JP6005955B2 - Photometric device and imaging device - Google Patents

Description

  The present invention relates to a photometric device, and in particular, it is possible to divide a photometric area into a plurality of parts, set a correction amount based on photometric information of each photometric area, and set a correction amount suitable for each shooting condition. The present invention relates to a photometric device and an imaging device that calculate a proper luminance value.

  Conventionally, as a photometric method, there has been a method called average photometry in which a luminance value is calculated by averaging photometric information in a photometric area with the entire photographing screen as a photometric area. In addition to average metering, various inventions have been disclosed that can determine a more optimal luminance value depending on the situation where the main subject is placed.

  One method of photometry is evaluation photometry. In the evaluation photometry, photometry is performed for each of the photometric areas divided into several parts, and the photometric value obtained in each photometric area is evaluated to calculate an optimum exposure value.

  One type of evaluation photometry is a photometry device that has only one pattern of photometry area and always performs photometry on the same photometry area.

  In addition, there are photometric devices in which a plurality of patterns are prepared for the photometric area, and photometry is performed for a photometric area appropriately selected from the patterns. Patent Document 1 discloses a photometry control device characterized by evaluation photometry for selecting a photometry area from three patterns of a full screen, a central large window, or a central small window. The photometric device described in Patent Document 1 includes means for dividing a photographed image into m × n to obtain m × n luminance signal data, and a full screen and a large center from the m × n luminance signal data. A means for calculating luminance signal data of a window or a small window in the center, and a means for determining a distribution pattern of m × n luminance signal data; a distribution pattern of m × n luminance signal data and a full screen And a means for calculating the target value to obtain an optimal exposure level by comparing the luminance signal data of the central large window or the central small window, and a means for controlling the exposure so that the luminance data of the entire screen matches the target value. It has the composition which consists of.

JP 2002-094879 A

  However, in the above-described conventional photometric device, since the photometric area is fixed to a specific pattern, there is a problem that an accurate correction amount cannot be set when the photometric area is not appropriate for the shooting conditions. .

  The present invention has been made in view of such a situation, and it is possible to divide a photometric area and set a photometric area that does not depend on a specific pattern according to shooting conditions. An object of the present invention is to provide a photometric device capable of performing accurate exposure correction by setting.

  In order to solve the above-described problem, a first aspect of the present invention is a photometric device for a camera, which calculates a luminance value BV used for determining an exposure value according to a focus position set by a photographer. In the photometric device of the camera for calculating the basic luminance value BVbas, a boundary discriminating correction unit that divides the photometric area according to the field luminance value BVi, compares the divided photometric areas, and sets a correction amount from the comparison result And an additional correction means for determining whether the shooting condition in which the main subject is placed is a backlight state, the presence of a strong light source, shooting with a very uniform luminance subject, and setting an additional correction amount according to the determination result, A photometric device for a camera that calculates a luminance value BV from a basic luminance value BVbas, a correction amount, and an additional correction amount.

  A second invention for solving the above-described problem is the photometric device according to the first invention, wherein the filter means for applying a filter to the field luminance value BVi and the field luminance after applying the filter are provided. A total value calculating means for calculating a total value for each row and each column of the photometric area using the value BVi, and a boundary determining means for determining a boundary row and a boundary column using the result of the total value calculating means; A photometric area average luminance value calculating means for calculating each average luminance value BVave of a plurality of photometric areas divided by boundary rows and boundary columns based on the field luminance value BVi, and the boundary discrimination correcting means Then, the correction amount is set based on the calculation result of the photometric area average luminance value calculating means, and the additional correction means is based on the calculation result of the photometric area average luminance value calculating means. Condition or presence of strong light source, extremely uniform brightness Taken or discrimination by the object, photometric apparatus characterized by setting the additional correction amount in accordance with the discrimination result.

  Further, a third invention for solving the above-described problem is the photometric device according to the second invention, wherein the boundary discrimination correcting unit is configured to calculate each average luminance value as a calculation result of the photometric region average luminance value calculating unit. A photometric device comprising a first photometric area average luminance value comparing means for comparing BVaves and a correction amount setting means for setting a correction amount based on a comparison result of the first photometric area average luminance value comparing means .

Further, a fourth invention for solving the above-described problem is the photometry device according to the third invention, wherein the first photometry area average luminance value comparison means has determined that the photometry areas are the same as a result of the comparison calculation. The number of segments and the determination value are output, and the correction amount setting means sets the correction amount based on the number of segments and the determination value output by the first photometry area average luminance value comparison means. Photometric device characterized by

  A fifth invention for solving the above-mentioned problems is the photometric device according to any one of the second to fourth inventions, wherein the additional correcting means is a photometric area average luminance value calculating means. Based on the comparison results of the second photometric area average luminance value comparing means and the second photometric area average luminance value comparing means for comparing the average luminance values BVave as the calculation results and the basic luminance value BVbas with each average luminance value BVave. And an additional correction amount setting means for setting the additional correction amount.

  A sixth invention for solving the above-mentioned problems is an image pickup apparatus comprising the photometric device according to any one of the first to fifth inventions.

  According to the present invention, it is possible to set an accurate correction amount by setting a photometric area in accordance with photographing conditions.

It is a block diagram which shows the structure of the imaging device to which the photometry apparatus of the camera of this invention is applied. FIG. 2A is a diagram showing a division pattern of a photometry sensor and a distribution pattern of a distance measurement sensor, FIG. 2A is an example of division of a photometry area, FIG. 2B is an example of distribution of distance measurement points, and FIG. The positional relationship is shown. FIG. 2d is a diagram showing an example of a weighting pattern. It is a block diagram for demonstrating AF control and AE control of the imaging device shown in FIG. It is a flowchart regarding luminance value BV determination. It is a flowchart regarding boundary discrimination correction. It is a flowchart explaining in detail step # 7 of boundary discrimination correction. It is a flowchart regarding additional correction.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In addition, this invention is not limited by this embodiment.

