JP4921717B2 - Camera with image blur correction function - Google Patents

Description

  The present invention relates to an image blur correction device mounted on an optical apparatus such as a camera or binoculars.

Conventionally, some optical devices such as cameras and binoculars have an image blur correction function. In the image blur correction process using the image blur correction function, for example, the blur (the blur direction and the blur amount) of the optical device is calculated based on a gyro sensor. In the case of a digital camera, the CCD is driven so that the calculated blur is canceled. In the case of a silver salt camera or binoculars, the correction optical system is driven so that the calculated blur is canceled. As a result, image blur caused by camera shake or the like is corrected, and a good image and field of view can be obtained.
JP-A-6-67255

  When a subject is photographed with a camera, the hue is adjusted according to the external environment (weather, photographing location, etc.) at the time of photographing. However, the conventional image blur correction does not consider such an external environment. That is, the drive control of the correction optical system and the CCD is performed based only on the output of the above-described gyro sensor under any photographing condition. Accordingly, it has been impossible to perform image blur correction with high accuracy according to the photographing conditions.

  SUMMARY An advantage of some aspects of the invention is to perform image blur correction with higher accuracy in accordance with shooting conditions.

  The camera according to the present invention adjusts the output result of the shake detecting means based on the output of the shake detecting means for detecting the camera shake amount, the color temperature measuring means for measuring the color temperature of the subject, and the color temperature measuring means. It is characterized by comprising adjusting means and blur canceling means for canceling camera shake based on the output result adjusted by the adjusting means.

  Preferably, the adjustment unit extracts a predetermined frequency component from the output result of the shake detection unit based on the color temperature measured by the color temperature measurement unit.

  For example, when the measurement result of the color temperature measurement means indicates that the image is taken under a clear sky, the adjustment means extracts the high frequency component, the medium frequency component, and the low frequency component from the output result of the shake detection means, and the color temperature When the measurement result of the measuring means indicates shooting under cloudy weather, when the medium frequency component and low frequency component are extracted from the output result, and the measurement result of the color temperature measuring means indicates indoor shooting Alternatively, only the low frequency component may be extracted from the output result.

  The predetermined frequency component extracted by the adjusting means is a component of a normal camera shake frequency band, the high frequency component corresponds to a relatively high frequency band in the predetermined frequency component, and the medium frequency component is a predetermined frequency. The component corresponds to a relatively medium frequency band, and the low frequency component corresponds to a relatively low frequency band in the predetermined frequency component.

  The shake detection unit is, for example, a gyro sensor, and the adjustment unit may be configured to include a plurality of low-pass filters having different cutoff frequencies and a changeover switch that switches connection between the plurality of low-pass filters and the gyro sensor. .

  The blur canceling unit may cancel the blur by driving the image sensor, or may cancel the blur by driving a correction optical system that constitutes a part of the photographing optical system.

  The camera according to the present invention also includes a shake detection unit that detects a camera shake amount, an adjustment unit that adjusts an output result of the shake detection unit, and a camera shake that is canceled based on the output result adjusted by the adjustment unit. And a blur canceling unit, wherein the adjusting unit extracts a predetermined frequency component from the output result in accordance with a combination range of the shutter speed and the aperture value. This predetermined frequency component is a component in a normal camera shake frequency band.

  As described above, according to the present invention, the blur is canceled after adjusting the output result of the blur detection means based on the color temperature of the subject. Therefore, it is possible to perform highly accurate correction suitable for the shooting conditions in the image blur correction caused by the user's camera shake or the like.

FIG. 1 is a block diagram of a digital camera to which an embodiment according to the present invention is applied.
The CPU 10 is, for example, a microprocessor that controls the entire digital camera. The power switch SWMAIN is controlled to be turned on and off by operating a power button (not shown) provided on the casing of the digital camera. When the power switch SWMAIN is turned on, power is supplied to the CPU 10.

  The photometry switch SWS is turned on when a shutter button (not shown) of the housing is half-pressed. When the photometry switch SWS is turned on, the CPU 10 executes photometry processing and distance measurement processing. That is, the exposure value is calculated based on the input from the photometric device 11, and the aperture value, shutter speed, and charge accumulation time of the image sensor 20 necessary for photographing are calculated based on the exposure value. Further, the driving amount of the focusing lens (not shown) is calculated based on the input from the distance measuring device 12, and a control signal is output to the focus driving circuit 21, and the driving signal from the focus driving circuit 21 to the focusing lens is accordingly generated. Is output.

