JP2008134419A - Imaging device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device which is contrived to suppress image quality deterioration when taking images by using a flash lighting unit, and its control method. <P>SOLUTION: This imaging device has a preliminary light emitting control section to make the flash lighting unit emit preliminary light before taking images; a received light amount detector to detect the amount of the preliminary light reflected back from the object; a sensitivity setup section that integrates for each area the light amounts received on the unit areas obtained by dividing the unit light receiving elements, counts the number of the areas within the limits between thresholds by comparing them with each of one or more thresholds, and sets up the sensitivity based on the count distribution; and a main light amount setup section to make the flash lighting unit emit light following the preliminary light emission based on the sensitivity set in the sensitivity setup section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a photographing apparatus and a photographing apparatus control method that include a flash light emitting unit that emits a flash toward a subject and that performs photographing to form an image on the imaging element and generate an image signal representing the subject.

  2. Description of the Related Art Conventionally, there has been known a photographing apparatus that performs focusing based on the contrast of a subject image formed on an image sensor.

  Some of these imaging devices have low accuracy in determining the distance to the subject, and if the distance to the subject is inaccurate when shooting with a flash or other flash unit, Depending on the sensitivity, there is a risk of image quality deterioration due to so-called whiteout or blackout.

  Therefore, when shooting using the flash unit, the so-called pre-emission, which is less emitted than the actual emission, is directed toward the subject, and the reflected light from the subject due to this pre-emission is flashed. There has been proposed an imaging apparatus that controls light reception sensitivity by receiving light with a light control sensor provided in a light-emitting unit and estimating a distance to a subject based on the amount of light received by the light control sensor (see Patent Document 1). ).

  However, even in the above proposal, due to the parallax between the photographing optical axis and the light control sensor, the estimation accuracy of the distance to the subject is still low, and there is a possibility that the image quality is deteriorated due to overexposure or blackout.

Therefore, the reflected light from the subject due to this pre-light emission is received by an image sensor that has no parallax with the photographic optical axis, and the light reception level is determined around the center of the image sensor, so that the estimation accuracy of the distance to the subject is improved The proposal which raises is made | formed (for example, refer patent document 2).
JP 2001-2222049 A JP 2004-236300 A

  However, in the above proposal, there is a possibility that the sensitivity is set to be incorrect when the main subject does not exist in the center.

  In view of the above circumstances, an object of the present invention is to provide a photographing apparatus and a photographing apparatus control method that are devised to suppress deterioration in image quality in photographing using a flash light emitting unit.

In order to achieve the above object, the first photographing device of the photographing device of the present invention is:
A photographing unit that includes a flash light emitting unit that emits a flash toward a subject, and forms an image of the subject on an imaging element that is a set of a plurality of unit light receiving elements arranged two-dimensionally to generate an image signal representing the subject. In an imaging device that performs
A pre-emission control unit that causes the flash emission unit to perform pre-emission prior to shooting when receiving a shooting instruction involving flash emission;
A received light amount detecting unit for detecting a received light amount in the imaging element of reflected light reflected from the subject side by pre-emission by the flash light emitting unit;
When the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, the received light amount by the pre-light emission in each unit light receiving element in each area is integrated for each area, and the integrated received light amount is 1 or more. A sensitivity setting unit that counts the number of areas within each received light amount range divided by this threshold value in comparison with each threshold value, and sets the received light sensitivity based on the distribution of the counted value;
Based on the light receiving sensitivity set by the sensitivity setting unit, a main light emission amount determination unit that determines the amount of main light emission to be performed by the flash light emission unit subsequent to the pre-emission,
And a main light emission control unit that causes the flash light emission unit to perform main light emission with the light amount determined by the main light emission light amount determination unit during photographing following the pre-light emission.

  In the first photographing apparatus of the present invention, the amount of received light for each area on the image sensor is counted. For example, if the distribution of the count is biased toward the side with the larger amount of received light, it is determined that the distance to the subject is short. If the light receiving sensitivity is lowered and the light receiving light amount is biased toward the smaller amount, the distance to the subject is determined to be long, and the light receiving sensitivity is increased to suppress the occurrence of whiteout or blackout. Therefore, according to the first photographing apparatus of the present invention, the luminance of the main subject can be reflected in the sensitivity setting regardless of whether the main subject is within the photographing angle of view. It is possible to suppress deterioration in image quality. In addition, according to the first photographing apparatus of the present invention, the sensitivity setting is performed based on the received light amount for each area in which a plurality of unit light receiving elements on the photographing element are gathered to some extent. Compared with the case where the sensitivity is set based on the amount of received light of each light receiving element, the processing can be speeded up.