  FIG. 1 is a diagram showing a main configuration of an imaging apparatus 100 to which a photometric device for a camera according to the present invention is applied.

  As illustrated in FIG. 1, the imaging apparatus 100 includes an interchangeable lens 200 and a camera body 300.

  The interchangeable lens 200 is a zoom lens having a substantially cylindrical shape, and includes an imaging optical system 210 therein.

  The interchangeable lens 200 includes a lens side mount (not shown) at the rear end.

  The camera body 300 includes a camera-side mount (not shown) on the front surface. The interchangeable lens 200 and the camera body 300 are detachably fixed by coupling both mounts.

  The inside of the camera body 300 on the optical axis of the coupling optical system 210 includes an image sensor 310 composed of a CCD, a CMOS, or the like that photoelectrically converts a subject light beam.

  Focus on the appearance of the camera body 300. The camera body 300 includes a display device (LCD, organic EL, etc.) and various operation units (not shown) on the back. The photographer can operate the various operation units to display the photographed image on the display device for confirmation, or to change settings such as exposure correction and white balance.

  Further, the camera body 300 includes a recording medium slot (not shown) on the side surface. Image data obtained by the image sensor 310 in the camera body 300 is recorded on a recording medium loaded in this slot.

  The camera body 300 includes a release button (not shown), a mode setting dial, and the like on the upper surface of the exterior.

  The release button includes a first switch that is turned on when the photographer is half-pressed and a second switch that is turned on when the photographer is fully pressed. The imaging apparatus 100 performs shooting preparation operations such as focus detection, automatic focusing on a main subject, and photometry of a field luminance value when the first switch is on. When the second switch is continuously turned on, the image data of the subject is acquired via the image sensor 310 under the shooting conditions set by the shooting preparation operation.

  The shooting mode is changed with a mode setting dial (not shown). The mode setting dial is a rotatable dial switch. A plurality of exposure mode icons that can be recognized by the photographer are printed on the upper surface of the dial. The photographer can arbitrarily set the shooting mode of the imaging apparatus 100 by rotating the mode setting dial so that the icon of the intended shooting mode is positioned at the index position.

  The type of shooting mode is, for example, auto mode (AUTO) in which all parameters such as shutter speed, aperture value, ISO sensitivity, white balance are automatically determined on the camera side, and parameters other than shutter speed and aperture value are set on the camera side. There is a program mode (P) that is automatically determined in step S1, and a manual mode (M) in which the photographer manually sets all parameters according to preference. As for other types of shooting modes, the photographer sets an arbitrary aperture value and the camera side automatically determines the optimum shutter speed accordingly, and the photographer sets an arbitrary shutter speed. There is a shutter speed priority mode (S) or the like in which the camera side automatically determines the optimum aperture value accordingly. In addition to these still image shooting modes, there may be a moving image shooting mode for shooting moving images.

  Pay attention to the inside of the imaging apparatus 100. In the camera body 300, in addition to the image sensor 310 described above, a plurality of photometric sensors 320 that measure a plurality of divided photometric areas and output a plurality of field luminance values BVi corresponding to the photometric areas, A distance measuring sensor 330 that measures the distance between the distance measuring points and outputs distance measurement information on the focus state of the subject at each distance measuring point, and an exposure time of the image sensor 310, that is, a shutter speed (not shown) is adjusted. A shutter drive unit 340 for driving a focal plane shutter is provided. The image sensor 310, the photometric sensor 320, the distance measuring sensor 330, and the shutter driving unit 340 are connected to a camera CPU 350 further provided in the camera main body 300, and are controlled by the camera CPU 350 so as to operate appropriately. The

  Inside the interchangeable lens 200, in addition to the imaging optical system 210 described above, a lens driving unit 220 for driving a focus adjustment lens 211 in the imaging optical system 210 to perform a focusing operation, and imaging optics A diaphragm drive unit 230 for adjusting the aperture amount of the system 210, a lens memory 241 for storing lens data unique to the interchangeable lens 200, a focus encoder 250 for detecting a focus position when a focusing operation is performed, and a magnification change A zoom encoder 260 and the like for detecting the zoom position when operated are provided.

  The lens data stored in the lens memory 241 includes, for example, information on the focal length and open F value of the interchangeable lens 200, whether or not the interchangeable lens 200 is a zoom lens with a variable focal length, and the like. The lens memory 241 further stores a shooting distance data table including a focus position signal output from the focus encoder 250 and a shooting distance corresponding to the position signal as lens data. Similarly, the lens data stored in the lens memory 241 also stores a focal length data table relating to a zoom position signal output from the zoom encoder 260 and a focal length corresponding to the position signal. Thereby, the photographing distance and the focal length at that time can be known from the position signal obtained by each encoder.

  These lens drive unit 220, aperture drive unit 230, focus encoder 250, and zoom encoder 260 are connected to a lens CPU 240 further provided in the interchangeable lens 200. The lens CPU 240 appropriately controls the connected lens driving unit 220, aperture driving unit 230, focus encoder 250, and zoom encoder 260.

  The lens memory 241 constitutes a part of the lens CPU 240. The lens CPU 240 accesses the lens memory 241 as necessary, and acquires and rewrites necessary information. The lens CPU 240 is electrically connected to the camera body 300 through the communication contact 110, and transmits lens data in the lens memory 241 to the camera body 300 and receives various commands from the camera body 300 side.

