JP2017040799A - Imaging device and photometry method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase of a calculation load for photometry calculation, and perform correct photometry when performing photometry to a narrow region.SOLUTION: A digital camera 100 comprises: a second imaging element 116 having plural photometry blocks 300 formed of plural pixels; a whole body control part 101 for designating a partial area of a subject image acquired by the second imaging element 116 to a designated area; and a second imaging signal processing part 117 for calculating a luminance value of the subject image. The whole body control part 101 calculates the luminance value of the designated area on the basis of outputs of pixels corresponding to the designated area, in plural pixels forming the second imaging element 116 for a pixel unit, when a size of the designated area is equal to or smaller than a reference value, and calculates a luminance value of whole photometry block in which the designated area strides, for a photometry block unit, as the luminance value of the designated area, when the size of the designated area is larger than the reference value.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a photometric method in an imaging apparatus such as a digital camera.

  Digital that sequentially guides the light from the subject to the imaging lens, quick return mirror, pentaprism, and optical viewfinder, and to the photometric sensor located at a position off the finder optical axis, and measures the luminance value of the subject using the photometric sensor A single-lens reflex camera is known. In such a digital single lens reflex camera, a plurality of functions such as exposure calculation, subject color determination, face detection, subject tracking, and the like are realized using an output signal from a photometric sensor.

  In recent years, the resolution of photometric sensors tends to be increased in order to improve face detection performance. Therefore, a technique has been proposed for reducing the computational load by using coarse image data with a small number of divisions for normal photometry, and improving face detection performance by using fine image data with a large number of divisions for face detection ( Patent Document 1). Thereby, the balance between the face detection performance and the photometric calculation load can be made appropriate.

JP 2013-44995 A

  However, in the technique described in Patent Document 1, even when face photometry calculation is performed, the number of divisions of the photometry area cannot be said to be sufficiently fine, and photometry calculation is performed in an area that does not match the face area. , Photometric accuracy will be reduced. This problem is the same when spot photometry calculation is performed, and photometric calculation is performed in an area that does not match the spot photometry area, resulting in a decrease in photometry accuracy.

  An object of the present invention is to provide a photometric method capable of performing accurate photometry when measuring a narrow region while suppressing an increase in calculation load for photometric calculation.

  An image pickup apparatus according to the present invention includes an image pickup device having a plurality of photometric blocks composed of a plurality of pixels, a designation unit for designating a partial region of a subject image acquired by the image pickup device as a designated region, A calculating means for calculating a luminance value; and when the size of the designated area is equal to or smaller than a predetermined reference value, a pixel corresponding to the designated area among the plurality of pixels constituting the image sensor in units of the pixel. When the luminance value of the designated area is calculated based on the output and the size of the designated area is larger than the predetermined reference value, the luminance of the entire photometric block spanned by the designated area in units of the photometric block Control means for switching a calculation method of the luminance value by the calculation means according to the size of the designated area so as to calculate a value as a luminance value of the designated area.

  According to the present invention, accurate photometry can be performed when measuring a narrow area such as a face area or a spot photometry area while suppressing an increase in calculation load for photometry calculation.

1 is a block diagram illustrating a schematic configuration of a digital camera according to an embodiment of the present invention. It is sectional drawing which shows the arrangement | positioning position of the main components of the digital camera of FIG. It is a figure which shows typically the positional relationship of the photometry block and distance measuring point in the 2nd image pick-up element in the digital camera of FIG. 2 is a flowchart for explaining a normal photometry sequence in the digital camera of FIG. 1. 3 is a flowchart for explaining a photometry sequence using a spot photometry function in the digital camera of FIG. 1. It is a figure which shows typically the relationship between the 1st image sensor for imaging in the digital camera of FIG. 1, and the photometry block of the 2nd image sensor for photometry. It is a figure explaining the luminance value calculation method of the conventional face area when a small face is detected in Step S102. It is a figure explaining the luminance value calculation method of the face area in Step S103 concerning this embodiment when a small face is detected in Step S102. It is a figure explaining the luminance value calculation method of the face area in Step S103 concerning this embodiment when a big face is detected in Step S102. It is a figure which shows in detail the positional relationship of the face area | region when a small face is detected in step S102, and the photometry block which a face area straddles. It is a table for determining the weighting coefficient used for the correction | amendment performed when calculating | requiring the luminance value matching a face area.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present embodiment, a digital single-lens reflex camera (hereinafter referred to as “digital camera”) will be described as an example of an imaging apparatus according to the present invention.

