value with the shortest exposure time, as the representative value Dim.

[0027] Here, the representative value Dim may be any value calculated based on the absolute value of the bokeh offset amount Di. For example, the image evaluation device 15 may calculate the representative value Dim by statistical processing that determines the average value or median value of the bokeh offset amount for the entire range or a part of the range of shutter speed values. Alternatively, the image evaluation device 15 may extract the bokeh offset amount corresponding to a specific shutter speed value and calculate the representative value Dim.

[0028] In S305, the image evaluation device 15 determines whether the representative value Dim of the blur offset amount is equal to or greater than a threshold value Dth (Dim≧Dth). The threshold value Dth corresponds to a second determination level, among a plurality of determination levels for the shake correction effect, which is set to a smaller amount of blur than the default determination level (also referred to as the first determination level). The threshold value Dth in S305 may be the same as the amount of blur at the second determination level, or may be a value obtained by multiplying the amount of blur at the second determination level by a predetermined coefficient.

[0029] The determination level is used to define a specific amount of blur when calculating a reference shutter speed value and an actually measured shutter speed value, which will be described later, in the evaluation value calculation in S500.

[0030] If the representative value Dim is equal to or greater than the threshold value Dth in S305, the process proceeds to S306. In S306, the image evaluation device 15 sets the determination level of the shake correction effect (specific amount of shake) to the first determination level, and then ends the process in FIG.

[0031] On the other hand, if the representative value Dim is less than the threshold value Dth in S305, the process proceeds to S307. In S307, the image evaluation device 15 sets the determination level of the shake correction effect (specific amount of blur) to a second determination level that is smaller than the first determination level, and then ends the process in FIG.

[0032] FIG. 5 is a flowchart showing details of the evaluation value calculation (S500) in FIG. Here, a program for realizing the operation of setting the judgment level in S500 (FIG. 5 or FIG. 7 described later) is stored in the RAM 103, the storage unit 104, or the ROM 102, and is executed by the CPU 101.

[0033] In S502, the image evaluation device 15 calculates a theoretical amount of blur based on the vibration waveform data 13. The theoretical amount of blur is a theoretical value equivalent to the amount of blur that can be measured from an image captured with the shake correction function turned off when the imaging device 11 is vibrated with the vibration waveform of the vibration waveform data 13.

[0034] In S503, the image evaluation device 15 calculates the estimated total amount of blur for each of a plurality of shutter speed values. The estimated total amount of blur is calculated by taking the square root of the sum of the squares of the theoretical blur amount and the blur offset amount. In other words, the image evaluation device 15 calculates the estimated total amount of blur using the blur offset amount Di for each shutter speed value calculated in the determination level setting in S300 and the theoretical blur amount in S502.

[0035] In S504, the image evaluation device 15 acquires an evaluation image in the vibration state of the imaging device 11 (an image of the chart 14 captured in the vibration state in S400).

[0036] In S505, the image evaluation device 15 calculates the measured total amount of blur from the evaluation images in the vibrating state. For example, the image evaluation device 15 calculates the square root of the sum of the squares of the amount of blur at the boundary between different color regions (for example, the boundary between white and black bands) in each evaluation image. Then, the image evaluation device 15 calculates the measured total amount of blur for each shutter speed value by averaging the sum of the calculated values ​​at the same shutter speed value by the number of images captured.

[0037] In S506, the image evaluation device 15 subtracts the corresponding blur offset amount from the estimated total blur amount for each shutter speed value, and calculates the theoretical reference blur amount for each shutter speed value.

[0038] In S507, the image evaluation device 15 subtracts the corresponding blur offset amount from the actually measured total blur amount for each shutter speed value, and calculates the actually measured blur amount for each shutter speed value.

[0039] In S508, the image evaluation device 15 uses the multiple reference blur amounts calculated for each shutter speed value to calculate the shutter speed value at which the reference blur amount reaches the judgment level set in the judgment level setting (S300) as the reference shutter speed value.

[0040] The reference amount of blur is obtained discretely for each shutter speed value. Therefore, for example, the image evaluation device 15 may linearly interpolate the reference amount of blur for two shutter speed values ​​that sandwich the determination level for the shake correction effect, and calculate the reference shutter speed value from the intersection of the interpolated line of the reference amount of blur and the determination level.

