JP2008199518A - Camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a camera which performs flash photographing and flash-off photographing as consecutive photographing at short photographing intervals. <P>SOLUTION: There are provided an imaging unit 3 which performs photoelectric conversion on a subject image incident through an imaging lens 31 onto a light receiving plane thereof and outputs the image as a photographic image and a light emitting unit 2 which emits flash light to an object 1. When continuously outputting a plurality of photographic images from the imaging unit 3, an imaging control unit 8 controls the light emitting unit 2 so as to include a flash photographic image that is obtained when flash light is emitted, and a flash-off photographic image that is obtained when flash light is not emitted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a camera having a flash photographing function.

  When shooting with a digital camera or the like, flash shooting is performed when shooting in a dark place or in a place where the amount of light is insufficient, such as in a room, or when making up for a shortage of light during shooting. By the way, in general, flash light strikes strongly against a short-distance subject, and hits a long-distance subject weakly. The balance may become unnatural. On the other hand, as a technique for shooting in a place where the amount of light is insufficient while using shooting without using a flash (referred to as flashless shooting), a technique for shooting with increased sensitivity of the image sensor and a longer exposure time of the image sensor. The method of taking pictures is also used. In this case, if the sensitivity of the image sensor is excessively increased, noise components in the captured image become conspicuous, and the image quality of the captured image is degraded. If the exposure time is too long, the captured image may be blurred due to camera shake during shooting or movement of the subject.

Therefore, in order to compensate for the unnatural darkness in a long-distance subject that deteriorates the luminance balance during flash photography, for example, in Patent Document 1, flash photography with a weak light emission amount suitable for a short-distance subject and strong matching for a long-distance subject. There has been proposed a technique of performing flash photography of the amount of emitted light and synthesizing images obtained by both photography. Japanese Patent Application Laid-Open No. 2004-228688 proposes a technique of performing flash photography and flashless photography without using a flash, and synthesizing images obtained by both photography.
Japanese Patent Laid-Open No. 11-205666 JP 2005-86488 A

  Here, in the method of continuously performing flash photography in Patent Document 1 described above, since a flash charge time of several seconds for the second flash photography is required after the first flash photography, A long time lag occurs before the second shooting. Further, in the method of performing flash photography and flashless photography in Patent Document 2 described above, there is no particular mention of processing between flash photography and flashless photography, and photography can be completed in a short time. Not necessarily.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a camera that performs flash shooting and flashless shooting by continuous shooting with a short shooting interval.

  In order to achieve the above object, the camera of the first aspect of the present invention photoelectrically converts an image of a subject incident on the light receiving surface via an optical system and outputs it as a photographed image. An imaging unit that continuously outputs a plurality of photographed images without the need for a light shielding member for blocking the incidence of the subject image on the subject, a light emitting unit that emits a flash to the subject, and the imaging unit When the plurality of photographed images are continuously output by the above, the light emitting unit is configured to include a first photographed image when the flash is emitted and a second photographed image when the flash is not emitted. And an imaging control unit for controlling.

  ADVANTAGE OF THE INVENTION According to this invention, the camera which performs flash photography and flashless photography by continuous photography with a short imaging | photography space | interval can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram of a camera according to the first embodiment of the present invention. The camera shown in FIG. 1 includes a light emitting unit 2, an imaging unit 3, an image calculation unit 4, a display unit 5, a photometric unit 6, a distance measuring unit 7, an imaging control unit 8, and an operation unit 9. It is configured.

  The light emitting unit 2 includes a flash light emitting unit 21 and a light control unit 22. The flash light emitting unit 21 emits flash light to the subject 1. The light control unit 22 determines the light emission amount of the flash light emitting unit 21.