  The release switch SWR is turned on when the shutter button is fully pressed. When the release switch SWR is turned on, the CPU 10 calculates the drive amounts of the aperture drive mechanism (not shown) and the shutter (not shown) according to the aperture value calculated in the photometric process. Based on the calculation result, a control signal is output from the CPU 10 to the aperture driving circuit 22 and the shutter driving circuit 23. A drive signal is output from the aperture drive circuit 22 to an aperture drive mechanism (not shown), thereby driving the aperture drive mechanism. When the aperture driving mechanism is driven, the movement is transmitted to an aperture (not shown), and the aperture diameter of the aperture is set to a predetermined size. Further, a drive signal is output from the shutter drive circuit 23 to the shutter, thereby releasing the shutter for a predetermined time. With the above control, light that has passed through a photographing optical system (not shown) enters the light receiving surface of the image sensor 20.

  Further, a control signal is output to the image sensor drive circuit 24 based on the above-described charge accumulation time, and a drive signal is output from the image sensor drive circuit 24 to the image sensor 20. The image sensor 20 photoelectrically converts an optical image of a subject formed in the light receiving area and outputs an analog image signal. The analog image signal is converted into a digital image signal by the A / D conversion circuit 25 and input to the CPU 10.

  The digital image signal is subjected to predetermined image processing based on the control of the CPU 10. The DRAM 30 temporarily stores image data in the course of image processing. Image data that has undergone predetermined image processing is displayed on the LCD 31 provided on the back of the camera body.

  The EEPROM 32 stores various programs for moving the camera. When the amount of light of the subject is insufficient, a drive signal is output from the CPU to the flash circuit 33, and flash light is supplied.

  The X-axis gyro sensor 40X of the X-axis gyro sensor output system outputs a voltage proportional to the rotational angular velocity around the X axis on a plane perpendicular to the camera optical axis. The X-axis gyro sensor 40X can be connected to the first low-pass filter 51X, the second low-pass filter 52X, and the third low-pass filter 53X via the changeover switch 50X. The first low-pass filter 51X cuts off frequency components higher than 30 Hz and extracts frequency components of 30 Hz or less. The second low-pass filter 52X cuts off frequency components higher than 20 Hz, and extracts frequency components of 20 Hz or less. The third low-pass filter 53X cuts off frequency components higher than 10 Hz and extracts frequency components of 10 Hz or less. That is, the frequency component extracted from the output voltage of the X-axis gyro sensor 40X can be changed by controlling the changeover switch 50X.

  The Y axis gyro sensor 40Y of the Y axis gyro sensor output system outputs a voltage proportional to the rotational angular velocity around the Y axis orthogonal to the X axis on a plane perpendicular to the camera optical axis. The Y-axis gyro sensor 40Y can be connected to the first low-pass filter 51Y, the second low-pass filter 52Y, and the third low-pass filter 53Y via the changeover switch 50Y. The first low-pass filter 51Y cuts off frequency components higher than 30 Hz and extracts frequency components of 30 Hz or less. The second low-pass filter 52Y cuts off frequency components higher than 20 Hz, and extracts frequency components of 20 Hz or less. The third low-pass filter 53Y cuts off frequency components higher than 10 Hz and extracts frequency components of 10 Hz or less. That is, the frequency component extracted from the output voltage of the Y-axis gyro sensor 40Y can be changed by controlling the changeover switch 50Y.

  An AWB (Auto White Balance) sensor 60 is a sensor for measuring the color temperature of the shooting location. Based on the output of the AWB sensor 60, the CPU 10 determines the conditions of the shooting location (outdoor or indoor, outdoor or sunny or cloudy, indoor or under fluorescent lamp or bulb). Further, the above-described changeover switches 50X and 50Y are controlled according to the determination result, and the frequency component to be cut off is determined from the output voltage of the gyro sensor 40. Instead of the AWB sensor 60, the image signal obtained from the image sensor 20 may be processed to measure the color temperature at the shooting location. However, in this embodiment, the color temperature measurement time and the speed of control are high. In consideration of the above, a single AWB sensor 60 is used.

