JP2015207900A - Light-emitting device, control method thereof, control program and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire high-accuracy color information including a change of color information during light emission, and to reduce color nonuniformity of an image in accordance with the color information.SOLUTION: A stroboscope 10 is mounted on a camera 20 for imaging a subject, and includes an LED 6 that emits a light illuminating the subject in imaging the subject with the camera, as an image source. A microcomputer 1 detects a device temperature of the LED, controls light emission of the LED, calculates color information indicating a light-emitting color of the LED from exposure start to exposure end at predetermined time intervals in accordance with the device temperature, calculates light emission timing information indicating a time at which the color information is calculated, and transmits the color information and the light emission timing information to the camera. The camera performs color balance processing on the image in accordance with the color information and the light emission timing information.

Description

  The present invention relates to a light emitting device, a control method thereof, a control program, and an imaging device, and more particularly to control of the light emitting device.

  In general, photographing may be performed by an imaging device such as a digital camera using a light emitting device (also referred to as a flash device) such as a strobe device (hereinafter simply referred to as a strobe). In such a case, correction of color balance in image data obtained as a result of shooting is performed using emission color information (hereinafter simply referred to as color information) indicating the emission color of strobe light ( Patent Document 1).

JP 2004-228723 A

  By the way, conventionally, an Xe tube is generally used as the light source of the strobe. However, in recent years, with the evolution of the LED, the LED tends to be used as the light source of the strobe. However, in the case of the Xe tube, although the emission color does not change greatly during light emission, in the LED, the element temperature rises due to heat generated by the light emission of the LED itself, and color information indicating the emission color of the strobe light Will change.

  In Patent Document 1 described above, acquisition of color information when using an LED as a light source of a light emitting device is described. However, in Patent Document 1, it is difficult to grasp changes in color information during light emission. . A change in color information during light emission appears as color unevenness in an image obtained by slit exposure. That is, with the method described in Patent Document 1, it is difficult to correct an image obtained as a result of photographing with high color balance accuracy such as white balance.

  Accordingly, an object of the present invention is to obtain a highly accurate color information including a change in color information during light emission, and to accurately correct the color balance of an image according to the color information, and a control method therefor And a control program and an imaging apparatus.

  In order to achieve the above object, a light emitting device according to the present invention is equipped with an LED that is mounted on an imaging device that photographs a subject and emits light that illuminates the subject when the subject is photographed by the imaging device. A light-emitting device, element temperature detecting means for detecting an element temperature of the LED, and color information indicating light emission color of the LED from the start of exposure to the end of exposure according to the element temperature by controlling the light emission of the LED Control means for obtaining light emission timing information indicating the time for obtaining the color information, and transmitting the color information and the light emission timing information to the imaging device.

  An image pickup apparatus according to the present invention receives an image pickup unit for picking up an image by picking up an image of the subject, the color information and the light emission timing information from the light emitting device, and the color information and the light emission timing information for the image. And image processing means for performing color balance processing accordingly.

  A control method according to the present invention is a control method for a light emitting device that is mounted on an imaging device that captures a subject, and includes, as a light source, an LED that emits light that illuminates the subject when the subject is captured by the imaging device. An element temperature detecting step for detecting the element temperature of the LED; and light emission control of the LED, and color information indicating a light emission color of the LED from the start of exposure to the end of exposure according to the element temperature is predetermined. And a control step of obtaining light emission timing information indicating the time for obtaining the color information, and transmitting the color information and the light emission timing information to the imaging apparatus.

  The control program according to the present invention is a control program used in a light-emitting device that is mounted on an imaging device that captures a subject and that includes, as a light source, an LED that emits light that illuminates the subject when the subject is captured by the imaging device. Then, an element temperature detecting step for detecting an element temperature of the LED in a computer included in the light emitting device, and the LED is controlled to emit light, and the LED emits light from the start of exposure to the end of exposure according to the element temperature. A control step of obtaining color information indicating a color at a predetermined time interval, obtaining light emission timing information indicating a time for obtaining the color information, and transmitting the color information and the light emission timing information to the imaging device; , Is executed.

