JP2009157004A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a preliminary light emission condition to perform optimum preliminary light emission for preventing a red-eye phenomenon in stroboscopic photography. <P>SOLUTION: In preliminary light emission to be performed in the stroboscopic photography, optimum preliminary light emission control for preventing a red-eye phenomenon is performed. In the preliminary light emission control, the preliminary light emission condition to perform the preliminary light emission is set according to a case where a human face is included in a subject, whether the subject is in a backlight state or a front-light state and a distance between the subject and the imaging apparatus, and the preliminary light emission is performed under the set preliminary light emission condition. Specifically, the number of light-emitting times and/or light-emitting time and/or light-emitting interval is included in the preliminary light emission condition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus that prevents red-eye reduction that occurs when a subject such as a person is illuminated and imaged.

  In a conventional imaging device having a light emitting device for adjusting the amount of light when a person is imaged, when a person is illuminated from the light emitting device to perform color imaging, a phenomenon in which the eyes of the person appear red often occurs. The phenomenon in which a person's eyes appear red is referred to here as the red-eye phenomenon. The red-eye phenomenon is because red light is reflected by blood vessels in the eyeball when illuminated by a light-emitting device with the pupil of the eye open. In the captured image, the pupil is reproduced in red.

Therefore, in order to prevent the red-eye phenomenon when performing color imaging by illuminating a person from a light emitting device, a preliminary illumination operation (pre-light emission operation) is performed on the person prior to the illumination operation, and the degree of pupil opening is increased. There is a technique for reducing the red-eye phenomenon by performing a normal lighting operation. As described above, various proposals have been made to devise a pre-light emission operation for preventing the red-eye phenomenon.
JP 09-133949 A [G03B 15/05]

  In the flash light emitting device of the prior art 1 described in Patent Document 1, the red-eye phenomenon is generated with less energy without giving the user a sense of incongruity due to whether flash light is emitted or not regardless of the user's intention. In order to prevent the occurrence of red eyes, in the red-eye pre-flash operation to reduce the red-eye, measure the brightness of the person who is the subject, measure the distance to the subject, and if the measured brightness is higher than a predetermined value, Alternatively, when the distance is longer than a predetermined distance, the red-eye pre-emission amount emitted from the flashlight illumination device is made smaller than usual.

  However, in the related art 1, when it is determined that the luminance value of the subject is higher than the predetermined value, or when it is determined that the distance to the subject is longer than the predetermined distance, the red-eye pre-emission operation control is performed to reduce the red-eye pre-emission amount. It is carried out. Now, the degree of opening of the pupil is small during backlight imaging, the degree of opening of the pupil is small during continuous light imaging, and the degree of opening of the pupil is significantly different between the two. Therefore, the red-eye pre-emission operation control that reduces the red-eye pre-emission amount based on the determination that the luminance value of the subject is higher than the predetermined value as in the prior art 1 cannot cope with the backlight imaging and the backlight imaging. There is a risk of reducing the amount of light emission even during imaging.

  In addition, when the face of a person faces in the horizontal direction with respect to the direction of the optical axis of the image pickup apparatus, the red-eye phenomenon tends to hardly occur. However, the prior art 1 does not disclose any red-eye pre-flash operation control in consideration of the face direction of a person.

  The present invention solves the above-described problems, and provides an imaging apparatus capable of performing an optimal pre-flash operation according to the conditions of a subject when imaging a subject such as a person.

  The imaging apparatus according to claim 1, an imaging unit that captures an optical image of a subject and outputs an image signal, a light emitting unit that illuminates the subject when capturing the optical image, and a predetermined light emission condition for the subject prior to the illumination operation by the light emitting unit. Pre-light emitting means for illuminating according to the above, partial signal detecting means for detecting a partial signal corresponding to the face area of the subject from the image signal, the overall brightness of the image signal as the overall brightness level, and the brightness of the partial signal as the partial brightness It comprises a luminance detecting means for detecting each level, a comparing means for comparing the overall luminance level and the partial luminance level, and a condition changing means for changing a predetermined light emission condition based on a comparison result by the comparing means.

  The image pickup apparatus according to a second aspect is dependent on the image pickup apparatus according to the first aspect, and the predetermined light emission condition is a condition of the number of times of light emission and / or a light emission time and / or a light emission period in the illumination operation.