  The first to third low-pass filters 51X, 52X, 53X of the X-axis gyro sensor output system and the first to third low-pass filters 51Y, 52Y, 53Y of the Y-axis gyro sensor output system are connected to the camera shake correction calculation circuit 70. Has been. The output voltage of the X-axis gyro sensor 40X in which a predetermined frequency component is cut by the low-pass filter connected through the changeover switch 50X among the first to third low-pass filters 51X, 52X, 53X is the camera shake correction calculation circuit 70. Applied to. Similarly, the output voltage of the Y-axis gyro sensor 40Y, in which a predetermined frequency component is cut by the low-pass filter connected through the changeover switch 50Y among the first to third low-pass filters 51Y, 52Y, 53Y, is corrected for camera shake. Applied to the arithmetic circuit 70. In the camera shake correction calculation circuit 70, the angular velocity around the X axis and the Y axis is integrated based on the input voltage. As a result, a displacement around a predetermined X axis and Y axis of the camera, that is, a change in position information is calculated. Thereby, the amount of camera shake around the X axis and Y axis of the camera is calculated.

  Further, the camera shake correction calculation circuit 70 calculates drive data of the image sensor 20 for canceling the calculated shake amount. The drive data is a drive direction and a drive amount along a plane perpendicular to the optical axis of the camera. The calculated drive data is output to the camera shake correction mechanism 80. The image sensor 20 is moved along a plane perpendicular to the camera optical axis by the camera shake correction mechanism 80.

  FIG. 2 is a flowchart showing a shooting processing procedure in the present embodiment. In step S100, the state of the switch SWS is checked to determine whether the shutter button provided on the camera casing is half-pressed. If it is confirmed that the shutter button is pressed halfway and the switch SWS is turned on, the process proceeds to step S102. In step S102, a photometric process and a distance measuring process are executed.

  Next, in step S104, the color temperature of the shooting location is measured by the AWB sensor 60. In steps S106 to S112, the output of the AWB sensor 60 is checked.

  If the color temperature of the output of the AWB sensor 60 is about 5500K (Kelvin) in step S106 and it is confirmed that the image is taken in a clear sky, the process proceeds to step S114, and the X-axis gyro sensor 40X detects the first low-pass filter 51X. The changeover switches 50X and 50Y are controlled so that the Y-axis gyro sensor 40Y is connected to the first low-pass filter 51Y. As a result, frequency components higher than 30 Hz are cut in the output voltages of the gyro sensors 40X and 40Y, and only frequency components of 30 Hz or less are input to the camera shake correction arithmetic circuit 70.

  If it is confirmed in step S108 that the color temperature is about 6000 K and the image is cloudy, the process proceeds to step S116, where the X-axis gyro sensor 40X is connected to the second low-pass filter 52X, and the Y-axis gyro sensor 40Y. Are connected to the second low-pass filter 52Y, the changeover switches 50X and 50Y are controlled. As a result, frequency components higher than 20 Hz are cut in the output voltages of the gyro sensors 40X and 40Y, and only frequency components of 20 Hz or less are input to the camera shake correction arithmetic circuit 70.

  In step S110, it is confirmed that the output of the AWB sensor 60 is out of the output range of the black body radiation-type light source, and it is confirmed that the image is taken under a fluorescent lamp, or in step S112, the color temperature is about 3000 K, and the light bulb If it is confirmed that the image is taken at the bottom, the process proceeds to step S118. In step S118, the selector switches 50X and 50Y are controlled so that the X-axis gyro sensor 40X is connected to the third low-pass filter 53X and the Y-axis gyro sensor 40Y is connected to the third low-pass filter 53Y. As a result, frequency components higher than 10 Hz are cut in the output voltages of the gyro sensors 40X and 40Y, and only frequency components of 10 Hz or less are input to the camera shake correction arithmetic circuit 70.

  If the cutoff process of the frequency component of the output voltage of the gyro sensors 40X and 40Y is executed in any of steps S114, S116, and S118, the process proceeds to step S120. In step S120, the state of the switch SWR is checked to determine whether the shutter button has been fully pressed. If it is confirmed that the shutter button is fully pressed and the switch SWR is turned on, the process proceeds to step S122. In step S122, the image pickup device 20 is driven and subject photographing processing is executed.

  In general, the range of vibration of camera shake that must be corrected to prevent occurrence of image blur in a captured image is 600 to 1800 vibrations / minute. In other words, the normal camera shake frequency is about 30 Hz or less, and correction processing must be performed corresponding to a frequency component of about 30 Hz or less in the output voltages of the gyro sensors 40X and 40Y. FIG. 3 is a diagram illustrating a frequency component of 30 Hz or less in the output voltage of the X-axis gyro sensor 40X as a square wave. This square wave includes a 30 Hz square wave component, a 20 Hz square wave component, and a 10 Hz square wave component shown in FIG. 4.