In order to achieve the above object, the second imaging device of the imaging device of the present invention is:
A photographing unit that includes a flash light emitting unit that emits a flash toward a subject, and forms an image of the subject on an imaging element that is a set of a plurality of unit light receiving elements arranged two-dimensionally to generate an image signal representing the subject. In an imaging device that performs
A pre-emission control unit that causes the flash emission unit to perform pre-emission prior to shooting when receiving a shooting instruction involving flash emission,
A received light amount detecting unit for detecting a received light amount in the image sensor of reflected light reflected from the subject side by pre-emission by the flash light emitting unit;
An integrated value obtained by integrating the amount of light received by the pre-emission in each unit light receiving element in each area when the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, and currently set A reference light amount determination unit that determines a reference light amount serving as a reference for the main light emission to be performed by the flash light emission unit subsequent to the pre-light emission based on the light receiving sensitivity;
A sensitivity setting unit that compares the reference light amount determined by the reference light amount determination unit with one or more threshold values and resets the light reception sensitivity according to the region to which the reference light amount belongs among the regions divided by the threshold values;
A main light emission amount that is determined based on a detection result by the received light amount detection unit and a sensitivity set by the sensitivity setting unit, which is to be performed by the flash light emission unit subsequent to the pre-emission at the time of shooting. And a main light emission control unit that causes the flash light emitting unit to perform main light emission of the light amount determined by the main light emission light amount determination unit during photographing following the pre-light emission.

  In the second photographing apparatus of the present invention, the distance to the subject can be estimated with high accuracy based on the amount of the reference light amount determined based on the received light amount integrated for each area on the image sensor. In other words, in the second photographing apparatus of the present invention, the luminance of the main subject can be reflected in the reference light amount regardless of whether the main subject is within the shooting angle of view, and can be obtained with high accuracy based on the reference light amount. The light receiving sensitivity is set according to the distance to the subject, and the main light emission amount is determined based on the newly set sensitivity. Therefore, according to the second photographing apparatus of the present invention, it is possible to suppress the occurrence of overexposure and blackout, and it is possible to suppress deterioration in image quality in photographing using the flash light emitting unit.

  Here, in the second photographing apparatus of the present invention, it is preferable that the sensitivity setting unit resets the sensitivity to be higher as the reference light quantity belongs to a larger region.

  In this way, the same effect can be obtained as when the flash reach distance is extended.

In order to achieve the above object, a first imaging apparatus control method of the imaging apparatus control method of the present invention includes a flash light emitting unit that emits a flash toward a subject, and a plurality of units arranged two-dimensionally. In an imaging apparatus control method for controlling an imaging apparatus that performs imaging to form an image of an object on an image sensor made up of a set of light receiving elements and generate an image signal representing the object,
A pre-light emission process for causing the flash light emission part to perform pre-light emission prior to photographing when receiving a shooting instruction with flash light emission;
A received light amount detection process for detecting the received light amount in the image sensor of the reflected light reflected from the subject side in the pre-emission process;
When the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, the received light amount by the pre-light emission in each unit light receiving element in each area is integrated for each area, and the integrated received light amount is 1 or more. The number of areas in each received light quantity range divided by this threshold value is compared with each threshold value, and the received light sensitivity is set based on the received light quantity. Setting process,
Based on the light receiving sensitivity set by the sensitivity setting process, a main light emission amount determination process for determining the amount of main light emission to be performed by the flash light emitting unit following the pre-light emission,
And a main light emission process for causing the flash light emitting section to perform main light emission with the light amount determined in the main light emission light amount determination process at the time of photographing following the pre-light emission.

Of the imaging device control methods of the present invention for achieving the above object, the second imaging device control method comprises:
A photographing unit that includes a flash light emitting unit that emits a flash toward a subject, and forms an image of the subject on an imaging element that is a set of a plurality of unit light receiving elements arranged two-dimensionally to generate an image signal representing the subject. In the photographing apparatus control method for performing
A pre-emission control process for causing the flash emission unit to perform pre-emission prior to shooting when receiving a shooting instruction involving flash emission,
A received light amount detection process for detecting a received light amount in the image sensor of reflected light reflected from the subject side by pre-emission in the pre-emission control process;
An integrated value obtained by integrating the amount of light received by the pre-emission in each unit light receiving element in each area when the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, and currently set A reference light amount determination process for determining a reference light amount serving as a reference of the main light emission to be performed by the flash light emitting unit following the pre-light emission based on the light receiving sensitivity;
A sensitivity setting process in which the reference light amount determined in the reference light amount determination process is compared with one or more threshold values, and the light receiving sensitivity is reset according to the region to which the reference light amount belongs among the regions divided by the threshold values;
A main light emission amount determined by the detection result of the received light amount detection process and the sensitivity set by the sensitivity setting process for the main light emission amount to be performed by the flash light emitting unit following the pre-light emission at the time of shooting. And a main light emission control step of causing the flash light emitting section to perform main light emission of the light amount determined in the main light emission amount determination step subsequent to the pre-light emission in photographing.

  According to the image capturing apparatus and the image capturing apparatus control method of the present invention, it is possible to suppress deterioration in image quality in image capturing using the flash light emitting unit.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is an external perspective view of a digital camera, which is an embodiment of the first imaging apparatus of the present invention, in which an embodiment of the first imaging apparatus control method of the present invention is implemented.

  FIG. 1 shows an external perspective view of the digital camera 1 according to the present embodiment from the front.