  FIG. 1 is a block diagram showing a schematic configuration of a digital camera 100 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the arrangement positions of main components of the digital camera 100.

  The digital camera 100 includes a camera body 100A and an interchangeable lens barrel 200 that is detachable from the camera body 100A. The camera body 100A includes an overall control unit 101, a mirror 102, a mirror driving device 103, a shutter 104, a shutter driving device 105, a first imaging element 106, a first imaging signal processing unit 107, a first timing generation unit 108, and A memory unit 109 is provided. The camera body 100A includes a storage medium control I / F unit 110, a display driving unit 112, a display device 113, an external interface 114, a second image sensor 116, a second image signal processing unit 117, and a second timing. A generator 118 is provided. Furthermore, the camera body 100A includes a pentaprism 119, a distance measuring drive device 120, a phase difference distance measuring unit 121, an eyepiece lens 123, and a release switch 125.

  The overall control unit 101 is specifically a microprocessor including a CPU, and performs overall control of the digital camera 100 (camera body 100A and interchangeable lens barrel 200). The mirror 102 is generally called a quick return mirror, and guides the light that has passed through the interchangeable lens barrel 200 to the viewfinder side in the photometric state shown in FIG. To 106. The mirror driving device 103 drives the mirror 102. The shutter 104 is a shutter mechanism corresponding to a focal plane type front curtain / rear curtain, and controls exposure time of the first image sensor 106 of light passing through the interchangeable lens barrel 200 and shields it. The shutter driving device 105 drives the shutter 104.

  The light that has passed through the interchangeable lens barrel 200 forms an optical image of the subject on the surface of the first image sensor 106. The first image sensor 106 converts the optical image into an electrical signal (image signal) and outputs the electrical signal to the first image signal processor 107. Specifically, the first image sensor 106 is a CMOS sensor formed with XY addresses. The first image signal processor 107 amplifies the image signal output from the first image sensor 106, converts the analog signal into a digital signal (A / D conversion), and the image after the A / D conversion process. Various correction processes such as defect correction for data, compression process for compressing image data, and the like are performed. The first timing generator 108 supplies various timing signals to the first image sensor 106 and the first image signal processor 107.

  The memory unit 109 temporarily stores image data processed by the first imaging signal processing unit 107, various adjustment values, programs for the overall control unit 101 to execute various controls, and the like. It is comprised by ROM which memorize | stores. The storage medium control I / F unit is an interface for performing a process of writing image data or the like to the storage medium 111 or a process of reading image data or the like from the storage medium 111. The storage medium 111 is, for example, a semiconductor memory that stores various data such as image data, and is detachable from the camera body 100A.

  The display device 113 is a liquid crystal display or the like that displays a captured still image or moving image, a menu screen (UI) for setting imaging parameters in the camera body 100A, and the like. The display driving unit 112 drives the display device 113. The external interface 114 is an interface that enables transmission and reception of information such as an image signal and a control signal between the computer 115 and the like, which are an example of an external device, and the overall control unit 101.

  The second image sensor 116 functioning as an AE sensor is a photoelectric conversion element for acquiring an AE signal / light source detection signal, and is a sensor having an RGB Bayer arrangement. A CCD sensor having a global electronic shutter function is generally used for the second imaging element 116, but even a CMOS sensor can be used if reading is fast (reading time is short). The second imaging signal processing unit 117 performs various correction processes such as an amplification process of an image signal output from the second imaging element 116, an A / D conversion process, and a defect correction for image data after A / D conversion, A compression process for compressing image data is performed. The second timing generation unit 118 supplies various timing signals to the second imaging element 116 and the second imaging signal processing unit 117.

  The pentaprism 119 is a member for guiding the light bent by the mirror 102 to the eyepiece lens 123 of the finder and the second image sensor 116. The phase difference distance measuring unit 121 acquires two images whose phases change according to the defocus amount of the subject by the light beam transmitted through the mirror 102 by the phase difference method, and calculates the defocus amount of the subject from the shift amount of the two images. Calculate. The distance measuring drive device 120 drives the phase difference distance measuring unit 121.

  The release switch 125 has a switch SW1 that is turned on when half-pressed and a switch SW2 that is turned on when fully pressed. When SW1 is turned on, imaging exposure preparation is started and automatic exposure, autofocus, and the like are performed. When SW2 is turned on, the main imaging is performed by the first image sensor 106, and continuous shooting is performed when the state where SW2 is turned on is maintained.

