JP2006352229A - Digital camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital camera for storing an image photographed in a multiple exposure imaging mode together with an original image to a recording medium. <P>SOLUTION: An image processing circuit 6 sets a digital gain of each image imaged by an imaging element 2 in the multiple exposure mode depending on the number of frames imaged in the multiple exposure mode and composes the images by reducing the gain of each image on the basis of the set digital gain and thereafter summating pixel data at the same positions of each image. It can be set so that only the composite image is stored in the recording medium 11 or stored together with the original image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital camera with a multiple exposure function that combines images captured by multiple exposure.

  The following digital camera is known from Patent Document 1. A multiple-exposure photographed image is generated by superimposing a plurality of images captured by multiple exposure, the multiple-exposure photographed image is stored, and unnecessary original images are deleted.

JP 2003-69888 A

  However, in the conventional digital camera, since only the multiple exposure photographed image is stored, the original image cannot be referred to.

(1) The digital camera according to the first aspect of the invention stores a plurality of images captured by the image sensor when the multiple exposure shooting mode is set, and is stored in the storage unit. When performing a process of recording a multiple-exposure photographed image synthesized by the synthesizing unit on a recording medium by combining a plurality of images and generating a multiple-exposure photographed image, the image is stored in the storage unit together with the multiple-exposure photographed image And a recording control means for recording the original image before composition on a recording medium.
(2) The invention described in claim 2 is a digital camera according to claim 1, wherein when performing the process of recording the multiple exposure photographed image on the recording medium, the first recording mode records only the multiple exposure photographed image. And a recording selection means for selecting a second recording mode for recording the multiple-exposure photographed image and the original image.
(3) The invention described in claim 3 is the digital camera according to claim 2, wherein a gain determined so that the sum is 1 based on the number of multiple exposure shots is given to a plurality of captured images. And a gain applying unit for generating the multiple exposure photographed image by combining the plurality of images after the gain is applied by the gain applying unit.
(4) According to a fourth aspect of the present invention, in the digital camera according to the third aspect, when the image is combined by the combining unit, a gain is applied by the gain applying unit, and then a plurality of images are combined and multiple exposure shooting is performed. The image processing apparatus further includes a combination selection unit that selects a first combination mode for generating an image and a second combination mode for combining a plurality of images and generating a multiple-exposure photographed image without applying gain by the gain applying unit. It is characterized by that.
(5) According to the invention described in claim 5, in the digital camera according to claim 4, when the second recording mode is selected by the recording selection unit, the synthesis unit selects the second synthesis mode by the synthesis selection unit. Even after the gain is applied to the original image by the gain applying means, a plurality of images are combined to generate a multiple exposure photographed image, and the recording control means multi-exposures the original image to which no gain is applied. It records on a recording medium with a picked-up image, It is characterized by the above-mentioned.
(6) The invention described in claim 6 is the digital camera according to claim 1, wherein a gain determined so that the sum is 1 based on the number of multiple exposure shots is given to a plurality of captured images. And a gain applying unit configured to generate a multiple-exposure photographed image by combining a plurality of images after the gain is applied by the gain applying unit.
(7) According to the seventh aspect of the present invention, in the digital camera according to the sixth aspect, when the image is combined by the combining unit, a gain is applied by the gain applying unit, and then a plurality of images are combined to perform multiple exposure shooting. The image processing apparatus further includes a combination selection unit that selects a first combination mode for generating an image and a second combination mode for combining a plurality of images and generating a multiple-exposure photographed image without applying gain by the gain applying unit. It is characterized by that.

  According to the present invention, since the original image is stored together with the multiple exposure photographed image, the original image can be referred to as necessary.

