JP2017063247A - Imaging apparatus and method of controlling filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which when a user changes the posture of a camera which controls rotation of a polarizing filter while maintaining a polarization rate, a camera posture front-rear polarization rate is different if the polarizing filter is only held constant in a right upward direction since the user puts some snap on his or her wrist or re-holds the camera from one hand to the other to cause the camera to rotate in a pitch direction and a yaw direction in a process for changing the posture of the camera.SOLUTION: If it is determined that a camera is rotated in a pitch direction and a yaw direction as well as a movement in a roll direction, an image is scanned while a filter is rotated after a camera posture is changed so as to find a polarization cutting rate, and the filter is so controlled that the polarization cutting rate after change in camera posture is equal to the polarization cutting rate before the posture change.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an imaging apparatus, a filter control method, and a control program.

  Conventionally, when shooting a camera equipped with an optical filter that rotates perpendicular to the optical axis, such as a polarization cut filter, the filter rotates with the camera when the user changes the camera posture, so there is a polarization effect during shooting. A method of preventing change is disclosed.

  Japanese Patent Laid-Open No. 2004-151867 keeps the rotation angle of the reference axis and the filter constant even when the user changes the camera posture when taking the vertical position and the horizontal position with the reference axis as the reference axis. Thus, it has been proposed to keep the change in the polarization effect constant regardless of the change in the camera posture by rotating the filter.

JP 2014-22799 A

  However, when the user rotates the camera posture by 90 degrees with respect to the upper direction for horizontal position shooting and vertical position shooting, that is, when the user rotates the camera by 90 degrees in the roll direction, the user changes the posture of the camera. In the process, the wrist may be snapped or the camera may be changed, which may cause the camera to rotate in the pitch or yaw direction.

  If the rotation in the pitch direction or yaw direction is applied, the polarization effect of the polarizing filter before and after the camera posture will not be constant because the camera direction with respect to the subject is oblique before and after the camera posture is changed. There is.

  When photographing using a polarizing filter, the maximum amount of light that can be depolarized varies depending on the angle of the lens with respect to incident light. Change the camera posture for the purpose of finding the angle that allows the user to remove the maximum polarization, such as when looking for a camera posture that can remove the maximum reflection from the glass to shoot a subject behind the glass. There may be. Since it is necessary to find a state in which polarized light can be removed by combining the camera posture and the rotation angle of the polarization filter, it is not possible to find a camera posture capable of removing polarized light to the maximum even if the filter angle is constant with respect to the upward direction. .

In order to solve the above problems, an imaging apparatus according to the present invention provides:
A mechanism for rotating the filter and a means for detecting the posture change are provided, and the rotation of the filter is maintained at a constant angle with respect to the reference axis direction regardless of the camera posture according to the movement direction and amount of the detected posture change. It is characterized by switching between control and control to determine the rotation angle of the filter according to the evaluation value.

  In other words, if the user determines that the polarization effect is to be constant, such as when shooting horizontally and vertically for the same subject, scan the image while rotating the filter when the camera orientation changes. In this way, the filter is controlled so that the polarization rate before the change of posture becomes the same after the change of the camera posture.

  In addition, if the user determines that the camera posture has been changed in order to remove reflection from the subject, the filter rotation angle is searched for the maximum polarization cut while rotating the filter. Adjust the filter to an angle that can cut polarized light as much as possible.

  According to the imaging apparatus of the present invention, when the user wants to maintain a constant polarization rate before and after the camera posture, the user does not intend by snapping the camera or changing the camera in the process of changing the camera posture. Even if the movement of the direction is applied to the camera, the polarization rate of the filter can be kept constant.

  In addition, if the user determines that the camera posture is changed for the purpose of removing reflection from the subject, the filter effect can be adjusted to the user's intention by setting the filter to a rotational position that can remove polarized light as much as possible. Can be obtained.