  A lens barrel 11 is provided in the center of the front surface of the housing 10 of the digital camera 1 shown in FIG. 1, and a zoom lens 111 is incorporated in the lens barrel 11. A finder objective window 10a is provided at the upper front of the housing 10, and a photographing auxiliary light emission window 10b is provided on the right side of the finder objective window 10a. The photographing auxiliary light emission window 10b emits photographing auxiliary light toward the subject when it is determined that irradiation of photographing auxiliary light is necessary based on a detection result of an AE detection circuit 23 (see FIG. 2) described later. . A shutter button 12 and a mode dial 13 are provided on the upper surface of the housing 10. The mode dial 13 is operated when a desired mode is selected from the shooting mode, the playback mode, and the like. Although detailed illustration in FIG. 1 is omitted, a picture 131 corresponding to the mode is printed on the upper surface of the dial.

  In the digital camera 1, a mode corresponding to the picture matched with the arrow is selected by matching the picture corresponding to the desired mode with the arrow 132 printed on the upper surface of the housing 10. .

  FIG. 1B shows an external perspective view of the digital camera 1 from the back side. A liquid crystal panel 14 is provided on the back surface of the housing 10 of the digital camera 1, and a finder eyepiece window 10 c is provided above the liquid crystal panel 14. A menu button 16, an OK switch 17, and a cancel switch 18 are provided on the right side of the liquid crystal panel 14, and a cross key 19 is provided on the diagonally upper right side of the menu button 16. The menu button 16 is operated when a menu such as sensitivity setting and recording pixel number setting is displayed on the liquid crystal panel 14, and the cross key 19 is a menu displayed on the liquid crystal panel 14 when the menu button 16 is operated. It is operated when selecting one of. By selecting one of the menus displayed on the liquid crystal panel 14 by operating the cross key 19 and then operating the OK switch 17, this selection controls the overall operation of the digital camera 1. (See FIG. 2). Further, a power switch 15 is provided on the right side of the cancel switch 18, and when the power switch 15 is turned on, the digital camera 1 enters an operating state. The cross key 19 is also used for adjusting the optical zoom when the menu is not displayed on the liquid crystal panel 14.

  FIG. 2 is a configuration block diagram of an electrical system inside the digital camera shown in FIG.

  The digital camera 1 according to the present embodiment is entirely controlled by the CPU 20 described above. The CPU 20 includes a mode dial 13, a cross key 19, a menu button 16, a power switch 15, and the like shown in FIG. A signal is transmitted. The CPU 20 performs processing in accordance with the transmitted signal, and an EEPROM 202 is connected to the CPU 20 via the data bus 200. The EEPROM 202 is necessary for the operation of the digital camera 1. The program is written. The SDRAM 201 has three counter areas, which will be described in detail later.

  Here, the internal configuration of the digital camera 1 will be described in detail while explaining the operation control in the digital camera 1 when the power switch 15 is turned on.

  When the power switch 15 is turned on, power is supplied from the battery 30 as a power source to each part in the digital camera 1, and when the shooting mode is selected by the mode dial 13, the power passes through the lens barrel. An image signal representing the subject image formed on the CCD 40 is output from the CCD 40, and the subject image represented by the output image signal is displayed on the liquid crystal panel 14. The CCD 40 is supplied with a timing signal from a timing generator 41 (hereinafter, this timing generator is referred to as TG), and an image signal is thinned out at predetermined intervals by this timing signal and output. The TG 41 outputs a timing signal in response to an instruction from the CPU 20, and this timing signal controls the operation of the mechanical shutter 114 and the photographing auxiliary device 50 built in the lens barrel 11 in addition to the CCD 40.

  The image signal output from the CCD 40 is converted into a digital image signal by the A / D unit 42, and the white balance / γ adjustment unit 43 performs white balance adjustment and γ adjustment. Further, the image signal that has passed through the white balance / γ adjustment unit 43 is supplied to the YC processing unit 22 for YC separation processing. The image buffer 21 is for adjusting the processing timing between the white balance / γ adjusting unit 43 and the YC processing unit 22. The image signal supplied to the YC processing unit 22 via the image buffer 21 is converted from the RGB signal to the YC signal by the YC processing unit 22 and then supplied to the liquid crystal panel 14 via the data bus 200 and Y A signal is supplied to the AE detection circuit 23 and the AF detection circuit 24.

  The YC signal is converted from the YC signal to the RGB signal by the YC / RGB conversion unit 28, and the converted RGB signal is supplied to the driver 281, and the subject image based on the RGB signal is displayed on the liquid crystal panel 14 by the driver 281. Is done.

  In the AE detection circuit 23 to which a Y signal including a luminance signal is supplied, an exposure necessary for obtaining a through image having an appropriate brightness is adjusted by controlling the aperture diameter of the iris 113 based on the Y signal. .

  The AF detection circuit 24 to which a Y signal including a luminance signal is supplied continuously adjusts the focus of the through image by detecting the contrast from the Y signal and controlling the position of the focus lens 112.