  The interchangeable lens barrel 200 includes a lens control unit 201, an imaging lens 202, a lens driving device 203, a diaphragm 204, and a diaphragm driving device 205. The imaging lens 202 forms an optical image of the subject on the first imaging element 106. The lens driving device 203 moves the imaging lens 202 in the optical axis direction based on the defocus amount calculated by the phase difference distance measuring unit 121 to focus on the subject. A diaphragm 204 controls the amount of light passing through the imaging lens 202. The aperture driving device 205 drives the aperture 204 based on a photometric value obtained from the output of the second image sensor 116 that acquires (captures) a subject image. The lens control unit 201 communicates with the overall control unit 101 and performs operation control with the interchangeable lens barrel 200 based on a command from the overall control unit 101.

  FIG. 3 is a diagram schematically showing the positional relationship between the photometry block 300 and the distance measuring point 303 in the second image sensor 116. The second image sensor 116 has a total of 54 photometric blocks 300 divided into 9 parts in the horizontal direction and 6 parts in the vertical direction. The second image sensor 116 obtains a photometric value for each photometric block 300 in which a plurality of pixels are collected, not for each pixel, and performs photometric calculation.

  The second image sensor 116 includes 13 distance measuring points 303 (AF sensors) with respect to the subject image (captureable range), and one or a group of them (for example, arranged in the vertical direction). 3 or 5) is configured to be selectable. Note that the arrangement and number of distance measuring points 303 are not limited to the form shown in FIG. The distance measuring point 303 may be selected before the release switch 125 is half-pressed and SW1 is turned on, or may be selected while the release switch 125 is half-pressed and SW1 is turned on. It may be configured.

  FIG. 4 is a flowchart for explaining a normal photometry sequence in the digital camera 100. Each process of the flowchart of FIG. 4 is realized by the overall control unit 101 executing a predetermined program to control the operation of each unit of the digital camera 100, and each unit performing a predetermined operation or calculation.

  When the release switch 125 is pressed halfway and SW1 is turned on, in step S101, the overall control unit 101 performs overall photometry with the second image sensor 116 for photometry. In subsequent step S102, the overall control unit 101 uses the output image of the second image sensor 116 by the second imaging signal processing unit 117 as an example of setting a partial region in the output image as a main photometric target. Perform face detection. As a result, the position and size of the face in the subject image are detected, and the face area is determined. It should be noted that a well-known technique is used for face detection, and therefore description thereof is omitted here.

  Next, in step S103, the overall control unit 101 uses the face area extracted in step S102 as a designated area, and the second imaging signal processing unit 117 calculates a luminance value (brightness) of the designated area. Details of step S103 will be described later. In step S <b> 104, the overall control unit 101 calculates a luminance value for each photometric block 300.

  Subsequently, in step S105, the overall control unit 101 causes the second imaging signal processing unit 117 to calculate the luminance value of the designated area (face area) calculated in step S103 and the luminance for each photometric block 300 calculated in step S104. The photometric value that can be imaged is calculated using the value. At this time, the second imaging signal processing unit 117 adjusts the brightness of the subject so as not to be over or under based on the brightness value of the designated area (face area), and based on the brightness value of each photometric block 300. Make adjustments so that whiteout and blackout do not occur in the entire image. When the photometric value calculation in step S105 is completed, the photometric process is terminated, and a still image is captured using the photometric value calculated in step S105, triggered by the fact that SW2 of the release switch 125 is turned on.

  FIG. 5 is a flowchart for explaining a photometry sequence using the spot photometry function in the digital camera 100. Each process of the flowchart in FIG. 5 is realized by the overall control unit 101 executing a predetermined program to control the operation of each unit of the digital camera 100, and each unit performing a predetermined operation or calculation.

  In step S <b> 201, the overall control unit 101 detects which ranging point is selected by the photographer from among a plurality of ranging points 303 (see FIG. 3) provided in the digital camera 100. Here, the following steps will be described on the assumption that one of the 13 distance measuring points 303 has been selected by the photographer. In subsequent step S202, the overall control unit 101 uses the distance measurement point area detected in step S201 as the designated area, and the second imaging signal processing unit 117 adds the outputs of the pixels corresponding to the designated area. calculate. The reason for using such a luminance value calculation method in step S202 will be described later.

