JP5392336B2 - Imaging apparatus, imaging method, and imaging program - Google Patents

Description

  The present invention relates to a digital camera and the like, and relates to an imaging apparatus, an imaging method, and an imaging program that perform night scene photography.

  Conventionally, a digital camera has a so-called “night scene shooting” method in which a flash is emitted to shoot a person in front with an appropriate exposure, and a night scene in the background is shot at a considerably slow shutter speed, for example. It was.

  FIG. 13 is a timing chart showing an example of operation of a digital camera according to the prior art during night scene shooting. When shooting night scenes, the mechanical shutter is first opened, and when the shutter button is pressed, the flash is emitted for a predetermined time, and then the mechanical shutter is closed after the predetermined time has elapsed. As a result, an image of the person in the foreground is mainly captured during the flash emission period, and an image of the background (night view) is captured during the period from when the shutter button is pressed until the mechanical shutter is closed.

  In this case, it is necessary to slow down the shutter speed in order to obtain appropriate exposure in a background where the flash light is difficult to reach. When shooting the person and background in the foreground in this way, the shutter speed must be slowed down as a whole, so it is necessary to fix the digital camera body, such as a tripod, to prevent camera shake. It was. Also, there was a problem that if there were moving objects in the night view, the film flowed thinly.

Therefore, a technique has been proposed in which shooting with a flash and shooting without a flash are performed in response to a single shooting instruction, the correlation between both images is detected, and the shot image is corrected based on the correlation. (For example, refer to Patent Document 1).

JP 2000-102022 A

  However, with the above-described conventional technology, an image with a good balance between brightness and noise can be obtained even if the captured image is corrected using an image shot with the flash and an image shot without the flash. There is a problem that can not be. In addition, two complex operations, correlation detection processing for identifying an image portion affected by flash light and an image portion not affected by flash light, and image correction processing for the identified image portion are performed. Since it needs to be performed separately, there is a problem that the circuit configuration or software becomes complicated.

  Therefore, the present invention secures sufficient brightness for a photographed image, particularly in night photography, and obtains an image having a good balance with noise due to sensitivity change and camera shake due to shutter speed change by simple arithmetic processing. An object is to provide an imaging device, an imaging method, and an imaging program.

An image pickup apparatus according to the present invention has an image pickup means for picking up a subject image, an acquisition means for picking up images under two different shooting conditions by the image pickup means to acquire two image data, and a relationship between two luminance values in advance. By defining the relationship between the two luminance values and the composition ratio by subdividing the obtained region into a plurality of regions by dividing the region by a plurality of inclined boundary lines and assigning a different composition ratio for each region; Determination of determining a composition ratio corresponding to pixel values of two pixels to be combined based on the definition of the defining means when combining the two image data acquired by the acquisition means with different composition ratios for each pixel And a composite recording means for recording image data obtained by combining the two image data for each pixel at a composite ratio determined by the determining means.
The imaging method according to the present invention also includes an acquisition step of acquiring two image data by performing imaging under two different imaging conditions by an imaging means, and a boundary line that inclines a region obtained by the relationship between two luminance values. And subdividing into multiple regions by assigning different composition ratios to each region, assigning different composition ratios for each area, referring to the defining information that defines the relationship between the two luminance values and the composition ratios, and obtaining by the acquisition step A determining step of determining a combining ratio corresponding to pixel values of two pixels to be combined based on the defining information referred to in the reference step when combining the two image data with different combining ratios for each pixel; And a combination recording step for recording image data obtained by combining the two image data for each pixel at a combination ratio determined by the determination step. And wherein the Mukoto.
In addition, an imaging program according to the present invention includes an imaging unit that captures a computer of an imaging device, an acquisition unit that acquires two image data by performing imaging under two different imaging conditions using the imaging unit, By dividing the region obtained by the relationship between the two luminance values by a plurality of inclined boundary lines, the region is subdivided into a plurality of regions, and by assigning different composition ratios for each region, the two luminance values and the composition ratio A defining means for defining the relationship and a combining ratio corresponding to the pixel values of the two pixels to be combined when the two image data acquired by the acquiring means are combined at different combining ratios for each pixel. Determining means for determining based on the stipulations, and a composite recording device for recording image data obtained by combining the two image data for each pixel at a composite ratio determined by the determining means When, characterized in that to function with.