  The photometric sensor 320 provided in the imaging apparatus 100 is divided into a total of 77 photometric areas of 7 rows × 11 columns as shown in FIG. 2A. The photodiode in each photometry area is divided into each photometry area. The photodiode in each photometric area outputs an electric signal corresponding to the luminance in each photometric area, thereby obtaining the field luminance value BVi of the entire photometric area.

  In the following description, when focusing on a specific photometric area of the photometric sensor 320, the photometric sensor will be referred to as a segment 321. When referring to the photometric area divided by the boundary row and the boundary column, the term photometric area will be used. When referring to all photometric areas, the term “all photometric areas” will be used for explanation. Each segment 321 is numbered as shown in FIG. That is, the photometric sensor 320 is composed of a total of 77 segments 321 from the first to the 77th.

  The boundary row and the boundary column are boundaries that divide the photometric area set by the boundary discrimination correction. The boundary row and the boundary column will be described later.

  The field luminance value BVi is a field luminance value corresponding to each segment 321 of the photometric area.

  As shown in FIG. 2b, the distance measuring sensor 330 provided in the imaging apparatus 100 is composed of eleven distance measuring points 331 from 331a to 331k arranged at predetermined positions in the imaging region. That is, the distance measuring points 331a to 331c are arranged in the upper stage of the imaging area, the distance measuring points 331d to 331h are arranged in the middle area of the imaging area, and the distance measuring points 331i to 331k are arranged in the lower stage of the imaging area. The distance measuring points 331d are arranged in the first column from the left of the imaging area, the distance measuring points 331a, 331e, and 331i are arranged in the second column from the left of the imaging area, and the distance measuring points 331b, 331f, and 331j are imaged. The distance measurement points 331c, 331g, and 331k are arranged in the fourth column from the left side of the imaging area, and the distance measurement point 331h is arranged in the fifth column from the left side of the imaging area. .

  Each distance measuring point 331 includes a known phase difference AF optical system that separates a subject light beam that has passed through the imaging optical system 210 into two light beams, and a line sensor that includes a pair of photodiodes corresponding to the separated two light beams. It is composed of The line sensor converts the acquired subject luminous flux into an electrical signal and outputs it. Ranging information at each ranging point 331 is obtained by comparing and calculating the acquired pair of electrical signals. The distance measuring points 331a to 331k are cross line sensors.

  As shown in FIG. 2c, the imaging apparatus 100 is arranged such that the three distance measuring points 331d, 331f, and 331h are within a predetermined segment. Specifically, the middle 331d in the first vertical column from the left side of the shooting area is the 46th segment 321, the third middle 331f from the left side of the shooting area is the first segment 321, and the fifth middle 331h from the left side of the shooting area. Are arranged at positions corresponding to the 28th segment 321.

  The four distance measuring points 331a, 331c, 331i, and 331k are arranged so as to be surrounded by predetermined segments. Specifically, the upper 331a in the second column from the left of the shooting area is the fifth, sixteenth, seventeenth, and eighteenth segments 321 and the upper 331c in the fourth column from the left of the shooting area is the seventh and twentieth. In the 21st and 22nd segments 321, the lower 331i in the second column from the left side of the shooting area is in the third, twelfth, thirteenth, and fourteenth segments 321 and in the lower fourth column from the left side of the shooting area 331k. Are arranged at positions surrounded by the ninth, tenth, twenty-fourth and twenty-fifth segments 321 and the respective segments.

  The other four distance measuring points 331b, 331e, 331g, and 331j are arranged so as to be sandwiched between predetermined segments. Specifically, the upper 331b in the third vertical column from the left side of the imaging region is taken in the sixth and 19th segments 321 and the middle 331e in the second vertical column from the left side in the imaging region is taken in the fourth and fifteenth segments 321. The middle 331g in the fourth row from the left side of the region is sandwiched between the eighth and 23rd segments 321, and the lower 331j in the third row from the left side of the imaging region is sandwiched between the second and eleventh segments 321. Has been placed.

  Next, AF (autofocus) control in the imaging apparatus 100 to which the camera photometry device of the present invention is applied will be briefly described with reference to FIG. The AF control is started when the release button is pressed halfway by the photographer and the first switch is turned on. When the first switch is turned on, a ranging start signal is sent from the camera CPU 350 to the ranging sensor 330 in the camera body 300, and the ranging operation is started. As described above, when the ranging operation is started, the line sensors provided at the respective ranging points 331 of the ranging sensor 330 acquire the ranging information. The acquired distance measurement information of each distance measurement point 331 is sent to the camera CPU 350.

  In the camera CPU 350, the in-focus state at each distance measuring point 331 is calculated based on the input distance measurement information, and the defocus amount at each distance measuring point 331 (hereinafter referred to as distance measuring point defocus amount) is also obtained. At the same time, from among the 11 distance measuring points 331, a distance measuring point 331 that is most suitable for focusing, that is, an AF in-focus position is determined. Since many techniques are disclosed for the algorithm for determining the focal point by AF control, these known controls may be used.

  The camera CPU 350 selects a defocus amount at the determined AF in-focus position (hereinafter referred to as an in-focus defocus amount) from the eleven focus detection point defocus amounts. The camera CPU 350 calculates the driving direction and driving amount of the focus adjustment lens 211 necessary for focusing based on the selected in-focus defocus amount, and generates an AF driving signal. The camera CPU 350 sends the generated AF drive signal to the lens CPU 240 via the communication contact 110. Upon receiving the AF drive signal, the lens CPU 240 controls the lens drive unit 220 based on the received AF drive signal, and drives the focus adjustment lens 211 by a predetermined amount in a predetermined direction. This completes focusing on the subject at the AF in-focus position.

