JP5212156B2 - Electronic camera - Google Patents

Description

  The present invention relates to an electronic camera.

  A camera that performs predetermined control by examining a difference between frames based on a periodically captured through image frame is known (see Patent Document 1). The thing of patent document 1 is controlled to a power saving state, when the state whose difference is below a reference value continues for a predetermined time.

JP 2004-186919 A

  In the prior art, the acquisition interval of the acquired information (through image cycle) and the contribution of past values (which frame to check for differences) are fixed, so appropriate control according to the usage state of the camera is performed. It was difficult.

  An electronic camera according to the present invention includes control amount calculation means for calculating a control amount used for camera processing based on a plurality of pieces of latest information arranged in the order of acquisition among periodically acquired information, and motion detection for detecting camera motion. And control means for controlling the control amount calculation means so that the magnitude of the contribution to the control amount by the past information among the plurality of latest information differs according to the detection information by the motion detection means. And

  According to the present invention, it is possible to appropriately calculate a control amount used for camera processing in accordance with the state of the camera.

It is a block diagram explaining the structural example of the electronic camera by one embodiment of this invention. It is a flowchart explaining the flow of the process which determines the magnitude of the control period and past value ratio which CPU performs. It is a figure explaining the example of a setting of the control period and past value ratio with respect to the camera shake and image blur of an electronic camera. It is a figure explaining the convergence control in a camera process. It is a figure explaining the convergence control in a camera process. It is a figure explaining the convergence control in a camera process. It is a figure explaining the convergence control in a camera process.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration example of an electronic camera according to an embodiment of the present invention. In FIG. 1, an electronic camera includes an imaging optical system 11, an image sensor 12, an AFE (Analog front end) circuit 13, an image processing circuit 14, an LCD monitor 15, a buffer memory 16, a flash memory 17, A CPU 18, a memory card interface (I / F) 19, an operation member 20, a shake detection sensor 21, and a timing generator (TG) 22 are provided.

  The CPU 18, the buffer memory 16, the flash memory 17, the memory card interface 19, the image processing circuit 14, and the LCD monitor 15 are connected via a bus 23.

  The photographing optical system 11 includes a plurality of lens groups including a zoom lens and a focusing lens, and forms a subject image on the light receiving surface of the image sensor 12. In order to simplify FIG. 1, the photographing optical system 11 is shown as a single lens.

  The TG 22 generates a predetermined timing signal in response to an instruction sent from the CPU 18 and supplies timing signals to the image sensor 12, the AFE circuit 13, and the image processing circuit 14, respectively. The image pickup device 12 and the like are driven and controlled by the timing signal, whereby the image pickup timing by the image pickup device 12 and the readout timing of the analog image signal from the image pickup device 12 are controlled.

  The imaging element 12 is configured by a CCD image sensor, a CMOS image sensor, or the like in which light receiving elements are two-dimensionally arranged on the light receiving surface. The image sensor 12 photoelectrically converts a subject image by a light beam that has passed through the photographing optical system 11 to generate an analog image signal. The analog image signal is input to the AFE circuit 13.

  The AFE circuit 13 performs analog processing such as correlated double sampling and gain adjustment on the analog image signal, and converts the image signal after the analog processing into digital image data. The digital image data is input to the image processing circuit 14. The image processing circuit 14 performs various types of image processing (color interpolation processing, gradation conversion processing, contour enhancement processing, white balance adjustment processing, image compression processing, image expansion processing, etc.) on the digital image data.

  The LCD monitor 15 is constituted by a liquid crystal panel, and displays an image, an operation menu screen, and the like according to an instruction from the CPU 18. The buffer memory 16 temporarily stores digital image data in the pre-process and post-process of image processing by the image processing circuit 14. The flash memory 17 stores a program executed by the CPU 18.

  The CPU 18 comprehensively controls operations performed by the electronic camera by executing a program stored in the flash memory 17. The CPU 18 also performs AF (autofocus) operation control and automatic exposure (AE) calculation. The AF operation uses, for example, a contrast detection method for obtaining a focus position of a focusing lens (not shown) based on contrast information of a through image. The through image refers to a monitor image that is repeatedly acquired by the image sensor 12 at a predetermined time interval (for example, 10 frames / second to 30 frames / second) before a shooting instruction, and is also referred to as a live view image.

  The memory card interface 19 has a connector (not shown), and a storage medium 51 such as a memory card is connected to the connector. The memory card interface 19 writes data to the connected storage medium 51 and reads data from the storage medium 51. The storage medium 51 is configured by a memory card incorporating a semiconductor memory, a hard disk drive, or the like.