  When photographing is performed indoors or under a streetlight at night, the brightness (brightness) of the subject is relatively low, and thus the shutter speed is set to be somewhat slow. In other words, the combination range of the shutter speed and the aperture value becomes narrow. Therefore, if a correction process is performed corresponding to a low frequency component of about 10 Hz, an effect of camera shake correction can be obtained. On the other hand, when shooting is performed outdoors in fine weather, the luminance (brightness) of the subject is relatively high, and the range of combinations of shutter speed and aperture value is widened. Therefore, under this shooting condition, it is necessary to perform correction processing corresponding to a frequency component of about 30 Hz or less so as to be able to handle a wide range of combinations of shutter speed and aperture value. Further, when shooting is performed outdoors on a cloudy day, the luminance (brightness) of the subject is higher than indoor shooting, but is lower than that when shooting outdoors on a sunny day. Therefore, although the shutter speed is limited to a certain degree, the range of combinations of the shutter speed and the aperture value is wide as compared with indoor photography. Therefore, under this photographing condition, it is necessary to perform a correction process corresponding to a frequency component of about 20 Hz or less.

  As described above, in this embodiment, the changeover switches 50X and 50Y are controlled based on the detection result of the AWB sensor 60, and cut off from the voltage output from the gyro sensors 40X and 40Y and input to the camera shake correction arithmetic circuit 70. Frequency components to be determined are determined. Accordingly, only frequency components corresponding to the shooting conditions are extracted from the output voltages of the gyro sensors 40X and 40Y indicating camera shake, and the camera shake correction process is executed. As a result, it is possible to perform camera shake correction with high accuracy suitable for the shooting conditions.

  In this embodiment, since the cutoff frequency is determined based on the detection result of the AWB sensor 60, the luminance of the subject is not affected. Therefore, camera shake correction with higher accuracy is executed.

  In addition, although this embodiment has the structure which cancels camera shake by driving the image pick-up element 20, it is not restricted to this. The control of the cut-off frequency of the output voltages of the gyro sensors 40X and 40Y based on the detection result of the AWB sensor 60 is also applied to a camera that cancels camera shake by driving a correction optical system that forms part of the photographing optical system. Applicable.

1 is a block diagram of a camera to which an embodiment according to the present invention is applied. It is a flowchart which shows the imaging | photography process sequence. It is a figure which shows the frequency component below 30 Hz in the output voltage of a gyro sensor with a square wave. It is a figure which shows the square wave component contained in the output voltage of a gyro sensor.

Explanation of symbols

10 CPU
20 Image sensor 40X X-axis gyro sensor 40Y Y-axis gyro sensor 50X, 50Y changeover switch 51X, 51Y First low-pass filter 52X, 52Y Second low-pass filter 53X, 53Y Third low-pass filter 60 AWB sensor 70 Camera shake correction arithmetic circuit

Claims (4)

Camera shake detecting means for detecting the camera shake amount;
Color temperature measuring means for measuring the color temperature of the subject;
Adjusting means for adjusting the output result by extracting a predetermined frequency component from the output result of the blur detecting means based on the color temperature measured by the color temperature measuring means;
A camera shake canceling unit that cancels camera shake based on the output result adjusted by the adjusting unit ;
The predetermined frequency component is a component of a normal camera shake frequency band,
When the adjustment unit indicates that the measurement result of the color temperature measurement unit is shooting under a clear sky, a high frequency component corresponding to a relatively high frequency band in the predetermined frequency component, and the predetermined frequency component In this case, a medium frequency component corresponding to a relatively medium frequency band and a low frequency component corresponding to a relatively low frequency band in the predetermined frequency component are extracted from the output result, and the measurement result is cloudy The medium frequency component and the low frequency component are extracted from the output result, and when the measurement result indicates indoor shooting, only the low frequency component is extracted from the output result. A camera equipped with an image blur correction function characterized by extracting images. The shake detection means is a gyro sensor,
2. The image blur correction according to claim 1 , wherein the adjustment unit includes a plurality of low-pass filters having different cutoff frequencies, and a changeover switch that switches connection between the plurality of low-pass filters and the gyro sensor. A camera with functions.   The camera with an image blur correction function according to claim 1, wherein the blur canceling unit cancels the blur by driving an image pickup device. A correction optical system that forms part of the photographic optical system
2. The camera having an image blur correction function according to claim 1, wherein the blur canceling unit cancels the blur by driving the correction optical system.

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