  When focusing on the main subject by AF control, the camera CPU 350 automatically starts AE (auto exposure) control. The AE control in the imaging apparatus 100 to which the photometry device of the camera of the present invention is applied is an APEX value of a luminance value necessary for determining an exposure value from the field luminance value BVi obtained in a plurality of multi-division photometry areas. This is a kind of evaluation photometry for obtaining a certain luminance value BV, and it is possible to obtain a more accurate luminance value BV by setting a correction amount necessary for the optimum luminance value BV.

  Specifically, this AE control is performed according to the flow of determining the luminance value BV in FIG. First, the field luminance value BVi in the i-th segment 321 of the imaging region, which is an essential parameter necessary for later correction, is acquired. Next, this field luminance value BVi is appropriately weighted by a weighted average to calculate a basic luminance value BVbas used for determining an exposure value. Thereafter, boundary discrimination correction for automatically changing the photometric area according to the photographing conditions is performed, and a correction amount for the calculated basic luminance value BVbas is set. Further, in the additional correction, the field luminance value BVi is used again to determine whether there is backlight and a strong light source in the shooting area, and whether the subject is a luminance box. Is set to an additional correction amount that is corrected in addition to the correction amount set in the boundary discrimination correction. The luminance value BV can be calculated by applying the correction amount set in the boundary determination correction and the additional correction amount set in the additional correction to the basic luminance value BVbas. Based on the obtained brightness value BV, a combination of ISO sensitivity, aperture, and shutter speed that is optimal for photographing the main subject is determined, and AE control ends.

  The luminance value BV indicates the field luminance value among the APEX values of the luminance values necessary for determining the exposure value. The luminance value BV can be calculated from the correction amount set by boundary determination correction and the additional correction amount set by additional correction to the basic luminance value BVbas.

  The basic luminance value BVbas can be calculated from the field luminance value BVi. A method for calculating the basic luminance value BVbas will be described later.

  When the AE control is started, as shown in FIG. 3, the camera CPU 350 sends a photometry start signal to the photometry sensor 320 in the camera body 300 in order to obtain the field luminance value BVi of the shooting area. In response to this, the photometric sensor 320 starts a photometric operation. When the photometric operation starts, photometric information is sent to the camera CPU 350. The camera CPU 350 that has acquired the photometric information acquires the field luminance value BVi for all 77 of the i-th segment 321 out of the 77 based on the photometric information.

  The acquired field luminance value BVi is used to calculate the basic luminance value BVbas and the average luminance value BVave.

  The basic luminance value BVbas will be described.

  The basic luminance value BVbas is obtained from the field luminance value BVi in the segment 321 around the set AF distance measuring point. A distance measuring point 331 is set as the AF distance measuring point. It is considered that the subject that the photographer wants to photograph exists in the area of the segment 321 close to the distance measuring point 331. Therefore, the segment 321 around the AF distance measuring point is weighted.

  As an example, the basic luminance value BVbas can be calculated by weighted averaging the field luminance values BVi in the 77 segments 321 of the photometric area, as shown in Equation 1. Here, αi is a weighting coefficient for weighting the field luminance value BVi in the i-th segment 321.

  The weighting coefficient αi is determined in advance according to the AF in-focus position. The weighting pattern generally corresponds to the distance from the AF in-focus position. In general, the weighting coefficient αi is reduced as the distance from the AF in-focus position increases.

  The weighting pattern can be set as shown in FIG. 2d. In this weighting pattern, the weighting coefficient αi is changed in three stages. In the drawing, the weighting pattern is represented by the shading of the color, and the weighting coefficient αi is reduced as the color becomes lighter.

  As described above, the basic luminance value BVbas is calculated. The basic luminance value BVbas is corrected to the luminance value BV by being corrected by the correction amount set by the boundary determination correction and the additional correction.

  The average luminance value BVave is a luminance value of the photometric area divided by the boundary row and the boundary column. It can be calculated by dividing the total value of the field luminance values BVi of the segments in the photometry area divided by the boundary rows and the boundary columns by the number of segments.

  The camera CPU 350 that has acquired the basic luminance value BVbas described above further performs boundary determination correction and additional correction in the flowchart shown in FIG. 4 using the field luminance value BVi. The boundary determination correction and additional correction will be described later.

  Hereinafter, the boundary determination correction will be described.

  In the boundary discrimination correction, the photometric area can be changed by setting a boundary row and a boundary column according to the photographing conditions.

  Next, the merit that the photometric area can be changed will be described.

  In order to output the luminance value BV, an averaging process is required using the field luminance value BVi in the photometric area. The correction amount to the accurate luminance value BV is determined by the average luminance value BVave obtained by this averaging process. Therefore, even if the images are captured in completely different states, the correction amount is the same if the output average luminance value BVave is the same.

  For example, when the photometric area is fixed, the field luminance value BVi of segments having greatly different values may be included in the photometric area. The correction amount set based on the average luminance value BVave obtained by the averaging process of the photometry area is different from the accurate correction amount of the object field luminance value BVi in the photometry area. As a result, an accurate luminance value BV cannot be set.

  However, the boundary discrimination correction can select a boundary for each photographing condition and set a photometric area for each photographing condition. The photometric area divided by the boundary is a segment having a near field luminance value BVi. Therefore, the field luminance value BVi and the average luminance value BVave in the photometric area do not take a greatly deviated value. The correction amount set by the average luminance value BVave is an accurate correction amount suitable for the field luminance value BVi in the photometric area. Boundary discrimination correction sets a photometric area for each shooting condition, thereby reducing the influence of averaging of the field luminance value BVi in the photometric area, setting a more accurate correction amount, and an accurate luminance value BV Can be calculated.

  As specific shooting conditions, a person who easily reflects light, such as white clothes and accessories, moves within the shooting area while shooting multiple shots in a short time like continuous shooting or interval shooting. Or when a light source such as a headlight of a car moves in the shooting area. That is, a portion with a high luminance value moves in the shooting area, but the average luminance value BVave in the shooting area does not change.