  The operation member 20 includes a release button (not shown), a zoom switch, a menu switch, and the like. The operation member 22 sends an operation signal corresponding to each operation, such as a function operation or a menu selection operation, to the CPU 18.

   The shake detection sensor 21 is constituted by an angular velocity sensor, for example. The shake detection sensor 21 detects an angular velocity generated in the pitch direction and the yaw direction of the electronic camera, and sends an angular velocity detection signal to the CPU 18.

  In the present embodiment, when calculating a control amount used for camera processing, for example, when calculating each color calculation gain used for white balance adjustment processing, focusing position calculation in AF operation, and AE calculation, It is characterized in that the calculation interval and the ratio of the past value in the information used in each calculation are made different. Hereinafter, a description will be given focusing on the process of determining the length of the control cycle (calculation interval) and the level of the past value ratio in such convergence control.

  FIG. 2 is a flowchart for explaining the flow of processing for determining the control cycle and the past value ratio executed by the CPU 18. The CPU 18 repeatedly executes the process of FIG. 2 when the main switch of the electronic camera is turned on.

  In step S101 in FIG. 2, the CPU 18 starts to acquire a through image and proceeds to step S102. In step S102, the CPU 18 starts obtaining the detection signal by the shake detection sensor 21, and proceeds to step S103.

  In step S103, the CPU 18 determines whether or not the magnitude of the motion vector is smaller than the first image blur determination threshold and the magnitude of the shake detection signal is smaller than the first shake determination threshold. Specifically, for a predetermined range (for example, the center of the screen) of the through image, subject motion vectors (speed and direction of subject motion) that are common between the frames based on corresponding data between the previous frame and the relevant frame. ) If the magnitude of the motion vector is smaller than the first image blur determination threshold and the magnitude of the shake detection signal is smaller than the first blur determination threshold, an affirmative determination is made in step S103 and the process proceeds to step S108. If at least one of the motion vector and the shake detection signal is equal to or greater than the corresponding first determination threshold, the CPU 18 makes a negative determination in step S103 and proceeds to step S104.

  Instead of obtaining a motion vector using a predetermined range (for example, the center of the screen) in the through image, a motion vector may be obtained using a predetermined range different from the center of the screen. Further, the motion vector of the subject may be obtained using data corresponding to the entire range of the through image between the previous frame and the frame.

  In step S108, the CPU 18 switches the past value ratio in the convergence control to the high side, and proceeds to step S109. In step S109, the CPU 18 determines that the magnitude of the motion vector is smaller than the first image blur determination threshold and greater than the second image blur determination threshold (where the second image blur determination threshold is smaller than the first image blur determination threshold). In addition, it is determined whether or not the magnitude of the shake detection signal is smaller than the first shake determination threshold and greater than the second shake determination threshold (wherein the second shake determination threshold <the first shake determination threshold). If at least one of the motion vector or the shake detection signal is smaller than the corresponding second determination threshold, the CPU 18 makes a negative determination in step S109 and proceeds to step S111.

  When both the motion vector and the shake detection signal are larger than the corresponding second determination threshold and smaller than the corresponding first determination threshold, the CPU 18 makes a positive determination in step S109 and proceeds to step S110.

  In step S111, the CPU 18 switches the control cycle in the convergence control to the long side, and proceeds to step S112. In step S110, the CPU 18 switches the control cycle in the convergence control to the short side and proceeds to step S112.

  In step S104, which proceeds after making a negative determination in step S103 described above, the CPU 18 switches the control cycle in the convergence control to the longer side, and proceeds to step S105. In step S105, the CPU 18 determines whether or not the magnitude of the motion vector is larger than the first image blur determination threshold and the magnitude of the shake detection signal is larger than the first shake determination threshold. When both the motion vector and the shake detection signal are larger than the corresponding first determination threshold, the CPU 18 makes a positive determination in step S105 and proceeds to step S106. If at least one of the motion vector or the shake detection signal is smaller than the corresponding first determination threshold, the CPU 18 makes a negative determination in step S105 and proceeds to step S107.

  In step S106, the CPU 18 switches the past value ratio in the convergence control to 0 (convergence off), and proceeds to step S112. In step S107, the CPU 18 switches the past value ratio in the convergence control to the low side, and proceeds to step S112.

  In step S112, the CPU 18 performs a calculation in accordance with the control cycle and the past value ratio determined as described above in a predetermined camera process (for example, white balance calculation, AF calculation, and AE calculation) and performs the process shown in FIG. Exit. Specifically, the camera processing is calculated using the signal amount A (T) calculated using Equation (1) described later.