  According to the present invention, the color information indicating the light emission color of the LED from the start of exposure to the end of exposure is obtained at predetermined time intervals, and the light emission timing information indicating the time for obtaining the color information is obtained. And the light emission timing information are sent to the imaging apparatus. Accordingly, the imaging apparatus can reduce color unevenness of the image by adjusting the color balance for each line of the image based on the color information in accordance with the light emission timing information.

It is a block diagram which shows the structure of an example of the light-emitting device by embodiment of this invention with an imaging device. It is a figure which shows the relationship between the element temperature of a general white LED, and the change of chromaticity. It is a figure for demonstrating the change of the color information in the strobe which uses LED as a light source. 2 is a flowchart for explaining a flash emission process and a camera shooting process shown in FIG. 1. 5 is a time chart for explaining operation timings in the light emission process and the imaging process shown in FIG. 4. It is a figure which shows the relationship between the imaging surface prescribed | regulated by the color information recorded on the camera shown in FIG. 1, and light emission timing information. It is a figure for demonstrating the inter-line_interpolation calculation process performed with the camera shown in FIG. 2 is a flowchart for explaining a reference forward voltage and reference color information recording process (LED recording) performed by the strobe shown in FIG. 1.

  Hereinafter, an example of an imaging device to which a light emitting device according to an embodiment of the present invention is connected will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an example of a light emitting device according to an embodiment of the present invention together with an imaging device.

  The illustrated light emitting device (hereinafter referred to as a strobe) 10 is mounted on an imaging device such as a digital camera, for example, and illuminates the subject by driving and controlling the LED 6 as a light source when photographing the subject. The strobe 10 includes a microcomputer 1, and the microcomputer 1 detects the forward voltage (Vf) of the LED 6 that is a light source, and ON / OFF of the power supply control unit 2 that is an LED drive circuit, and Color information indicating the emission color of the LED light is calculated. Further, the microcomputer 1 determines the LED driving conditions and controls the light emission of the strobe.

  An imaging device 20 such as a digital camera (hereinafter simply referred to as a camera) is connected to the microcomputer 1, and a strobe emission command is sent from the camera 20 to the microcomputer 1. Further, the color information of the LED 6 is sent from the microcomputer 1 to the camera 20, and the camera 20 performs a color balance process for correcting the car balance of the image data according to the color information, as will be described later.

  The strobe 10 has a power source 3 such as a battery, and the charging circuit 5 charges a charging unit (for example, a capacitor) 4 with the power source 3 under the control of the microcomputer 1. Here, for example, an electric double layer capacitor is used as the capacitor 4.

  Under the control of the microcomputer 1, the charge control unit 2 drives the LED (light emitting unit) 6 connected to the output side with a predetermined current using the capacitor 4 as a power source (that is, the input side) (LED drive). The power supply control unit 2 is, for example, a step-down switching converter circuit, and has an input side connected to the capacitor 4 and an output side connected to the LED 6.

  Further, a voltage detection resistor 7 is connected to the LED 6 in series. A spectrometer 30 is arranged facing the LED 6, and color information relating to light emission of the LED 6 is measured in advance by the spectrometer 30 as described later, and the color information is sent to the microcomputer 1.

  As shown in the figure, the microcomputer 1 includes a calculation unit 11, a recording unit 12, a voltage detection unit 13, and a light emission current determination unit 14. The microcomputer 1 periodically detects the forward voltage of the LED 6 and obtains color information of the LED light that changes during light emission according to the forward voltage Vf of the LED. The microcomputer 1 integrates the color information obtained for each forward voltage Vf to obtain accurate color information (hereinafter referred to as final color information) including color information that changes during light emission.

  Here, as will be described later, the element temperature of the LED 6 is obtained according to the forward voltage Vf, but the method for detecting the LED element temperature is not limited to this.

  As described above, the strobe 10 is connected to the camera 20, and the camera 20 has a photographing lens unit (hereinafter simply referred to as a lens) 200. Then, an optical image (that is, a subject image) is formed on the image sensor (image sensor) 21 via the lens 200. The image sensor 21 photoelectrically converts the optical image and outputs an electrical signal (analog signal).

  An analog signal that is an output of the image sensor 21 is sent to the A / D converter 22, and the A / D converter 22 converts the analog signal into a digital signal. Then, the digital signal is sent to the image processing unit 23, and the image processing unit 23 performs predetermined image processing on the digital signal to generate image data.