According to the present invention, an area obtained by the relationship between two luminance values is divided into a plurality of areas by dividing the area by a plurality of inclined boundary lines, and two synthesis ratios are assigned to each area, thereby The relationship between the luminance value and the composition ratio can be defined more flexibly. When two image data acquired by imaging under two different shooting conditions are combined at a different composition ratio for each pixel , a more balanced image Can be obtained by simple arithmetic processing.

It is a block diagram which shows the structure of the digital camera by 1st Embodiment of this invention. It is a timing chart which shows the operation | movement at the time of night view imaging | photography of the digital camera by this 1st Embodiment. It is a conceptual diagram which shows the threshold value at the time of synthesize | combining the image at the time of high sensitivity imaging | photography with the digital camera of this 1st Embodiment, and the image at the time of flash light emission imaging | photography. 4 is a flowchart for explaining the operation of the digital camera according to the first embodiment during night scene shooting. It is a schematic diagram which shows the image at the time of night view photography of the digital camera by this 1st Embodiment, and an example of an image synthesis. It is a conceptual diagram which shows the threshold value at the time of synthesize | combining the image at the time of high sensitivity imaging | photography with the digital camera of 2nd Embodiment of this invention, and the image at the time of flash light emission imaging | photography. It is a flowchart for demonstrating operation | movement at the time of night view imaging | photography of the digital camera by this 2nd Embodiment. It is a conceptual diagram which shows the threshold value at the time of synthesize | combining the image at the time of high sensitive imaging | photography with the digital camera of 3rd Embodiment of this invention, and the image at the time of flash light emission imaging | photography. It is a flowchart for demonstrating operation | movement at the time of night view imaging | photography of the digital camera by this 3rd Embodiment. It is a flowchart for demonstrating operation | movement at the time of night view imaging | photography of the digital camera by this 3rd Embodiment. It is a conceptual diagram which shows the threshold value at the time of synthesize | combining the image at the time of high sensitivity imaging | photography with the digital camera of 4th Embodiment of this invention, and the image at the time of flash light emission imaging | photography. It is a conceptual diagram which shows the threshold value at the time of synthesize | combining the image at the time of high sensitivity imaging | photography with the digital camera of the modification of this invention, and the image at the time of flash light emission imaging | photography. It is a timing chart which shows operation | movement of the digital camera at the time of night view photography by a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

A. First embodiment A-1. Configuration of First Embodiment FIG. 1 is a block diagram showing a configuration of a digital camera according to a first embodiment of the present invention. In the figure, the image acquisition unit 10 includes a lens 11, a shutter 12, and an LPF 13. The lens 11 is a normal optical lens and includes a lens group in which aspherical lenses are stacked. The shutter 12 is a so-called mechanical shutter that is operated by a driver 14 driven by the control unit 20 when a shutter button is operated. Depending on the digital camera, a mechanical shutter may not be provided. In the case of a model equipped with a retractable lens structure and a mechanical zoom, these drivers are also controlled by the driver 14. The LPF 13 is a crystal low-pass filter and is mounted to prevent the occurrence of moire.

  Next, the analog signal processing unit 15 includes an image sensor (CCD, CMOS) 16, a sampling / signal amplification processing unit 17, and an A / D converter 18. The imaging sensor 16 forms a subject image (image), and converts the intensity of light of each color of RGB into a current value. The sampling / signal amplification processing unit 17 performs correlated double sampling processing and signal amplification processing for suppressing noise and color unevenness. The A / D converter 18 is also called an analog front end, and converts the sampled / amplified analog signal into a digital signal (converts each color of RGB and CMYG into 12-bit data and outputs it to the bus line).

  Next, the control unit (CPU) 20 controls the entire digital camera 1 (imaging device) according to a program stored in a program memory described later. In particular, in the first embodiment, in night scene shooting, a background night scene and a subject (such as a person) in the foreground are shot by two exposures. Although details will be described later, in the first shooting (high-sensitivity shooting), the ISO sensitivity is increased and exposed, and in the second shooting (flash flash shooting), the ISO sensitivity is decreased and the flash is emitted for exposure. Then, the first image and the second image are combined according to a predetermined threshold and a predetermined combining ratio (weight) described later. The control unit 20 controls the operation at the time of night scene shooting, image capture, image composition, and the like.

  The preview engine 22 is stored in the image buffer 26 immediately after detection of digital data input via the image acquisition unit 10 and the analog signal processing unit 15 in the recording mode (also referred to as recording mode or photographing mode) or shutter operation detection. Thinning processing is performed in order to display the digital data and the digital data stored in the image memory 31 on the display unit 25. The D / A converter 23 converts the digital data thinned out by the preview engine 22 and outputs it to the driver 24 at the subsequent stage.