  The image pickup apparatus according to claim 3 is dependent on any one of the image pickup apparatuses according to claim 1, wherein the overall luminance level in the comparison means is an average level of the overall luminance of the image signal, and the partial luminance level is the luminance of the partial signal. In the condition change means, the predetermined light emission condition is changed so that the amount of light emitted by the pre-light emission means is reduced when the partial luminance level is larger than the overall luminance level in the comparison result by the comparison means. It is characterized by doing.

  The imaging device according to claim 4 is dependent on the imaging device according to any one of claims 1 to 2, wherein the overall luminance level in the comparing means is an average level of the overall luminance of the image signal, and the partial luminance level is the luminance of the partial signal. When the partial brightness level is smaller than the overall brightness level in the comparison result by the comparison means, the condition changing means sets the predetermined light emission condition to increase the amount of light emitted by the pre-light emission means. It is characterized by changing.

  The image pickup apparatus according to claim 5 includes an image pickup unit that captures an optical image of a subject and outputs an image signal, a light emission unit that illuminates the subject when capturing the optical image, and a predetermined light emission condition for the subject prior to the illumination operation by the light emission unit. Pre-light emitting means for illuminating according to the above, partial signal detecting means for detecting a partial signal corresponding to the face area of the subject from the image signal, and whether the angle between the face direction and the optical axis of the imaging means is greater than a predetermined angle And a condition changing means for changing a predetermined light emission condition when it is determined that the angle is larger than a predetermined angle as a result of the determination by the determining means.

  The image pickup apparatus according to a sixth aspect is dependent on the image pickup apparatus according to the fifth aspect, wherein the predetermined light emission condition is a condition of the number of times of light emission and / or the light emission time and / or the light emission period in the illumination operation.

  The imaging device according to claim 7 is dependent on any one of the imaging devices according to claims 5 to 6, and the condition changing means changes the predetermined light emission condition so as to reduce the light emission amount by the illumination of the pre-issuing means. Features.

  The imaging method according to claim 8 includes: an imaging unit that captures an optical image of a subject and outputs an image signal; and an illuminating unit that illuminates the subject when capturing the optical image. An imaging method for controlling pre-emission to illuminate a light source, the step of illuminating the subject according to a predetermined light emission condition prior to the illumination operation by the light emitting means, and the step of detecting a partial signal corresponding to the face area of the subject from the image signal And detecting the luminance of the image signal as the overall luminance level and the luminance of the partial signal as the partial luminance level, respectively, and changing the predetermined light emission condition based on the comparison result by the comparing means. .

  The imaging method according to claim 9 includes: an imaging unit that captures an optical image of a subject and outputs an image signal; and an illuminating unit that illuminates the subject when capturing the optical image. An imaging method for controlling pre-emission to illuminate a light source, the step of illuminating the subject according to a predetermined light emission condition prior to the illumination operation by the light emitting means, and the step of detecting a partial signal corresponding to the face area of the subject from the image signal And a step of determining whether or not an angle formed by the orientation of the face and the optical axis of the image pickup means is larger than a predetermined angle, and a step of changing the predetermined light emission condition if it is determined that the angle is larger than the predetermined angle as a result of the determination by the determination means. It is characterized by comprising.

  According to the imaging apparatus of the present invention, when imaging a subject such as a person, it is possible to perform an optimum pre-flash operation according to the subject condition.

  Hereinafter, as an embodiment of the imaging apparatus of the present invention, the embodiment implemented in the digital camera 10 will be specifically described with reference to the drawings. FIG. 1 shows a block diagram of a digital camera 10 of this embodiment.

  The digital camera 10 according to the first embodiment includes an optical lens 12, an aperture 14, a motor driving unit 16, a CCD imager 18, a CCD driving unit 20, an operation unit 22, a CPU 24, an AFE circuit 28, a bus 30, an SDRAM 32, and a signal processing circuit 34. An image compression / decompression processing circuit 36, a card control circuit 38, an external memory card 40, a strobe control circuit 48, a strobe light emitting unit 50, a focus evaluation circuit 52, a face detection circuit 54, and a luminance evaluation circuit 56. In the digital camera 10 of the present embodiment, the operation unit 22 is operated to set “on”, “off”, and “auto” in the strobe emission mode in which the strobe light emission unit 50 emits light and illuminates the subject. it can. When the strobe flash mode is on, a pre-flash operation and a main flash operation are performed when capturing an optical image of an object to be recorded on the external memory card 40 (imaging operation). The light emission operation is prohibited. In addition, when performing an imaging operation in the auto state, it is determined whether the main flash operation is necessary or not. If it is determined that it is necessary, the pre-flash operation and the main flash operation are performed. The pre-light emission operation and the main light emission operation are not performed. The digital camera 10 of this embodiment will be described on the assumption that the flash emission mode is set to the auto state.