  As illustrated, the image processing unit 23 includes a white balance processing unit 230, a color processing unit 231, and other image processing units 232. The white balance processing unit 230 performs processing for adjusting the color ratio of the R, G, and B signals by multiplying each of the R (red), G (green), and B (blue) signals that constitute the digital signal by a gain. Do. The color processing unit 231 performs color conversion processing such as color density, hue adjustment, and 3D-LUT. The other image processing unit 232 performs development processing such as pixel interpolation processing, brightness adjustment processing, and gamma processing, for example.

  The camera 20 includes a memory 24 and a camera control unit 25, and various types of data to be described later used in the white balance processing unit 230 are stored in the memory 24. The camera control unit 25 controls the camera 20 and communicates with the microcomputer 1 provided in the strobe 10.

  FIG. 2 is a diagram showing the relationship between the element temperature of a general white LED and the change in chromaticity.

  In FIG. 2, each of the horizontal axis and the vertical axis represents chromaticity. When white is obtained by a combination of a blue LED and a yellow phosphor, which is a general configuration of a white LED, light emission occurs when the white LED becomes high temperature. The color shifts in the blue direction. That is, when a current is passed through the white LED, the LED generates heat and its color information changes, but the change of the color information in the white LED has regularity.

  FIG. 3 is a diagram for explaining a change in color information in a strobe using an LED as a light source.

  In FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the element temperature of the LED. It is assumed that the strobe light emission starts at the start of exposure and the strobe light emission stops at the end of the exposure. At this time, the element temperature of the LED changes as indicated by a curve 201 from the start of exposure to the end of exposure, and the element temperature becomes the highest at the end of exposure. That is, the color information of the LED 6 changes between the exposure start time and the end time. And the area | region shown with the oblique line in a figure is an area | region where element temperature is lower than element temperature at the time of completion | finish of exposure.

  As shown in FIG. 3, when the element temperature of the LED changes, if the element temperature is detected after the end of light emission and color information is to be obtained, the color information includes color information during light emission from the start of light emission. As a result, an error occurs in the color information.

  As described above, when the light emission color of the LED changes during light emission, for example, when so-called slit exposure is performed in which the shooting condition of the camera 20 is equal to or higher than the synchronization speed of the shutter, the change in color information during light emission remains as it is in the image. Appears as uneven color. In order to prevent such color unevenness, the microcomputer 1 periodically detects color information during light emission of the LED 6 here. Then, the microcomputer 1 gives timing information indicating the elapsed time from the start of exposure to the color information. As the timing information, for example, time elapsed information from the start of exposure triggered by the start of exposure is used. Then, in the camera 20, as described later, the color information is made to correspond to the exposure position of the image sensor 21 in accordance with the timing information, and the white balance processing is performed for each line.

  FIG. 4 is a flowchart for explaining the light emission processing of the strobe 10 and the photographing processing of the camera 20 shown in FIG. Note that the processing according to the illustrated flowchart is performed under the control of the camera control unit 25 and the microcomputer 1.

  FIG. 5 is a time chart for explaining the operation timing at the time of the light emission processing and photographing processing shown in FIG.

  Referring to FIGS. 4 and 5, when LED light emission processing is started in strobe 10, calculation unit 11 controls charging circuit 5 to start charging power supply 3 to capacitor 4, and sets capacitor 4 to a predetermined value. (Step S100). On the other hand, when a shutter button (not shown) is pressed in the camera 20 (step S101), the camera control unit 25 performs photometry and distance measurement operations on a known subject.

  Subsequently, the camera control unit 25 transmits the photometry result to the microcomputer 1 and transmits the light emission command determined according to the photographing condition setting to the microcomputer 1 (step S101: light emission command communication). The light emission command includes the light emission amount and the light emission time, and also includes timing information indicating the exposure start time.

  The microcomputer 1 receives the light emission command transmitted from the camera control unit 25 (step S103). Then, the light emission current determination unit 14 determines the current value (light emission current) and the light emission time that flow through the LED 6 according to the light emission command (that is, the light emission amount and the light emission time), and controls the power supply control unit 2 to control the capacitor 4. Is reduced to cause the LED 6 to emit light (step S104: start of LED emission).