  The imaging unit 3 includes an imaging lens 31, a focus mechanism 32, a diaphragm mechanism 33, and an imaging element 34. The imaging lens 31 is an optical system including a focus lens and the like, and forms an image of the subject 1 on the imaging element 34. The focus mechanism 32 adjusts the focus of the imaging lens 31 by moving the focus lens included in the imaging lens 31 in the optical axis direction. The diaphragm mechanism 33 includes a diaphragm and a drive mechanism for the diaphragm, and limits the incident amount of the image of the subject incident through the imaging lens 31 by adjusting the aperture of the diaphragm. The image sensor 34 converts the image of the subject incident through the imaging lens 31 into electric charge by photoelectric conversion, and then outputs it as a captured image.

  Here, in the present embodiment, the image sensor 34 is assumed to be an image sensor having an electronic shutter function. The electronic shutter function is a function for ending the exposure of the image sensor 34 without using a light shielding member (shutter) by discharging the electric charge accumulated in the image sensor 34 at the time of exposure at the same time as the exposure is completed. By using such an electronic shutter function, exposure can be completed at a higher speed than when the light receiving surface of the image sensor 34 is mechanically shielded using a light shielding member (shutter).

  The image calculation unit 4 performs image processing on the captured image output from the imaging element 34 of the imaging unit 3. The display unit 5 displays the image processed by the image calculation unit 4. The photometry unit 6 measures the luminance of the subject in order to perform automatic exposure control (AE) during shooting. The distance measuring unit 7 measures the distance to the subject in order to perform automatic focus control (AF) during shooting.

  The imaging control unit 8 performs an imaging operation by controlling the operation of each block illustrated in FIG. The operation unit 9 is an operation member including a release button or the like for giving a shooting instruction to the imaging control unit 8 by the photographer.

  Hereinafter, the operation of the first embodiment will be described. FIG. 2 is an embodiment of a flowchart of the shooting operation in the camera having the configuration as shown in FIG. 1, and FIG. 3 is a diagram showing the effect of shooting according to the flowchart of FIG. Here, FIG. 3A is a diagram showing a flash photographed image using the light emitting unit 2, and FIG. 3B is a diagram of a flashless photographed image not using the light emitting unit 2, and FIG. FIG. 4 is a diagram of an image obtained by combining FIG. 3A and FIG. 3A to 3C, A is a person, and B is a wall at a position farther than the person.

  In flash photography shown in FIG. 3A, the flash from the light emitting unit 2 is emitted toward the person A. For this reason, the person A has the highest luminance because the amount of flash reflection from the light emitting unit 2 is the largest. On the other hand, the brightness of the wall B at a distance where the flash from the light emitting unit 2 does not reach is extremely lower than that of the person A. Further, in the flashless photographing shown in FIG. 3B, photographing is performed without emitting the flash from the light emitting unit 2. However, since the brightness of the entire image is low as it is, the sensitivity of the image sensor 34 is increased (the amount of amplification of the signal from the image sensor 34 is increased). In such flashless shooting, the brightness of the entire image is balanced. However, since the sensitivity of the image sensor 34 is increased in order to increase the brightness of the entire image in flashless shooting, noise also increases.

  Next, the photographing operation in the camera having the configuration of FIG. 1 will be described with reference to the flowchart of FIG. The example in FIG. 2 shows an example of continuous shooting in which a plurality of images are continuously captured.

  First, the user sets the continuous shooting number N using the operation unit 9 (step S1). Next, the imaging control unit 8 initializes a parameter n indicating the number of times of flashless imaging to 0 (step S2). Thereafter, the imaging control unit 8 stands by until the release button of the operation unit 9 is pressed (half-pressed) to the first stage (step S3).

  When the release button is pressed halfway in the determination in step S3, the imaging control unit 8 causes the distance measuring unit 7 to measure the subject distance for AF (step S4). After the subject distance is measured by the distance measuring unit 7, the imaging control unit 8 performs focus adjustment by operating the focus mechanism 32 of the imaging unit 3 based on the measurement result of the subject distance (step S5). Next, the imaging control unit 8 causes the photometry unit 6 to measure subject luminance under normal light (step S6). After the subject luminance is measured by the photometry unit 6, the imaging control unit 8 performs an exposure calculation based on the measurement result of the subject luminance, and the common aperture value, exposure time, and image sensor 34 are used when the flash is not emitted. The exposure conditions such as sensitivity are determined (step S7).

