JP5042453B2 - Strobe control device, strobe control program, strobe control method - Google Patents

Description

  The present invention relates to a strobe control device that corrects strobe light, a strobe control program, and a strobe control method.

2. Description of the Related Art Conventionally, in a digital camera, when a subject to be photographed is dark when taking an image, the brightness is compensated by emitting strobe light to take the image. Here, there is a problem that if the flash light is simply emitted to capture an image, the atmosphere of the surrounding light source is not utilized by the strobe light, resulting in an unnatural color.
In view of this, a strobe device has been proposed that performs photographing taking advantage of the surrounding atmosphere even when a strobe is emitted in a digital camera (see, for example, Prior Art Document 1). In this strobe device, the ambient color temperature is measured using a photometric sensor, and the color temperature of the strobe light is corrected based on the measurement result, thereby relaxing the unnatural color caused by the strobe light.
JP-A-6-308586

  However, in the strobe device of the above-mentioned prior art document 1, since the photometric sensor is used, the number of parts increases, the cost increases, and the weight of the strobe device increases. Was. In digital cameras and the like, it is desirable to reduce the weight in consideration of carrying around.

  The present invention has been made in view of such circumstances, and a purpose thereof is a strobe control device, a strobe control program, and a strobe control program that can take an image without giving a sense of incongruity due to the emission of strobe light without using a photometric sensor, The object is to provide a strobe control method.

  In order to solve the above-described problems, the present invention is a strobe control device used in an image pickup apparatus that emits strobe light and images a subject by an image pickup means, and is based on an image pickup result picked up by the image pickup means. It has a correction means for detecting a color temperature and correcting the light emission amount of the strobe light or the color temperature of the strobe light based on the detected color temperature.

  Further, according to the present invention, in the above-described strobe control device, the color temperature information of the light source according to the ratio of R and G and the ratio of B and G, and strobe light emission amount data for strobe emission according to the color temperature, 1, and the correction means calculates integrated values of R, G, and B based on RGB data that is the imaging result captured by the imaging means. And calculating means for calculating, among the integrated values of the RGB data generated by the integrated value generating means, integrated value data that is a ratio of R and G and integrated value data that is a ratio of B and G Then, referring to the first storage means, the strobe emission amount data is read based on the integrated value data of the ratio of R and G and the integrated value data of the ratio of B and G calculated by the calculating means, Read flash output data Based on, and having a control means for emitting the strobe device.

  The present invention is also a strobe control device used in an imaging apparatus that emits strobe light and images a subject, based on a detection unit that detects a white balance gain of the subject, and a detection result of the detection unit. It has a correction means for detecting the color temperature and correcting the light emission amount of the strobe light or the color temperature of the strobe light based on the detected color temperature.

  The present invention further includes a second storage unit that stores the white balance gain and strobe light emission amount data corresponding to the color temperature corresponding to the white balance gain in association with each other in the above-described strobe control device, The correcting means refers to the second storage means, reads strobe light emission data corresponding to the white balance gain of the white balance detection means, and causes the strobe device to emit light based on the read strobe light emission data. It has 2 control means.

  According to the present invention, in the above-described strobe control device, there is provided a color filter unit that stores a plurality of color filters that correct the color of the strobe light, and the control device includes a color filter stored in the filter unit. Among them, a color filter corresponding to the detected color temperature is set in the light emission path of the strobe device.

  Further, the present invention is a strobe control program used in a strobe control device used in an image pickup apparatus that emits strobe light and images a subject by an image pickup means, and a color based on an image pickup result picked up by the image pickup means And detecting a temperature, and causing the computer to execute a step of correcting the light emission amount of the strobe light or the color temperature of the strobe light based on the detected color temperature.

  The present invention is also a strobe control program for use in a strobe control device used in an image pickup apparatus that emits strobe light and images a subject, the step of detecting a white balance gain of the subject, and a detected white A color temperature is detected based on the balance gain, and the computer is caused to execute a step of correcting the light emission amount of the strobe light or the color temperature of the strobe light based on the detected color temperature.

  The present invention also relates to a strobe control method used in a strobe control device used in an image pickup apparatus that emits strobe light and picks up an image of a subject by an image pickup means, and a color based on an image pickup result picked up by the image pickup means. The temperature is detected, and the light emission amount of the strobe light or the color temperature of the strobe light is corrected based on the detected color temperature.