  Thereby, the subject in the direction to which the zoom lens 111 or the like is directed is always displayed on the liquid crystal panel 14 as a subject image. When the shutter button 12 is pressed while visually recognizing the displayed subject image, an image signal representing the subject image formed on the CCD 40 is output as an RGB signal, and the subject based on the RGB signal is output to the liquid crystal panel 14. The image is displayed as a still image. Therefore, when the OK switch 17 shown in FIG. 1B is pressed, the RGB signal is converted into a YC signal by the YC processing unit 22 and then compressed by the compression / decompression unit 27 to be interface (I / F) 271. Is recorded on the recording medium 60 with a header. In the compression / decompression unit 27, compression is performed by a compression method compliant with the JPEG standard, and compression information, shooting information, and the like are written in the header portion. When the subject image based on the RGB signal is displayed as a still image on the liquid crystal panel 14 by pressing the shutter button 12, if the cancel switch 18 shown in FIG. 1B is pressed, a through image is displayed on the liquid crystal panel 14. Is displayed again.

  On the other hand, when the playback mode is selected with the mode dial 13 of the digital camera 1, the header portion is read from the recording medium 60, and the corresponding compressed image signal is read based on the compression information in the header portion. The compression / decompression unit 27 decompresses the read compressed image signal to restore the image signal. The restored image signal is displayed on the liquid crystal panel 14 through the above-described route.

  Further, the digital camera 1 is provided with a lens driver 110 connected to the CPU 20, and the opening size of the iris 113 can be changed according to the detection results of the AE detection circuit 23 and the AF detection circuit 24. The focus lens 112 is moved by the lens driver 110. Further, the lens driver 110 moves the zoom lens 111 according to the operation of the cross key 19.

  In the digital camera 1, depending on the detection result from the AE detection circuit 23, the photographing auxiliary device 50 emits photographing auxiliary light toward the subject.

  The photographing auxiliary device 50 provided in the digital camera 1 is of a type in which the amount of photographing auxiliary light is controlled by the length of time. In the case of a small amount of light emission, the light emission time is short, and a large amount of light emission. In this case, the light emission time is controlled to be long.

  Here, in the digital camera 1 of the present embodiment, when it is determined that the irradiation of the photographing auxiliary light is necessary based on the detection result from the AE detection circuit 23, the pre-emission from the photographing auxiliary device 50 to the subject is performed in advance. Small light emission called light emission is performed. The reflected light reflected from the subject by this pre-emission is received by the CCD 40.

  The CCD 40 is a so-called 3 million pixel image sensor in which unit light-receiving elements exceeding 3 million are two-dimensionally arranged, and these are conceptually divided into 64 areas of 8 columns and 8 columns. Has been.

  FIG. 3 is a diagram showing a state in which the CCD provided in the digital camera is conceptually divided into 64 areas.

  FIG. 3 shows a state in which the CCD 40 is conceptually divided into a total of 64 areas of 8 vertical rows and 8 horizontal rows. Each of these 64 areas is numbered from 1 to 64. ing. For convenience of explanation, the following description will be made using numbers assigned to the respective areas.

  FIG. 4 is a diagram showing a flow of photographing control when the photographing auxiliary device is used, which is performed in the digital camera of the present embodiment.

  In this digital camera 1, when it is determined that irradiation of shooting assistance light is necessary, first, in the pre-light emission process of step S 100 shown in FIG. 4, pre-light emission is performed by the shooting auxiliary device 50, and area integration in step S 110 is performed. In the process, the amount of received light reflected by the subject by pre-emission and received on the CCD 40 is integrated for each area from 1 to 64. In the process of counting the number of areas in step S120, the area to which the 64 areas belong to which of the three areas divided by the two integration thresholds A and B is distributed according to the integrated value of each area. Numbers are counted for each region. In the sensitivity setting process in step S130, the light receiving sensitivity is set based on the number of areas in each region. In the main light emission amount determination process in step S140, the light emission time of the main light emission of the photographing auxiliary device 50 is determined based on the light receiving sensitivity set in the sensitivity setting process in step S130 and the current field luminance. In the main light emission process in step S150, the main light emission is performed for the light emission time determined in the main light emission amount determination process in step S140.

  The shooting control for the area integration process in step S110, the area number counting process in step S120, and the sensitivity setting process in step S130 is actually performed by the sensitivity setting circuit 25, the emitted light quantity determination circuit 26, and the CPU 20 shown in FIG. The reflected light reflected from the subject by the pre-emission is received by the CCD 40 and received by each unit belonging to 64 areas conceptually shown in FIG. 3 (from the first area to the 64th area). The amount of light received by the element is integrated for each area, the number of areas where the integrated value in each area by pre-emission is greater than or equal to the integrated value A, the number of areas where the integrated value is less than the integrated value A and the integrated value B or more, and the integrated value The number of areas less than B is counted, and the luminance of the main subject can be high if the number of areas whose accumulated value is equal to or greater than the accumulated value A is equal to or greater than the predetermined number C. Light-receiving sensitivity is adapted to be set to a relatively low sensitivity as high. If the number of areas whose integrated value is less than the integrated value B is equal to or greater than the predetermined number D, the luminance of the main subject is likely to be low, and the light receiving sensitivity is set to a relatively high sensitivity. When the number of areas is not more than the predetermined number C, and when the number of areas less than the integrated value B is not more than the predetermined number D, the light receiving sensitivity is set to a relatively medium sensitivity. It has become. Thereafter, the main light emission amount from the photographing auxiliary device 50 is determined based on the set light reception sensitivity and the field luminance as a detection result in the AE detection circuit 23. In the digital camera 1, the photographing auxiliary device 50 emits light for a time corresponding to the determined light amount.

