JP2017139577A - Photometric device and imaging device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for acquisition of a photometric value closer to the user's intended photometric value, in an imaging device using an image sensor as a photometric sensor.SOLUTION: In a digital camera, photometry is performed using the output from an image sensor. When holding a photometric value by user's photometric value lock instruction (shutter button halfway push) M, a determination is made whether the photometric results are good or poor, and when a determination is made that the photometric results are poor (NG), photometry E is performed again by changing the photometric conditions. When a determination is made that photometry B of the photometric value lock instruction M is poor, the photometric value to be held is selected from any one of the photometric value of the photometric results (1) of photometry A obtained before the photometric value lock instruction M, or the photometric value of the photometric results (2) of the photometry E after photometric conditions change, on the basis of the operation mode of the digital camera.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an imaging apparatus that uses an image sensor for photometry.

  In recent years, for example, an image sensor is sometimes used as a photometric sensor without mounting a photometer-dedicated photodiode on a camera. However, since an image sensor is a two-dimensional array of a large number of small photodiodes, the dynamic range is narrower than that of a photometering-dedicated photodiode, and saturation or blackout may occur during photometry. In particular, when a small image sensor is used, such a problem becomes significant. If saturation or blackout exists, an accurate photometric value cannot be obtained unless the luminance range is estimated from the photometric result and the photometry is performed again under appropriate conditions. For this reason, it takes time to obtain an accurate photometric value, and it may not be possible to immediately respond to a user's shooting instruction, thereby missing a photo opportunity. Also, control values for exposure control are acquired in advance during shooting standby, changes in the imaging condition control results are monitored before imaging starts, and main imaging is performed using the control values during shooting standby accordingly. A configuration is also known in which it is determined whether to perform main imaging after acquiring a control value again by provisional imaging (Patent Document 1).

Japanese Patent No. 4305283

  However, even in the configuration of Patent Document 1, there is a problem in that a photometric value cannot always be obtained in response to a user's shooting instruction, and a photometric value intended by the user cannot be obtained.

  An object of the present invention is to make it possible to acquire a photometric value closer to a photometric value intended by a user in an imaging apparatus using the image sensor as a photometric sensor.

  A photometric device of the present invention is a photometric device using an image sensor mounted on an imaging device, and a photometric unit that performs photometry using an output from the image sensor, and a photometric unit based on a photometric value lock instruction by a user Metering value lock means for holding the metering value obtained by the above, a metering result judgment means for judging whether the result of the metering is good, and a metering result for changing the metering condition when the metering result is judged to be bad in the metering result judgment means When the condition change means and the photometry result determination means determine that the photometry value acquired at the time of the photometry value lock instruction is defective, the photometry value lock instruction is issued for the photometry value held in the photometry value lock means. A photometric value selection unit that selects from either a photometric value obtained before or a photometric value obtained after changing the photometric condition, and the photometric value selection unit is configured to operate the imaging apparatus. It is characterized by determining a photometric value on the basis selected.

  When it is determined in the photometric result determination means that the photometric value acquired when the photometric value lock instruction is instructed, there is no problem, the photometric value lock means holds the photometric value acquired when the photometric value lock instruction is issued. When a photometric value lock instruction is received after the latter half of the photometric condition changing process, the photometric value obtained after the photometric condition change is held in the photometric value lock means. The photometric conditions are changed based on, for example, an estimated value of the luminance range of the subject. The above-described operation mode is an operation mode in which, when a photometric value lock instruction is given by the user, it is estimated whether the user is looking at the subject through the optical filter or the image display monitor. The operation mode includes any one of a photometry-related setting change, a photometry area change, a live view / optical finder change, and a view angle change.

  The image pickup apparatus of the present invention is characterized in that the above-mentioned photometric device is mounted.

  ADVANTAGE OF THE INVENTION According to this invention, in the imaging device which used the image sensor for the photometry sensor, the photometry value close | similar to the photometry value which a user intends can be acquired.