  The present invention is also a strobe control method used in a strobe control device used in an imaging apparatus that emits strobe light and images a subject, wherein the white balance gain of the subject is detected and the detected white balance gain is detected. The color temperature is detected based on the color temperature, and the light emission amount of the strobe light or the color temperature of the strobe light is corrected based on the detected color temperature.

  As described above, according to the present invention, the color temperature is specified based on the detection result (for example, RGB data) or the white balance gain of the imaging means, rather than simply referring to the ambient brightness, and the color The strobe emission amount and the color of the strobe emission are controlled according to the temperature, so that the natural color that matches the atmosphere of the ambient light source can be reproduced without using a photometric sensor and without causing a sense of incongruity. .

  In addition, according to the present invention, when the strobe light is emitted, the color filter corresponding to the color temperature is switched, so that the color of the photograph is prevented from becoming the dominant color of the strobe light. It is possible to create a photo with natural color that does not make you feel strobe light without being affected by the color.

  Hereinafter, an imaging apparatus using a strobe control device according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a digital camera will be described as an example of an imaging apparatus according to the present invention. FIG. 1 is a schematic block diagram showing the configuration of a digital camera according to the first embodiment of the present invention.

  The digital camera of this embodiment includes an image sensor (CCD) 4 and an amplifier (AMP) circuit 9 as image capturing means for capturing an image of a subject. A lens is disposed in front of the image sensor 4, and subject image light that passes through the lens is imaged on the light receiving surface of the image sensor 4. The image sensor 4 photoelectrically converts the subject image light imaged on the light receiving surface. As this image sensor 4, a CCD (Charge Coupled Device) image sensor, a CMOS (Complementary MOS) image sensor, or the like is used. The image sensor 4 is driven based on an instruction from a CPU 19 described later.

  The AMP circuit 9 includes a gain variable unit that varies the degree of amplification of the output of the image sensor 4 that is the output of the imaging unit. The AMP circuit 9 constitutes an exposure changing unit that changes the exposure state in the imaging unit.

  The digital camera of this embodiment includes an A / D converter 10, an image signal processing circuit 12, an image compression processing circuit 13, a video encoder 14, an image display device 15, a CPU 19, an AF detection circuit 20, an AWB detection circuit 21, A memory 22, a VRAM 23, a media controller 24, a recording medium 25, and an AE detection circuit 26 are provided.

  The CPU 19 controls the entire digital camera. An AWB (Automatic White Balance) detection circuit 21 detects an image signal level for white balance. An AE (Automatic Exposure) detection circuit 26 detects an image signal level for performing exposure. The AWB detection circuit 21 and the AE detection circuit 26 form an exposure control signal and a white balance control signal, and the exposure control signal and the white balance control signal are supplied to the CPU 19. Thus, the CPU 19, the AWB detection circuit 21, and the AE detection circuit 26 constitute an automatic exposure adjustment unit that variably controls the state of the exposure change unit (AMP circuit 9) based on the output of the image sensor 4.

  The output signal of the image sensor 4 is supplied to the A / D converter 10 via the AMP circuit 9. The A / D converter 10 converts the image signal output from the AMP circuit 9 into a digital signal. The output signal of the A / D converter 10 is taken into the CPU 19. Further, the CPU 19 performs focus control (AF).

  The AF (Automatic Focus) detection circuit 20 is for performing AF based on the output of the image sensor 4. The AF detection circuit 20 detects the high frequency component level of the image signal in order to perform focus control. Based on the detected high-frequency component level, the CPU 19 controls the lens so that it is in the in-focus position.

  Further, the CPU 19 controls the aperture of the diaphragm mechanism provided in the lens in accordance with the exposure control signal output from the AE detection circuit 26, and the white balance control signal from the AWB detection circuit 21. Accordingly, the gain of the three primary color signals is controlled by the image signal processing circuit 12. Further, the CPU 19 supplies a gain control signal to the AMP circuit 9 and controls the gain of the AMP circuit 9 so that the signal level becomes a predetermined level.

  A shutter switch (not shown) is a switch that is pressed when taking an image. When the shutter switch is pressed, a shutter signal is sent to the CPU 19 and the image at that time is taken into the image sensor 4. The image signal for one screen at this time is stored in the memory 22.

  The image signal for one screen captured in the memory 22 is supplied to the image compression circuit 13 after being subjected to image processing by the image signal processing circuit 12. The image compression circuit 13 compresses and encodes image data. For example, JPEG (Joint Photographic Experts Group) is used as a compression method of image data. JPEG is a standard for compressing an image using DCT (Discrete Course Transform). Note that the image data compression method is not limited to JPEG.