It is a figure which shows the digital camera which shows the example of a structure of this invention. It is a flowchart which shows the example which determines the filter rotation method of this embodiment. It is a figure explaining the example of the camera moving direction obtained from a sensor in this embodiment. It is a figure which shows the example of the luminance change by filter rotation of this embodiment. It is a figure which shows the example of the evaluation area | region of this embodiment. It is a figure which shows the example of filter rotation according to the camera attitude | position of this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a digital camera showing an example of the configuration of the present invention.

  In FIG. 1, reference numeral 100 denotes an image processing apparatus. 10 is a photographic lens, 11 is a polarizing filter, 12 is a mechanical shutter having a diaphragm function, 14 is an image sensor that converts an optical image into an electrical signal, and 16 is an A / A that converts an analog signal output of the image sensor 14 into a digital signal. D converter. The eleventh polarizing filter can be retracted from the optical axis by 41 filter control means described later, and by retracting it, it is possible to take an image without passing through the polarizing filter.

  A timing generation circuit 18 supplies a clock signal and a control signal to the image sensor 14 and the A / D converter 16, and is controlled by the memory control circuit 22 and the system control circuit 50. In addition to the twelve mechanical shutters, the accumulation time can be controlled as an electronic shutter by controlling the reset timing of the eighteen image sensors, and can be used for moving image shooting and the like.

  An image processing circuit 20 performs predetermined pixel interpolation processing and color conversion processing on the data from the A / D converter 16 or the data from the memory control circuit 22. Further, an electronic zoom function is realized by performing image cutting and scaling processing by 20 image processing circuits.

  Further, the image processing circuit 20 performs predetermined calculation processing using the captured image data, and the system control circuit 50 controls the exposure control means 40 and the distance measurement control means 42 based on the obtained calculation result. TTL AF processing, AE processing, and EF processing are performed.

  Further, the image processing circuit 20 performs predetermined arithmetic processing using captured image data, and also performs TTL AWB (auto white balance) processing based on the obtained arithmetic result.

  A memory control circuit 22 controls the A / D converter 16, the timing generation circuit 18, the image processing circuit 20, the memory 30, and the compression / decompression circuit 32. The data of the A / D converter 16 is written into the memory 30 via the image processing circuit 20 and the memory control circuit 22, or the data of the A / D converter 16 is directly written via the memory control circuit 22.

  Reference numeral 28 denotes an image display unit composed of a TFT LCD or the like, and display image data written in the memory 20 is displayed by the image display unit 28 via the memory control circuit 22. If the image data captured using the image display unit 28 is sequentially displayed, the electronic viewfinder function can be realized. The image display unit 28 can arbitrarily turn on / off the display according to an instruction from the system control circuit 50. When the display is turned off, the power consumption of the image processing apparatus 100 can be greatly reduced. I can do it.

  Reference numeral 30 denotes a memory for storing captured still images and moving images, and has a sufficient storage capacity to store a predetermined number of still images and a predetermined time of moving images. This makes it possible to write a large amount of images to the memory 30 at high speed even in continuous shooting or panoramic shooting in which a plurality of still images are continuously shot. The memory 30 can also be used as a work area for the system control circuit 50.

  Reference numeral 31 denotes a non-volatile memory composed of a flash ROM or the like. The program code executed by the system control circuit 50 is written in the nonvolatile memory 31, and the program code is executed while being read sequentially. In addition, an area for storing system information and an area for storing user setting information are provided in the nonvolatile memory, and various information and settings are read and restored at the next startup.

  Reference numeral 32 denotes a compression / decompression circuit that compresses and decompresses image data by adaptive discrete cosine transform (ADCT) or the like, reads an image stored in the memory 30, performs compression processing or decompression processing, and stores the processed data in the memory 30. Write to.

  Reference numeral 40 denotes an exposure control means for controlling the shutter 12 having a diaphragm function, and has a flash light control function in conjunction with the flash 48.

  41 is a means for controlling the polarizing filter 11, and has a function of retracting the polarizing filter 11 from the optical axis or returning it to the optical axis, and when the filter is placed on the optical axis, the filter is controlled together with rotation control. It has a function of grasping the rotation angle of the filter from the rotation amount.