  Subsequently, in step S203, the overall control unit 101 uses the second imaging signal processing unit 117 to calculate a photometric value for imaging using the luminance value of the photometric block calculated in step S202. When the photometric value calculation in step S203 is completed, the spot photometric process is terminated, and a still image is captured using the photometric value calculated in step S203, triggered by the fact that SW2 of the release switch 125 is turned on.

  Next, a method for calculating a photometric value in the normal photometry described with reference to FIG. 4 will be specifically described. FIG. 6 is a diagram schematically showing the relationship between the first image sensor 106 for main imaging and the photometry block 300 of the second image sensor 116 for photometry. Actually, since the first image sensor 106 and the second image sensor 116 have different optical paths, the first image sensor 106 and the second image sensor 116 do not appear to overlap as shown in FIG. The element 106 and the second imaging element 116 have a positional relationship as shown in FIG.

  The arrangement of the photometric block 300 of the second image sensor 116 is the same as that shown in FIG. In the following description, for the sake of convenience, when a specific photometric block 300 is shown, reference numerals 11 to 19, 21 to 29, 31 to 39, 41 to 49, 51 to 59, 61 to 69 are used as shown in FIG. Further, for example, it is described as a photometric block 300_11.

  FIG. 7 is a diagram for explaining a conventional method of calculating the brightness value of a face area when a small face is detected in step S102 by normal photometry. In FIG. 7, a face area 301 including the entire detected face is surrounded by a broken line, and the face area 301 extends over four photometric blocks 300_34, 35, 44, and 45. Generally, the face area 301 when the detected face is small straddles several photometric blocks of about 4 blocks or less.

  Conventionally, a weighted average is calculated from the luminance values of the photometric blocks 300_34, 35, 44, and 45 straddling the face area 301 and the contribution ratio of the face area 301 that overlaps the photometric blocks 300_34, 35, 44, and 45, respectively. By doing so, the brightness value of the face is calculated. However, in recent years, the number of pixels of the second image sensor 116 has been increased in order to improve the face detection capability, and as a result, smaller faces are being detected. In this case, the area other than the face area 301 (shown by diagonal lines) in the area of the photometric blocks 300_34, 35, 44, and 45 across the face area 301 is wider than the face area 301, and the brightness of the face area 301 is increased. The value calculation accuracy decreases.

  To solve this problem, the present embodiment switches the method for calculating the brightness value of the face area according to the size of the detected face, as will be described below.

  FIG. 8 is a diagram for explaining the method of calculating the brightness value of the face area in step S103 when a small face is detected in step S102. FIG. 8 shows all the photometric blocks 300. However, in the present embodiment, the luminance value of the face area 301 is calculated based only on the output of the pixel corresponding to the face area 301 without using the photometric block 300 as a unit. That is, luminance values are not calculated from the entire areas of the photometric blocks 300_34, 35, 44, and 45, and pixels that overlap with the face area 301 among a plurality of pixels included in these photometric blocks are output. Are added to calculate the luminance value of the face region 301. Therefore, it is possible to obtain a luminance value that matches the face area 301, thereby improving the luminance value calculation accuracy of the face area 301.

  FIG. 9 is a diagram for explaining the method of calculating the brightness value of the face area in step S103 in the present embodiment when a large face is detected in step S102. In FIG. 9, a face area 302 including the entire detected face is surrounded by a broken line, and the face area 302 extends over the photometric blocks 300_13 to 16, 23 to 26, 33 to 36, and 43 to 46. I'm scared. When the face area 302 extends over many photometric blocks in this way, the area other than the face area 302 (shaded area) within the entire photometric block over which the face area 302 extends is narrow. Become.

  In this case, when the small face described with reference to FIG. 8 is detected, the luminance value of the face area 302 is obtained using the output from each pixel in units of pixels corresponding to the face area 302. , It takes a long time to calculate. Therefore, when a large face is detected, the luminance value of the entire photometric block spanned by the face area 302 is obtained as the luminance value of the face area 302 with the photometric block 300 as a unit. Even if it does in this way, the precision of face luminance calculation does not fall, and also it can avoid calculation increase and can finish calculation in a short time.

  As described above, in the present embodiment, when a small face is detected (when the designated area is small), the luminance value of the face area 301 is calculated from the output of the pixel corresponding to the face area 301 of the small face in units of pixels. Ask for. When a large face is detected (when the designated area is large), the luminance value of the face area 302 of the large face is obtained using the preset photometric block 300 as a unit. That is, the method for determining the luminance value of the face area (designated area) is switched according to the determination result of the size of the detected face area (that is, according to the size of the designated area).