[0041] In S509, the image evaluation device 15 uses the multiple measured amounts of blur calculated for each shutter speed value to calculate the shutter speed value at which the measured amount of blur reaches the judgment level set in the judgment level setting (S300). Note that the method for calculating the measured shutter speed value is the same as the method for calculating the reference shutter speed value, except that the measured amount of blur is used instead of the reference amount of blur, so a duplicated explanation will be omitted.

[0042] In S510, the image evaluation device 15 calculates an evaluation value indicating the shake correction effect using the reference shutter speed value (S508) and the measured shutter speed value (S509). Specifically, the image evaluation device 15 obtains the evaluation value from the difference between the reference shutter speed value and the measured shutter speed value (the number of steps of shake correction effect). Then, the processing in FIG. 5 ends.

[0043] The effects of the first embodiment will be described below with reference to FIG. First, the amount of bokeh offset is ideally constant regardless of the shutter speed value. However, the actual amount of bokeh offset varies depending on the shutter speed value due to measurement errors, variations between images, the influence of exposure time, etc. In general, it is considered that the greater the absolute value of the amount of bokeh offset, the greater the amount of variation in the amount of bokeh offset.

[0044] Fig. 6(A) is a graph showing an example of the estimated total blur amount. When the amount of fluctuation in the blur offset amount is large, the error in the estimated total blur amount calculated using the blur offset amount also becomes large. The dotted line in Fig. 6(A) shows the estimated total blur amount (ideal value) when the blur offset amount is constant regardless of the shutter speed value. It can be seen that the actual estimated total blur amount does not form a smooth curve because there is an error from the ideal value due to fluctuations in the blur offset amount.

[0045] Furthermore, the estimated total blur amount is calculated as the square root of the sum of the squares of the theoretical blur amount and the blur offset amount, as described above. Since the theoretical blur amount increases as the shutter speed value increases, the error in the estimated total blur amount increases when the shutter speed value is relatively small.

[0046] FIG. 6B is a graph showing an example of the reference blur amount and the measured blur amount. When the amount of variation in the bokeh offset amount is large, the error in the reference blur amount and the measured blur amount calculated using the bokeh offset amount also becomes large. The dotted lines in FIG. 6B show the estimated total bokeh amount (ideal value) and the measured total bokeh amount (ideal value) when the bokeh offset amount is constant regardless of the shutter speed value. It can be seen that the actual reference blur amount and the measured blur amount do not form a smooth curve because errors occur relative to the ideal values ​​due to variations in the bokeh offset amount.

[0047] Furthermore, the reference blur amount and the measured blur amount are calculated by subtracting the blur offset amount from the estimated total blur amount and the measured total blur amount, respectively, as described above. Since the estimated total blur amount and the measured total blur amount increase as the shutter speed value increases, the error between the estimated total blur amount and the measured total blur amount increases when the shutter speed value is relatively small.

[0048] Fig. 6C is a graph showing an example of evaluation values. In Fig. 6C, evaluation value 1 is an evaluation value calculated using a first determination level, and evaluation value 2 is an evaluation value calculated using a second determination level that has a smaller amount of blur than the first determination level.

[0049] As described above, as the shutter speed value increases, the reference amount of blur and the measured amount of blur increase, and therefore, it can be seen that evaluation value 2 is calculated in a range where the shutter speed value is short compared to evaluation value 1. Also, as the shutter speed value increases, the difference between the reference amount of blur and the measured amount of blur increases, and therefore, this difference is smaller for evaluation value 2 than for evaluation value 1. For these reasons, evaluation value 2, i.e., when the judgment level is small, is more susceptible to the influence of fluctuations in the bokeh offset amount than evaluation value 1.

[0050] In the first embodiment, the determination level of the shake correction effect is selected based on the blur offset amount, which is the amount of image degradation (S300). For example, when the blur offset amount is equal to or greater than a threshold Dth, the determination level of the shake correction effect is set to a first determination level (S305, S306). Then, in calculating the evaluation value of the shake correction effect, the evaluation value is calculated using the first determination level (S500). On the other hand, when the blur offset amount is less than the threshold Dth, the determination level of the shake correction effect is set to a second determination level that is smaller than the first determination level (S305, S307). Then, in calculating the evaluation value of the shake correction effect, the evaluation value is calculated using the second determination level (S500).