  After step S7, the imaging control unit 8 determines whether the release button of the operation unit 9 has been pressed to the second stage (fully pressed) (step S8). If it is determined in step S8 that the release button has not been fully pressed, it is determined whether the release button has been opened (step S9). If the release button is not released and is not fully pressed, the processes in steps S6 to S7 are repeated, and the exposure calculation is repeated so that the latest exposure is always obtained even if the photographing composition is changed. If it is determined in step S9 that the release button has been released, the process ends.

  Next, in step S8, when the release button is fully pressed, the imaging control unit 8 causes the flash light emitting unit 21 of the light emitting unit 2 to emit light and perform preliminary light emission. The light control unit 22 measures the reflected light from the subject subject to preliminary light emission by the flash light emitting unit 21 (step S10), and calculates the optimum flash light amount for the main light emission (flash shooting) based on the measured value (step S10). S11).

  Thereafter, the imaging control unit 8 controls the aperture diameter of the aperture mechanism 33 of the imaging unit 3 so that the aperture value determined in step S7 is obtained (step S12). Next, the imaging control unit 8 sets an exposure time for flash photography (step S13). In step S13, after setting the exposure time for flash photography, flash photography is performed with the flash quantity determined in step S11 (step S14). After the end of flash photography, the image calculation unit 4 reads a photographed image corresponding to FIG. 3A from the image sensor 34 (step S15).

  After flash photography, the imaging control unit 8 sets an exposure time for flashless photography (step S16). In the example of FIG. 2, flashless shooting is performed a plurality of times. However, the exposure times are not necessarily the same and may be variable. After setting the exposure time for flashless shooting, flashless shooting is performed (step S17). After the end of flashless shooting, the image calculation unit 4 reads a shot image corresponding to FIG. 3B from the image sensor 34 (step S18).

  Next, the imaging control unit 8 adds 1 to the parameter n indicating the number of times of flashless shooting (step S19), and determines whether or not this n has reached the number of consecutive shots N set by the user (step S19). Step S20). If it is determined in step S20 that n has not reached the number N of continuous shots, the process returns to step S16. On the other hand, if n has reached the number of consecutive shots N, the process proceeds to step S21 and subsequent steps.

  Here, between the first flash photography and the second and subsequent flashless photography, if the mechanical shutter system is used, a shutter charge time is required as preparation for operating the shutter mechanism. On the other hand, since the electronic shutter system is adopted in the first embodiment, no shutter charge time is required. In addition, the exposure of the image sensor 34 is started in order to adjust the exposure amount of the image sensor 34 by controlling the exposure time of the image sensor 34 by making the focus of the imaging lens 31 and the aperture of the aperture mechanism 33 the same in a series of photographing. The mechanical drive of the focus mechanism 32 and the diaphragm mechanism 33 does not intervene until the end of exposure. Therefore, the photographing time can be greatly shortened.

  After all exposures are completed, the imaging control unit 8 causes the image calculation unit 4 to perform background separation processing on the flash photographed image shown in FIG. 3A and each flashless photographed image shown in FIG. Then, the wall B as the background subject and the person A as the main subject are separated (step S21). Thereafter, the image calculation unit 4 obtains a difference in luminance between the flash photographed image (FIG. 3A) and each flashless photographed image (FIG. 3B) for each block. The distance relationship is recognized (step S22). That is, the section of the person A with a large luminance difference is recognized as a short-distance subject at a position close to the camera, and the section of the wall B with a small luminance difference is recognized as a long-distance object at a position far from the camera. Thereafter, the image calculation unit 4 extracts and synthesizes the section of the person A who is a short-distance subject from the flash photographed image and the section of the wall B which is a long-distance subject, and corresponds to FIG. Composite images for the number of continuous shots are generated (step S23). Note that the short distance subject and the long distance subject may be recognized based on the subject distance information by the distance measuring unit 7.