  The driver 24 includes a buffer area for temporarily storing digital data displayed on the display unit 25 at the subsequent stage, and drives the display unit 25 based on a control signal input via the key operation unit 27 and the control unit 20. The display unit 25 includes a color TFT liquid crystal, an STN liquid crystal, or the like, and displays a preview image, image data after shooting, a setting menu, and the like.

  The image buffer 26 temporarily stores digital data immediately after photographing until it is input via the analog signal processing unit 15 or the digital signal processing unit 28 and passed to the digital signal processing unit 28. The key operation unit 27 includes a shutter button, a recording / playback mode selection slide switch, a menu button, a cross key (determined by pressing the center), and the like.

  The digital signal processing unit 28 performs white balance processing, color processing, gradation processing, contour emphasis, conversion from RGB format to YUV format, YUV format for digital data input via the analog signal processing unit 15. To JPEG format. In particular, in the first embodiment, the digital signal processing unit 28 emits a flash by lowering the ISO sensitivity and the image of the first shooting (high-sensitivity shooting), which is exposed with increased ISO sensitivity during night scene shooting. The image obtained by the second shooting (flash flash shooting) is then combined in accordance with a predetermined threshold value and a predetermined combining ratio (weight) described later.

  The image compression / decompression processing unit 29 compresses and encodes the digital data input via the digital signal processing unit 28 into the JPEG format, generates a motion JPEG format movie file, or converts the motion JPEG format movie file to MPEG. It is converted into a moving image file in a format, or in a reproduction mode, a moving image file in JPEG format, motion JPEG format, or MPEG format is expanded.

  The program memory 30 stores various programs loaded in the control unit 20, EV values in the best shot function, color correction information, and the like. The image memory 31 stores image data temporarily stored in the image buffer 26, digital data converted into various file formats, moving image data, and the like. The card I / F 32 controls data exchange between the external recording medium 33 and the imaging apparatus main body.

  The external recording medium 33 is a detachable recording medium composed of a compact flash (registered trademark), a memory stick, an SD card, or the like. The external connection I / F 34 includes a USB connector slot and the like, is connected to a personal computer or the like, and is used for transferring photographed image data. The RAM 35 stores various parameters necessary for control of the control unit (CPU) 20, various parameters at the time of night scene shooting (gain (ISO sensitivity), aperture, shutter speed, threshold for image composition, weight, etc.), and the like. .

  Next, FIG. 2 is a timing chart showing the operation of the digital camera according to the first embodiment during night scene shooting. During night scene shooting, first, when the mechanical shutter is opened and the shutter button is pressed, first, in the exposure period ET1, the ISO sensitivity is increased to expose the image, the mechanical shutter is closed, and the data is transferred in the transfer period TT1. Read with. This image corresponds to an image of a night view of the background (far view). Thereafter, the mechanical shutter is immediately opened, the ISO sensitivity is lowered, the flash is emitted, the exposure is performed with the exposure time ET2, the data is read out in the transfer period TT2 after the mechanical shutter is closed. The image corresponds to an image of a subject such as a person in front.

  Next, FIG. 3 is a conceptual diagram showing a threshold when combining an image at the time of high-sensitivity shooting with the digital camera of the first embodiment and an image at the time of flash emission shooting. In the first embodiment, for the image data D2 captured at the time of the second flash photography, it is determined for each pixel whether the luminance value of the pixel is larger than the threshold value THA, and the luminance value of the pixel is larger than the threshold value THA. If it is in A, the pixel of the image data D2 (D1 × 0% + D2 × 100%) captured at the time of the second flash photography is used, and if the luminance value of the pixel is equal to or lower than the threshold THA and in the region B, the first time An image for recording is obtained by synthesizing images using pixels of image data D1 (D1 × 100% + D2 × 0%) during high-sensitivity shooting. The synthesis ratio of the threshold THA and the image data D1 and D2 is stored in the above-described RAM 35 in the form of a data table or a calculation formula.

AB. Operation of the First Embodiment Next, the operation of the first embodiment will be described. Here, FIG. 4 is a flowchart for explaining the operation of the digital camera according to the first embodiment during night scene shooting. FIG. 5 is a schematic diagram showing an image at the time of night scene shooting and an example of image synthesis.