  In the digital camera 1 of the present embodiment described above, the amount of received light for each area on the CCD 40 is counted, and if the distribution of the counted value is biased toward the side with the larger amount of received light, it is determined that the distance to the subject is short. Decrease the light reception sensitivity, and if it is biased toward the smaller received light amount, it is determined that the distance to the subject is long and the light reception sensitivity is increased. Can be reflected in the sensitivity setting, so that deterioration of image quality due to occurrence of overexposure or underexposure in shooting using the shooting assisting device 50 can be suppressed. Further, in the digital camera 1 of the present embodiment, the sensitivity is set based on the amount of received light for each area where a plurality of unit light receiving elements on the CCD are gathered to some extent, so that each unit light receiving element on the CCD receives light. Compared with the case where sensitivity is set based on the amount of light, the processing is speeded up.

  FIG. 5 is a flowchart illustrating a routine that is executed in the digital camera of the present embodiment when the shutter button is pressed.

  In step S1 shown in FIG. 5, first, luminance detection by the AE detection circuit 23 is instructed to detect the field luminance, and in step S2, detection of the focus position is instructed by the AF detection circuit 24. In step S <b> 3, it is determined based on the detection result of the AE detection circuit 23 whether or not auxiliary light from the photographing auxiliary device 50 is necessary. If it is determined in step S3 that auxiliary light is not necessary, the process proceeds to step S18. If it is determined that auxiliary light is necessary, the process proceeds to step S4. In step S4, the photographing auxiliary device 50 is instructed to perform pre-emission. In step S5, an instruction is given for the integration of the amount of light received in each area of the CCD 40 by this pre-emission. In step S6, a count value 1 representing an area number is substituted into the counter N secured in the SDRAM 201 shown in FIG. In step S7, since the count value of the counter N is 1, it is determined whether or not the integrated value of the received light quantity in the first area (see FIG. 3) is equal to or greater than the integrated value A. If it is determined in step S7 that the accumulated value is equal to or greater than A, the process proceeds to step S8, and the count value of the counter L secured in the SDRAM 201 for counting the number of areas equal to or greater than the accumulated value A is incremented by one. The process proceeds to step S11. If it is determined in step S7 that it is less than the integrated value A, the process proceeds to step S9, and it is determined whether or not the integrated value of the received light quantity in the first area is less than the integrated value B that is smaller than the integrated value A. To do. If it is determined in step S8 that the integrated value in the first area is greater than or equal to the integrated value B, the process proceeds to step S10. If it is determined in step S9 that the integrated value in the first area is less than the integrated value B, step Proceeding to S10, the count value of the counter M secured in the SDRAM 201 for counting the number of areas less than the integrated value B is incremented, and then proceeding to Step S11. On the other hand, if it is determined in step S9 that the integrated value in the first area is less than the integrated value A but greater than or equal to the integrated value B, the process proceeds to step S11. In step S11, the count value of the counter M reserved in the SDRAM 201 for counting the number of areas is incremented by one. In step S12, it is determined whether or not the count value of the counter N is less than 65, that is, whether or not the determination of the integrated value from the first area to the 64th area has been completed. In step S12, the counter N is counted. If it is determined that the value is less than 65, the process returns to step S7. If it is determined in step S12 that the count value of the counter N is 65 or more, the process proceeds to step S13, and the count value of the counter L, that is, the relatively integrated value. It is determined whether or not the count value of the counter L counting the number of high areas exceeds a predetermined value C. If it is determined in step S13 that the count value of the counter L is equal to or greater than the predetermined value C, that is, the number of areas with a large amount of received light is large, the process proceeds to step S14, the set sensitivity is set to low sensitivity, and then the process proceeds to step S18. If it is determined in step S13 that the count value of the counter L is less than the predetermined value C, the process proceeds to step S15. In step S15, it is determined whether or not the count value of the counter M, that is, the count value of the counter M counting the number of areas having relatively low integrated values exceeds a predetermined value D. If it is determined in step S15 that the count value of the counter M exceeds the predetermined value D, that is, the number of areas with a small amount of received light is large, the process proceeds to step S16, the set sensitivity is set to high sensitivity, and then the process proceeds to step S18. . If it is determined in step S15 that the count value of the counter M is less than the predetermined value D, the process proceeds to step S17, the set sensitivity is set to medium sensitivity, and then the process proceeds to step S18. In step S18, the light emission amount of the photographing auxiliary light by the photographing auxiliary device 50 is calculated based on the set sensitivity and the detection result in the AE detection circuit 23, and the light emission of the auxiliary light is instructed. In step S19, the counters N, L, and M are reset to zero, and this routine is terminated.