  The digital camera 10 according to the present embodiment can set “ON” / “OFF” of the red-eye prevention mode for preventing the red-eye phenomenon by operating the operation unit 22. The red-eye phenomenon is a phenomenon that occurs when strobe light emission (main light emission) is performed. By performing pre-light emission a plurality of times before main light emission, the degree of pupil opening is reduced to reduce the red-eye phenomenon. Therefore, the red-eye prevention mode is invalid when the flash emission mode is in the off state.

  Hereinafter, red-eye pre-emission is pre-emission performed to reduce the red-eye phenomenon, and pre-emission is described as pre-emission performed to determine the light emission amount and exposure amount for the main light emission. .

  The CPU 24 sets the flag Fp of the register 24a (Fp = 1) when the red-eye prevention mode is set to “ON” by the operation unit 22, and resets the flag Fp when it is set to “OFF” ( Fp = 0).

  Next, a still image capturing operation of the digital camera 10 when the red-eye prevention mode in the present embodiment is “off”, that is, when the flag is not set (Fp = 0) will be described.

  When a release button (not shown) which is a part of the operation unit 22 is pressed halfway, the CPU 24 controls the motor driving unit 16 to move the optical lens 12 to a far point. Then, an optical image of the subject is taken into the CCD imager 18 through the optical lens 12 and the aperture 14. The CPU 24 controls the CCD drive unit 20 to output an analog image signal for one frame from the CCD imager 18. The output analog imaging signal is input to the AFE circuit 28, subjected to correlated double sampling processing, gain adjustment and clamping processing, and further A / D converted and stored in the SDRAM 32 as a digital imaging signal via the bus 30. .

  The digital imaging signal stored in the SDRAM 32 is input to the signal processing circuit 34, subjected to color separation processing, converted into Y, U, and V signals, and stored again in the SDRAM 32 as a digital image signal.

  The CPU 24 inputs the Y signal in the digital image signal stored in the SDRAM 32 to the focus evaluation circuit 52. In the focus evaluation circuit 52, the high frequency component of the input Y signal is integrated over one frame period, and this integrated value is calculated as a focus evaluation value. The CPU 24 controls the motor driving unit 16 to sequentially move the optical lens 12 to the near point, and a plurality of frames are sequentially output from the CCD imager 18. The output analog imaging signal is converted into a digital image signal by the signal processing circuit 34, and the Y signal therein is input to the focus evaluation circuit 52 to calculate a focus evaluation value. Based on the focus evaluation value calculated for each of a plurality of frames acquired when the optical lens 12 is moved from the far point to the near point, the position where the focus evaluation value is maximized is determined as the focus position P. The in-focus position P is stored in the register 24b in the CPU 24. These processes are called autofocus processes. Further, the value of the distance K from the in-focus position P to the subject is calculated, and the value of the distance K is recorded in the register 24c in the CPU 24.

  The CPU 24 controls the motor drive unit 16 to move the optical lens 12 to the in-focus position P and output an analog image signal for one frame from the CCD imager 18. The analog imaging signal is converted into a digital image signal by the signal processing circuit 34 through the AFE circuit 28 and stored in the SDRAM 32. The Y signal in the digital image signal is input to the luminance evaluation circuit 56. In the luminance evaluation value circuit 56, the entire average luminance value Q (total luminance value Q) for one frame is detected and compared with the threshold value Th1. This threshold value Th1 is a threshold value Th1 for determining whether or not to perform the main light emission operation. When the threshold value Th1 is equal to or higher than the threshold value Th1, the object field is sufficiently bright and the main light emission operation is not performed. This is a threshold value for determining that the main light emission operation is performed when the object scene is not sufficiently bright. If the threshold value Th1 is equal to or greater than the threshold value Th1, the flag ST of the register 24d in the CPU 24 is reset (ST = 0). If the threshold value Th1 is less than the threshold value Th1, the flag ST is set (ST = 1).

  Here, the processing after comparing the threshold value Th1 and the overall luminance value Q differs depending on whether the flag ST = 0 or the flag ST = 1.