  In this way, a short-distance subject with a relatively strong flash is taken from a flash-captured image with less noise. Therefore, it is possible to obtain a composite image with a natural brightness balance and low noise as the entire image. Furthermore, as described above, the shooting interval between a series of shootings is greatly shortened.

  After step S23, the imaging control unit 8 displays the composite image on the display unit 5 (step S24), and the photographer confirms this.

  As described above, according to the first embodiment, the photographer can obtain a composite image with a natural balance of luminance and low noise in a short time by a single photographing instruction. That is, the exposure amount of the image sensor 34 is controlled by adjusting the exposure time while fixing the focus and the diaphragm after the release button is fully pressed and without using the mechanical shutter, and therefore includes a mechanical drive between photographing. Therefore, the shooting time can be shortened.

  Here, in the above-described first embodiment, the electronic shutter method is adopted as an exposure time adjustment method that does not use the mechanical shutter. However, in addition to this, for example, the light transmission state is changed by applying a voltage. It is also possible to employ a liquid crystal shutter that utilizes the properties of the liquid crystal to be produced.

  In addition, the light control method for determining the flash light emission amount of the light emitting unit 2 is not limited to the preliminary light emission light control method described above, but a flashmatic method for calculating the light emission amount of the flash light emitting unit 21 from the aperture value and the subject distance. It may be used.

  In the first embodiment described above, the blocks are divided by the background separation process, but may be divided by blocks having a predetermined shape such as a square.

  Further, in the first embodiment described above, an example in which n composite images are obtained by one flash shooting and n flashless shootings has been described. The present invention can also be applied to a case where a single composite image is obtained by performing the process one by one.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 4 shows a flowchart of the shooting operation in the second embodiment, and FIG. 5 shows the effect of shooting according to the flowchart of FIG. Here, it is assumed that the image sensor 34 in the second embodiment is an electronic shutter type image sensor capable of n-pixel mixed readout and all-pixel independent readout. Here, the n-pixel mixed readout is to read out signals by mixing (adding) signals of n pixels arranged in the vicinity among the pixels constituting the light receiving surface of the image sensor 34. By mixing and reading n pixels, it is possible to increase the luminance of the entire image while reducing the amount of noise. Further, the all-pixel independent reading is a signal reading independently from each pixel constituting the light receiving surface of the image sensor 34.

  In the process of FIG. 4 described below, the same processes as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  5A to 5C, A is a person, B is a wall farther than A, and C is a box closer to A. The difference in darkness of A, B, and C schematically shows the difference in luminance of the image. Further, FIG. 5 (a) is a diagram of a flash photographed image, FIG. 5 (b) is a diagram of a flashless photographed image, and FIG. 5 (c) is a luminance that increases the overall luminance of FIG. 5 (a). FIG. 5D is a diagram of an adjusted image, and FIG. 5D is a diagram of an image obtained by combining FIG. 5B and FIG. 5C.

  In FIG. 5A, the brightness increases in the order of the wall B, the person A, and the box C in inverse proportion to the distance to the camera. However, the wall B that is at a distance where the flash does not reach the person A and the box C. On the other hand, the brightness becomes extremely low. In FIG. 5B, since the brightness is balanced because it is flashless, and the sensitivity of the image sensor 34 is increased by mixing n pixels, the entire image has a brightness that is approximately between C and A in FIG. 5A. become. However, the resolution of the image is reduced by mixing n pixels.

  Next, the photographing operation of the flowchart of FIG. 4 will be described. First, the imaging control unit 8 stands by until the release button of the operation unit 9 is pressed (half-pressed) to the first stage (step S3).