1 is a block diagram illustrating a configuration of an imaging apparatus that is an embodiment of the present invention. It is a timing chart which shows the output of the timing of AE lock operation in the photometry process of this embodiment, photometry, and a photometry result (photometry value). It is a flowchart of the photometric value selection holding process of this embodiment. FIG. 3 is a timing chart when an AE lock operation M is executed during the second photometric value calculation of FIG. 2. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an imaging apparatus according to an embodiment of the present invention.

  The imaging apparatus of this embodiment is, for example, a digital camera 10 and includes a lens barrel 200 and a camera body 100. The light beam from the subject passes through the photographing lens 201, the diaphragm 202, and the shutter 105 and is received by the image sensor 106. The image sensor 106 is, for example, a CCD image sensor or a CMOS image sensor, and an image signal is output to the signal processing unit 107. The signal processing unit 107 amplifies the image signal with a gain corresponding to the ISO sensitivity and outputs the amplified image signal to the image processing unit (image processing engine) 108. The image processing engine 108 performs predetermined signal processing such as color interpolation, matrix calculation, and Y / C separation on the signal input from the signal processing unit 107 to generate a luminance signal Y and color difference signals Cb and Cr. Compress in a predetermined format such as JPEG. The buffer memory 109 is used as a temporary storage location for processing data when the image processing engine 108 executes processing.

  The camera body 100 is provided with an operation switch group (input means) 102 including a shutter button, an electronic dial, a cross key, an OK button, and the like. A control unit (CPU) 101 controls the entire digital camera 10 according to a control program stored in the ROM 116. A memory card 111 is detachably inserted into a card slot of the card interface (I / F) 110. The image processing engine 108 can communicate with the memory card 111 via the card interface 110. The image processing engine 108 stores the generated compressed image signal (photographed image data) in the memory card 111 (or a built-in memory (not shown) provided in the digital camera 10). The image processing engine 108 may convert the captured image data into an image signal of a predetermined format and output it to the image display monitor control unit 112 together with the captured image data storage process. The image display monitor control unit 112 causes the image display monitor 113 to display a confirmation image after photographing based on the image signal input from the image processing engine 108 for a predetermined time. The image display monitor 113 is an LCD, for example.

  The digital camera 10 of the present embodiment includes a photometric image sensor 106A. The control unit 101 obtains a photometric value based on the pixel value acquired by the image sensor 106A, and can drive (AE control) the aperture 202 and the shutter 105 via the aperture / shutter driving unit 104 according to the shooting mode. Is possible. The control unit 101 performs AF control of the photographing lens 201 through the lens driving unit 103 together with AE control. An active method, a phase difference detection method, a contrast detection method, or the like is applied to the AF control. The AE control is executed based on a photometric value held by the user's AE lock operation (described later), and the image sensor 106 performs imaging under the AE control. For example, a half-press operation of the shutter button is assigned to the AE lock operation.

  Next, with reference to FIG. 2 and FIG. 3, a photometric process executed by the imaging apparatus of the present embodiment will be described. FIG. 2 is a timing chart showing the timing of the AE lock operation and the output of photometry and photometry results (photometry values) in the photometry processing of this embodiment. FIG. 3 is a flowchart of the photometric value selection holding process of the present embodiment.

  Photometry in the imaging apparatus of the present embodiment is performed using an image sensor type photometric sensor (image sensor 106A). The photometry is periodically repeated, and the quality of the photometry result is judged from the image data of the image sensor 106 each time by the control unit 101 or the like. FIG. 2 shows five times of photometry from photometry A to photometry E. The photometry result (1) of photometry A has no problem, for example, and photometry B is executed following photometry A. In the example of FIG. 2, the AE lock operation M is executed, for example, by half-pressing the shutter button when performing photometry B with a photometric result of bad (NG). Note that the photometry result is determined to be defective (NG), for example, when the pixel value data from the image sensor 106 includes saturated or blackout data at a certain rate.