  For example, whether the detected face is a small face or a large face (whether the designated area is small or large) is determined by, for example, the number of photometric blocks over which the face area is straddling a predetermined reference value or less (for example, 4 or less) In this case, a method for determining that the face is small can be used. In addition, the ratio of the detected face area to the entire area of the photometric block across the face area (for example, the ratio of the face area 301 to the entire area of the photometric blocks 300_34, 35, 44, and 45) is less than the threshold value. In such a case, a method for determining a small face can be used. Here, the threshold value may be a preset fixed value, or the hardware and software of the digital camera 100 may be configured so that the photographer can arbitrarily set the threshold value. For example, the threshold value can be set in the range of 0.2 to 0.4. Not limited to this, it is determined whether the face is small or large based on the ratio of the detected face area to the area that does not overlap the face area in the photometric block area that the face area spans. It may be.

  By the way, it is desirable to add various corrections in order to obtain an accurate luminance value when adding the outputs of the pixels corresponding to the face region as described above to obtain the luminance value matching the face region. The various corrections in this case include shading correction for correcting a peripheral light amount drop by the optical system, and dark correction for correcting dark current variation of the second image sensor 116 for each region. The correction data when performing these corrections differs for each lens in the case of shading correction, and differs depending on the temperature in the case of dark correction. Therefore, for the purpose of reducing the entire data amount, correction data is generally stored in the memory unit 109 for each photometric block 300. Since this correction data is data for each photometric block 300, it cannot be used as it is for the brightness value of the face area obtained from the pixels. Therefore, a method of applying correction data for each photometric block 300 to the luminance value of the face area obtained in units of pixels will be described next.

  FIG. 10 shows the positional relationship between the face area 301 when a small face is detected and the photometric blocks 300_34, 35, 44, and 45 across the face area 301 in more detail, as in FIGS. FIG. In FIG. 10, the center of the face region 301 is indicated as a center O, and the centers of the photometric blocks 300_34, 35, 44, and 45 are indicated as centers A, B, C, and D, respectively. Assume that the correction data of the photometry block 300_34 is at the position of the center A, and similarly, the correction data of the photometry blocks 300_35, 44, and 45 are at the positions of the centers B, C, and D. In this case, when the center A and the center O are far away (the distance between the center A and the center O is long), the influence of the correction data located at the center A on the center O becomes small. And the center O are close to each other, the influence of the correction data located at the center A on the center O becomes large. The same can be said for the center B and the center O, the center C and the center O, and the center D and the center O.

  Therefore, the correction data Po at the center O obtained from the centers A, B, C, and D is given by the following formula 1. Here, Pa, Pb, Pc, and Pd are correction data for the centers A, B, C, and D, respectively, and Wa, Wb, Wc, and Wd are effects on the center O of the centers A, B, C, and D, respectively. (Weighting factor). The correction data at the center O can be calculated by fitting shading correction data, dark correction data, and the like with the following formula 1 for obtaining a weighted average.

  FIG. 11 is a table for determining weighting factors Wa, Wb, Wc, and Wd to be multiplied by the correction data Pa, Pb, Pc, and Pd, respectively. When the distance between the center A and the center B and the distance between the center A and the center C are respectively “8”, the distance in the horizontal direction (x direction) between the center O and the center A is “6” and the vertical direction (y If the (direction) distance is “1”, it can be read from FIG. 11 that the weight coefficient Wa of the center A is “56”. Similarly, it can be read that the weight coefficient Wb of the center B is “168”, the weight coefficient Wc of the center C is “8”, and the weight coefficient Wd of the center D is “24”. The table of FIG. 11 is “Wa + Wb + Wc + Wd = 256”, and is created so that the added values of the weighting factors Wa, Wb, Wc, Wd are constant.

  Next, a method for calculating a photometric value when the spot photometry described with reference to FIG. 5 is performed will be described. As shown in FIG. 3, a plurality of distance measuring points 303 may be included in one metering block 300 and may be straddled across a plurality of metering blocks 300. There are various forms in which ranging points overlap with 300.