  When the flag ST = 0, the CPU 24 determines the optimum exposure value based on the Y signal of the digital image signal for one frame, and the aperture value of the diaphragm 14 so that the optical image is within the optimum range of the dynamic range of the CCD imager 18. I is calculated. At the same time, the CPU 24 calculates a shutter speed R for obtaining the optimum charge accumulated in the CCD imager 18.

  Next, when the release button is fully pressed, the imaging process is executed. Specifically, the CPU 24 sends an instruction to the motor drive unit 16, and the motor drive unit 16 controls the optical lens 12 and the aperture 14 based on the focus position P and the aperture value I detected when the release button is half-pressed. Further, the CPU 24 sends an instruction to the CCD drive unit 20 and controls the CCD imager 18 based on the calculated shutter speed R.

  The CCD imager 18 captures an optical image at the shutter speed R1 controlled by the CCD drive unit 20 via the optical lens 12 and the diaphragm 14 controlled by the motor drive unit 16, and outputs an analog imaging signal. The output analog image pickup signal is subjected to the processing described above by the signal processing circuit 34 via the AFE circuit 28 and the SDRAM 32, and is stored again as a digital image signal in the SDRAM 32.

  The digital image signal stored in the SDRAM 32 is subjected to recording processing. More specifically, the image compression / decompression processing circuit 36 performs JPEG compression processing under the control of the CPU 24 and converts it into compressed image data. Under the control of the CPU 24, the card control unit 38 controls the external memory card 40 to record the compressed image data.

  When the flag ST = 1, the CPU 24 waits until the release button is fully pressed, and when detecting that the release button is fully pressed, the CPU 24 performs pre-flash for calculating the main flash amount and the optimum exposure value. A pre-flash instruction is sent to the strobe circuit 48. The strobe circuit 48 controls the strobe light emitting unit 50 to perform pre-light emission to illuminate the subject. Then, the CPU 24 takes in an analog imaging signal for one frame, determines the main light emission amount E and the optimum exposure value based on the Y signal of the converted digital image signal, and calculates the aperture value I and the shutter speed R. Then, the above-described imaging process and recording process for recording in the external memory card 40 are executed.

  Next, a still image capturing operation of the digital camera 10 when the red-eye prevention mode in this embodiment is “ON”, that is, when the flag is set (Fp = 1) will be described.

  When the release button is pressed halfway, the same operation as the autofocus process described when the red-eye prevention mode is “off” is performed, the in-focus position P is stored in the register 24b in the CPU 24, and the digital camera 10 And the distance K between the subject and the subject is calculated, and the value of the distance K is recorded in the register 24 c in the CPU 24. Further, the CPU 24 controls the luminance evaluation circuit 56 to calculate the overall luminance value Q.

  The digital image signal stored in the SDRAM 32 is input to the face detection circuit 54. The face detection circuit 54 detects whether or not a face exists in the subject. Further, the angle of the face direction with respect to the optical axis direction of the light receiving surface of the CCD imager 18 is detected from the position and area of the face and the position and size of the eyes. Presence / absence of face in these subjects, detection of face area and face direction are detected by detecting skin color in the whole digital image signal, detecting feature points (patterns) such as eyes, nose or mouth in human face, Alternatively, it is detected by a conventionally known facial image recognition method such as facial contour extraction. For example, the face detection circuit 54 in this embodiment has a function as disclosed in Japanese Patent Application Laid-Open Nos. 2005-128156 and 2006-208443.

  For example, when imaging a person (subject) in the middle of the scene as shown in FIG. 2, if the face detection circuit 54 determines that a face exists, the flag F1 of the register 54a in the face detection circuit 54 is set. If it is determined that it does not exist (F1 = 1), the flag F1 of the register 54a is reset (F1 = 0). If there is a face, the partial position S, which is the face area of the subject, is obtained and recorded in the memory 54 c of the face detection circuit 54.

  Further, it is determined whether or not the face direction is a predetermined angle A or more with respect to the optical axis direction of the light receiving surface of the CCD imager 18. For example, when the face direction of the person in the middle of the object scene as shown in FIG. 3 is approximately 90 degrees with respect to the optical axis direction of the light receiving surface of the CCD imager 18, it is determined that the angle is equal to or greater than the predetermined angle A. Then, the flag F2 of the register 54b in the face detection circuit 54 is set (F2 = 1). Further, when the face direction of the person as shown in FIG. 2 is approximately 0 degrees with respect to the optical axis direction of the light receiving surface of the CCD imager 18, it is determined that the angle is less than the predetermined angle A, and the flag F2 of the register 54b is determined. Is reset (F2 = 0). Here, the predetermined angle A is an angle at which the eyes of a person's face are imaged sufficiently small, and is assumed to be approximately 60 degrees in the present embodiment.