  The compressed and encoded image signal is supplied to the recording medium 25 via the media controller 24 and recorded on the recording medium 25. As the recording medium 25, for example, a card-type detachable memory using a flash memory is used. As the recording medium 25, a nonvolatile memory built in a digital camera, a magnetic tape, a magnetic disk, an optical disk, or the like may be applied.

  Next, the strobe controller 50 will be described. The strobe control unit 50 performs control to correct a strobe light emission amount or a strobe light color temperature emitted by a strobe light emitting unit (not shown) that emits strobe light. The RGB integrated value generation unit 31 calculates an integrated value based on RGB data that is output from the A / D converter 10 and is an imaging result captured by the imaging device 4. This integrated value is calculated for each of R, G, and B. This integration may be performed for all the pixels, or all the pixels may be divided into a plurality of pixels and may be integrated for the pixels in the divided area.

The R / G / B / G integrated value calculation unit 33 includes integrated value data and B that are ratios (R / G) of R and G among the integrated values of RGB data generated by the RGB integrated value generating unit. And integrated value data which is a ratio (B / G) between G and G is calculated.
The color temperature / light source data storage unit 34 stores a light source corresponding to a ratio of R and G and a ratio of B and G, and color temperature information of the light source. An example of data stored in the color temperature / light source data storage unit 34 is shown in FIG. In FIG. 2, the vertical axis is the ratio of the integrated values of B and G (B / G), and the horizontal axis is the ratio of R and G (R / G), and the corresponding light source and color temperature are stored. For example, here, shade / cloudy (shade / cloudy (symbol a) in FIG. 2), sunlight (symbol b), fluorescent lamp (symbol c), incandescent lamp (symbol d), tungsten (symbol e), 5 Color light information is stored such as 10000 ° C for shade and cloudiness, 5000 to 6000 ° C for sunlight, 4000 ° C for fluorescent light, 3000 ° C for incandescent light, and 2000 ° C for tungsten. Is done.
The data stored in the color temperature / light source data storage unit 34 is, for example, which light source of each light source is stored by previously storing the distance between the central coordinates and the coordinates on the vertical axis side and the horizontal axis side as coordinate values. It is possible to detect whether the coordinate range is entered. In addition, although illustrated about the case where this light source was classified into five types, four or less types may be sufficient and six or more types may be sufficient.

The color temperature / light source detection unit 35 refers to the color temperature / light source data storage unit 34 and outputs an R / G integration value and a B / G integration value output from the R / G / B / G integration value calculation unit 33. The light source and the color temperature corresponding to the combination are detected.
The storage unit 37 stores a light emission amount for performing strobe light emission according to the color temperature in association with the color temperature as strobe light emission amount data. Here, the strobe light emission amount data is stored such that the strobe light emission amount decreases as the color temperature decreases and the strobe light emission amount increases as the color temperature increases. The strobe light emission amount data may be stored in association with the color temperature or may be stored in association with the light source.
The strobe emission amount adjustment unit 39 refers to the storage unit 37, reads strobe emission amount data corresponding to the color temperature detected by the color temperature / light source detection unit 35, and based on the read strobe emission amount data, the strobe emission unit On the other hand, the amount of light that causes the flash to be emitted is controlled.

  The storage unit 41 stores color temperature information of a light source according to the ratio of R and G and the ratio of B and G, and color filter information that specifies a color filter to be used according to the color temperature. The strobe light emission color filter switching unit 43 includes a color filter unit that stores a plurality of color filters corresponding to the color temperature of the subject to be photographed. The storage unit 41 is referred to, and a plurality of colors stored in the color filter unit are stored. Among the filters, a color filter corresponding to the color filter information detected by the color temperature / light source detection unit 35 is set on the light emission path of the strobe device.

  Here, the strobe emission color filter switching unit 43 will be further described with reference to FIG. The color filter 200 is set between the light emitting glass surface 100 provided in the light source of the strobe light and the light source (on the light emission path) in the strobe light emitting unit that emits the strobe light of the imaging device. Here, a plurality of color filters 200 are stored in the color filter unit, and the color filter corresponding to the color filter information is transferred from the color filter unit to the light emitting glass surface 100 by the driving means included in the strobe light emission color filter switching unit 43. Set by moving between light sources. Based on the color filter information, this color filter is set to orange when the light source is tungsten, yellow filter when the light source is fluorescent light or incandescent light, blue filter when it is shaded, and the like. This color filter may be set by overlapping a plurality of sheets.