  If the photometric result is bad (NG), the first photometric value calculation is performed based on the photometric B result, photometric conditions such as shutter speed and aperture value are changed, and photometry C and photometry D are executed. Thereafter, an accurate luminance range is estimated based on the photometry results in photometry C and photometry D (second photometry value calculation), the optimum photometry condition is obtained, and the photometry condition is changed to perform photometry E again. That is, in the photometry E, an appropriate photometry result (2) is obtained. As shown in FIG. 2, since the result of the photometry B at the time of the AE lock operation M is defective (NG), the same result cannot be held and AE control based on this result cannot be performed. Therefore, there is no problem obtained before the AE lock operation M (there is no saturation or blackout data), or an appropriate photometry result obtained by photometry after changing the photometry condition (2 ) May be held.

  In metering using a conventional metering sensor, it is not necessary to perform metering again with a wide dynamic range, and the time required for one metering is short, so the results of metering on one side before and after the AE lock operation are obtained beforehand. There was no problem with holding and using. However, since photometry using an image sensor type photometry sensor takes time, using the photometry result (2), it takes a long time for the photometry value to be held after the user performs an AE lock operation, and the user intends In some cases, the photometric value is not held.

  Therefore, in this embodiment, it is selected whether to hold the photometric result (1) or the photometric result (2) based on the operation mode of the digital camera 10 by the user, and the photometric result (photometric value closer to the user's intention) is selected. ). In the present embodiment, the selection is made by paying attention to whether or not the subject is confirmed through the optical viewfinder or the image display monitor 113 particularly when the user performs the AE lock operation.

  When it is determined that the user confirms the subject through the optical viewfinder or the image display monitor 113 when performing the AE lock operation, the photometry result (1) of the photometry A closer to the time when the AE lock operation is performed is selected. . That is, the photometric result (1) is held, and is used for photographing when the shutter button is fully pressed as it is. This corresponds to, for example, a case where the photometry B is determined to be defective, for example, when a user attempts to take a picture and a dark subject crosses. Note that a situation in which the user may have performed an AE lock operation while checking the subject through the optical viewfinder or the image display monitor 113 may be a situation in which a certain amount of time has passed without changing the setting of the photometry related function.

  On the other hand, when it is determined that the subject is not confirmed through the optical finder or the image display monitor 113 when the user performs the AE lock operation, the AE lock operation M is greater than the photometric value based on the previous photometric result (1). It is desirable to adopt an appropriate photometry result (2) obtained by photometry under the changed photometry conditions. Therefore, in the present embodiment, when it is determined that the subject is not confirmed through the optical finder or the image display monitor 113 when the user performs the AE lock operation, the photometry result (2) is held and the shutter button is fully pressed as it is. When it is done, it will be used for shooting. Operation modes that are considered to be that the user has not confirmed the subject through the optical viewfinder or the image display monitor 113 are such that the photometric method and / or the photometric sensor such as switching between the live view and the optical viewfinder are changed immediately after the power is turned on, immediately after the photometric area is switched. Or immediately after changing the angle of view.

  Next, the procedure of the photometric value selection holding process of the present embodiment described with reference to FIG. 2 will be described with reference to the flowchart of FIG. This process is executed by the control unit 101 when the user half-presses the shutter button and instructs AE lock.

  In this process, in the order of steps S100, S102, S104, and S106, whether the AE lock operation is performed immediately after the power is turned on, immediately after the photometry area is changed, or the photometry method is changed (live view / optical viewfinder switching). It is determined whether it is immediately after or immediately after changing the angle of view. In addition, the transition to the next step in steps S100 to S106 is a case where it is determined that it is not immediately after the determination matter of that step in each step, and if it is determined that it is immediately after each of steps S100 to S106, In step S110, the photometry result (2) of photometry E shown in FIG. 2, which is the photometry value after the AE lock operation, is selected. In step S112, the photometry value of photometry E is held in the memory, and the process ends.