  Here, if it is determined that there is no face in the object scene, the same processing as in the above-described strobe light emission is in the on state (ST = 1) and the red-eye prevention mode is in the off state (Fp = 0) is performed. .

If it is determined that there is a face in the object scene, first, the pre-emission conditions for pre-emission, the number of times of light emission C, the emission time T, and the emission interval B are initially set in order to perform the red-eye pre-emission operation. Set to a value. In this embodiment, the initial value of the number of times of light emission C is u, the initial value of the light emission time T is x, and the initial value of the light emission interval B is y.

  Then, the CPU 24 refers to the partial position S stored in the memory 54 c and inputs the digital image data of the partial position S corresponding to the digital image signal for one frame stored in the SDRAM 32 to the luminance evaluation circuit 56. The average luminance value (partial luminance value O) of the partial position S is calculated. When the partial luminance value O is larger than the threshold value Th2, it is determined that the light is in the forward light state, and control is performed so that the red-eye pre-emission operation is not performed because the degree of pupil opening is small.

  Also, as shown in FIG. 3, when the face direction is not the front but the side, it is assumed that the imaged subject is unlikely to have a red-eye phenomenon, and the partial luminance value O is smaller than the threshold Th2. If the face direction is greater than or equal to the predetermined angle A, control is performed not to perform the pre-light emission operation.

  Further, when the partial luminance value O is smaller than the threshold value Th2, if the face direction is less than the predetermined angle A, the pre-emission condition is set so that the pre-emission operation is performed during the imaging operation.

  The pre-emission conditions in this example are the number of times of light emission C, the time of light emission T, and the time interval B of light emission. These are the initial value of the number of times of light emission C u, the initial value of the light emission time T is x and the initial value of the time interval B. It is initially set as y.

  These parameters u, x, and y are changed and set due to the overall luminance value Q, the partial luminance value O, and the distance K between the subject and the digital camera 10.

  Specifically, the total luminance value Q and the partial luminance value O are compared. When the total luminance value Q is large, it is determined that the light is backlit. When the partial luminance value O is large, it is determined that the light is direct light. Since the pupil of the person's eyes is closed, a setting is made to reduce the pre-emission amount under the pre-emission conditions (reduction of the number of times C is emitted). In the case of backlighting, the pupil of the person's eyes is open, so a setting for increasing the pre-emission amount in the pre-emission operation (increasing the number of times of emission) is performed.

  In addition, when the distance K between the digital camera 10 and the subject is long, the subject's eyes are captured small, so the possibility of a red-eye state is very low. Accordingly, a setting for reducing the pre-emission amount under the pre-emission conditions (reduction of the emission time T) is performed. When the distance K is short, the subject's eyes are imaged large, so there is a very high possibility that the subject will be in a red-eye state, and a setting for increasing the pre-emission amount (increase in the emission time T) is performed. As described above, when the number of times of light emission C is increased and the light emission time T is also increased, the light emission interval B is also increased. On the contrary, when the number of times of light emission C is reduced and the light emission time T is also reduced, the light emission interval B is also reduced. In this way, the light emission interval B is also adjusted and set according to the number of times of light emission C and the light emission time T.

  When the release button is fully pressed and the strobe light emission is in the on state, the set red-eye pre-emission operation is performed, and the pre-emission operation for determining the main emission amount E and the optimum exposure value is performed. Based on the overall luminance value Q from the digital image signal for one frame, the main light emission amount E and the optimum exposure value are determined, and the aperture value I2 of the aperture 14 is calculated. At the same time, the CPU 24 calculates the shutter speed R2 in order to acquire the optimum charge accumulated in the CCD imager 18 based on the optimum exposure value. Then, an imaging process and a recording process are executed.

  As described above, when the pre-flash condition is set, the light emission amount E and the optimum exposure value for the main light emission are set based on the overall luminance value Q, and the aperture value I of the aperture 14 is calculated. At the same time, the CPU 24 calculates the shutter speed R in order to acquire the optimum charge accumulated in the CCD imager 18 based on the optimum exposure value.