  On the other hand, in synchronization with the timing information indicating the exposure start time, the camera control unit 25 releases the shutter (not shown) and starts exposure (step S105). At the same time as the exposure is started by the camera 20, the voltage detection unit 13 detects the forward voltage Vf of the LED 6 by the voltage detection resistor 7 (step S106).

  The process according to step S106 is periodically performed until the light emission ends at a predetermined time interval. Therefore, a plurality of forward voltages Vf are detected from the start of light emission to the end of light emission of the LED 6.

  Subsequently, the calculation unit 11 calculates the change amount ΔT of the element temperature of the LED 6 using the detected forward voltage Vf (step S107). Since the forward voltage Vf of the LED has individual variations depending on the element, it is necessary to store the forward voltage Vf under a predetermined condition in order to obtain the element temperature from the amount of change in the forward voltage Vf.

  Here, the forward voltage recorded under a predetermined condition is referred to as a reference forward voltage Vfs, and α is a conversion coefficient for converting the change amount of the forward voltage Vf into the change amount ΔT of the element temperature of the LED 6. To do. Since the conversion coefficient α is determined by the physical properties of the white LED, the individual variation is small and a fixed value.

For example, the calculation unit 11 calculates the change amount ΔT of the element temperature by the following equation (1).
LED element temperature change amount ΔT = (Vfs−Vf) × α (1)

  Subsequently, the computing unit 11 calculates the color information K of the LED light according to the element temperature change amount ΔT (step S108). Since the color information of LED light varies widely among individuals, it is necessary to record color information (referred to as reference color information) that serves as a reference in conditions such as a predetermined environmental temperature, current value, and light emission time. .

  Here, the reference color information recorded in advance is Ks, and the conversion coefficient for converting the element temperature change amount ΔT into the color information change amount is β. As described with reference to FIG. 2, when a current is passed through the white LED, the LED generates heat, and its color information changes. However, the change in the color information in the white LED has regularity. A conversion coefficient β is obtained according to the regularity.

For example, the calculation unit 11 calculates the color information K by the following equation (2).
Color information K = Ks + ΔT × β (2)

  Subsequently, the calculation unit 11 adds elapsed time information indicating the elapsed time from the start of exposure and light emission timing information to the color information K obtained according to Equation (2) (step S109). The light emission timing information indicates the light emission start time, and the elapsed time information indicates a time obtained by counting the time elapsed with reference to the timing information indicating the exposure start time. Then, the microcomputer 1 transmits the color information K to which the elapsed time information and the light emission timing information are added to the camera 20 (step S110).

  When the color information K is received, the camera control unit 25 records the color information K to which the elapsed time information and the light emission timing information are added via the image processing unit 23 in the memory 24 (step S111).

  The calculation unit 11 determines whether or not the exposure is in progress (that is, during the light emission) in accordance with the light emission command of the camera 20 (step S112). If the light is being emitted, that is, if the camera 20 is being exposed (YES in step S112), the calculation unit 11 returns to the process of step S106, and the voltage detection unit 13 obtains the forward voltage Vf. On the other hand, when the camera 20 is not being exposed, that is, when the light emission ends (NO in step S112), the calculation unit 11 ends the LED light emission process.

  On the other hand, after recording the color information K in the memory 24, the camera control unit 25 ends the exposure (step S113). Then, under the control of the camera control unit 25, the A / D conversion unit 22 converts an analog signal that is an output of the image sensor 21 into a digital signal and sends the digital signal to the image processing unit 23.

  Subsequently, the image processing unit 23 determines what white balance processing is to be performed according to the color information K recorded in the memory 25 under the control of the camera control unit 25. That is, the image processing unit 23 performs color information difference determination that determines white balance processing according to the difference in color information (that is, the amount of change in color information).

  FIG. 6 is a diagram showing the relationship between the color information recorded in the camera 20 shown in FIG. 1 and the imaging surface defined by the light emission timing information.