[0051] In other words, when the amount of blur offset is relatively large, the evaluation value is calculated using the first determination level, which corresponds to a large amount of blur. Therefore, it is possible to prevent the accuracy of the evaluation value from being reduced by errors due to the amount of blur caused by factors other than camera shake. Furthermore, when the amount of blur offset is relatively small, less than the amount of blur at the second determination level, the evaluation value can be calculated using the second determination level, which is smaller than the first determination level. Therefore, when errors in the amount of blur caused by factors other than camera shake are small, it is possible to more precisely measure the shake correction effect of the imaging device 11.

[0052] (Second embodiment) Next, a second embodiment will be described. In the following description of each embodiment, elements common to the first embodiment will be assigned the same reference numerals, and redundant description will be omitted.

[0053] In the second embodiment, the configuration of the evaluation system 10 is the same as in the first embodiment. In the second embodiment, the process of FIG. 7 is performed instead of the process of FIG. 5 as the evaluation value calculation (S500) of the evaluation method shown in FIG.

[0054] Fig. 7 is a flowchart showing details of evaluation value calculation in the second embodiment. In Fig. 7, steps S502 to S507 are the same as those in Fig. 5. In Fig. 7, step S708 is performed after step S507.

[0055] In S708, the image evaluation device 15 uses the multiple reference blur amounts calculated for each shutter speed value to calculate the shutter speed value at which the reference blur amount becomes a specific blur amount as the reference shutter speed value. The specific blur amount in S708 is the first judgment level, regardless of the judgment level setting process in S300.

[0056] In S709, the image evaluation device 15 uses the multiple measured amounts of blur calculated for each shutter speed value to calculate the shutter speed value at which the measured amount of blur becomes a specific amount of blur. The specific amount of blur in S709 is the first judgment level, regardless of the judgment level setting process in S300.

[0057] In S710, the image evaluation device 15 calculates a first evaluation value indicating the shake correction effect using the reference shutter speed value (S708) and the actually measured shutter speed value (S709).

[0058] In S711, the image evaluation device 15 determines whether the evaluation level for the shake correction effect is set to the second evaluation level. If it is not set to the second evaluation level, the image evaluation device 15 ends the processing in Fig. 7. On the other hand, if it is set to the second evaluation level, the processing proceeds to S712.

[0059] In S712, the image evaluation device 15 uses the multiple reference blur amounts calculated for each shutter speed value to calculate the shutter speed value at which the reference blur amount becomes a specific blur amount as the reference shutter speed value. The specific blur amount in S712 is the value set in the determination level setting in S300, i.e., the second determination level.

[0060] In S713, the image evaluation device 15 uses the multiple measured amounts of blur calculated for each shutter speed value to calculate the shutter speed value at which the measured amount of blur becomes a specific amount of blur. The specific amount of blur in S713 is the value set in the determination level setting in S300, i.e., the second determination level.

[0061] In S714, the image evaluation device 15 calculates a second evaluation value indicating the shake correction effect using the reference shutter speed value (S712) and the actually measured shutter speed value (S713). After that, the processing in FIG.

[0062] In the second embodiment, a first evaluation value is calculated using a first determination level (S710). Furthermore, if a second determination level is selected based on the blur offset amount, which is the amount of image degradation, a second evaluation value is calculated using the second determination level (S714).

[0063] As a result, similar to the first embodiment, when the bokeh offset amount is relatively small, the evaluation value can be calculated using the second determination level, which is smaller than the first determination level. Therefore, when the error in the amount of bokeh due to factors other than camera shake is small, it is possible to more precisely measure the shake correction effect of the imaging device 11. Furthermore, in the second embodiment, the first evaluation value is calculated using the first determination level regardless of the magnitude of the bokeh offset amount. Therefore, in the second embodiment, the measurement result using at least the first determination level is guaranteed, and therefore compatibility with the evaluation of the shake correction effect for other imaging devices 11 is maintained.