  FIG. 1 is a block diagram illustrating a configuration of an embodiment of a digital camera according to the present embodiment. The digital camera 100 includes a photographing lens 1, an image sensor 2 such as a CCD, an A / D conversion circuit 3 that converts an analog signal output from the image sensor 2 into a digital signal, and a timing signal for the image sensor 2. A timing generator (TG) 4 for giving, an image memory (semiconductor memory) 5 for temporarily storing a plurality of captured images, an image processing circuit 6 for executing various image processing described later, and image processing by the image processing circuit 6 The compressed image data is compressed and converted into an image format such as JPEG, the display circuit 8 performs display processing for displaying the captured image on a display device 9 such as a TFT, and the compression circuit 7 compresses the image data. A memory 10 for temporarily storing the image data and a removable memory card or the like for copying and saving the image data stored in the memory 10 A recording medium 11, and a CPU12 which controls the digital camera 102, an input device 13, including a release button and various setting buttons operated by the user.

  In addition to the image display function described above, a menu for changing various setting values of the digital camera 100 is displayed on the display device 9, and the user operates the input device 13 in accordance with the displayed menu. The setting of the digital camera 100 can be changed.

  In the digital camera 100, when the user presses the release button, shooting is performed with an aperture and a shutter speed set according to the luminance of the subject, and charges corresponding to the subject image are accumulated in the image sensor 2. The The electric charge accumulated in the image pickup device 2 is converted into a digital signal by the A / D conversion circuit 3, and raw image data before various image processing is performed, that is, RAW data is stored in the image memory 5. The image memory 5 is a buffer memory and can store a plurality of pieces of RAW data.

  The image processing circuit 6 reads RAW data stored in the image memory 5 and performs known image processing such as interpolation, color temperature correction, and gradation correction, automatic gain correction described later, and image synthesis. Thereafter, the compression circuit 7 compresses and converts the image data into a predetermined compression format, for example, JPEG format, and stores it in the memory 10. The image data stored in the memory 10 is copied or stored in the recording medium 11 automatically or according to an instruction from the user. The image data that has been subjected to image processing by the image processing circuit 6 is subjected to display processing by the display circuit 8 and displayed on the display device 9.

  The digital camera 100 according to the present embodiment is capable of imaging by multiple exposure. When the multiple exposure shooting mode is set, an image having the number of frames (number of frames) preset by the user is displayed in the multiple exposure shooting mode. Take an image with. In addition, the original image used for synthesizing the multiple exposure photographed image can also be saved.

When the user designates the multiple exposure shooting mode, the multiple exposure setting screen shown in FIG. On the multiple exposure setting screen, the following three items can be set.
(A) The number of frames to be captured by multiple exposure is input and set in the frame number input field 2a. The number of frames can be arbitrarily set within a predetermined range, for example, between 2 frames and 10 frames.
(B) The user sets whether or not to perform automatic gain correction described later. Whether or not to perform automatic gain correction is set by selecting either “do not” (invalid) or “enable” (valid) automatic gain correction in the automatic gain correction setting field 2b. Note that, when the number of frames is not set in the frame number input field 2a, imaging by multiple exposure is not performed.
(C) The necessity of saving the original image used for the synthesis of the multiple exposure photographed image is set. This is set by selecting either “leave” or “do not leave” the original image in the original image storage necessity column 2c.

  In the multiple exposure shooting mode setting state where the number of frames for multiple exposure shooting is set by the user, each time the release switch is pressed, each frame is set with the set exposure value until the set number of frames is shot. An image is taken. Then, image data of each frame, that is, RAW data is stored in the image memory 5. For example, when the number of frames is set to 5, RAW data of 5 frames of image 1 to image 5 is stored in the image memory 5 as shown in FIG.

  The image processing circuit 6 adds and combines all the RAW data stored in the image memory 5. At this time, if the automatic gain correction is set to “OFF” on the multiple exposure setting screen shown in FIG. 2, all the RAW data stored in the image memory 5 are sequentially added and combined. That is, since each RAW data stored in the image memory 5 is digital data obtained by digitizing the charges output from each pixel of the image sensor 2, synthesis is performed by adding pixel data at the same position on the image. Is possible. Therefore, for example, after adding the image 2 to the image 1 (image 1 + image 2), and further adding the image 3 to the addition result, the images can be combined in order.