  When the release button is fully pressed, the imaging process and the recording process are executed under the control of the CPU 24.

  Next, the procedure of this embodiment will be described with reference to the flowcharts of FIGS.

  In step S <b> 1, the CPU 24 determines whether or not a release button that is a part of the operation unit 22 has been half-pressed. If YES is determined in the step S1, the process proceeds to a step S3, and the CPU 24 controls the SDRAM 32 and the focus evaluation circuit 52 to calculate the in-focus position P and the distance K between the digital camera 10 and the subject.

  In step S5, the CPU 24 inputs the digital image signal for one frame stored in the SDRAM 32 to the luminance evaluation circuit 56, and calculates the overall luminance value Q. In step S7, it is determined whether or not the overall luminance value Q is larger than the threshold value Th1. If YES is determined in the step S7, the process proceeds to a step S19, the flag ST of the register 24d is reset (ST = 0), and the process proceeds to the step S21. In step S21, an optimum exposure value is set based on the overall luminance value Q. In step S23, an aperture value I and a shutter speed R are set based on the optimum exposure value, and the process proceeds to step S37.

  If the CPU 24 determines NO in step S7, it proceeds to step S9, sets a flag ST (ST = 1), and proceeds to step S11. In step S11, it is determined whether the flag Fp in the register 24a is set (Fp = 1) or not (Fp = 0). If NO is determined in step S11, the process proceeds to step S37, and if YES is determined, the process proceeds to step S13.

  In step S13, the CPU 24 controls the face detection circuit 54 to execute face detection processing. Then, the process proceeds to step S15, where it is determined whether a face is detected by the face detection circuit 54 (F1 = 1) or not (F1 = 0). If NO is determined, the process proceeds to step S37.

  If the CPU 24 determines YES in step SS15, it proceeds to step S17, executes initial setting of the red-eye pre-emission condition, and proceeds to step S25. In step 25, the CPU 24 controls the face detection circuit 54 to detect a position (partial position S) corresponding to the face area in the subject. In step S27, the CPU 24 controls the luminance detection circuit 56 to calculate the partial luminance value O, and then proceeds to step S29.

  In step S29, it is determined whether or not the partial luminance value O is greater than or equal to a threshold value Th2. If YES is determined in the step S29, the flag Fp of the register 24a is reset (Fp = 0), and the process proceeds to a step S37. If NO is determined in the step S29, the process proceeds to a step S33 so as to determine whether or not the flag F2 of the register 54b is set (F2 = 1) or not (F2 = 0). If it determines with YES in step S33, it will progress to step S37, and if it determines with YES, it will progress to step S35.

  In step S35, a red-eye pre-emission condition setting process for executing an optimal red-eye pre-emission operation is executed. In the pre-flash setting process in step S35, a flowchart shown in a subroutine of FIG.

  After step S35, the process proceeds to step S37, where the CPU 24 determines whether or not the release button has been fully pressed, and repeats this branch until it is determined that the release button has been fully pressed (YES). If YES is determined in the step S37, the process proceeds to a step S39 so as to determine whether or not the flag ST of the register 24d is set (ST = 1) or not (ST = 0). If NO is determined in the step S39, the process proceeds to a step S47, and if YES is determined, the process proceeds to a step S40. In step S40, the CPU 24 sends an instruction to the strobe control circuit 48, and the strobe control circuit 48 controls the strobe light emitting unit 50 to illuminate the subject based on the parameters of the red-eye pre-emission condition set in step S35. In step S41, the CPU 24 causes the flash control circuit 48 to control the flash light emitting unit 50 to perform a pre-flash operation, and in the next step S42, executes an imaging process for one frame. In step S43, the main light emission amount is set based on the digital image signal converted from the analog imaging signal, the optimum exposure value is set in step S44, and the aperture value I and the optimum exposure value are set in step S45. Set the shutter speed R.

  In step S46, the CPU 24 sends an instruction to the strobe control circuit 48. The strobe control circuit 48 controls the strobe light emitting unit 50 to illuminate the subject based on the main light emission amount set in step S43. In S47, the imaging process for one frame is executed, and the process proceeds to Step S48 where the recording process is executed and the procedure is terminated.

  Next, the red-eye pre-emission condition setting process in step S35 will be described using the flowchart shown in FIG.