  When night scene shooting is selected, first, as a high sensitivity setting, the aperture is opened, the gain (ISO sensitivity) is set to the maximum, and the shutter speed is set to the maximum time without camera shake (step S10). Next, when the shutter button is pressed, high-sensitivity exposure (exposure period ET1 shown in FIG. 2) is performed, and a night view of a distant view is mainly photographed (step S12), which is transferred to the image buffer 26 as image data D1 and temporarily stored. Save (step S14). As shown in FIG. 5A, the night scene image is taken in a better state of the night scene as a background without camera shake. However, the foreground subject is underexposed.

  Next, as the flash exposure setting, the gain (ISO sensitivity) is set to the minimum, the flash is set to the maximum light emission, and others are set so that the highest quality image can be taken under the above two conditions (step S16). Next, a flash is emitted for exposure (exposure period ET2 shown in FIG. 2), a subject (such as a person) in the foreground is photographed (step S18), transferred to the image buffer 26 as image data D2, and temporarily stored (step S18). Step S20). As shown in FIG. 5B, the close-up image is taken in a better state of the person who is the subject. However, the night view of the distant view is underexposed because the flash light does not reach and the exposure time ET2 is short.

  Next, a loop process for creating data for each pixel is executed in steps S22 to S32. First, the image data D2 at the time of flash photography is read at a predetermined coordinate (step S24), and it is determined whether or not the luminance value of the image data D2 exceeds the threshold value THA (step S26). When the luminance value at the time of flash photography is greater than the threshold value THA, that is, when it is the area A in FIG. 2, the image data D2 at the time of flash photography (D1 × 0% + D2 × 100%). Is stored in the image memory 31 as composite data (step S28).

  On the other hand, when the luminance value at the time of flash photography does not exceed the threshold value THA, that is, in the region B in FIG. 2, the image data D1 (D1 × 100% + D2 × 0) at the time of the first high-sensitivity photography. %) Is stored in the image memory 31 as composite data (step S30). The above processing is performed for all pixels to obtain recording image data.

  As a result, as shown in FIG. 5C, the synthesized image is composed of a night view taken in a better state and a subject in the foreground taken in a better state. The captured image has a good balance of the / N ratio.

B. Second Embodiment Next, a second embodiment of the present invention will be described. The configuration of the digital camera is the same as that in FIG. Also, the operation of the digital camera at the time of night view shooting is the same as the timing chart shown in FIG. In the second embodiment, the method of setting the threshold value when the first image and the second image are combined is changed, and the threshold value THB is set at 1: 1 as shown in FIG. For each pixel, compare the brightness value of the image captured during the first high-sensitivity shooting with the brightness value of the image captured during the second flash shooting, and synthesize the image using the pixel with the higher luminance value. Thus, an image for recording is obtained.

  That is, if the luminance value of the pixel of the image captured at the second flash photography is larger, in other words, if it is in the area A, the image data D2 is the pixel value of the image captured at the second flash photography. (D1 × 0% + D2 × 100%) is used, and if the luminance value of the pixel of the image captured at the time of the first high-sensitivity shooting is larger, in other words, if it is in the region B, the first high-sensitivity shooting An image for recording is obtained by combining images using image data D1 (D1 × 100% + D2 × 0%) which is a pixel value of the captured image. The synthesis ratio of the threshold THB and the image data D1 and D2 is stored in the RAM 35 in the form of a data table or a calculation formula.

B-2. Operation of the Second Embodiment Next, the operation of the second embodiment described above will be described. Here, FIG. 7 is a flowchart for explaining the operation of the digital camera according to the second embodiment during night scene shooting. When night scene shooting is selected, first, as a high sensitivity setting, the aperture is opened, the gain (ISO sensitivity) is set to the maximum, and the shutter speed is set to the maximum time without camera shake (step S40). Next, when the shutter button is pressed, high-sensitivity exposure (exposure period ET1 shown in FIG. 2) is performed, and a night view of a distant view is mainly photographed (step S42), which is transferred to the image buffer 26 as image data D1 and temporarily stored. Save (step S44). As shown in FIG. 5A, the night scene image is taken in a better state of the night scene as a background without camera shake. However, the foreground subject is underexposed.