However, if the RAW data stored in the image memory 5 is synthesized as it is, there is a possibility that the image will be overexposed. Therefore, in order to avoid this, it is necessary to set the exposure value to be underexposed according to the number of frames to be subjected to multiple exposure. For example, when performing multiple exposure of 5 frames, the following equation (1) Therefore, it is necessary to calculate and set an appropriate exposure value.
Proper exposure value = Log (1/5) /Log2=2.3 (1)
Accordingly, it is understood that when multiple exposure of 5 frames is performed, it is only necessary to set the exposure under 2.3 steps in advance before imaging.

However, it is not preferable to calculate the appropriate exposure according to the number of frames to be subjected to multiple exposure each time when shooting with multiple exposure as described above, because the operation becomes complicated. Therefore, in the present embodiment, when the automatic gain correction is set to “Yes” on the multiple exposure setting screen shown in FIG. 2, each RAW data stored in the image memory 5 is digitally reduced in advance. Then, the pixel data at the same position on the image are added to be combined. For example, when five frames of multiple exposure are performed, the five pieces of RAW data stored in the image memory 5 are automatically gain set in advance by the following equation (2), that is, the gain is reduced and then added.
K1, image 1 + K2, image 2 + K3, image 3 + K4, image 4 + K5, image 5 (2)

  In Expression (2), variables K1 to K5 indicate the digital gain of each image, and are set so that the sum thereof is 1. For example, 1 is divided by the number of frames and multiplied (applied) to each image, such as K1 = K2 = K3 = K4 = K5 = 0.2, so that all images are gained down with the same digital gain. Can do. Further, by setting K1> K2> K3> K4> K5, the later captured RAW data becomes darker, and the image can be displayed so as to fade out, and K1 <K2 <K3 <K4 <K5. By doing this, the later captured RAW data becomes brighter and the image can be displayed so as to fade in.

  In this way, by multiplying each RAW data imaged by multiple exposure by a gain whose sum is 1 and reducing the gain, and adding the combined data, it is possible to prevent overexposure during synthesis. It is possible to obtain a multiple-exposure photographed image with proper exposure. Further, in the above-described method in which the raw data stored in the image memory 5 is synthesized as it is, when there are a large number of frames to be imaged by preset multiple exposure, the data is added in the middle of adding the raw data. Although there is a possibility of overflow, according to the present invention, since the gain is reduced before adding, it is possible to avoid this.

  Further, in this embodiment, when the original image is set to “not leave”, when the multiple exposure shooting is completed and the multiple exposure shooting image is recorded on the recording medium 11, only the multiple exposure shooting image is recorded. It is stored in the recording medium 11. On the other hand, when the original image is set to “leave”, when the multiple-exposure shooting is completed and the multiple-exposure shot image is recorded on the recording medium 11, the original image is stored in the recording medium 11 together with the multiple-exposure shot image. Is done.

  The case where “Yes” (valid) for automatic gain correction is selected is referred to as a first synthesis mode, and the case where “No” (invalid) for automatic gain correction is selected is referred to as a second synthesis mode. Further, the case where “Do not leave” the original image is selected is called a first recording mode, and the case where “Leave” the original image is selected is called a second recording mode.

Furthermore, in the present embodiment, the following processing is performed so that a multiple-exposure photographed image with a proper exposure can be obtained even when multiple exposure is interrupted in the middle. In addition, as a case where multiple exposure is interrupted in the middle, for example,
(A) When interruption of multiple exposure is instructed by the operation of the input device 13 by the user,
(B) When the digital camera 100 has a function of automatically turning off the power when the digital camera 100 is not operated for a predetermined time set in advance, the power is automatically turned off without being operated for the predetermined time. When
(C) When the input device 13 is operated by the user and the power of the digital camera 100 is turned off, one of the cases can be considered, and these are controlled by the CPU 12.