[0064] (Third embodiment) Next, a third embodiment will be described. First, the amount of fluctuation in the blur offset amount will be described with reference to FIG.

[0065] Fig. 8 is a graph showing an example of the blur offset amount. The dashed-dotted line in Fig. 8 indicates the average value of the blur offset amount within a predetermined shutter speed range, and the dashed-two-dotted line in Fig. 8 indicates the amount of variation De from the average value of the blur offset amount within the predetermined shutter speed range.

[0066] Here, the variation amount De may be a value calculated based on the distribution of the blur offset amount Di within the range of shutter speed values. For example, the image evaluation device 15 may calculate the variation amount De by statistical processing that determines the standard deviation or variance of the blur offset amount for the entire range or a part of the range of shutter speed values. The variation amount De of the blur offset amount indicates the relationship between the variation amount of the image degradation amount and the change in the shutter speed value, which is the exposure time.

[0067] In the third embodiment, the configuration of the evaluation system 10 is the same as in the first embodiment. In the third embodiment, the process of FIG. 9 is performed instead of the process of FIG. 4 as the evaluation level setting (S300) shown in FIG.

[0068] Fig. 9 is a flowchart showing details of the determination level setting in the third embodiment. In Fig. 9, steps S302 to S303 are the same as those in Fig. 4. In Fig. 9, step S804 is performed after step S303.

[0069] In S804, the image evaluation device 15 calculates the amount of fluctuation De of the blur offset amount based on the distribution of the blur offset amount Di within the range of the shutter speed value.

[0070] In S805, the image evaluation device 15 determines whether the fluctuation amount De of the blur offset amount is equal to or greater than a threshold value Dth (De≧Dth). The threshold value Dth corresponds to a second determination level, among a plurality of determination levels for the shake correction effect, which is set to a smaller amount of blur than the first determination level. The threshold value Dth in S805 may be the same as or different from the threshold value Dth (S305) in the first embodiment. Furthermore, the threshold value Dth in S805 may be any value based on the absolute value of the second determination level, and may be, for example, a value obtained by multiplying the amount of blur at the second determination level by a predetermined coefficient.

[0071] If the amount of fluctuation De is equal to or greater than the threshold value Dth in S805, the process proceeds to S306. In S306, the image evaluation device 15 sets the determination level of the shake correction effect (specific amount of shake) to the first determination level, and then ends the process in FIG.

[0072] On the other hand, if the amount of fluctuation De is less than the threshold value Dth in S805, the process proceeds to S307. In S307, the image evaluation device 15 sets the determination level of the shake correction effect (specific amount of blur) to a second determination level that is smaller than the first determination level, and then ends the process in FIG.

[0073] In the third embodiment, the fluctuation amount of the blur offset amount, which is the amount of image degradation, is compared with a threshold value Dth to select the judgment level of the shake correction effect (S300). For example, when the fluctuation amount De of the blur offset amount is equal to or greater than the threshold value Dth, the judgment level of the shake correction effect is set to a first judgment level (S805, S306). In this case, the first judgment level is used in calculating the evaluation value of the shake correction effect (S500). On the other hand, when the fluctuation amount De of the blur offset amount is less than the threshold value Dth, the judgment level of the shake correction effect is set to a second judgment level that is smaller than the first judgment level (S805, S307). In this case, the second judgment level is used in calculating the evaluation value of the shake correction effect (S500).

[0074] That is, in the third embodiment, when the amount of fluctuation in the amount of blur offset is equal to or greater than the threshold and the error in the amount of blur due to factors other than camera shake is relatively large, the evaluation value is calculated using a first determination level with a large amount of blur. Therefore, it is possible to prevent the accuracy of the evaluation value from being reduced due to the error in the amount of blur due to factors other than camera shake. Also, when the amount of fluctuation in the amount of blur offset is less than the threshold and the error in the amount of blur due to factors other than camera shake is relatively small, the evaluation value can be calculated using a second determination level that is smaller than the first determination level. Therefore, when the error in the amount of blur due to factors other than camera shake is small, it is possible to more precisely measure the shake correction effect of the imaging device 11.