  When the release button is pressed halfway in the determination in step S3, the imaging control unit 8 causes the distance measuring unit 7 to measure the subject distance for AF (step S4). After the subject distance is measured by the distance measuring unit 7, the imaging control unit 8 performs focus adjustment by operating the focus mechanism 32 of the imaging unit 3 based on the measurement result of the subject distance (step S5). The focus adjustment at this time adjusts the focus position of the imaging lens 31 so that the person A is in focus. Next, the imaging control unit 8 causes the photometry unit 6 to measure subject luminance under normal light (step S6). After the subject luminance is measured by the photometry unit 6, the imaging control unit 8 performs an exposure calculation based on the measurement result of the subject luminance, and the common aperture value, exposure time, and image sensor 34 are used when the flash is not emitted. The exposure conditions such as sensitivity are determined (step S7).

  After step S7, the imaging control unit 8 determines whether the release button of the operation unit 9 has been pressed to the second stage (fully pressed) (step S8). If it is determined in step S8 that the release button has not been fully pressed, it is determined whether the release button has been opened (step S9). If the release button is not released and is not fully pressed, the processes in steps S6 to S7 are repeated, and the exposure calculation is repeated so that the latest exposure is always obtained even if the photographing composition is changed. If it is determined in step S9 that the release button has been released, the process ends.

  Next, in step S8, when the release button is fully pressed, the imaging control unit 8 causes the flash light emitting unit 21 of the light emitting unit 2 to emit light and perform preliminary light emission. The light control unit 22 measures the reflected light from the subject subject to preliminary light emission by the flash light emitting unit 21 (step S10), and calculates the optimum flash light amount at the time of flash photographing based on the measured light value (step S11).

  Thereafter, the imaging control unit 8 controls the aperture diameter of the aperture mechanism 33 of the imaging unit 3 so that the aperture value determined in step S7 is obtained (step S12). Next, the imaging control unit 8 performs flashless shooting based on the exposure time during flashless shooting (step S31). After the end of flash photography, the image calculation unit 4 reads a photographed image corresponding to FIG. 5B from the image sensor 34 by n-pixel mixed readout (step S32). Thereafter, the imaging control unit 8 performs flash photography based on the exposure time during flash photography (step S33). After the end of flash photography, the image calculation unit 4 reads a photographed image corresponding to FIG. 5A from the image sensor 34 by independent reading of all pixels (step S34).

  As described above, in the second embodiment, the sensitivity of the image sensor 34 at the time of flashless imaging is increased by about n times while the noise is suppressed by reading out the image of the previously performed flashless imaging by n pixel mixture. At the same time, it can be read out at a speed about n times as high as that of independent reading of all pixels. Thereby, it is possible to further shorten the shooting interval between the flashless shooting and the flash shooting compared to the first embodiment. In addition, by performing dimming before the first flashless shooting instead of just before flash shooting, there is no extra operation between flashless shooting and flashless shooting. It is possible to shorten the shooting interval between flash shootings.

  After all exposure is completed, the imaging control unit 8 causes the image calculation unit 4 to perform background separation processing on the flash photographed image shown in FIG. 5A and the flashless photographed image shown in FIG. A wall B as a background subject, a person A as a main subject, and a box C as a sub subject are classified (step S35). After that, the image calculation unit 4 calculates the luminance difference between the flash photographed image shown in FIG. 5A and the flashless photographed image shown in FIG. 5B in the block including the best focus position (that is, the person A). Then, the brightness is adjusted so that the brightness in the block is higher in the flash photographed image (step S36). Specifically, in the second embodiment, since the focus is performed on the block in which the person A exists, a signal related to the person A in the flash photographed image is amplified by, for example, digital calculation, and flashless. The luminance is set higher than that of the person A in the photographed image. Thereby, the image shown in FIG. 5C is obtained.

  Next, the image calculation unit 4 compares the luminance of the flash photographed image adjusted in luminance shown in FIG. 5C with the luminance of the flashless photographed image shown in FIG. 5B for each block (step S37). A subject with high brightness is extracted and combined to obtain a combined image as shown in FIG. 3D (step S38).

  In this way, by adjusting the brightness of the flash photographed image before composition and then compositing, the block selected by the photographer in the composite image (for example, the block that is in focus. The flash image can be forcibly extracted from the block selected by operating. That is, it is possible to finish the block with high image quality by extracting it from the flash image with less noise, assuming that the block in focus is a block that the photographer wants to capture beautifully.