  If the photometry area is fixed with respect to such shooting conditions, the average luminance value BVave is affected by the influence of the field luminance value BVi serving as the light source. As a result, an incorrect correction amount is set because the field luminance value BVi and the average luminance value BVave in the photometric area are different from each other. Therefore, an accurate luminance value BV cannot be calculated. However, since the photometric area can be changed in the boundary discrimination correction, it is difficult to be affected by this. Therefore, it is possible to accurately calculate the brightness value BV by performing exposure correction accurately.

  Next, in boundary discrimination correction, the camera can automatically change the photometric area every time it is photographed, and an accurate correction amount can be set. Therefore, it is not necessary for the photographer to set for each photographing. It is possible to save the trouble of setting the photographer.

  Details of the boundary discrimination correction are shown in FIG.

  Step # 1 calculates the filter calculation result of each segment using a horizontal SOBEL filter generally known for the field luminance value BVi of each of the 77 segments in the photometric area. Proceed to step # 2. Step # 1 corresponds to the filter means because the filter is applied.

  The reason why the SOBEL filter is used in step # 1 is that the pixel that is the edge can be detected by the filter calculation. By using a pixel that is a detected edge as a boundary, a photometric area divided by the boundary is a collection having close luminance values.

  Although the SOBEL filter is used in this embodiment, it is needless to say that other filters can be used as long as the edge can be detected. Further, a Laplacian filter may be used to use the zero crossing method, and a segment instead of − to + may be used as a boundary.

  In step # 2, using the filter calculation result of each segment obtained in the filter calculation of step # 1, a total value obtained by summing up the absolute values of the filter calculation results of each segment is calculated for each row. Proceed to step # 3. Step # 2 corresponds to the total value calculation means because it calculates the total value for each row of the photometric area.

  In step # 3, the line having the largest absolute value for each line calculated in step # 2 is determined as the boundary line. At this time, when the total value of the absolute values is the same in a plurality of rows, the segment having the largest absolute value of the filter calculation result in one column is determined as the row edge segment. A row with many row edge segments is determined as the first boundary row. Proceed to step # 4. Step # 3 corresponds to the boundary determining means because the boundary line is determined.

  In step # 4, as in step # 1, the filter calculation result is calculated by applying the vertical filter of the filter used in step # 1 to the field brightness value BVi of each of the 77 segments in the photometry area. Proceed to step # 5. Step # 4 corresponds to the filter means because the filter is applied.

  Step # 5 uses the filter calculation result of each segment obtained by the filter calculation of Step # 4 in the same manner as Step # 2, and adds the total value of the absolute values of the filter calculation results of each segment to each column. Calculate every time. Proceed to step # 6. Step # 5 corresponds to the total value calculation means because the total value for each column of the photometric area is calculated.

  In step # 6, as in step # 3, the column having the largest total value for each column calculated in step # 5 is determined as the boundary column. At this time, if the total value of the absolute values is the same in a plurality of columns, the segment having the largest absolute value of the filter calculation result in one row is determined as the column edge segment. A row having many column edge segments is determined as the first boundary column. Proceed to step # 7. Step # 6 corresponds to the boundary determining means because it determines the boundary row.

  Step # 7 determines whether to add a boundary row and a boundary column. Details will be described later. Step # 7 corresponds to the boundary determining means because the boundary row and the boundary column are determined.

  In step # 8, an average luminance value BVave of each photometric area divided by the boundary row and boundary column determined from step # 3, step # 6, and step # 7 is calculated. Proceed to step # 9. Step # 8 corresponds to the photometric area average luminance value calculating means because it calculates the average luminance value BVave.

  In step # 9, the average luminance value BVave of each photometric area calculated in step # 8 is compared and determined. The comparison method will be described later. Step # 9 corresponds to the first photometric area average luminance value comparing means because the average luminance values BVave are compared with each other.

  In step # 10, a correction amount is set based on the determination condition obtained in step # 9. The correspondence table of judgment conditions and correction amounts will be described later. Thereafter, the process returns to the additional correction shown in FIG. Step # 10 corresponds to correction amount setting means because it sets a correction amount.

  The addition determination of the boundary row and the boundary column described in Step # 7 of FIG. 5 will be described in detail using the flowchart shown in FIG. Steps # 701 to # 710, which will be described below, correspond to boundary determination means because the boundary rows and the boundary columns are determined.

  Step # 701 selects boundary line candidates. The boundary line candidate is the most of the total values obtained by adding the absolute values of the filter calculation results of the segments calculated in step # 2 in FIG. 5 for each line, excluding lines that have already been determined as boundary lines. A large line.

  Step # 702 compares the most recently determined boundary line with the boundary line candidate selected in step # 701 under the following conditions.

  A segment having the largest absolute value of the filter operation in each column from the filter operation result is set as a row edge segment. Let M be the number of edge segments included in the most recently determined boundary row. When the number of row edge segments included in the boundary row candidate selected in step # 701 is M−1 or more, the process proceeds to step # 704. If not M-1 or more, the process proceeds to # 703.

  In step # 703, the boundary line determined most recently and the boundary line candidate selected in step # 701 are compared under the following conditions as in step # 702.

  Let N be the total absolute value of each segment of the boundary line determined most recently. When the total absolute value of each segment of the boundary line candidate is 90% or more of N, the process proceeds to step # 704. If N is not 90% or more, the process proceeds to step # 706.

  Step # 704 compares the boundary line already determined with the boundary line candidate under the following conditions.

  If the already determined boundary line and the boundary line candidate are not adjacent to each other, the process proceeds to step # 705. If they are adjacent to each other, the process proceeds to step # 706.