  Next, as the flash exposure setting, the gain (ISO sensitivity) is set to the minimum, the flash is set to the maximum light emission, and others are set so that the highest quality image can be taken under the above two conditions (step S46). Next, the flash is fired for exposure (exposure period ET2 shown in FIG. 2), a subject (such as a person) in the foreground is photographed (step S48), transferred to the image buffer 26 as image data D2, and temporarily stored (step S48). Step S50). As shown in FIG. 5B, the close-up image is taken in a better state of the person who is the subject. However, the night view of the distant view is underexposed because the flash light does not reach and the exposure time ET2 is short.

Next, a loop process for creating data for each pixel is executed in steps S52 to S62. First, the predetermined coordinate, reading the image data D2 at the time of image data D1 and flash photography High ISO speed (step S54), the luminance value of the image data D1 whether larger than the luminance value of the image data D2 Is determined (step S56). If the luminance value at the time of high-sensitivity shooting is larger, that is, in the region B of FIG. 6, the image data D1 (D1 × 100% + D2 × 0%) at the time of the first high-sensitivity shooting is obtained. The synthesized data is stored in the image memory 31 (step S58).

  On the other hand, when the luminance value at the time of flash photography is larger, that is, in the area A of FIG. 6, the image data D2 (D1 × 0% + D2 × 100%) at the time of the second flash photography is obtained. The synthesized data is stored in the image memory 31 (step S60). The above processing is performed for all pixels to obtain recording image data.

  As a result, the synthesized image is composed of a night view taken in a better state and a subject in the foreground taken in a better state, and has a good balance between exposure and S / N ratio without camera shake. It becomes.

C. Third Embodiment Next, a third embodiment of the present invention will be described. The configuration of the digital camera is the same as that in FIG. In the third embodiment, the threshold value and the composition ratio for combining the first image and the second image are changed, and threshold values THC1 and THC2 are provided as shown in FIG. The area obtained by the relationship between the brightness value of the image and the brightness value at the time of high-sensitivity shooting is subdivided into four areas A to D. Note that the boundary between the region B and the region C is determined by size comparison. Then, for each pixel, the luminance value of the image captured at the first high-sensitivity shooting is compared with the luminance value of the image captured at the second flash shooting, and it is determined whether the luminance value is in which area. The pixel composition ratio to be used as the (image) is determined.

  For example, in the area A, the pixel value of the composite image is set to the image data D1 × 0% at the time of high sensitivity shooting + the image data D2 × 100% at the time of flash shooting, and in the area B, the image data D1 at the time of high sensitivity shooting. X25% + image data D2 × 75% during flash photography, and in area C, image data D1 × 75% during high sensitivity photography + image data D2 × 25% during flash photography, and in area D, D1 × 100% + D2 × 0%. The synthesis ratios of the threshold values THC1 and THC2 and the image data D1 and D2 are stored in the above-described RAM 35 in the form of a data table or a calculation formula.

  Next, the operation of the third embodiment will be described. Here, FIGS. 9 and 10 are flowcharts for explaining the operation of the digital camera according to the third embodiment at the time of night scene shooting. When night scene shooting is selected, first, as a high sensitivity setting, the aperture is opened, the gain (ISO sensitivity) is set to the maximum, and the shutter speed is set to the maximum time without camera shake (step S70). Next, when the shutter button is pressed, high-sensitivity exposure (exposure period ET1 shown in FIG. 2) is performed, and a night view of a distant view is mainly photographed (step S72), which is transferred to the image buffer 26 as image data D1 and temporarily stored. Save (step S74). As shown in FIG. 5A, the night scene image is taken in a better state of the night scene as a background without camera shake. However, the foreground subject is underexposed.

  Next, as the flash exposure setting, the gain (ISO sensitivity) is set to the minimum, the flash is set to the maximum light emission, and others are set so that the highest quality image can be taken under the above two conditions (step S76). Next, a flash is emitted for exposure (exposure period ET2 shown in FIG. 2), a subject (such as a person) in the foreground is photographed (step S78), transferred to the image buffer 26 as image data D2, and temporarily stored (step S78). Step S80). As shown in FIG. 5B, the close-up image is taken in a better state of the person who is the subject. However, the night view of the distant view is underexposed because the flash light does not reach and the exposure time ET2 is short.