  In the embodiment described above, the number of areas belonging to the three received light quantity ranges divided by the integrated values A and B is counted as the integrated value threshold, and the number of areas equal to or greater than the integrated value A is equal to or greater than the predetermined value C. If there is a low sensitivity and the number of areas less than the integrated value B is set to a high value when the number is less than or equal to the predetermined value D, other examples are set to medium sensitivity, but the present invention is integrated for each area. If the received light quantity is to be compared with one or more threshold values, the number of areas belonging to two or four received light quantity ranges may be counted, and each received light sectioned by one or more threshold values. If the number of areas in the light amount range is counted and the light receiving sensitivity is set based on the distribution of the counted values, the predetermined value C and the predetermined value D are not particular.

  Next, an embodiment of the second imaging apparatus of the present invention in which an embodiment of the second imaging apparatus control method of the present invention is implemented will be described.

  Differences between the digital camera of the present embodiment and the digital camera 1 which is an embodiment of the first imaging apparatus of the present invention, in which an embodiment of the first imaging apparatus control method of the present invention is implemented. In contrast, the sensitivity setting in the digital camera 1 is performed based on the distribution of the amount of received light in each area of the CCD 40 by pre-emission, whereas the sensitivity setting in the digital camera of the present embodiment is pre-emission. To the level of the reference light emission amount that is a reference of the light emission amount in the main light emission by the photographing auxiliary device 50 determined based on the integrated value of the received light amount in each area of the CCD and the setting sensitivity before the sensitivity setting is corrected. This is based on this. Further, in the digital camera of the present embodiment, the light receiving sensitivity is set to a high sensitivity, assuming that the level of the reference light emission amount is high, that is, the distance to the subject is longer as the light emission amount is larger. Since the external appearance and internal blocks of the digital camera of this embodiment are almost the same, their illustration and detailed description are omitted. In the following description, the members of the digital camera according to the present embodiment and the members of the same type as those of the member of the digital camera 1 according to the embodiment of the first photographing apparatus are used as the digital camera 1. The same reference numerals as those in FIG.

  FIG. 6 is a diagram illustrating a flow of shooting control performed by the digital camera according to the present embodiment when the shooting assisting device is used.

  In this digital camera 1, when it is determined that the shooting assist light needs to be irradiated, first, in the pre-emission process of step S 200 shown in FIG. 6, pre-emission is performed by the imaging auxiliary device 50, and area integration in step S 210 is performed. In the process, the amount of received light reflected by the subject by pre-emission and received on the CCD 40 is integrated for each area from 1 to 64. In the reference light quantity determination process in step S220, the reference of the light emission quantity during the main light emission in the photographing auxiliary device 50 based on the total received light quantity integrated in the area integration process in step S210 and the currently set light reception sensitivity, A reference light emission time is determined. In the sensitivity setting process in step S230, the light receiving sensitivity is set based on which of the three regions divided by the two time threshold values A and B belongs to this reference light emission time. In the main light emission amount determination process in step S240, the light emission time of the main light emission of the photographing auxiliary device 50 is determined based on the light receiving sensitivity set in the sensitivity setting process in step S230 and the current field luminance. In step S250, the main light emission is performed for the light emission time determined in the main light emission amount determination process in step S240.

  The shooting control for the area integration process in step S210, the reference light quantity determination process in step S220, and the sensitivity setting process in step S230 is actually performed by the sensitivity setting circuit 25, the emitted light quantity determination circuit 26, and the CPU 20 shown in FIG. Reflected light reflected from the subject by the pre-emission is received by the CCD 40, and each of the 64 areas conceptually shown in FIG. 3 (reflections reflected from the subject by the first pre-emission from the first area). The light is received by the CCD 40, and the received light quantity in each unit light receiving element belonging to each of the 64 areas conceptually shown in FIG. 3 (from the first area to the 64th area) is integrated and summed for each area. The reference emission time that is determined based on the total integrated value and the currently set photosensitivity and serves as a reference for the emission time during the main flash. If it is equal to or greater than the time threshold A, the light receiving sensitivity is set with high sensitivity because the distance to the subject is far, and if it is less than the time threshold A but equal to or greater than the time threshold B, it is set to medium sensitivity. If it is less than the time threshold B, the distance to the subject is set to be low and the sensitivity is set low, and then, based on the set light reception sensitivity and the field luminance that is the detection result of the AE detection circuit 23, The main light emission amount from the photographing auxiliary device 50 is determined, In the digital camera 1, the photographing auxiliary device 50 emits light for a time corresponding to the determined light amount.

  FIG. 7 is a graph showing the contents of a table that is referred to when the above-described reference light emission amount is determined.

In FIG. 7, on the graph with the Ev value on the vertical axis and the reference light emission time (μsec) on the horizontal axis, the reflected light reflected from the subject by the pre-light emission in each of the unit light receiving elements belonging to 64 areas. The total amount of light received is integrated for each area as a total amount of received light: ipre, the total amount of received light from each area from the same subject immediately after the pre-emission is completed: it, and the target total integration Value: iob and the following equation Ev = log ₂ (iob / (ipre-ith))
The correlation between the Ev value obtained by substituting for and the reference light emission time corresponding to this Ev value is shown.