  First, in step S49, the overall luminance value Q and the partial luminance value O are compared. If the overall luminance value Q is larger than the partial luminance value O as a result of the comparison in step S49, the process proceeds to step S51, and a predetermined number Z is set with respect to the initial value u of the number of times of light emission C of the pre-emission condition that is initially set. Is subtracted to reduce the number C of light emission. If the partial brightness value O and the overall brightness value Q are equal, the process proceeds to step S53, and the light emission count C remains unchanged at the initial value u. If the partial luminance value O is larger than the overall luminance value Q, the process proceeds to step S55, where a predetermined number Z is added to the initial value u of the number of times of light emission C, and the number of times of light emission C is increased. Then, after step S51, step S53, and step S55, the process proceeds to step S57, and the value of the number of times of light emission C is updated.

  In step S59, the distance K between the subject and the digital camera 10 is compared with the threshold Th3. This threshold value Th3 is, for example, 5 meters. When the value of the distance K is smaller than the threshold value Th3, the process proceeds to step S63, and the predetermined value p is added to the initial value x of the light emission time T of the pre-light emission condition that is initially set to increase the light emission time T. . If the distance K is equal to the threshold Th3, the process proceeds to step S61, and the light emission time T remains unchanged at the initial value x. Further, after step S61 and step S63, the process proceeds to step S65, and the value of the number of light emission times C updated in step S57 is compared with the predetermined number G. When the value of the number of times of light emission C is larger than the predetermined number G, the process proceeds to step S71, and the predetermined value q is added to the initial value y of the light emission interval B of the pre-light emission condition that has been initially set. On the other hand, if the value of the light emission count C is equal to the predetermined number G, the process proceeds from step S65 to step S69, and the light emission interval B remains unchanged at the initial value y. On the other hand, if the value of the light emission count C is smaller than the predetermined number G, the process proceeds from step S65 to step S67, and the predetermined value q is subtracted from the initial value y of the light emission interval B. After step S67, step S69, and step S71, the process proceeds to step S83.

  In step S59, the distance K between the subject and the digital camera 10 is compared with the threshold Th3. If the distance K is larger than the threshold Th3, the process proceeds to step S73, and the pre-flash that has been initially set is set. The predetermined value p is subtracted from the initial value x of the condition issue time T. Then, the process proceeds to step S75, the value of the number of light emission C updated in step S57 is compared with the predetermined number G, and if the value of the number of light emission C is smaller than the predetermined number G, the process proceeds to step S77. In step S77, a predetermined number q is added to the initial value y of the light emission interval B of the pre-light emission conditions that have been initially set. If the value of the number of times of light emission C is equal to the predetermined number G, the process proceeds from step S75 to step S79, and the light emission interval B remains unchanged at the predetermined value y. On the other hand, when the value of the light emission count C is larger than the predetermined number G, the process proceeds from step S75 to step S81, and the predetermined number q is subtracted from the initial value y of the light emission interval B. After step S77, step S79, and step S81, the process proceeds to step S83. In step S83, the calculated value of the light emission time T and the value of the light emission interval B are updated, and this subroutine is finished.

  As described above, according to the present embodiment, when the red-eye pre-light emission operation for preventing red-eye is executed, the partial luminance O corresponding to the face position and the overall luminance Q of the entire image are compared, so that the order of backlighting can be reduced. Since the light emission number C, the light emission time T, and the light emission interval B are changed according to the distance between the subject and the digital camera 10, it is possible to perform an optimal red-eye pre-light emission operation. It is effective in preventing red eyes.

  Further, when the degree of opening of the pupil is small or when the area occupied by the eyes in the subject is extremely small, the power consumption can be reduced by not performing the red-eye pre-emission operation.

  In the digital camera of this embodiment, when the area occupied by the eyes in the subject is extremely small, the red-eye pre-emission operation is not performed, but the red-eye pre-emission condition parameter is set so as to reduce the red-eye pre-emission amount. May be set.

  Further, in the digital camera 10 of the present embodiment, the red-eye pre-emission control operation in the case where one face exists in the subject has been described, but when there are a plurality of faces, the respective partial luminance values O are calculated, The overall brightness value Q may be compared, the distance between each face and the digital camera 10 may be calculated, and the red-eye pre-emission setting parameter may be determined based on the average of each.