  FIG. 3 is a diagram illustrating a setting example of a control period and a past value ratio for camera shake and image blur of the electronic camera. When the process proceeds from step S108 in FIG. 2 to step S111, it corresponds to the first level (1) and the second level (3) from the top of the left column of FIG. 3, and the first level (2) from the top of the center column. . Lowering the convergence control cycle is equivalent to switching the convergence control cycle to the longer side.

  In FIG. 3 (1), for example, it is assumed that the main subject or the landscape occupies most of the imaging angle of view in a state where the electronic camera is left (placed). In this case, the CPU 18 determines that the angle of view does not change, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) as shown in FIG. 4 (setting example 1).

<Setting example 1>
In FIG. 4, the horizontal axis represents time, and the vertical axis represents the magnitude of the signal amount A used for camera processing. The signal amount A is, for example, the color component ratio of image data in the case of white balance calculation, the focus evaluation value in the case of AF calculation, the subject brightness in the case of AE calculation, and the like. The CPU 18 performs camera processing by weighting the past value A (tx) and the current value (latest value) A (t) by the following equation (1) using the signal amount A (t) obtained discretely. A signal amount A (T) used for the calculation is calculated. In the case of setting example 1, even if the ratio β of the past value A (tx) is increased and the most recent input information A (t) changes, it does not follow the sudden change in the signal amount A (t) and is smooth. A signal amount A (T) is obtained so that a variable control amount for camera processing is obtained.

A (T) = A (t) × α (%) + A (tx) × β (%) (1)
However, A (t) is the latest signal amount, and A (tx) is the past signal amount.

  In FIG. 3 (2), for example, a situation before photographing in which the imaging angle of view has already been determined in a state where the electronic camera is held by hand is assumed. In this case, the CPU 18 determines that the angle of view does not change, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) in the same manner as in setting example 1 (FIG. 4).

  In FIG. 3 (3), for example, it is assumed that the subject is moving while the electronic camera is fixed to a tripod or the like. In this case, the CPU 18 determines that the angle of view does not change, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) in the same manner as in setting example 1 (FIG. 4).

  When the process proceeds from step S108 in FIG. 2 to step S110, it corresponds to the second row (4) from the top in the center row in FIG. (4) in FIG. 3 assumes, for example, a situation in which the subject is moving in a state where the electronic camera is being held and before the photographing in which the imaging angle of view has already been determined. In this case, the CPU 18 determines that the angle of view is about to change, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) as in setting example 2 (FIG. 5).

<Setting example 2>
In FIG. 5, the horizontal axis represents time, and the vertical axis represents the magnitude of the signal amount A used for camera processing. The signal amount A is, for example, the color component ratio of image data in the case of white balance calculation, the focus evaluation value in the case of AF calculation, the subject brightness in the case of AE calculation, and the like. In the case of setting example 2, even if the ratio β of the past value A (tx) is increased and the latest input information amount A (t) changes, it does not follow the sudden change in the signal amount A (t), A signal amount A (T) is obtained so as to smoothly change the control amount for camera processing. In addition, compared to the setting example 1 (FIG. 4), the signal amount A (t) acquisition interval and the control amount calculation interval x are narrowed, and the signal amount A (T) used for camera processing is set to the setting example 1. Calculate more finely.

  When proceeding from step S104 in FIG. 2 to step S107, the first row (5), the second row (6), the third row (7) from the top of the left column, and the center of the right column in FIG. This corresponds to the third row (8) from the top of the column. In FIG. 3 (5), for example, a situation is assumed in which the main subject or the uniform luminance plane occupies most of the imaging angle of view when the electronic camera is in a moving state. In this case, the CPU 18 determines that the angle of view is about to change, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) as in setting example 3 (FIG. 6).

<Setting example 3>
In FIG. 6, the horizontal axis represents time, and the vertical axis represents the magnitude of the signal amount A used for camera processing. The signal amount A is, for example, the color component ratio of image data in the case of white balance calculation, the focus evaluation value in the case of AF calculation, the subject brightness in the case of AE calculation, and the like. In setting example 3, when the ratio β of the past value A (tx) is lowered and the latest input information A (t) changes, the signal amount A (t) changes more quickly than in setting example 2. A signal amount A (T) is obtained so as to obtain a control amount for camera processing that smoothly follows. Since the acquisition interval of the signal amount A (t) and the calculation interval of the control amount are narrower than in the case of setting example 1 (FIG. 4), the signal amount A (T) used for camera processing is the same as in setting example 2. Is calculated in detail.