Next, a loop process for creating data for each pixel is executed in steps S82 to S104. First, the predetermined coordinate, reading the image data D2 at the time of image data D1 and flash photography High ISO speed (step S84), the luminance value of the image data D1 whether larger than the luminance value of the image data D2 Is determined (step S86). When the brightness value of the image data D1 at the time of high-sensitivity shooting is larger, that is, in the region C or the region D in FIG. 8, the brightness value of the image data D1 and the brightness value of the image data D2 are It is determined whether or not the difference is larger than a threshold value THC2 shown in FIG. 8 (step S88). If the difference between the luminance value of the image data D1 and the luminance value of the image data D2 is larger than the threshold value THC2, it is determined that the region is in the region D, and the image data D1 (D1 × 100) at the time of the first high-sensitivity shooting. % + D2 × 0%) is stored in the image memory 31 as composite data (step S90).

  On the other hand, when the difference between the luminance value of the image data D1 and the luminance value of the image data D2 is equal to or less than the threshold value THC2, it is determined that the region is in the region C, and the combined image data Db is image data D1 × 3/4 + image data. D2 × 1/4 is calculated (step S92), and the composite image data Db is stored in the image memory 31 (step S94).

  On the other hand, if the brightness value of the image data D2 at the time of flash photography is larger in step S86, that is, if it is the area A or the area B in FIG. 8, the brightness value of the image data D1 and the image data It is determined whether or not the difference between the luminance value of D2 is larger than the threshold value THC1 shown in FIG. 8 (step S96). If the difference between the luminance value of the image data D1 and the luminance value of the image data D2 is smaller than the threshold value THC1, it is determined that the region is in the region B, and the combined image data Dc is image data D1 × 1/4 + image data. D2 × 3/4 is calculated (step S98), and the composite image data Dc is stored in the image memory 31 (step S100).

  On the other hand, when the difference between the luminance value of the image data D1 and the luminance value of the image data D2 is equal to or greater than the threshold value THC1, it is determined that the area is A, and the image data D2 (D1 × 0) at the time of the second flash photography. % + D2 × 100%) is stored in the image memory 31 as composite data (step S102).

  As a result, the synthesized image is composed of a night view taken in a better state and a subject in the foreground taken in a better state, and has a good balance between exposure and S / N ratio without camera shake. It becomes.

D. Fourth Embodiment Next, a fourth embodiment of the present invention will be described. The configuration of the digital camera is the same as that in FIG. In the fourth embodiment, the threshold value and the composition ratio for combining the first image and the second image are changed, and threshold values THD1 to THD4 are provided as shown in FIG. The area obtained by the relationship between the brightness value of the image and the brightness value at the time of high-sensitivity shooting is subdivided into nine areas A to I. Then, for each pixel, the luminance value of the image captured at the first high-sensitivity shooting is compared with the luminance value of the image captured at the second flash shooting, and it is determined whether the luminance value is in which area. The pixel composition ratio to be used as the (image) is determined.

  For example, in regions A and I, the pixel values of the composite image are set to image data D1 × 50% at the time of high-sensitivity shooting + image data D2 × 50% at the time of flash shooting, and regions B, C, E, G, H The image data D1 × 0% at the time of high-sensitivity shooting and the image data D2 × 100% at the time of flash shooting are set. In the regions D and F, the image data D1 × 100% at the time of high-sensitivity shooting + The image data D2 × 0%. The synthesis ratios of the threshold values THD1 to THD4 and the image data D1 and D2 are stored in the above-described RAM 35 in the form of a data table or a calculation formula. Note that the region determination and the image composition are basically the same as those in the third embodiment described above, and thus the description thereof is omitted.

E. Modified Example Next, a modified example of the present invention will be described. In the first to fourth embodiments described above, different composition ratios are clearly set for each region for determining the pixel composition ratio. That is, in the adjacent regions, the composition ratios are different even when they exist in the vicinity of the boundary. On the other hand, in this modification, as shown in FIG. 12, for example, the boundary portion between the region A and the region B is divided into finer regions C1 to C6, and the composition ratio is changed stepwise. . This makes it possible to obtain a finer composite image.

  As another modification, as described above, the boundary portion between the region A and the region B may not be divided more finely, but the synthesis ratio may actually be gradually changed by an analog circuit. Further, although the pixel value at each position is determined by combining the pixels at the same position, pixels in the peripheral area may be used. Three or more captured images may be used.

  In the above-described embodiment, identification processing for accurately identifying the front subject portion and the background subject portion is performed by simultaneously performing identification and pixel synthesis of the front subject portion and the background subject portion. Although not required, if distance measurement information indicating the distance to the subject can be used, the distance information may be used for identification.