[0075] (Fourth embodiment) Next, a fourth embodiment will be described. In the fourth embodiment, the configuration of the evaluation system 10 is the same as that of the first embodiment. In the fourth embodiment, the process of FIG. 10 is performed instead of that of FIG. 4 as the determination level setting (S300) shown in FIG. 3.

[0076] FIG. 10 is a flowchart showing details of the determination level setting in the fourth embodiment. In S902, the image evaluation device 15 acquires optical information of the image pickup device 11, which is the device under test. Here, the optical information is information related to the resolution of the image pickup device 11, and includes, for example, information such as the pixel pitch of the image pickup element, the f-number of the lens, the focal length and aberration of the lens, etc.

[0077] In S903, the image evaluation device 15 calculates the amount of image degradation Do that occurs in an image captured by the image capture device 11, based on the parameters of the optical system obtained from the above optical information. The image evaluation device 15 may calculate the amount of image degradation Do based on, for example, the allowable circle of confusion diameter calculated from the pixel pitch, assuming that the smaller the allowable circle of confusion diameter, the more likely the image will be blurred. Alternatively, the image evaluation device 15 may calculate the depth of field from, for example, the focal length and f-number of the image capture device 11, and calculate the amount of image degradation Do based on the assumption that the shallower the depth of field, the more likely the image will be blurred.

[0078] In S904, the image evaluation device 15 determines whether the amount of image degradation Do is equal to or greater than a threshold value Dth (Do≧Dth). The threshold value Dth corresponds to a second determination level, among a plurality of determination levels for the shake correction effect, which is set to a smaller amount of shake than the first determination level. The threshold value Dth in S904 may be the same value as the threshold value Dth (S305) of the first embodiment or the threshold value Dth (S805) of the third embodiment, or may be a different value.

[0079] If the amount of image degradation Do is equal to or greater than the threshold value Dth in S904, the process proceeds to S306. In S306, the image evaluation device 15 sets the determination level of the shake correction effect (specific amount of shake) to the first determination level, and then ends the process in FIG.

[0080] On the other hand, if the image degradation amount Do is less than the threshold value Dth in S805, the process proceeds to S307. In S307, the image evaluation device 15 sets the determination level of the shake correction effect (specific amount of blur) to a second determination level that is smaller than the first determination level, and then ends the process in FIG.

[0081] In the fourth embodiment, the determination level of the shake correction effect is selected based on the amount of image degradation calculated from optical information of the imaging device 11 (S300). For example, when the amount of image degradation Do is equal to or greater than a threshold value Dth, the determination level of the shake correction effect is set to a first determination level (S904, S306). In this case, the first determination level is used to calculate the evaluation value of the shake correction effect (S500). On the other hand, when the amount of image degradation Do is less than the threshold value Dth, the determination level of the shake correction effect is set to a second determination level that is smaller than the first determination level (S904, S307). In this case, the second determination level is used to calculate the evaluation value of the shake correction effect (S500).

[0082] That is, in the fourth embodiment, when the amount of image degradation Do in the optical system is equal to or greater than the threshold value and the error in the amount of blur due to factors other than camera shake is relatively large, the evaluation value is calculated using a first determination level with a large amount of blur. Therefore, it is possible to prevent the accuracy of the evaluation value from being reduced due to the error in the amount of blur due to factors other than camera shake. Furthermore, when the amount of image degradation Do in the optical system is less than the threshold value and the error in the amount of blur due to factors other than camera shake is relatively small, the evaluation value can be calculated using a second determination level that is smaller than the first determination level. Therefore, when the error in the amount of blur due to factors other than camera shake is small, it is possible to more precisely measure the shake correction effect of the imaging device 11.

[0083] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments and various modifications and changes are possible within the scope of the gist of the present invention.

[0084] For example, the present invention does not preclude the application of the first determination level as the determination level for the shake correction effect even when the blur offset amount is less than the threshold value Dth.

[0085] Furthermore, the evaluation value calculation process of the second embodiment (FIG. 7) is not limited to the judgment level setting of the first embodiment (FIG. 4), but may be applied in combination with the judgment level setting of the third embodiment (FIG. 9) or the judgment level setting of the fourth embodiment (FIG. 10).