  Next, the operation of the digital camera in the above-described embodiment will be described with reference to the drawings centering on the operation of the strobe controller 50. FIG. 4 is a flowchart for explaining the operation of the digital camera when the strobe light is emitted using the strobe control unit 50 to capture an image. Here, the case where a light source is a tungsten light source is demonstrated as an example. First, when taking an image, it is detected with reference to a user instruction input via a switch or the like as to whether or not the flash photography mode is set (step S11). If it is not in the flash photography mode, the flash is not emitted, and the process is finished after taking an image.

  On the other hand, in the flash photography mode, subject image light is received by the image sensor 4 during pre-photometry, amplified by the AMP circuit 9, and RGB data converted into digital values by the A / D converter 10 is generated. Then, the RGB integrated value generation unit 31 acquires this RGB data. Next, the RGB integrated value generation unit 31 calculates an integrated value for each of R, G, and B based on the RGB data, and outputs the integrated value to the R / G · B / G integrated value calculation unit 33. When the integrated value output from the RGB integrated value generating unit 31 is acquired (step S12), the R / G / B / G integrated value calculating unit 33 calculates the integrated values of R / G and B / G, and calculates The result is output to the color temperature / light source detector 35 (step S13).

  The color temperature / light source detection unit 35 refers to the color temperature / light source data storage unit 34 to detect a color temperature and a light source corresponding to each integrated value of R / G and B / G. Here, the data shown in FIG. 2 is referred to, and it is detected that the coordinates of the intersection of the integrated value of R / G and the integrated value of B / G are within the region indicating the tungsten light source. The color temperature corresponding to the tungsten light source is detected as color temperature information (step S14). The strobe emission amount adjustment unit 39 acquires the color temperature information detected by the color temperature / light source detection unit 35, reads the strobe emission amount corresponding to the acquired color temperature information from the storage unit 37, and sets the read strobe emission amount to the read strobe emission amount. The strobe light quantity is instructed to the strobe light emitting unit (step S15).

  On the other hand, the strobe light emission color filter switching unit 43 acquires the color temperature information detected by the color temperature / light source detection unit 35, reads out the color filter information corresponding to the acquired color temperature information from the storage unit 41, and reads the read color. The color filter corresponding to the filter information is switched and mounted by moving the color filter from the color filter unit onto the light emission path between the light source and the light emitting glass surface (step S16). Here, since the light source is a tungsten light source, it is switched to an orange color filter. Then, when the half-pressed shutter is further pushed in, an orange strobe light corresponding to the tungsten light source is emitted according to the instruction of the strobe light amount adjustment unit 39, and imaged (step). S17).

According to the embodiment described above, strobe light emission can be performed with a strobe light emission amount and a color temperature of the strobe light according to the light source. For example, in the case of a tungsten light source, it is possible to emit light while suppressing the strobe light as a whole with a setting that emphasizes the atmosphere, thereby reducing the atmosphere such as the profound feeling of the tungsten light source without using a photometric sensor. Images can be taken without any loss. When the light source is a fluorescent lamp, a mode, etc., since the dark atmosphere is not important, the strobe light emission amount is increased as compared with the tungsten light source to emit light.
In addition, by switching to a color filter corresponding to the color temperature of the light source, it is possible to capture images while maintaining the atmosphere of the light source that would normally be extinguished by the strobe light. The image gap can be reduced, and an image with an atmosphere that does not feel the flash emission even when the flash is emitted can be generated.

  Next, a second embodiment will be described. In the above-described embodiment, the case where the value obtained by calculating the RGB integrated value based on the information acquired from the image sensor 4 is used when controlling the strobe light emission. However, in this embodiment, the image sensor is used. The case where the white balance value is used instead of the information obtained from 4 will be described.

  The configuration in the second embodiment is the same as the configuration in FIG. 1, but the function is different. The differences will be described below. The AWB detection circuit 21 detects the white balance gain and outputs the detection result to the color temperature / light source detection unit 35. The color temperature / light source data storage unit 34 stores the white balance gain and the color temperature corresponding to the white balance gain in association with each other as table information. The color temperature / light source data storage unit 34 stores the color temperature and the light source corresponding to the color temperature in association with each other as table information.