Now, let K1 be the color information of the LED 6 at the start of exposure, and Kn be the color information at the end of exposure. Then, a predetermined color information difference used for the color information difference determination is set to δKs (threshold value). In the color information difference determination, the image processing unit 23 determines whether or not the condition expressed by the following equation (3) is satisfied (step S114).
δKs> Kn−K1 (3)

When the condition shown in Expression (3) is satisfied (YES in step S114), that is, when the change amount of the color information is small (less than the threshold value), the image processing unit 23 averages the color information over the entire image. The batch color information calculation is performed (step S115). Here, the image processing unit 23 obtains an average value (average color information) KAVE of color information by the following equation (4). Note that n is the number of times of color temperature detection.
KAVE = (K1 + K2 + K3... Kn) / n (4)

  Then, the image processing unit 23 performs white balance processing on the digital signal (that is, the entire image) according to the average color information KAVE by the white balance processing unit 23 (step S116). This white balance processing is usually called white balance processing. When the normal white balance processing is completed, the image processing unit 23 performs color space conversion processing using a 3D-LUT (three-dimensional lookup table) by the color processing unit 231 and the other image processing unit 232 under the control of the camera control unit 25. In addition, pixel interpolation processing, brightness adjustment processing, and gamma processing are performed. Then, the camera control unit 25 ends the camera shooting process.

  In the normal white balance processing, the white balance processing unit 230 performs white balance processing on each pixel of RGB according to a coefficient obtained by multiplying the average color information KAVE by the white balance coefficient.

  The white balance coefficient is a coefficient that matches the sensitivity of each RGB color in the image sensor 21, and the white balance coefficient varies depending on each color. The white balance coefficient is determined by the characteristics of the image sensor 21 and is stored in the memory 24 in advance.

Here, the white balance coefficients of R, G, and B are WbGainR, WbGainG, and WbGainB, respectively, and the R, G, and B values before white balance adjustment are R0, G0, and B0, respectively. The R, G, and B values after white balance adjustment are R1, G1, and B1, respectively. In this case, the normal white balance process shown in step S116 is performed according to the following equation (5).
R1 = WbGainR × KAVE × R0
G1 = WbGainG × KAVE × G0 (5)
B1 = WbGainB × KAVE × B0

  On the other hand, if the condition shown in Expression (3) is not satisfied (NO in step S114), that is, if the amount of change in color information is large (if it is greater than or equal to the threshold), the image processing unit 23 is greatly affected by color unevenness. Since it appears, interline interpolation processing for obtaining color information for each line of the image sensor 21 is performed (step S117).

  As described above, in step S <b> 111, the camera control unit 25 records the light emission timing information when the color information is detected in the memory 24. Since the light emission timing information is generated according to the timing information indicating the exposure start time, the color information and the scanning line of the image sensor 21 can be associated with each other by the light emission timing information. In the inter-line_interpolation calculation process, color information between lines that are not associated with color information is obtained by interpolation calculation.

  FIG. 7 is a diagram for explaining interline interpolation processing performed by the camera 20 shown in FIG. FIG. 7 is a partially enlarged view of FIG.

  Here, it is assumed that color information is detected in the lines L1 and L2. Here, the color information is calculated by interpolation processing for the lines L11 to L14 located between the line L1 (t1K1: 03 msec 5000k) and the line L2 (t1K2: 0.6 msec 5070k). In FIG. 6, a line indicated by t3K3: 0.9 msec 5140k and a line indicated by tnKn: 10 msec 6000k are lines in which color information is detected. Tn indicates the time (msec) from the start of light emission, and Kn indicates the color information (k).

  Paying attention to the line L11, let the color information difference δK between the L1 and L2 lines be δL. Here, δK = K2−K1, K1 is the color information of the line L1, and K2 is the color information of the line L2.

The color information change amount δKL per line is expressed by the following equation (6).
δKL = δK / δL (6)
However, (delta) L shows a line space | interval.

As a result, the color information KL11 of the line L11 is expressed by the following equation (7).
KL11 = K1 + δKL × (L1: difference in number of lines between L11) (7)

  Subsequently, the image processing unit 23 performs white balance processing by the white balance processing unit 230 for each line in accordance with the color information recorded in the memory 24 and the color information obtained by the interpolation processing (step S118). This white balance process is called a line-by-line white balance process. In this white balance processing for each line, white balance processing is performed using color information for each line.