[0086] In the above embodiment, the shutter speed was set to change the expected amount of blur while capturing images in a stationary state and in a vibrating state. However, other methods may be used. For example, the expected amount of blur may be changed by changing the brightness of the chart 14, which is the subject. When changing the brightness of the chart 14, the present invention can also be applied to cameras that do not allow the shutter speed to be set externally. When changing the brightness of the chart 14, the variation De of the bokeh offset amount is determined by the relationship between the variation in the amount of image degradation and the change in brightness.

[0087] The present invention can also be realized by supplying a program that realizes one or more functions of the embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. [Explanation of symbols]

[0088] 11 Imaging device 12 Shaking table 13 Excitation waveform data 14 Charts 15 Image evaluation device

Claims

1. A method for evaluating a shake correction effect of an imaging device, comprising: an evaluation step of calculating an evaluation value of the shake correction effect based on a shutter speed value at which a reference blur amount theoretically calculated based on a blur waveform applied to the imaging device and an actual blur amount calculated using an image captured while the imaging device is vibrating each become specific blur amounts; a setting step of setting the specific amount of blur, The setting step includes: a first calculation step of calculating an amount of image degradation of the imaging device caused by factors other than external vibration; a selection step of selecting a determination level that defines the specific amount of blur from a plurality of determination levels having different amounts of blur based on the amount of image deterioration; Including, the plurality of determination levels include a first determination level and a second determination level having a smaller amount of blur than the first determination level, In the selection step, when the amount of image deterioration is a first amount, the first determination level is selected as the determination level that defines the specific amount of blur, and when the amount of image deterioration is a second amount that is smaller than the first amount, the second determination level is selected as the determination level that defines the specific amount of blur. An evaluation method characterized by:

2. An evaluation method as described in Claim 1, wherein in the selection process, when the amount of image degradation is less than the amount of blur at the second judgment level, the second judgment level is selected as the judgment level that defines the specific amount of blur.

3. A method for evaluating the image stabilization effect of an imaging device, comprising: an evaluation step of calculating an evaluation value of the shake correction effect based on a shutter speed value at which a reference blur amount theoretically calculated based on a blur waveform applied to the imaging device and an actual blur amount calculated using an image captured while the imaging device is vibrating each become specific blur amounts; a setting step of setting the specific amount of blur, The setting step includes: a first calculation step of calculating an amount of image degradation of the imaging device caused by factors other than external vibration; a selection step of selecting a determination level that defines the specific amount of blur from a plurality of determination levels having different amounts of blur based on the amount of image deterioration; Including, the plurality of determination levels include a first determination level and a second determination level having a smaller amount of blur than the first determination level, In the selection step, when the amount of change in the amount of image deterioration with respect to a change in exposure time or brightness is a first amount, the first determination level is selected as the determination level that defines the specific amount of blur, and when the amount of image deterioration is a second amount that is smaller than the first amount, the second determination level is selected as the determination level that defines the specific amount of blur. An evaluation method characterized by:

4. An evaluation method as described in claim 3, wherein in the selection process, the amount of change in the amount of image degradation with respect to changes in exposure time or brightness is compared with the second judgment level, and if the amount of change in the amount of image degradation is less than the amount of blur at the second judgment level, the second judgment level is selected as the judgment level that defines the specific amount of blur.

5. The evaluation step includes: a second calculation step of calculating, for a plurality of shutter speed values, a reference blur amount that is theoretically calculated based on a blur waveform applied to the image capture device and an actual blur amount that is calculated using images captured while the image capture device is vibrating; a third calculation step of calculating a reference shutter speed value when the reference blur amount becomes a specific blur amount, and an actual shutter speed value when the actual blur amount becomes the specific blur amount; an evaluation value calculation step of calculating an evaluation value of the shake correction effect using the reference shutter speed value and the actually measured shutter speed value; The evaluation method according to claim 1 , comprising:

6. The amount of image degradation is a blur offset amount calculated using an image captured while the imaging device is stationary. The evaluation method according to any one of claims 1 to 5.

7. The amount of image degradation is calculated from parameters of the optical system of the imaging device. The evaluation method according to any one of claims 1 to 5.