  When the image processing circuit 6 determines that the multiple exposure is interrupted in the middle according to any of the above (A) to (C), the image processing circuit 6 uses the formula (2) based on the RAW data of the number of frames captured at the time of the interruption. ). For example, when the number of frames to be captured by multiple exposure is set to 8, if there is no interruption, the digital gain is set so that the sum of K1 to K8 is 1 for the captured 8 frames of RAW data. Based on (2), composition is performed with automatic gain setting, but if multiple exposure is interrupted at the time of five-frame imaging, the sum of K1 to K5 is 1 for the captured five-frame RAW data. In this way, the digital gain is set and the automatic gain is set based on the equation (2) to perform synthesis. As a result, even when multiple exposure is interrupted, a multiple exposure photographed image with appropriate exposure can be obtained.

  FIG. 4 is a flowchart showing the flow of processing in the digital camera 100 of the present embodiment. The processing shown in FIG. 4 is executed by the CPU 12 as a program that starts when the power of the digital camera is turned on. In step S10, it is determined whether or not the release button has been pressed by the user. If it is determined that the user has pressed the release button, the process proceeds to step S20. In step S <b> 20, the subject is imaged by the image sensor 2 through the photographing lens 1. At this time, if the exposure condition is the automatic exposure shooting mode, an appropriate exposure value is set according to the luminance of the subject. Thereafter, the process proceeds to step S30. In step S <b> 30, RAW data obtained by converting the charge accumulated in the image sensor 2 into a digital signal by the A / D conversion circuit 3 is stored in the image memory 5.

  Thereafter, the process proceeds to step S40, and it is determined whether the multiple exposure shooting mode is instructed on the multiple exposure setting screen shown in FIG. 2 by the user, that is, whether the number of frames to be captured by multiple exposure is set. If imaging by multiple exposure is not instructed, the process proceeds to step S100 described later. On the other hand, if the multiple exposure shooting mode is instructed, the process proceeds to step S50. In step S50, it is determined whether or not imaging of the number of frames to be captured with multiple exposure preset by the user is completed. If it is determined that the imaging of the number of frames to be imaged by the multiple exposure is completed, the process proceeds to step S70.

  On the other hand, if it is determined that the imaging of the number of frames to be imaged by multiple exposure is not completed, the process proceeds to step S60. In step S60, it is determined whether or not multiple exposure is interrupted in the middle for any of the reasons (A) to (C) described above. If it is determined that the multiple exposure is not interrupted, the process returns to step S10 and waits for the release switch to be pressed. When the release switch is pressed, the above-described processing is performed. On the other hand, if it is determined that multiple exposure has been interrupted, the process proceeds to step S70.

  In step S70, it is determined whether or not the automatic gain correction is set to “Yes” by the user on the multiple exposure setting screen shown in FIG. If it is determined that the automatic gain correction is set to “OFF”, the process proceeds to step S90. On the other hand, if it is determined that the automatic gain correction is set to “YES”, the process proceeds to step S80, and the image processing circuit 6 is stored in the image memory 5 based on the equation (2) as described above. The process proceeds to step S90 after the gain of each RAW data is reduced. As described above, since the gain K is set based on the number of frames, in the case of interruption, the gain determined according to the predetermined number of frames is not used, but based on the actual number of frames taken. Use the determined gain.

  In step S90, the image processing circuit 6 adds and synthesizes each RAW data stored in the image memory 5 or the RAW data after gain reduction in step S80, and proceeds to step S100. In step S100, known image processing such as interpolation, color temperature correction, and gradation correction is executed, and the process proceeds to step S110. In step S 110, the image synthesized by the image processing circuit 6 is compressed and converted into a predetermined compression format by the compression circuit 7 and stored in the memory 10. The image data stored in the memory 10 is copied and stored in the recording medium 11 automatically or in accordance with an instruction from the user. The image synthesized by the image processing circuit 6 is displayed on the display device 9 by the display circuit 8.