  In step # 705, the boundary line candidate selected in step # 701 is determined as the boundary line. Next, by repeating the same from step # 701 to step # 704, the determination as to whether or not a boundary line can be added is repeated.

  Step # 706 selects a boundary column candidate. The boundary column candidate is the largest column among the total values obtained by summing the absolute values of the filter calculation results of the segments calculated in step # 5 for each column, excluding columns that have already been determined as boundary columns. And

  In step # 707, the boundary sequence determined most recently is compared with the boundary sequence candidates selected in step # 706 under the following conditions.

  A segment having the largest absolute value of the filter operation in each row from the filter operation result is defined as a column edge segment. Let S be the number of edge segments included in the most recently determined boundary sequence. If the number of column edge segments included in the boundary row candidate selected in step # 706 is S-1 or more, the process proceeds to step # 709. If not S-1 or more, the process proceeds to step # 708.

  In step # 708, as in step # 707, the boundary sequence determined most recently is compared with the boundary sequence candidate selected in step # 706 under the following conditions.

  Let T be the total value of the absolute values of the segments of the boundary row determined most recently. When the total absolute value of each segment of the boundary column candidate is 90% or more of T, the process proceeds to step # 709. If not 90% or more of T, go to RETURN.

  Step # 709 compares the already determined boundary sequence with the boundary sequence candidate under the following conditions.

  If the already determined boundary row and the boundary row candidate are not adjacent to each other, the process proceeds to step # 710. If they are adjacent, proceed to RETURN.

  In step # 710, the boundary column candidate selected in step # 706 is determined as the boundary column. Next, by repeating the same from step # 706 to step # 709, the determination as to whether or not to add a boundary row is repeated.

  Note that even if the boundary row and the boundary column are set at the end of the photometric sensor, the photometric area cannot be separated. Therefore, the row and column at the end of the photometric sensor do not become a boundary row and a boundary column.

  Therefore, although filter calculation is performed in step # 1 and step # 4, the end segment in the photometric sensor may not be subjected to filter calculation.

  Through the above process, boundary rows and boundary columns are determined.

  In this embodiment, a boundary row is selected after selecting a boundary row when performing boundary discrimination correction. However, it goes without saying that a boundary row may be selected after selecting a boundary column.

  Next, a method for calculating the average luminance value BVave of each photometric area in step # 8 will be described.

  The average luminance value of each photometric area divided by the boundary row and boundary column selected from step # 3, step # 6, and step # 7 is defined as an average luminance value BVave. The average brightness value BVave is calculated by adding the object field brightness values BVi in the segments 321 in the photometry area and dividing the result by the number of segments 321 in each photometry area.

  By performing the above calculation for all photometric areas, it is possible to calculate the average luminance value BVave of each photometric area.

  Next, comparison of each photometric area in step # 9 will be described in detail.

  A method of calculating the degree of coincidence between the photometric areas by comparing the photometric areas divided by the boundary rows and the boundary columns determined up to step # 7 will be described.

The average brightness value BVave of each photometry area divided by the boundary row and the boundary column is compared for each photometry area. If the average brightness value BVave of each photometry area is within 0.4 BV ave , The average luminance value BVave of the area is determined to be coincident. The total number of segments 321 in the photometric areas determined to be coincident is calculated, and the correction amount is set by using the calculated number of segments as a parameter.

  Only the method for comparing the average luminance values BVave of the respective photometric areas described above greatly varies the correction amount that is set when the average luminance values BVave are slightly different. Therefore, in order to improve the accuracy of the correction amount, a determination value for determining coincidence is introduced as a second comparison method.

  The determination value is a value for representing the degree of matching of the compared regions.

The judgment value is obtained from the following equation.
Determination value = total number of segments in which the average luminance value BVave of each photometric area is within 0.4 BV ave + (the total number of segments in which the average luminance value BVave is within 0.4 BV ave to 0.5 BV ave ) × 1/2 + (Total number of segments with an average luminance value BVave within 0.5 BV ave to 0.7 BV ave ) × 1/3

  The number of matched photometric areas and the calculated determination value are used as the photometric area average luminance value comparison result. Proceed to step # 10.

  In step # 10, the correction amount is set according to the following Table 1, using the number of segments of the photometric area calculated in step # 9 and the determination value as parameters.

  In the boundary determination correction, the correction amount is set by determining the degree of coincidence between the photometric areas divided by the boundary rows and boundary columns.

  Therefore, the boundary determination correction can be performed only for a subject having a uniform luminance distribution such as the sky or the sea. In addition, when the average luminance value BVave is high only in a specific photometry area from the setting of the correction amount, it is possible to suppress whiteout by subtracting the exposure.

  In this embodiment, there is no restriction on the number of boundary rows / boundary columns. However, as the number of boundaries increases, the number of photometric areas also increases, so the calculation for setting the correction amount also increases. Therefore, it will take time.

  Therefore, the number of boundaries may be limited by setting.

  Hereinafter, the additional correction will be described in detail with reference to FIG.

  In the additional correction, it is determined whether or not there is backlight in the imaging region, whether or not there is a strong light source, and whether or not the subject is a luminance box. Using the determined result, an additional correction amount is set to the correction amount set in the boundary determination correction.

  The boundary discrimination correction is insufficient to discriminate a specific subject such as a strong light source or backlight. Therefore, it is necessary to perform additional correction in order to set an accurate correction amount based on the basic luminance value BVbas.

  First, the determination of whether or not the shooting area is backlit will be described.

Step # 1001 compares the basic luminance value BVbas with the average luminance value BVave of each photometric area. If no area lower than the basic brightness value BVbas exists in the average brightness value BVave, the process proceeds to step # 1003. If it exists, the process proceeds to step # 1002. Step # 1001 corresponds to second photometric area average luminance value comparison means.