  In FIG. 3 (6), for example, it is assumed that both the electronic camera and the main subject move. In this case, the CPU 18 determines that there is a change in the angle of view, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) in the same manner as in setting example 3 (FIG. 6).

  In FIG. 3 (7), for example, it is assumed that the electronic camera is fixed to a tripod or the like and the subject is moving greatly (panning). In this case, the CPU 18 determines that the angle of view is about to change, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) in the same manner as in setting example 3 (FIG. 6).

  In FIG. 3 (8), for example, a situation is assumed in which the imaging field angle is about to be determined while the electronic camera is being held by hand. In this case, the CPU 18 determines that there is a change in the angle of view, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) in the same manner as in setting example 3 (FIG. 6).

  When the process proceeds from step S104 in FIG. 2 to step S106, it corresponds to the third row (9) from the top of the right column in FIG. In FIG. 3 (9), for example, it is assumed that the electronic camera is moving and the electronic camera is largely moved to determine the imaging angle of view. In this case, the CPU 18 determines that the angle of view is switched, and performs convergence control in camera processing (for example, white balance calculation, AF calculation, and AF calculation) as in setting example 4 (FIG. 7).

<Setting example 4>
In FIG. 7, the horizontal axis represents time, and the vertical axis represents the magnitude of the signal amount A used for camera processing. The signal amount A is, for example, the color component ratio of image data in the case of white balance calculation, the focus evaluation value in the case of AF calculation, the subject brightness in the case of AE calculation, and the like. In the case of setting example 4, when the convergence processing using the past value A (tx) is turned off (β = 0) and the latest input information A (t) changes, the signal amount A (t) immediately changes. A signal amount A (T) is obtained so as to obtain a control amount for camera processing that follows. The point of finely calculating the signal amount A (T) used for camera processing is the same as in the case of setting example 2 and setting example 3.

According to the embodiment described above, the following operational effects can be obtained.
(1) The CPU 18 of the electronic camera is used for camera processing based on the latest (most recent) information A (t) and A (tx) arranged in the order of acquisition among the periodically acquired information (signal amount A). When calculating the control amount, the movement of the camera is detected, and the magnitude of the contribution to the control amount by the past information A (tx) among the latest information A (t) and A (tx) is determined as the motion detection information. It was controlled to be different according to. Thereby, an appropriate control amount can be calculated according to the movement / still state of the camera from the past.

(2) Since the CPU 18 further controls the time intervals of a plurality of pieces of information contributing to the control amount to be different according to the motion detection information, the control having an appropriate tracking characteristic according to the movement / still state of the camera. The amount can be calculated.

(3) The camera 18 further includes a shake detection sensor 21 that detects camera shake, and imaging devices 12, 13, 14, 16, and 22 that sequentially capture a subject image and acquire frame images sequentially. Since the camera motion is detected using the shake detection signal and image blur information based on the difference between frames before and after the frame image, both the movement caused by the shake of the electronic camera itself and the movement of the subject can be detected. Can do.

(4) The CPU 18 further assigns different weights to the past information A (tx) and the latest information A (t) among the latest plurality of information A (t) and A (tx), and performs camera processing. The signal amount A (t) used to calculate the control amount used for the calculation was calculated. The calculation of the signal amount A (t) that makes the ratio of the past information A (t−x) contributing to the control amount different can be realized by a simple arithmetic expression (the above expression (1)).

(5) According to setting example 1 (FIG. 4), since the control cycle is low, the burden on the CPU 18 can be reduced as compared with the case where the control cycle is high. In addition, since the ratio β of the past value A (tx) is increased, even if the latest input information A (t) changes, the control amount for camera processing can follow the sudden change in the signal amount A (t). Sudden changes can be suppressed and changed smoothly.

(6) According to setting example 2 (FIG. 5), since the control cycle is high, the control amount can be obtained at a finer time interval than when the control cycle is low. In addition, since the ratio β of the past value A (tx) is increased, even if the latest input information A (t) changes, the control amount for camera processing can follow the sudden change in the signal amount A (t). Sudden changes can be suppressed and changed smoothly.

(7) According to setting example 3 (FIG. 6), since the control cycle is high, the control amount can be obtained at a finer time interval than when the control cycle is low. Further, since the ratio β of the past value A (tx) is lowered, when the latest input information A (t) changes, the control amount for camera processing is changed smoothly and more quickly than in the setting example 2. be able to.