It is a block diagram which shows the digital camera which concerns on a present Example. It is an illustration figure which shows a part of object scene which concerns on a present Example. It is an illustration figure which shows the other part of the object scene which concerns on a present Example. It is an illustration figure which shows a part of luminance distribution of the object scene which concerns on a present Example. It is a flowchart which shows a part of procedure of the digital camera which concerns on a present Example. 6 is a flowchart showing a part of a procedure following the flowchart shown in FIG. 5. 6 is a flowchart showing another part of the procedure following the flowchart shown in FIG. 5. 7 is a subroutine showing a part of a procedure of pre-flash condition setting processing shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Digital camera 12 ... Optical lens 14 ... Aperture 16 ... Motor drive part 18 ... CCD imager 20 ... CCD drive part 24 ... CPU
24a ... Register 24b ... Register 24c ... Register 24d ... Register 32 ... SDRAM
48 ... Strobe control circuit 50 ... Strobe light emitting unit 52 ... Focus evaluation circuit 54 ... Face detection circuit 54a ... Register 54b ... Register 54c ... Register 56 ... Luminance evaluation circuit

Claims (9)

Imaging means for capturing an optical image of a subject and outputting an image signal;
A light emitting means for illuminating the subject when capturing the optical image;
Pre-light emission means for illuminating the subject according to a predetermined light emission condition prior to the illumination operation by the light emission means;
Partial signal detection means for detecting a partial signal corresponding to the face area of the subject from the image signal;
A luminance detecting means for detecting the luminance of the image signal as an overall luminance level and the luminance of the partial signal as a partial luminance level;
An imaging apparatus comprising condition changing means for changing the predetermined light emission condition based on a comparison result by the comparing means.   The imaging apparatus according to claim 1, wherein the predetermined light emission condition is a condition of the number of times of light emission and / or a light emission time and / or a light emission period in the illumination operation. The overall luminance level in the comparison means is an average level of luminance of the image signal, and the partial luminance level is an average level of luminance of the partial signal,
The condition changing means changes the predetermined light emission condition so as to reduce the amount of light emitted by the pre-light emission means when the partial luminance level is higher than the overall luminance level in the comparison result by the comparison means. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is an image pickup apparatus. The overall luminance level in the comparison means is an average level of luminance of the image signal, and the partial luminance level is an average level of luminance of the partial signal,
The condition changing means changes the predetermined light emission condition so as to increase the amount of light emitted by the pre-light emission means when the partial luminance level is smaller than the overall luminance level in the comparison result by the comparison means. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is an image pickup apparatus. Imaging means for capturing an optical image of a subject and outputting an image signal;
A light emitting means for illuminating the subject when capturing the optical image;
Pre-light emission means for illuminating the subject according to a predetermined light emission condition prior to the illumination operation by the light emission means;
Partial signal detection means for detecting a partial signal corresponding to the face area of the subject from the image signal;
A discriminating unit for discriminating whether an angle formed by the orientation of the face and the optical axis of the imaging unit is larger than a predetermined angle;
An imaging apparatus comprising condition changing means for changing the predetermined light emission condition when it is determined that the angle is larger than the predetermined angle as a result of determination by the determining means.   The imaging apparatus according to claim 5, wherein the predetermined light emission condition is a condition of the number of times of light emission and / or a light emission time and / or a light emission period in the illumination operation.   The imaging apparatus according to claim 5, wherein the condition changing unit changes the predetermined light emission condition so as to reduce an amount of light emitted by illumination of the pre-light emitting unit. An imaging device including an imaging unit that captures an optical image of a subject and outputs an image signal, and a light emitting unit that illuminates the subject when capturing the optical image. An imaging method for controlling light emission,
Illuminating the subject according to a predetermined light emission condition prior to an illumination operation by the light emitting means;
Detecting a partial signal corresponding to the face area of the subject from the image signal;
Detecting the brightness of the image signal as an overall brightness level and the brightness of the partial signal as a partial brightness level;
An imaging method comprising the step of changing the predetermined light emission condition based on a comparison result by the comparison means. An imaging device including an imaging unit that captures an optical image of a subject and outputs an image signal, and a light emitting unit that illuminates the subject when capturing the optical image. An imaging method for controlling light emission,
Illuminating the subject according to a predetermined light emission condition prior to an illumination operation by the light emitting means;
Detecting a partial signal corresponding to the face area of the subject from the image signal;
Determining whether an angle formed by the orientation of the face and the optical axis of the imaging means is greater than a predetermined angle;
An imaging method comprising the step of changing the predetermined light emission condition when it is determined that the angle is larger than the predetermined angle as a result of the determination by the determining means.