  Reference numeral 42 denotes distance measurement control means for controlling the focusing of the photographing lens 10, and reference numeral 44 denotes zoom control means for controlling the zooming of the photographing lens 10.

  A flash 48 has an AF auxiliary light projecting function and a flash light control function.

  The exposure control means 40 and the distance measurement control means 42 are controlled using the TTL method. Based on the calculation result obtained by calculating the captured image data by the image processing circuit 20, the system control circuit 50 performs the exposure control means 40 and the distance measurement. Control is performed on the control means 42.

  A system control circuit 50 controls the entire image processing apparatus 100. Reference numerals 60, 62, 64, 66, 70, and 72 denote operation means for inputting various operation instructions of the system control circuit 50. A single unit such as a switch, a dial, a touch panel, pointing by line-of-sight detection, a voice recognition device, or the like Consists of multiple combinations.

  Here, a specific description of these operating means will be given. Reference numeral 60 denotes a mode dial switch, which can switch and set various function modes such as power-off, automatic shooting mode, shooting mode, panoramic shooting mode, moving image shooting mode, playback mode, and PC connection mode.

  Reference numeral 62 denotes a shutter switch SW1, which is turned on during the operation of the shutter button, and instructs to start operations such as AF (autofocus) processing, AE (automatic exposure) processing, and AWB (auto white balance) processing.

  A shutter switch SW2 64 is turned on when the operation of the shutter button is completed. In the case of flash photography, after performing EF (flash pre-emission) processing, the image sensor 14 is exposed for the exposure time determined in the AE processing. In flash photography, light is emitted during this exposure period, and the exposure period. Simultaneously with the end of the exposure, the exposure control means 40 shields the light, thereby completing the exposure to the image sensor 14.

  A read process for writing the image data to the memory 30 via the A / D converter 16 and the memory control circuit 22 for the signal read from the image sensor 14, a development process using computations in the image processing circuit 20 and the memory control circuit 22; The image data is read from the memory 30 and compressed by the compression / decompression circuit 32. Next, the start of a series of processing operations such as recording processing for writing image data to the recording medium 200 is instructed.

  Reference numeral 66 denotes a display changeover switch, which can change the display of the image display unit 28. With this function, when photographing is performed using the optical viewfinder 104, it is possible to save power by cutting off the current supply to the image display unit including a TFT LCD or the like.

  Reference numeral 70 denotes an operation unit including various buttons, a touch panel, a rotary dial, and the like, which include a menu button, a set button, a macro button, a multi-screen playback page break button, a flash setting button, a single shooting / continuous shooting / self-timer switching button, and the like. . Menu move + (plus) button, menu move-(minus) button, playback image move + (plus) button, playback image-(minus) button, shooting quality selection button, exposure compensation button, date / time setting button, etc. is there.

  Reference numeral 72 denotes a zoom switch unit as zoom operation means for a user to give an instruction to change the magnification of a captured image. Hereinafter, the zoom switch 72 is also referred to. The zoom switch 72 includes a tele switch that changes the imaging field angle to the telephoto side and a wide switch that changes the imaging angle of view to the wide angle side. By using the zoom switch 72, the zoom control unit 44 is instructed to change the imaging field angle of the photographing lens 10 and becomes a trigger for performing an optical zoom operation. In addition, it also serves as a trigger for electronic zooming change of the imaging angle of view by image cropping by the image processing circuit 20 or pixel interpolation processing.

  Reference numeral 86 denotes a power supply means including a primary battery of an alkaline battery, a secondary battery such as a NiCd battery, a NiMH battery, or a Li ion battery, an AC adapter, or the like.

  Reference numeral 90 denotes an interface with a recording medium such as a memory card or hard disk, and reference numeral 92 denotes a connector for connecting to a recording medium such as a memory card or hard disk.

  Reference numeral 102 denotes protection means that is a barrier that prevents the imaging unit from being soiled or damaged by covering the imaging unit including the lens 10 of the image processing apparatus 100.

  Reference numeral 104 denotes an optical viewfinder, which can take an image using only the optical viewfinder without using the electronic viewfinder function of the image display unit 28.