  In the above formula, since “iob” of the numerator of “iob / (ipre-ith)” is constant, if the denominator “ipre-ith” is large, that is, the distance to the subject is short, the Ev value is As the negative denominator “ipre-ith” decreases, that is, the distance to the subject increases, the Ev value increases. Here, for example, the reference emission time when the Ev value in the above equation is “−4” is “10 μsec”, and the reference emission time when the Ev value in the above equation is “3” is “90 μsec”. 'Become.

  When the reference light emission time is determined, the sensitivity is set and adjusted according to the length of the reference light emission time. Thereafter, the main light emission amount from the photographing assisting device 50 is determined based on the field luminance that is the detection result of the AE detection circuit and the sensitivity that has been set and adjusted. Note that, as described above, the control of the light emission amount in the photographing assisting device 50 is controlled by the light emission time.

  As described above, in the digital camera of this embodiment, the luminance of the main subject can be reflected in the reference light amount regardless of whether the main subject is within the shooting angle of view. The light receiving sensitivity is set according to the distance to the subject obtained in this step, and the main light emission quantity is determined based on the newly set sensitivity. Therefore, according to the digital camera of the present embodiment, occurrence of overexposure and blackout can be suppressed, and deterioration in image quality in shooting using the shooting assisting device 50 can be suppressed. In addition, according to the digital camera of the present embodiment, the sensitivity setting is reset to a higher sensitivity as the reference light quantity belongs to a larger area, and therefore, the same effect as that of the flash reaching distance can be obtained. At the same time, the instability of flash emission due to the extremely small flash emission amount can be reduced.

  FIG. 8 is a flowchart illustrating a routine that is executed in the digital camera of this embodiment when the shutter button is pressed. In the following description, it is assumed that the photographing assistance light is emitted automatically by the photographing assistance device 50 according to the field luminance without any instruction from the user.

  In step S21 shown in FIG. 8, first, luminance detection by the AE detection circuit is instructed to detect the field luminance, and in step S22, focus adjustment by the AF detection circuit is instructed. In step S23, the pre-flash is instructed to the photographing assisting device 50. In step S24, an instruction is given for the integration of the amount of received light for each area on the CCD 40 by this pre-emission. In step S25, a reference light emission time is acquired based on the above mathematical formula and table. In step S26, it is determined whether or not the obtained reference light emission time is not less than time A. If it is determined in step S26 that the reference light emission time is not less than time A, the process proceeds to step S27, where a relatively high sensitivity is obtained. After that, proceed to step S31. If it is determined in step S26 that the reference light emission time is less than the time A, the process proceeds to step S28, and it is determined whether or not the obtained reference light emission time is the time B or more. If it is determined in step S28 that the reference light emission time is less than time B, the process proceeds to step S30, a relatively low sensitivity is set, and then the process proceeds to step S31. If it is determined in step S28 that the reference light emission time is equal to or longer than the time B, the process proceeds to step S29, a medium sensitivity is set, and then the process proceeds to step S31. In step S31, the main light emission time by the photographing auxiliary device is calculated based on the sensitivity that has been re-set and the field luminance detected by the AE detection circuit, and light emission is performed based on the main light emission time. To do.

  In the above-described embodiment, an example in which one of the three light emission time ranges divided by the time threshold values A and B is determined as the light emission time threshold value according to the reference light emission amount has been described. In the present invention, as long as the reference light emission time is compared with one or more threshold values, it may be determined whether the light emission time belongs to two or four light emission time ranges. Alternatively, the amount of emitted light may be controlled. The determination of the reference light emission time is not limited to the above formula.

1 is an external perspective view of a digital camera that is an embodiment of a first imaging apparatus of the present invention, in which an embodiment of a first imaging apparatus control method of the present invention is implemented. FIG. FIG. 2 is a configuration block diagram of an electrical system inside the digital camera shown in FIG. 1. It is a figure which shows a mode that CCD provided with this digital camera is divided | segmented conceptually into 64 areas. It is a figure which shows the flow of imaging | photography control at the time of using the imaging | photography assistance apparatus performed with the digital camera of this embodiment. It is a figure which shows the flowchart of the routine performed in the digital camera of this embodiment, when a shutter button is pressed down. It is a figure which shows the flow of imaging | photography control at the time of using the imaging | photography assistance apparatus performed with the digital camera of this embodiment. It is a graph showing the content of the table referred when determining the reference | standard light emission light quantity mentioned above. It is a figure which shows the flowchart of the routine performed in the digital camera of this embodiment, when a shutter button is pressed down.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 11 Lens barrel 12 Shutter button 13 Mode dial 14 Liquid crystal panel 20 CPU
25 Sensitivity setting circuit 26 Light emission quantity determination circuit 40 CCD
50 Shooting assistance device

Claims (5)