8. In the evaluation step, calculating a first evaluation value of the shake correction effect using the shutter speed value calculated based on the first determination level; When the second determination level is selected as the determination level that defines the specific amount of blur, a second evaluation value of the blur correction effect is further calculated using the shutter speed value calculated based on the second determination level. The evaluation method according to any one of claims 1 to 7.

9. The setting step is performed before the evaluation step. The evaluation method according to any one of claims 1 to 8.

10. An apparatus for evaluating the shake correction effect of an imaging apparatus, comprising: an evaluation means for calculating an evaluation value of the shake correction effect based on a shutter speed value at which a reference blur amount theoretically calculated based on a blur waveform applied to the image capture device and an actual blur amount calculated using an image captured while the image capture device is vibrated each become specific blur amounts; and a setting means for setting the specific amount of blur, The setting means a first calculation means for calculating an amount of image degradation of the imaging device caused by factors other than external vibration; a selection means for selecting a determination level that defines the specific amount of blur from a plurality of determination levels having different amounts of blur based on the amount of image deterioration; and the plurality of determination levels include a first determination level and a second determination level having a smaller amount of blur than the first determination level, the selection means selects the first determination level as the determination level for defining the specific amount of blur when the amount of image degradation is a first amount, and selects the second determination level as the determination level for defining the specific amount of blur when the amount of image degradation is a second amount smaller than the first amount. An evaluation device characterized by:

11. An apparatus for evaluating the shake correction effect of an imaging device, comprising: an evaluation means for calculating an evaluation value of the shake correction effect based on a shutter speed value at which a reference blur amount theoretically calculated based on a blur waveform applied to the image capture device and an actual blur amount calculated using an image captured while the image capture device is vibrated each become specific blur amounts; and a setting means for setting the specific amount of blur, The setting means a first calculation means for calculating an amount of image degradation of the imaging device caused by factors other than external vibration; a selection means for selecting a determination level that defines the specific amount of blur from a plurality of determination levels having different amounts of blur based on the amount of image deterioration; and the plurality of determination levels include a first determination level and a second determination level having a smaller amount of blur than the first determination level, the selection means selects the first determination level as the determination level for defining the specific amount of blur when the amount of change in the amount of image deterioration with respect to a change in exposure time or brightness is a first amount, and selects the second determination level as the determination level for defining the specific amount of blur when the amount of image deterioration is a second amount smaller than the first amount. An evaluation device characterized by:

12. an evaluation step of calculating an evaluation value of the shake correction effect based on a shutter speed value at which a reference shake amount theoretically calculated based on a shake waveform applied to the imaging device and an actual measured shake amount calculated using an image captured while the imaging device is vibrating each become specific shake amounts; a setting step of setting the specific amount of blurring, The setting step includes: a first calculation step of calculating an amount of image degradation of the imaging device caused by factors other than external vibration; a selection step of selecting a determination level that defines the specific amount of blur from a plurality of determination levels having different amounts of blur based on the amount of image deterioration; Including, the plurality of determination levels include a first determination level and a second determination level having a smaller amount of blur than the first determination level, In the selection step, when the amount of image deterioration is a first amount, the first determination level is selected as the determination level that defines the specific amount of blur, and when the amount of image deterioration is a second amount that is smaller than the first amount, the second determination level is selected as the determination level that defines the specific amount of blur. A program characterized by:

13. An evaluation process for calculating an evaluation value of the shake correction effect based on the shutter speed value when a reference shake amount theoretically calculated based on a shake waveform applied to an imaging device and an actual measured shake amount calculated using an image captured while the imaging device is vibrated each become specific shake amounts; a setting step of setting the specific amount of blurring, The setting step includes: a first calculation step of calculating an amount of image degradation of the imaging device caused by factors other than external vibration; a selection step of selecting a determination level that defines the specific amount of blur from a plurality of determination levels having different amounts of blur based on the amount of image deterioration; Including, the plurality of determination levels include a first determination level and a second determination level having a smaller amount of blur than the first determination level, In the selection step, when the amount of change in the amount of image deterioration with respect to a change in exposure time or brightness is a first amount, the first determination level is selected as the determination level that defines the specific amount of blur, and when the amount of image deterioration is a second amount that is smaller than the first amount, the second determination level is selected as the determination level that defines the specific amount of blur. A program characterized by:

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