(8) According to setting example 4 (FIG. 7), since the control cycle is high, the control amount can be obtained at finer time intervals than when the control cycle is low. Further, since the ratio of the past value A (tx) is set to 0, when the latest input information A (t) changes, the control amount for camera processing immediately follows the change in the signal amount A (t). Can be changed.

(Modification 1)
In the above description, the electronic camera has been described as an example. However, the present invention can be applied to any electronic device that calculates a predetermined control amount by inputting a signal that changes over time.

(Modification 2)
In the above description, the signal amount A (T) used to calculate the control amount is obtained by weighting the input information A (t) and A (tx) acquired to calculate the control amount in the camera processing. Calculated. The CPU 18 of the electronic camera calculates a predetermined control amount using the signal amount A (T), and obtains the color adjustment gain used for the white balance adjustment process, the focus position in the AF process, and the exposure by the AE process. Instead, when the processing capacity of the CPU 18 has a margin, the predetermined control amount is calculated sequentially using the input information A (t) and A (tx), and the above formula is calculated for the sequentially calculated control amount. A control amount used in camera processing may be calculated by performing the same weighting as in (1).

  The above description is merely an example, and is not limited to the configuration of the above embodiment.

DESCRIPTION OF SYMBOLS 12 ... Image sensor 13 ... AFE circuit 14 ... Image processing circuit 16 ... Buffer memory 18 ... CPU
21 ... shake detection sensor 22 ... timing generator

Claims (10)

Control amount calculation means for calculating a control amount used for camera processing based on a plurality of latest information arranged in the order of acquisition among the periodically acquired information;
Motion detection means for detecting the motion of the camera;
Control means for controlling the control amount calculation means so that the contribution of the past information to the control quantity among the plurality of latest information differs depending on the detection information by the motion detection means. A featured electronic camera. The electronic camera according to claim 1,
The control unit further controls the control amount calculation unit so that a time interval of the plurality of pieces of information contributing to the control amount varies according to information detected by the motion detection unit. . The electronic camera according to claim 1,
Shake detection means for detecting camera shake;
Imaging means for capturing a subject image every predetermined time and sequentially acquiring frame images;
The electronic camera according to claim 1, wherein the motion detection unit detects a camera motion using a shake detection signal from the shake detection unit and image blur information based on a difference between frames before and after the frame image. The electronic camera according to claim 1,
The control means performs the control so that the proportion of the past information contributing to the control amount varies by performing different weighting on the past information and the latest information among the plurality of latest information. An electronic camera characterized by controlling a quantity calculating means. The electronic camera according to claim 3.
When the shake detection signal is smaller than a first shake determination threshold and the image blur information is smaller than a first image blur determination threshold, the control unit determines that the past information is the control amount. An electronic camera characterized in that the control amount calculation means is controlled so as to increase a ratio that contributes to. The electronic camera according to claim 5,
The control means is configured such that the shake detection signal is smaller than a second shake determination threshold smaller than the first shake determination threshold, or the second image blur is smaller than the first image blur determination threshold. An electronic camera that controls the control amount calculation means so as to widen a time interval between the plurality of pieces of information that contribute to the control amount when it is smaller than a determination threshold. The electronic camera according to claim 5,
The control means is configured such that the shake detection signal is larger than a second shake determination threshold smaller than the first shake determination threshold and smaller than the first shake determination threshold, and the image blur information is When the second image blur determination threshold value is smaller than the first image blur determination threshold value and smaller than the first image blur determination threshold value, the time intervals of the plurality of information contributing to the control amount are set. An electronic camera characterized in that the control amount calculation means is controlled to be narrowed. The electronic camera according to claim 3.
The control means includes the plurality of contributions that contribute to the control amount when at least the shake detection signal is greater than a first shake determination threshold value, or at least when the image blur information is greater than a first image blur determination threshold value. An electronic camera characterized in that the control amount calculation means is controlled so as to narrow a time interval of information. The electronic camera according to claim 8,
When the shake detection signal is greater than the first shake determination threshold value and the image blur information is greater than the first image blur determination threshold value, the control unit determines that the past information is An electronic camera characterized by controlling the control amount calculation means so as not to contribute to a control amount. The electronic camera according to claim 8,
The control means contributes to the control amount when the shake detection signal is less than or equal to the first shake determination threshold value or when the image blur information is less than or equal to the first image shake determination threshold value. An electronic camera characterized in that the control amount calculation means is controlled so as to reduce the ratio of the control.

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