  Reference numeral 106 denotes a gyro sensor, which can obtain an angular velocity based on a plurality of axes. It becomes possible to grasp the camera posture from the angular velocity obtained from the gyro sensor.

  A communication unit 110 has various communication functions such as USB, IEEE1394, LAN, and wireless communication. Reference numeral 112 denotes a connector for connecting the image processing apparatus 100 to another device by the communication unit 110 or an antenna in the case of wireless communication.

  Reference numeral 200 denotes a recording medium such as a memory card or a hard disk. The recording medium 200 includes a recording unit 202 composed of a semiconductor memory, a magnetic disk, or the like, an interface 204 with the image processing apparatus 100, and a connector 206 for connecting to the image processing apparatus 100. Reference numeral 210 denotes a recording medium such as a memory card or a hard disk.

  Next, the filter rotation method will be described with reference to FIG. FIG. 2 is a flow executed according to the amount of change in the camera posture after the camera posture is changed.

  First, in S201, it is determined whether or not the amount of rotation in the roll direction when the camera posture is changed is greater than A. The rotation amount 106 in the roll direction can be acquired from the gyro sensor.

  Here, the rotation direction acquired from the gyro sensor 106 will be described. From the gyro sensor 106, it is possible to obtain a roll with the front and rear axes, a pitch with the left and right axes, and an angular velocity about the three axes of the yaw with the vertical axes. The position where the surface with the lens is facing forward and the shutter button is up is the reference position, and the rotation direction in that case is shown in FIG. The arrow R in FIG. 3 is the roll direction, P is the pitch direction, and Y is the yaw direction.

  When the camera posture is at the reference position, the roll direction is a rotation direction around the optical axis direction, for example, when switching from horizontal position shooting to vertical position shooting. The pitch direction rotates from the reference position in the direction of gravity or directly above, for example, when the camera is moved up and down. The yaw direction rotates so that the surface with the lens faces rightward or leftward when the camera is held at the reference position.

  The rotation axis may be set anywhere as long as the rotation direction matches. For example, the axis in the yaw direction may be a vertical axis that passes through the center of the camera, or may be a vertical axis that is centered on the grip of the camera.

  If it is determined in S201 that the amount of rotation in the roll direction is greater than A, the process proceeds to S202, and if the amount of rotation is A or less, the process proceeds to S207. In S202, when the rotation amount in the pitch direction is larger than B, the process proceeds to S204, and when the rotation amount is B or less, the process proceeds to S203. In S203, when the rotation amount in the yaw direction is larger than C, the process proceeds to S204, and when the rotation amount is C or less, the process proceeds to S206.

  In S204, the polarization cut rate after the camera posture is scanned. The polarization cut rate is determined by obtaining an evaluation value determined by an image, a luminance value, a luminance distribution, saturation, or a combination thereof. These evaluation values are obtained at the respective filter angles while rotating the polarizing filter. When the evaluation values are obtained at all angles, the process proceeds to S205.

  In S205, in order to make the polarization cut rate after the camera posture the same as before the camera posture, the respective polarization cut rates are obtained from the evaluation values of the respective filter angles obtained in S205. From the obtained result, the polarization filter is rotated to an angle at which the polarization cut rate matches that before the camera attitude change.

  An example of how to obtain the polarization cut rate will be described with reference to FIG. In the graph of FIG. 4, the horizontal axis is the rotation angle from the reference angle of the filter, and the vertical axis is the luminance.

  The reference angle of the filter is an angle at which the filter is fixed when the rotation of the filter is reset such as when the camera is started. Since the same effect is obtained when the polarizing filter is rotated 180 degrees, the rotation angle is set to 0 degrees to 180 degrees.

  When the evaluation value is luminance and the luminance obtained by rotating the polarizing filter from 0 degree to 180 degrees is FIG. 4, the lowest angle is 60 degrees and the highest angle is 150 degrees. In this case, the filter angle at which the most polarization can be removed is 60 degrees, and the polarization cut rate is 100%.