Here, assuming that KLx is color information obtained for each line, white balance processing is performed for all lines by the following equation (8).
R1 = WbGainR × KLx × R0
G1 = WbGainG × KLx × G0 (8)
B1 = WbGainB × KLx × B0

  When the line-by-line white balance processing is completed, the image processing unit 23 performs color space conversion using a 3D-LUT (three-dimensional lookup table) by the color processing unit 231 and the other image processing unit 232 under the control of the camera control unit 25. In addition to processing, pixel interpolation processing, brightness adjustment processing, and gamma processing are performed. Then, the camera control unit 25 ends the camera shooting process.

  In the above example, color temperature information is used as the color information, but other types of color information may be used. Furthermore, although the element temperature of LED6 was calculated | required using the forward voltage Vf, you may make it detect the detection of the element temperature of LED using another method.

  As described above, in the LED, there is an individual variation (individual difference) in both the forward voltage Vf and the color information, and when the final color information Ke is obtained, the reference forward voltage Vf and the color information are used as a reference. It is necessary to record in advance as forward voltage and reference color information.

  FIG. 8 is a flowchart for explaining recording processing (LED recording) of reference forward voltage and reference color information performed by the strobe shown in FIG. Note that the processing according to the illustrated flowchart is performed under the control of the microcomputer 1.

  When the LED recording process is started, the calculation unit 11 controls the charging circuit 5 to start charging the capacitor 4 from the power source 3 to charge to a predetermined voltage (step S200). Next, when a light emission command is received from the camera 20, the light emission current determination unit 14 determines a current value (light emission current) to be supplied to the LED 6, and controls the power supply control unit 2 to step down the voltage of the capacitor 4 to control the LED 6. Light is emitted (step S201).

  Simultaneously with the start of light emission of the LED 6, the voltage detector 13 detects the forward voltage Vf of the LED 6 by the voltage detection resistor 7 (step S202). The voltage detector 13 sets the detected forward voltage Vf as the reference forward voltage Vfs.

  The detection of the reference forward voltage Vfs is performed under a predetermined condition, that is, the LED 6 is caused to emit light under a predetermined condition, so that the relationship between the element temperature and the reference forward voltage Vfs can be grasped. Even if the forward voltage Vf fluctuates, the element temperature can be obtained accurately.

  After the reference forward voltage Vfs is obtained, the light emission current determination unit 14 controls the power supply control unit 2 to end the light emission of the LED 6 (step S203).

  During the processing of steps S201 to S203, the emitted light of the LED 6 is received by the spectrometer 30, and the spectrometer 30 generates color information corresponding to the emitted light. Here, the color information output from the spectrometer 30 is set as the reference color information Ks (step S204).

  Thereby, the color information unique to the LED 6 is acquired as the reference color information KS. If the reference color information ks is used as a reference, the final color information can be accurately obtained even if the element temperature varies.

  The calculation unit 11 records the reference forward voltage Vfs and the reference color information Ks acquired in steps S202 and S204 in the recording unit 12 (step S205), and ends the LED recording process.

  As described above, appropriate white balance processing is performed even when the strobe 10 is used for the high-speed shutter shooting in which the shooting condition of the camera 20 is equal to or higher than the synchronization speed of the shutter. be able to. That is, the occurrence of color unevenness can be reduced by detecting color information that changes during light emission and performing white balance processing for each line.

  In the above-described embodiment, an example in which color information is detected or calculated for each line has been described. However, a plurality of lines are grouped as one group, and color information that is representative for each group is detected or calculated to be the same. The lines belonging to the group may use the same color information. In this configuration, the accuracy of the color information in each line is lower than that in the configuration in which the color information is detected or calculated for each line, but it is possible to reduce the load of calculation processing for obtaining the color information.

  As is clear from the above description, in the example shown in FIG. 1, the calculation unit 11, the voltage detection unit 13, and the voltage detection resistor 7 function as element temperature detection means. Moreover, the calculating part 11, the light emission current determination part 14, and the power supply control part 2 function as a control means. Furthermore, the voltage detection unit 13 and the voltage detection resistor 7 function as a voltage detection unit, and the calculation unit 11 functions as a change amount calculation unit.