  On the other hand, if it is determined in all of Steps S100 to S106 that it is not immediately after each determination item, in Step S108, the photometric result (1) of the photometric A in FIG. 2, which is the photometric value before the AE lock operation, is selected. In step S112, the photometric value of photometric A is held in the memory, and the present process ends. Whether or not it is immediately after the determination item in each step is determined by whether or not it is within a predetermined time set for each.

  Further, when the photometry is performed in the sequence shown in FIG. 2, the AE lock operation M is the latter half of the photometry condition changing process (the period from the start of the first photometry value calculation to the end of the second photometry value calculation). When operated after that, the photometric value of the photometric E is closer to the time of the AE lock operation M than the photometric A, and the photometric value (2) is more in line with the user's intention. It is thought that it is near. Therefore, the timing of the AE lock operation M with respect to the photometry condition change process is monitored, and when the AE lock operation M is operated after the latter half of the photometry condition change process, the photometry value selection holding process shown in FIG. A configuration in which the photometric result (2) is preferentially selected and held may be adopted. FIG. 4 shows a timing chart when the AE lock operation M is executed during the second photometric value calculation of FIG.

  As described above, according to the present embodiment, even when an image sensor is used as the photometric sensor, the timing at which the photometric value to be held is acquired is more appropriately determined by the user according to the operation state (operation mode) of the imaging apparatus. It becomes possible to always adopt a photometric value close to the intention.

  In this embodiment, the configuration using the photometric image sensor separately from the imaging image sensor has been described. However, the photometric value is obtained based on the pixel value acquired in a predetermined area of the imaging image sensor. You can also. Further, the image sensor for photometry may be used for white balance adjustment. In this embodiment, a digital camera has been described as an example. However, the present invention can be applied to any device including a photometric device, and can be used for a camera-equipped mobile phone, a smart phone, a video camera, and the like.

10 Digital Camera 101 Control Unit (CPU)
DESCRIPTION OF SYMBOLS 102 Operation switch group 103 Lens drive part 104 Aperture / shutter drive part 105 Shutter 106,106A Image sensor 201 Lens 202 Aperture

Claims (7)

A photometric device using an image sensor mounted on an imaging device,
Photometric means for performing photometry using the output from the image sensor;
Based on the user's photometric value lock instruction, photometric value lock means for holding the photometric value obtained by the photometric means,
A photometric result judging means for judging the quality of the photometric result;
In the photometric result determining means, a photometric condition changing means for changing the photometric condition when the photometric result is determined to be defective,
When the photometric result determination unit determines that the photometric value acquired at the time of the photometric value lock instruction is defective, the photometric value held by the photometric value lock unit is changed to the photometric value lock instruction before the photometric value lock instruction is issued. A photometric value selecting means for selecting from either the photometric value obtained in step 1 or the photometric value obtained after changing the photometric condition,
The photometric value selection unit determines a photometric value to be selected based on an operation mode of the imaging device.   When it is determined that there is no problem with the photometric value acquired at the photometric value lock instruction in the photometric result determination means, the photometric value lock means holds the photometric value acquired at the photometric value lock instruction. The photometric device according to claim 1.   3. The photometric value lock means holds the photometric value obtained after the photometric condition change when a photometric value lock instruction is received after the latter half of the photometric condition change process. 4. The photometric device according to one item.   The photometric device according to claim 1, wherein the photometric condition is changed based on an estimated value of a luminance range of a subject.   The operation mode is an operation mode in which, when a photometric value lock instruction is given by a user, the user is inferred whether or not the user is looking through the optical filter or the image display monitor. 5. The photometric device according to any one of 4 above.   The photometric device according to claim 5, wherein the operation mode includes any one of a photometric setting change, a photometric area switching, a live view / optical finder switching, and a field angle change.   An imaging apparatus comprising the photometric device according to any one of claims 1 to 6.

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