Step # 1002 compares the basic luminance value BVbas with the average luminance value BVave of the adjacent photometric areas divided at the boundary. When there is a combination of adjacent photometric areas where the average luminance value BVave of each of the adjacent photometric areas among the boundaries divided by the boundary is 12 steps (= 1.5 EV) higher than the basic luminance value BVbas. Proceed to step # 1003. If not, the process proceeds to strong light source correction. Step # 1002 corresponds to second photometric area average luminance value comparison means.

In step # 1003, the amount of backlight correction is set according to the following Table 2 for the photographing determined to be backlight from step # 1001 and step # 1002. After setting the correction amount, the brightness value BV bas is calculated according to the control flowchart shown in FIG. Step # 1003 corresponds to additional correction amount setting means.

  When the photographing situation is backlight, the average luminance value BVave of all the photometric areas divided at the boundary is higher than the basic luminance value BVbas. Alternatively, there is a situation in which a certain difference or more occurs in the average luminance value BVave between adjacent photometric areas. When the boundary determination correction is applied in such a situation, the correction amount is corrected to the under side depending on the value of the average luminance value BVave of the surrounding photometry area from the basic luminance value BVbas, though the correction amount should be applied to the over side. The amount will be set.

  Therefore, it is determined whether or not the backlight is backlit by additional correction, and if it is backlit, the correction amount according to Table 2 is added to the correction amount set by the boundary discrimination correction.

  In step # 1004, it is determined whether or not a strong light source exists in the imaging region. Step # 1004 corresponds to second photometric area average luminance value comparison means.

  In step # 1005, a maximum value and a minimum value are obtained from the average luminance value BVave of each photometric area. Next, a difference is calculated from the obtained maximum average luminance value BVave and minimum average luminance value BVave. As a result, if it is greater than 24step (= 3EV), the process proceeds to step # 1006. If smaller, the process proceeds to step # 1008. Step # 1005 corresponds to the second photometric area average luminance value comparing means.

  In step # 1006, as in step # 1005, the maximum value and the minimum value are obtained from the average luminance value BVave. Next, a difference is calculated from the obtained maximum average luminance value BVave and minimum average luminance value BVave. The calculated difference is multiplied by the number of segments in the photometric area that provides the maximum average luminance value. As a result, if it exceeds 500, the process proceeds to step # 1007. If it does not exceed 500, the process proceeds to step # 1008. Step # 1006 corresponds to second photometric area average luminance value comparison means.

In step # 1007, the correction amount is set according to the following Table 3 for the strong light source correction for the shooting determined to have a strong light source in the shooting area. After setting the correction amount, the brightness value BV is calculated according to the control flowchart shown in FIG. Step # 1007 corresponds to additional correction amount setting means.

  When a strong light source is present in the imaging region, the average luminance value BVave of the photometry region where the strong light source exists is a high value, and a certain difference or more is generated from the basic luminance value BVbas. When the boundary determination correction is applied to such a situation, the average luminance value BVave of the photometry area where the strong light source exists and the other photometry areas do not coincide with each other even though it is desired to strongly overcorrect. The correction amount is set slightly on the over or under side.

  Therefore, the correction amount of the boundary discrimination correction is not sufficient, so the presence of a strong light source is determined in the shooting area by additional correction. Add the correction amount.

  Step # 1008 determines whether or not the subject is reference light such as a luminance box. Step # 1008 corresponds to the second photometric area average luminance value comparing means.

  Step # 1009 compares the basic luminance value BVbas with the average luminance value BVave of each photometric area divided at the boundary. If the average luminance value BVave of each photometric area divided at the boundary with the basic luminance value BVbas is all within 1 step (= 0.125 EV), the process proceeds to step # 1010. If it is not within 1 step (= 0.125 EV), the luminance value BV is calculated according to the control flowchart shown in FIG. Step # 1009 corresponds to second photometric area average luminance value comparison means.

  If all the results obtained by comparing the average luminance values BVave of the photometric areas divided at the boundary are within 1 step (= 0.125 EV), step # 1010 proceeds to step # 1011. If it is not within 1 step (= 0.125 EV), the luminance value BV is calculated according to the control flowchart shown in FIG. Step # 1010 corresponds to the second photometric area average luminance value comparing means.

  Step # 1011 determines that the subject is reference light such as a luminance box. The additional correction amount is a correction that cancels the correction amount set in the boundary discrimination correction. The luminance value BV is calculated according to the control flowchart shown in FIG. Step # 1011 corresponds to additional correction amount setting means.

  The reason why the additional correction amount is corrected to cancel the correction amount set in the boundary discrimination correction when it is determined that the reference light such as the luminance box is photographed will be described.

  Originally, when a reference light such as a luminance box is shot, the reference brightness is set in the camera, so the brightness recognized by the camera matches the brightness of the luminance box without performing boundary discrimination correction. . That is, when the image is taken in the luminance box, the correction amount is desirably ± 0. However, when the boundary determination correction is performed, the maximum amount of brightness correction is set.

  Therefore, when the conditions of step # 1009 and step # 1010 are satisfied, it is determined that the subject is reference light such as a luminance box. The correction was made to cancel the correction amount set in the boundary discrimination correction.

  A correction amount and an additional correction amount are set from the above boundary determination correction and additional correction. By applying the determined correction amount and the additional correction amount to the basic luminance value BVbas, the luminance value BV is calculated. As a result of the calculation, the luminance value BV is determined.

  The order of additional correction will be described.