In this configuration, when imaging is performed, if a white balance gain is detected by the AWB detection circuit 21 during pre-photometry, the detection result is output to the color temperature / light source detection unit 35. The color temperature / light source detection unit 35 acquires the color temperature corresponding to the white balance gain output from the AWB detection circuit 21 with reference to the table information in the color temperature / light source data storage unit 34. By detecting this color temperature, the light source corresponding to the color temperature is specified with reference to the table information.
Then, the color temperature / light source detection unit 35 specifies the color temperature and the light source, whereby the strobe emission amount adjustment unit 39 controls the strobe emission amount, and the strobe emission color filter switching unit 43 switches the color filter. Done.

  According to this embodiment, since the color temperature is specified according to the value of the white balance gain, the color temperature can be specified directly as compared with the first embodiment, and the color temperature can be specified. It is also possible to improve the specific accuracy.

  Note that, in the above-described embodiment, imaging may be performed with exposure corrected to be darker or brighter according to the detected color temperature.

Also, an RGB integrated value generation unit 31, an R / G / B / G integrated value calculation unit 33, a color temperature / light source detection unit 35, and a strobe emission amount adjustment unit 39 in FIG. A program for realizing the function of the AWB detection circuit 21 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the imaging apparatus and executed to control strobe light emission. Also good. The recording medium here is a memory card, magnetic disk, optical disk, memory built in the camera, or the like that can be read by the camera. This program may be downloaded from the Internet in addition to being performed via a recording medium.
In this case, switching of the color filter may be realized by separately purchasing a color filter unit and attaching it to the imaging apparatus, and reading the program into the imaging apparatus.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design and the like within a scope not departing from the gist of the present invention.

1 is a schematic block diagram illustrating a configuration of a digital camera according to a first embodiment of the present invention. 4 is a diagram illustrating an example of data stored in a color temperature / light source data storage unit 34; 6 is a diagram for explaining a strobe emission color filter switching unit 43; 6 is a flowchart for explaining the operation of a digital camera when shooting with a strobe light using a strobe control unit 50.

Explanation of symbols

21 AWB detection circuit 31 RGB integrated value generation unit 33 R / G / B / G integrated value calculation unit 34 color temperature / light source data storage unit 35 color temperature / light source detection unit 37, 41 storage unit 39 strobe light emission amount adjustment unit 43 strobe Luminescent color filter switching unit 50 Strobe control unit

Claims (4)

A strobe control device used in an imaging device that emits strobe light and images a subject,
Calculating means for detecting an image signal level of the subject and calculating a white balance gain for white balance based on the detected image signal level ;
First storage means for storing a white balance gain and a color temperature corresponding to the white balance gain in association with each other;
A second storage means for storing the color temperature and strobe light emission amount data corresponding to the color temperature in association with each other;
Referring to the first storage means, the color temperature corresponding to the white balance gain calculated by the calculation means is read, and the strobe light emission amount data corresponding to the read color temperature is referred to the second storage means. reading, on the basis of the read color temperature and amount of flash light emission data, a controlling unit for emitting flash light, wherein a correcting means for correcting the color temperature of the light-emitting amount or the flash light of the flash light Strobe control device. A color filter unit for storing a plurality of color filters for correcting the color of the strobe light;
The said strobe control apparatus sets the color filter corresponding to the said detected color temperature to the light emission path | route of the said strobe light among the color filters stored in the said filter part. Strobe control device. A strobe control program used in a strobe control device used in an imaging device that emits strobe light and images a subject,
Detecting an image signal level of the subject and calculating a white balance gain for white balance based on the detected image signal level ;
Reading the color temperature corresponding to the white balance gain which is the calculated from the first table information for associating the color temperature corresponding to the white balance gain and white balance gain, and a flash light emission amount data corresponding to the color temperature and the color temperature Read strobe light amount data corresponding to the read color temperature from the second table information to be associated, and correct the strobe light amount or the strobe light color temperature based on the read color temperature and strobe light amount data. A strobe control program characterized by causing a computer to execute the step of performing. A strobe control method used in a strobe control device used in an imaging device that emits strobe light and images a subject,
Detecting the image signal level of the subject, and calculating a white balance gain for white balance based on the detected image signal level ;
Reading the color temperature corresponding to the white balance gain which is the calculated from the first table information for associating the color temperature corresponding to the white balance gain and white balance gain, and a flash light emission amount data corresponding to the color temperature and the color temperature Read strobe light amount data corresponding to the read color temperature from the second table information to be associated, and correct the strobe light amount or the strobe light color temperature based on the read color temperature and strobe light amount data. A strobe control method characterized by:

Images