  After step S38, the imaging control unit 8 displays the composite image on the display unit 5 (step S39), and the photographer confirms this.

  As described above, according to the second embodiment, the reading interval of the flashless image for which the shooting sensitivity should be increased is set to the pixel mixture reading, so that the shooting interval between the flashless shooting and the flash shooting is set to the first. This can be further shortened compared to the embodiment. Also, by extracting a block that the photographer wants to capture beautifully from a flash image with little noise and using it for synthesis, a composite image with a natural balance of brightness and low noise can be obtained with a single shooting instruction. Obtainable.

  Although the present invention has been described above based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications and applications are naturally possible within the scope of the gist of the present invention.

  Further, the above-described embodiments include various stages of the invention, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some configuration requirements are deleted from all the configuration requirements shown in the embodiment, the above-described problem can be solved, and this configuration requirement is deleted when the above-described effects can be obtained. The configuration can also be extracted as an invention.

1 is a block diagram of a camera according to a first embodiment of the present invention. It is a flowchart shown about imaging | photography operation | movement in the camera of 1st Embodiment. It is a figure which shows the effect of imaging | photography according to the flowchart of FIG. It is a flowchart shown about imaging | photography operation | movement in the camera of 2nd Embodiment. It is a figure which shows the effect of imaging | photography according to the flowchart of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Light emission part, 3 ... Imaging part, 4 ... Image calculating part, 5 ... Display part, 6 ... Photometry part, 7 ... Distance measurement part, 8 ... Imaging control part, 9 ... Operation part, 21 ... Flash light emission part, 22 ... Dimming unit, 31 ... Imaging lens, 32 ... Focus mechanism, 33 ... Aperture mechanism, 34 ... Imaging element

Claims (9)

An image of a subject incident on the light receiving surface via an optical system is photoelectrically converted and output as a photographed image, and a plurality of light shielding members are not required to block the incidence of the subject image on the light receiving surface. An imaging unit that continuously outputs a plurality of captured images;
A light emitting unit for emitting a flash to the subject;
When continuously outputting a plurality of photographed images by the imaging unit, the first photographed image when the flash is emitted and the second photographed image when the flash is not emitted are included. An imaging control unit for controlling the light emitting unit;
A camera comprising: The imaging unit includes a diaphragm that limits an incident amount of an image of a subject incident through the optical system,
When the imaging control unit continuously outputs a plurality of captured images by the imaging unit, at least one of the focus state of the optical system and the aperture value of the aperture when each captured image is output. 2. The camera according to claim 1, wherein the cameras are controlled to be the same. The imaging control unit controls the light emitting unit so that the second captured image is captured prior to the first captured image;
The camera according to claim 1, wherein the imaging unit outputs a captured image generated by mixing a plurality of pixels located in the vicinity as the second captured image. The light-emitting unit includes a dimming unit that determines a flash amount prior to the flash emission,
4. The camera according to claim 3, wherein the imaging control unit determines the flash light amount by the dimming unit before the imaging unit outputs the second captured image. 5.   The camera according to claim 1, wherein the imaging unit receives the imaging instruction once and outputs the plurality of captured images continuously.   The camera according to claim 1, further comprising an image calculation unit that synthesizes the first captured image and the second captured image.   The image calculation unit divides the plurality of captured images into a plurality of blocks having the same configuration, the block including a subject located at a short distance in the first captured image, and the second captured image The camera according to claim 6, wherein the blocks including a subject located at a long distance are extracted and combined.   The image calculation unit divides the plurality of photographed images into a plurality of blocks having the same configuration, compares the brightness of the corresponding blocks of the first and second photographed images, and the brightness is high. The camera according to claim 6, wherein the blocks on the other side are extracted and synthesized.   The camera according to claim 7 or 8, wherein the image calculation unit extracts and synthesizes a selected block of the blocks from the first photographed image.

Images