  The polarization cut rate is determined from the ratio between the 0% polarization cut rate and the luminance value of 100%. In addition, when the luminance value is the minimum value that can be taken, the polarization cut rate 100%, the maximum value that can be taken may be set as the polarization cut rate 0%, or the saturation value may be used as the evaluation value instead of the luminance value. Of course, a combination of a luminance value and a saturation value may be used as the evaluation value.

  If the polarization removal rate is the same at multiple angles, the polarization filter is rotated by selecting the closest angle from the filter angle when the polarization filter angle is kept constant with respect to the direction of gravity and the direction of gravity. .

  Note that since the shooting angle of view changes due to a change in camera posture, an area for obtaining an evaluation value is set to an area that covers the angle of view before and after the change in camera posture. For example, FIG. 5 shows an example of an area for obtaining an angle of view and an evaluation value when shooting is performed by changing the camera posture in order to shoot from the horizontal position to the vertical position. In FIG. 5, the angle of view taken before the posture change is a frame for horizontal position photography. The shooting angle of view after the posture change is a frame for vertical shooting. The region for obtaining the evaluation value is within the frame of the evaluation region in FIG. 5 that covers both the angles of view before and after the posture change.

  Since the evaluation area is in an undecided state before the camera posture change, the image area is subdivided into blocks and the evaluation values for each block are stored in advance. When the evaluation region is determined after the posture change, the evaluation value using the block region in the evaluation region shown in FIG. 5 is set as the evaluation value before the posture change, and the evaluation value for the corresponding block region even after the posture change Ask for.

  In the present embodiment, the evaluation value is obtained in units of blocks. However, the evaluation value may be obtained by dividing the evaluation unit in units of objects such as persons and objects. If the polarizing filter is rotated so that the evaluation value is the same as that before the posture change in S205, the process ends.

  When the amount of rotation in the yaw direction becomes C or less in S203 and the process proceeds to S206, the camera posture is regarded as having been rotated only in the roll direction, and the polarization filter angle is kept constant with respect to the posture direction and the gravity direction. An example of the rotation of the filter at that time is shown in FIG. FIG. 6A shows an example of the state before the camera posture change. FIG. 6B is a diagram when the eleven polarizing filter is not rotated after the camera posture change. Since the filter rotates with the rotation of the camera from the state before the camera posture change, the filter angle differs before and after the camera posture with respect to the direction of gravity. FIG. 6C shows the 11 polarization filter rotated so that the 11 polarization filter becomes constant with respect to the direction of gravity after the camera posture is changed. The filter angle of the eleventh polarizing filter faces the same direction as before the camera posture change.

  In addition, since the same effect is acquired when the polarizing filter is rotated 180 degrees, the state where the polarizing filter is rotated 180 degrees from the original state is regarded as the same direction direction. Therefore, from the state of FIG. 6A before the camera posture change, the polarizing filter is rotated 90 degrees to the right and rotated to the left by 90 degrees even in the state of FIG. ).

  If the pitch direction is larger than B in S207, the process proceeds to S209, and the polarization cut rate scan after the camera posture is performed. In the scan of the polarization cut rate, the evaluation value at each angle is obtained while rotating the polarization filter in the same manner as in S204.

  In S209, the area for obtaining the evaluation value may be the entire screen considering that the change in the angle of view due to the camera posture change is small, or the area for obtaining the evaluation value is narrowed to the center of the whole screen for more accurate control. It doesn't matter. Further, as described above, the evaluation value may be obtained in units of blocks so as to cover before and after the camera posture.

  After performing the polarization cut rate scan in S209, the process proceeds to S210, and it is assumed that the user is looking for a combination of the camera posture and the filter angle that can maximize the polarization cut, and the polarization removal rate is the highest among the scans in S209. Rotate the polarizing filter to a higher angle. When the depolarization rate is high, the brightness decreases and the saturation increases, so the filter angle with low brightness and high saturation is determined from the combination of evaluation values such as the brightness value, brightness distribution, and saturation, and the polarization filter is Rotate to finish.