  Further, the lens 200, the image sensor 21, and the A / D conversion unit 22 function as an imaging unit, and the camera control unit 25 and the image processing unit 23 function as an image processing unit.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  Moreover, what is necessary is just to make a light-emitting device perform this control method by using the function of said embodiment as a control method. In addition, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the light emitting device. The control program is recorded on a computer-readable recording medium, for example.

  Each of the above control method and control program has at least an element temperature detection step and a control step.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various recording media, and the computer (or CPU, MPU, etc.) of the system or apparatus reads the program. To be executed.

6 LED
7 Voltage detection resistor 11 Calculation unit 12 Recording unit 13 Voltage detection unit 14 Light emission current determination unit 23 Image processing unit 25 Camera control unit 230 White balance processing unit 231 Color processing unit

Claims (11)

A light-emitting device that is mounted on an imaging device that captures a subject, and includes, as a light source, an LED that emits light that illuminates the subject when the subject is captured by the imaging device;
Element temperature detecting means for detecting the element temperature of the LED;
The LED is controlled to emit light, and color information indicating the emission color of the LED from the start of exposure to the end of exposure according to the element temperature is obtained at a predetermined time interval, and the time at which the color information is obtained is indicated. Control means for obtaining light emission timing information and transmitting the color information and the light emission timing information to the imaging device;
A light emitting device comprising: The element temperature detecting means is
Voltage detection means for detecting a forward voltage flowing in the LED;
Change amount calculating means for obtaining a change amount of the element temperature based on the forward voltage,
2. The light emitting device according to claim 1, wherein the control unit obtains the color information according to a change amount of the element temperature and reference color information indicating a predetermined emission color of the LED. The element temperature detecting means obtains a change amount of the element temperature at a predetermined cycle from the start of exposure to the end of exposure,
3. The light emitting device according to claim 2, wherein the control unit obtains a plurality of pieces of color information in accordance with the change amounts of the plurality of element temperatures obtained by the element temperature detection unit and the reference color information. . Imaging means for capturing an image of the subject to obtain an image;
Image processing means for receiving the color information and the light emission timing information from the light emitting device according to claim 1 and performing color balance processing on the image according to the color information and the light emission timing information;
An imaging device comprising:   The image processing means performs a predetermined first process as the color balance process when the difference between the color information at the start of exposure and the color information at the end of exposure is less than a preset threshold value. The imaging device according to claim 4.   When the difference between the color information at the start of exposure and the color information at the end of exposure is equal to or greater than the threshold, the image processing means performs a second process different from the first process as the color balance process. The imaging apparatus according to claim 5, characterized in that:   In the first process, the image processing means performs a color balance process using average color information obtained by averaging light emission colors indicated by the color information, regardless of the light emission timing information. The imaging device according to claim 5 or 6.   In the second processing, the image processing means performs color balance processing on each of the image lines according to color information corresponding to the image lines based on the light emission timing information. The imaging device according to claim 6.   When performing the second process, the image processing unit obtains color information of a line where the color information does not exist by interpolation processing if the color information corresponding to the line of the image does not exist. The imaging device according to claim 8. A method of controlling a light emitting device, which is mounted on an imaging device that captures a subject and includes, as a light source, an LED that emits light that illuminates the subject when the subject is captured by the imaging device,
An element temperature detecting step for detecting an element temperature of the LED;
The LED is controlled to emit light, and color information indicating the emission color of the LED from the start of exposure to the end of exposure according to the element temperature is obtained at a predetermined time interval, and the time at which the color information is obtained is indicated. A control step of obtaining light emission timing information and transmitting the color information and the light emission timing information to the imaging device;
A control method characterized by comprising: A control program used in a light-emitting device that is mounted on an imaging device that captures a subject and includes an LED that emits light that illuminates the subject when the subject is captured by the imaging device as a light source,
In the computer provided in the light emitting device,
An element temperature detecting step for detecting an element temperature of the LED;
The LED is controlled to emit light, and color information indicating the emission color of the LED from the start of exposure to the end of exposure according to the element temperature is obtained at a predetermined time interval, and the time at which the color information is obtained is indicated. A control step of obtaining light emission timing information and transmitting the color information and the light emission timing information to the imaging device;
A control program characterized by causing

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