  In this embodiment, the discrimination is performed in the order of backlight discrimination correction, strong light source correction, and luminance box correction. However, opportunities for photographing the luminance box on a daily basis are extremely limited. Therefore, it is desirable that the backlight discrimination correction and the strong light source correction, which are frequently encountered in daily shooting, be performed before the luminance box correction.

  It goes without saying that the additional correction is not limited to this order.

  In this embodiment, the backlight discrimination correction, the strong light source correction, and the luminance box correction are all determined by additional correction, but the luminance box is imaged at the time of factory shipment or repair. Opportunities to shoot the luminance box in everyday shooting are rare. Therefore, the luminance box correction may be set so that only the luminance box correction is performed without being included in the normal additional correction.

  The camera CPU 350 performs a well-known APEX operation on the determined brightness value BV using the formula shown in Formula 2, and, from a predetermined program diagram, the combination of the AV value, TV value, and SV value to be controlled. Calculate and determine the exposure control value. Here, the AV value is the APEX value of the aperture value at the time of exposure, and the TV value is the APEX value of the shutter speed representing the exposure time. The SV value is an APEX value of ISO sensitivity at the time of exposure. The ISO sensitivity is a value controlled in an amplifier circuit (not shown) that drives the image sensor 310.

(Equation 2)
BV = AV + TV-SV (2)

  When the camera CPU 350 determines a combination of exposure values, the control flowchart shown in FIG. Subsequently, when the second switch of the release button is turned on, that is, fully pressed by the photographer, a photographing operation based on each APEX value determined in the control flow is performed. That is, the aperture size used for shooting is calculated from the AV value, and an aperture drive signal corresponding to the aperture size is sent to the aperture drive unit 230, so that an optimum exposure time can be obtained. Furthermore, ISO sensitivity used for photographing can be obtained from the SV value. As a result, it is possible to obtain image data with proper exposure.

  In the camera photometric device of the above-described embodiment, the focal point is obtained from a plurality of distance measuring points using AF control. However, the photographer selects an arbitrary distance measuring point and selects the distance measuring point as the AF focal point. Even when AF control and AE control are executed as positions, it is obvious that the same effects as in the present embodiment can be obtained.

  Furthermore, although the imaging apparatus to which the present invention is applied has been described as an interchangeable lens type, it can also be applied to a lens-integrated imaging apparatus. In this case, all the members provided in the interchangeable lens are provided in the camera body.

  Furthermore, the camera photometric device of the above-described embodiment illustrates a weighting pattern. It goes without saying that the weighting pattern shown is merely an example, and is not limited to this pattern.

  As described above, according to the photometric device of the camera according to the present invention, exposure is performed by taking into consideration the shooting condition and backlight condition in which the main subject is placed, the presence of a strong light source, and shooting in a luminance box. It is possible to accurately calculate the luminance value BV by calculation.

  The photometric sensor used in this example is a 77 segment sensor, but it goes without saying that the present invention is not limited to the 77 segment.

DESCRIPTION OF SYMBOLS 100 Imaging device 200 Interchangeable lens 210 Imaging optical system 220 Lens drive unit 230 Aperture drive unit 240 Lens CPU
241 Lens memory 250 Focus encoder 260 Zoom encoder 300 Camera body 310 Image sensor 320 Photometric sensor 321 Segment 330 Distance sensor 340 Drive unit 350 Camera CPU

Claims (6)

In order to calculate the luminance value BV used for determining the exposure value,
In the photometric device of the camera that calculates the basic luminance value BVbas according to the in-focus position set by the photographer,
A boundary determination correction unit that divides a photometric area according to the field luminance value BVi, compares the divided photometric areas, and sets a correction amount based on the comparison result;
An additional correction means for determining whether the shooting condition in which the main subject is placed is a backlighting state, the presence of a strong light source, shooting with a very uniform luminance subject, and setting an additional correction amount according to the determination result;
Have
The photometric device characterized in that the luminance value BV is calculated from the basic luminance value BVbas, the correction amount, and the additional correction amount. Filter means for applying a filter to the field luminance value BVi;
Total value calculation means for calculating a total value for each row and each column of the photometric area using the field luminance value BVi after the filter application;
Boundary determining means for determining a boundary row and a boundary column using the result of the total value calculating means;
A photometric area average luminance value calculating means for calculating each average luminance value BVave of a plurality of photometric areas divided by the boundary row and the boundary column based on the field luminance value BVi;
Have
The boundary determination correction unit sets the correction amount based on the calculation result of the photometric area average luminance value calculation unit,
The additional correction means determines, based on the calculation result of the photometric area average luminance value calculation means, whether the photographing condition in which the main subject is placed is a backlighting state, the presence of a strong light source, photographing with a very uniform luminance subject, The photometric device according to claim 1, wherein the additional correction amount is set according to a determination result. The boundary discrimination correcting means is
First photometric area average luminance value comparing means for comparing the average luminance values BVave which are the calculation results of the photometric area average luminance value calculating means;
Correction amount setting means for setting the correction amount based on the comparison result of the first photometric area average luminance value comparison means;
The photometric device according to claim 2, comprising: The first photometric area average luminance value comparing means outputs the number of segments and the determination value, which are the number of photometric sensors in the photometric area determined to be coincident as a result of the comparison calculation,
4. The photometric device according to claim 3, wherein the correction amount setting unit sets the correction amount based on the number of segments output by the first photometric area average luminance value comparing unit and the determination value. . The additional correction means includes
Second photometric area average luminance value comparing means for comparing the average luminance values BVave and the basic luminance values BVbas with the average luminance values BVave, which are calculation results of the photometric area average luminance value calculating means;
An additional correction amount setting means for setting the additional correction amount based on a comparison result of the second photometric area average luminance value comparison means;
The photometric device according to claim 2, comprising:   An imaging device comprising the photometric device according to any one of claims 1 to 5.

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