  In this case, if the luminance value is obtained in units of the photometric block 300 in step S202, the photometric accuracy will be different for each distance measuring point. For example, due to the number and arrangement of the photometry blocks 300, among the plurality of distance measurement points 303, two photometry blocks 300 are used at one distance measurement point, and four photometry blocks are used at another distance measurement point. Then, in the latter case, the photometric accuracy may be lower than in the former case.

  Therefore, when performing spot metering, the luminance value of the distance measuring point 303 is calculated based only on the output of the pixel corresponding to the area of the distance measuring point 303, as in the case where a small face is detected by normal metering. I decided to. As a result, the luminance value matching the area of the distance measuring point 303 can be obtained, and the luminance value can be calculated with the same accuracy at all the distance measuring points 303.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. For example, in the above description, the second image sensor 116 for photometry is taken up and described, but the same photometry can be performed using the first image sensor 106 for imaging. Therefore, the present invention can be applied to any electronic device other than a digital single-lens reflex camera and provided with an imaging element for imaging.

DESCRIPTION OF SYMBOLS 100 Digital camera 101 Overall control part 106 1st image pick-up element 116 2nd image pick-up element 117 2nd image pick-up signal processing part 121 Phase difference ranging part 200 Interchangeable lens barrel 202 Imaging lens 300 Photometry block 301 Face area 302 Face area 303 AF points

Claims (8)

An image sensor having a plurality of photometric blocks composed of a plurality of pixels;
Designation means for designating a partial area of the subject image acquired by the imaging device as a designated area;
Calculating means for calculating a luminance value of the subject image;
When the size of the designated area is equal to or less than a predetermined reference value, the brightness of the designated area based on the output of the pixel corresponding to the designated area among the plurality of pixels constituting the imaging element, with the pixel as a unit When a value is calculated and the size of the designated area is larger than the predetermined reference value, the luminance value of the entire photometric block spanned by the designated area is set as the luminance value of the designated area in units of the photometric block. An imaging apparatus comprising: a control unit that switches a calculation method of a luminance value by the calculation unit according to the size of the designated region so as to calculate. A plurality of ranging points are provided in the imageable range of the image sensor,
The designation means sets the area of at least one or more ranging points selected from the plurality of ranging points as the designated area,
The imaging apparatus according to claim 1, wherein the size of one distance measuring point area is equal to or smaller than the reference value. Detecting means for detecting a face area from a subject image acquired by the image sensor;
The imaging apparatus according to claim 1, wherein the designation unit sets the face area as the designated area. The calculation means further calculates a luminance value of each of the plurality of photometric blocks,
The calculation unit according to claim 3, further comprising a calculation unit configured to calculate a photometric value of the subject image based on a luminance value of the designated area calculated by the calculation unit and a luminance value of each of the photometric blocks. Imaging device. Storage means storing correction data for correcting the luminance value of the subject image acquired by the image sensor in units of the plurality of photometric blocks;
The calculation means weights the correction data of each of the designated area and the plurality of photometric blocks according to the distance between the center of the designated area and the center of the plurality of photometric blocks across the designated area. The imaging apparatus according to claim 1, wherein the luminance value of the designated area is calculated by averaging. A table defining weighting factors for multiplying the correction data to obtain the weighted average is stored in the storage means;
The imaging apparatus according to claim 5, wherein when the calculation unit calculates a luminance value of the designated area by the weighted average, an addition value of the weighting factor read from the table is constant. A photometric method in an imaging apparatus comprising an imaging device having a plurality of photometric blocks composed of a plurality of pixels,
A specifying step of performing total photometry of the subject with the imaging device and designating a partial region of the subject image acquired by the imaging device as a designated region;
A determination step of determining whether the size of the designated area is larger than a predetermined reference value;
A switching step of switching the calculation method of the luminance value of the designated area based on the determination result in the determination step,
In the switching step, when the size of the designated area is equal to or smaller than the predetermined reference value, based on an output of a pixel corresponding to the designated area among a plurality of pixels constituting the imaging element, with the pixel as a unit. The brightness value of the designated area is calculated, and when the size of the designated area is larger than the predetermined reference value, the brightness value of the entire photometric block spanned by the designated area is calculated in units of the photometric block. A photometric method characterized in that the calculation method of the luminance value of the designated area is switched so as to calculate the luminance value of the designated area. In the specifying step, at least one ranging point among a plurality of ranging points provided in an imageable range of the image sensor or a face area detected from a subject image acquired by the image sensor is selected. The photometric method according to claim 7, wherein the photometric method is designated in the designated area.