A photographing unit that includes a flash light emitting unit that emits a flash toward a subject and forms an image of the subject on an imaging element that is a set of a plurality of unit light-receiving elements arranged two-dimensionally to generate an image signal representing the subject. In an imaging device that performs
A pre-emission control unit that causes the flash emission unit to perform pre-emission prior to shooting when receiving a shooting instruction with flash emission;
A received light amount detection unit for detecting a received light amount in the image sensor of reflected light reflected from the subject side by pre-emission by the flash light emitting unit;
When the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, the received light amount by the pre-light emission in each unit light receiving element in each area is integrated for each area, and the integrated received light amount is 1 or more. A sensitivity setting unit that counts the number of areas within each received light amount range divided by the threshold compared to each threshold, and sets the received light sensitivity based on the distribution of the counted value;
Based on the light receiving sensitivity set by the sensitivity setting unit, a main light emission amount determination unit that determines the amount of main light emission to be performed by the flash light emission unit following the pre-light emission,
An imaging apparatus comprising: a main light emission control unit that causes the flash light emission unit to perform main light emission with a light amount determined by the main light emission light amount determination unit during photographing following the pre-light emission. A photographing unit that includes a flash light emitting unit that emits a flash toward a subject and forms an image of the subject on an imaging element that is a set of a plurality of unit light-receiving elements arranged two-dimensionally to generate an image signal representing the subject. In an imaging device that performs
A pre-emission control unit that causes the flash emission unit to perform pre-emission prior to shooting when receiving a shooting instruction involving flash emission;
A received light amount detecting unit for detecting a received light amount in the image sensor of reflected light reflected from the subject side by pre-emission by the flash light emitting unit;
An integrated value obtained by integrating the amount of light received by the pre-emission in each unit light receiving element in each area when the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, and currently set A reference light amount determination unit that determines a reference light amount serving as a reference for main light emission to be performed by the flash light emission unit subsequent to the pre-light emission, based on light reception sensitivity;
A sensitivity setting unit that compares the reference light amount determined by the reference light amount determination unit with one or more threshold values and resets the light reception sensitivity according to the region to which the reference light amount belongs among the regions divided by the threshold values;
Main light emission that determines the amount of main light emission to be performed by the flash light emitting unit based on the detection result by the received light amount detection unit and the sensitivity set by the sensitivity setting unit at the time of shooting following the pre-light emission. A photographing unit comprising: a light amount determination unit; and a main light emission control unit that causes the flash light emitting unit to perform main light emission of the light amount determined by the main light emission light amount determination unit following the pre-light emission at the time of photographing. apparatus.   3. The photographing apparatus according to claim 2, wherein the sensitivity setting unit resets the sensitivity to be higher as the reference light quantity belongs to a larger area. A photographing unit that includes a flash light emitting unit that emits a flash toward a subject and forms an image of the subject on an imaging element that is a set of a plurality of unit light-receiving elements arranged two-dimensionally to generate an image signal representing the subject. In an imaging device control method for controlling an imaging device that performs
When receiving a shooting instruction with flash emission, a pre-light emission process for causing the flash light emission part to perform pre-light emission prior to shooting,
A received light amount detection process for detecting a received light amount in the image sensor of reflected light reflected from the subject side by the pre-emission process;
When the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, the received light amount by the pre-light emission in each unit light receiving element in each area is integrated for each area, and the integrated received light amount is 1 or more. A sensitivity setting process for counting the number of areas within each received light amount range divided by the threshold value in comparison with each threshold value, and setting the received light sensitivity based on the distribution of the counted value;
Based on the light receiving sensitivity set by the sensitivity setting process, a main light emission light quantity determination process for determining the light quantity of the main light emission to be performed by the flash light emitting unit subsequent to the pre-light emission,
A photographing apparatus control method comprising: a main light emission process for causing the flash light emitting section to perform a main light emission with a light amount determined in the main light emission light amount determination process at the time of photographing following the pre-light emission. A photographing unit that includes a flash light emitting unit that emits a flash toward a subject and forms an image of the subject on an imaging element that is a set of a plurality of unit light-receiving elements arranged two-dimensionally to generate an image signal representing the subject. In the photographing apparatus control method for performing
A pre-emission control process for causing the flash emission unit to perform pre-emission prior to shooting when receiving a shooting instruction with flash emission,
A received light amount detection process for detecting a received light amount in the image sensor of reflected light reflected from the subject side by pre-emission in the pre-emission control process;
An integrated value obtained by integrating the amount of light received by the pre-emission in each unit light receiving element in each area when the plurality of unit light receiving elements constituting the image sensor are divided into a plurality of areas, and currently set A reference light amount determination process for determining a reference light amount that is a reference of the main light emission to be performed by the flash light emitting unit subsequent to the pre-light emission based on the light receiving sensitivity;
A sensitivity setting process in which the reference light quantity determined in the reference light quantity determination process is compared with one or more threshold values, and the light receiving sensitivity is reset according to the area to which the reference light quantity belongs among the areas divided by the threshold values;
Main light emission for determining the amount of main light emission to be performed by the flash light emitting unit at the time of shooting following the pre-light emission based on the detection result by the received light amount detection process and the sensitivity set by the sensitivity setting process. An imaging process comprising: a light quantity determination process; and a main light emission control process that causes the flash light emitting unit to perform a main light emission of the light quantity determined in the main light emission light quantity determination process following the pre-light emission at the time of shooting. Device control method.

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