  If the amount of rotation in the yaw direction is larger than C in S208, the process proceeds to S209. If it is equal to or less than C, the process proceeds to S211 and the process is terminated without rotating the filter.

  The embodiment has been described based on the flow of FIG. 2, but the values of A, B, and C, which are thresholds of the rotation amount of the camera, may be changed as appropriate, and the thresholds of S202 and S207 are not the same B but different. It does not matter if it is a value. Further, the thresholds B and C employed for pitch and yaw may be dynamically changed according to the roll value.

  In the process of S211, the control not to rotate the filter and the control to keep the filter rotation angle constant with respect to the direction of gravity may be switched according to the threshold adopted in S208.

  The timing of starting the flow of FIG. 2 may be executed when the camera posture is stopped, or until the camera posture is stopped by performing the flow of FIG. 2 in the middle of the change of the camera posture. You may repeat the flow of FIG.

  In this embodiment, the gyro sensor is used for camera posture detection in FIG. 1, but posture detection may be performed by substituting another module such as an acceleration sensor.

  In this embodiment, the polarizing filter is built in the camera in FIG. 1, but there is an attachment that can be attached to the camera from the outside instead of incorporating the filter, and the attachment is attached to the camera by rotating the attachment. Alternatively, the filter may be configured to rotate. In this case, the 41 filter control means has a function of detecting whether or not the filter is attached to the camera. When it is determined that the filter is attached, the rotation of the filter is performed by controlling the rotation of the attachment according to the flow of FIG. To control.

10 photographing lens, 11 polarizing filter, 12 shutter, 14 image sensor,
16 A / D converter, 18 timing generation circuit, 20 image processing circuit,
22 memory control circuit, 28 image display unit, 30 memory, 32 image compression / decompression circuit,
40 exposure control means, 41 filter control means, 42 distance measurement control means,
44 zoom control means, 48 flash, 50 system control circuit,
60 mode dial switch, 62 shutter switch SW1,
64 Shutter switch SW2, 66 Display changeover switch, 70 Operation unit,
72 Zoom switch, 90 interface, 92 connector,
100 image processing apparatus, 102 protection means, 104 optical viewfinder,
106 gyro sensor, 110 communication means, 112 connector (or antenna),
200 recording medium, 202 recording unit, 204 interface, 206 connector

Claims (6)

  A mechanism for rotating the filter and a means for detecting the posture change are provided, and the rotation of the filter is maintained at a constant angle with respect to the reference axis direction regardless of the camera posture according to the movement direction and amount of the detected posture change. An imaging apparatus that switches between control and control to determine a rotation angle of a filter in accordance with an evaluation value.   The imaging apparatus according to claim 1, wherein the evaluation value uses at least one of luminance and saturation of an angle of view covering an imaging area before and after a posture change.   2. The apparatus according to claim 1, further comprising posture change detecting means in a roll direction and a pitch direction or a yaw direction, wherein when only a posture change in the roll direction is detected, the angle of the filter is kept constant with respect to the reference axis direction. The imaging device described.   The filter is a polarizing filter, and includes means for obtaining an evaluation value while rotating the filter and obtaining the polarization cut rate of the polarizing filter from the evaluation value. When determining the rotation angle of the filter according to the evaluation value, the polarization cut Control the rotation of the filter so that the rate is the same polarization cut rate before and after the posture change, or control the rotation of the filter so that the polarization cut rate after the posture change becomes a specific polarization cut rate The imaging device according to claim 1, wherein the imaging device is determined.   A posture change detecting means is provided for the roll direction, the pitch direction, and the yaw direction. When at least one movement in the pitch direction or the yaw direction is added in addition to the roll direction, the polarization cut rate is changed after the posture change and before the posture change. The imaging apparatus according to claim 4, wherein the rotation of the filter is controlled so that the same polarization cut rate is obtained.   5. The imaging apparatus according to claim 4, further comprising posture change detection means in a roll direction, a pitch direction, or a yaw direction, and if the posture change is only in the yaw direction or the pitch direction, the filter is rotated to a specific polarization rate. .