  In the above-described embodiments, different pixel composition methods have been described as different embodiments. However, one pixel composition method is set in advance by mode selection from a plurality of pixel composition methods, and a shooting instruction is issued. At this time, the setting mode may be determined, and pixel synthesis may be executed according to the selected pixel synthesis method. In this case, the setting of the pixel synthesis mode may be arbitrarily specified by the user, may be set automatically by sensing external brightness with a sensor, or based on image information obtained by the image sensor. May be set automatically.

  In the above-described embodiment, only the digital camera has been described. However, the present invention is not limited to this, and the present invention may be applied to an electronic apparatus including an imaging device such as a mobile phone. In addition, the image composition processing and the like according to the above-described embodiment are realized by software control by the control unit 20, and all or part of them is considered in consideration of processing speed, versatility, device size, cost, and the like. May be realized by a circuit.

1 Digital Camera 10 Image Acquisition Unit 11 Lens 12 Shutter 13 LPF
14 Driver 15 Analog Signal Processing Unit 16 Imaging Sensor (Imaging Means)
17 Sampling / Signal Amplification Processing Unit 18 A / D Converter 19 Flash (Light Emitting Unit)
20 control unit (photographing sensitivity setting means, photographing control means)
22 Preview Engine 23 D / A Converter 24 Driver 25 Display Unit 26 Image Buffer 27 Key Operation Unit 28 Digital Signal Processing Unit (Composition Unit)
29 Image compression / decompression processing unit 30 Program memory 31 Image memory 32 Card I / F
33 External recording medium 34 I / F for external connection
35 RAM

Claims (6)

Imaging means for capturing a subject image;
Obtaining means for obtaining two image data by performing imaging under two different photographing conditions by the imaging means;
By dividing a region obtained by the relationship between two luminance values in advance with a plurality of inclined boundary lines, the region is subdivided into a plurality of regions, and by assigning a different composition ratio for each region, two luminance values and a composition ratio Defining means for defining the relationship between
Determination of determining a composition ratio corresponding to pixel values of two pixels to be combined based on the definition of the defining means when combining the two image data acquired by the acquisition means with different composition ratios for each pixel Means,
Synthesis recording means for recording image data obtained by synthesizing the two image data for each pixel at a synthesis ratio determined by the determination means;
An imaging apparatus comprising: Further comprising a light emitting means,
Said acquisition means, according to claim 1, characterized in that acquires image data captured by the image pickup means said light emitting means and the image data picked up by the image pickup means by emitting the light emitting means without emitting Imaging device. The acquisition unit increases the imaging sensitivity when imaging by the imaging unit without causing the light emitting unit to emit light, and decreases the imaging sensitivity when imaging by the imaging unit by causing the light emitting unit to emit light. The imaging apparatus according to claim 2 .   The acquisition unit obtains the two image data by continuously performing imaging by the imaging unit that does not cause the light emitting unit to emit light and imaging by the imaging unit that causes the light emitting unit to emit light according to a single shooting instruction. The imaging apparatus according to claim 2 or 3, wherein An acquisition step of performing imaging under two different imaging conditions by an imaging means to acquire two image data;
By dividing the region obtained by the relationship between the two luminance values by a plurality of inclined boundary lines, it is subdivided into a plurality of regions, and by assigning a different composition ratio for each region, the relationship between the two luminance values and the composition ratio A reference step for referring to regulation information that defines
When the two image data acquired in the acquisition step are combined at different combining ratios for each pixel, the combining ratio corresponding to the pixel values of the two pixels to be combined is based on the defining information referred to in the referring step. A decision step to decide,
A composite recording step for recording image data obtained by combining the two image data for each pixel at a composite ratio determined by the determination step;
An imaging method comprising: The computer of the imaging device,
Imaging means for capturing a subject image;
Obtaining means for obtaining two image data by performing imaging under two different photographing conditions by the imaging means;
By dividing a region obtained by the relationship between two luminance values in advance with a plurality of inclined boundary lines, the region is subdivided into a plurality of regions, and by assigning a different composition ratio for each region, two luminance values and a composition ratio Defining means for defining the relationship between
Determination of determining a composition ratio corresponding to pixel values of two pixels to be combined based on the definition of the defining means when combining the two image data acquired by the acquisition means with different composition ratios for each pixel Means,
Synthesis recording means for recording image data obtained by synthesizing the two image data for each pixel at a synthesis ratio determined by the determination means;
An imaging program characterized by causing the function to function.

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