  When the original image is set to “leave”, when the composite image is stored in the recording medium 11, the original image is also stored. The original image to be recorded on the recording medium 11 may be an image with gain down or RAW data before gain down. A plurality of original images may be stored without any association with the composite image, or the composite image and the plurality of original images may be stored so that they can be recognized as a set of image groups.

  Thereafter, the process proceeds to step S120, and it is determined whether or not the power of the digital camera 100 is turned off. If it is determined that the power is not turned off, the process returns to step S10 and the process is repeated. On the other hand, if it is determined that the power is turned off, the process is terminated.

According to the present embodiment described above, the following operational effects can be obtained.
(1) When the original image is set to “leave” by the user, each RAW data stored in the image memory 5 and these are digitally gained in advance and combined into the image memory 5. Both stored composite image data are recorded on a recording medium. Thereby, the original image can be referred to.
(2) The user can set in advance whether the original image is “leave” or “do not leave”. As a result, the original image and the composite image may be recorded on the recording medium as necessary, and the recording capacity of the recording medium is not consumed unnecessarily.

(3) When the automatic gain correction is set to “Yes” by the user, each RAW data stored in the image memory 5 is digitally gained in advance and then pixel data at the same position on the image Was added to synthesize. Thereby, it is possible to prevent overexposure at the time of composition, and it is possible to obtain a multiple exposure photographed image with appropriate exposure. In addition, it is possible to avoid overflow of data while adding RAW data.

(4) Each RAW data imaged by multiple exposure is multiplied by a digital gain whose sum is 1, and the gain is reduced. Thereby, for example, the sum 1 can be gain-down by a digital gain calculated by dividing by the number of frames to be imaged by multiple exposure, and if each frame is imaged by an appropriate exposure value, the image is imaged by multiple exposure. A multiple-exposure photographed image with an appropriate exposure according to the number of frames can be obtained.

(5) When it is determined that the multiple exposure has been interrupted, the digital gain is calculated based on the number of imaging frames until the interruption, and the image data obtained by multiplying the captured RAW data by the digital gain is synthesized. It was decided. This makes it possible to obtain a multiple exposure photographed image with appropriate exposure even when multiple exposure is interrupted.
(6) The user can set in advance whether the automatic gain setting is “Yes” or “No”. As a result, it is possible to capture an appropriate multiple-exposure photographed image in consideration of the subject imaging conditions.

In addition, it can also deform | transform as follows.
(1) If the original image is set to “leave”, the automatic gain correction may be forcibly set to “Yes”, and the original image that has not been gain-down may be stored in the recording medium. Thereby, it can be referred to as an original image in the same exposure state as the composite image.
(2) In the above-described embodiment, when the automatic gain setting is set to “Yes”, the RAW data is temporarily stored in the image memory 5, and then the image processing circuit 6 is stored in the image memory 5. The example in which the RAW data is read, and the automatic gain is set and combined has been described. However, the present invention is not limited to this, and the RAW data may be stored in the image memory 5 after the automatic gain setting. If multiple exposure is interrupted halfway, it is necessary to perform automatic gain setting again based on the actual number of shot frames after the interruption.

(3) In the above-described embodiment, an example in which image processing such as interpolation, color temperature correction, and gradation correction is performed on the combined image data after combining the RAW data has been described. However, the present invention is not limited to this. When image processing is performed on the RAW data, and if data that can be synthesized is obtained by adding pixel data at the same position on the image, various image processing is performed. Synthesis may be performed later.

(4) In the above-described embodiment, the example in which the image processing circuit 6, the compression circuit 7, and the display circuit 8 are mounted on the digital camera 100 has been described. However, the present invention is not limited thereto, and the image processing circuit 6 and the compression circuit 7 are not limited thereto. The functions realized by the display circuit 8 may be mounted on an external device such as a personal computer. In this case, various processes are performed after the RAW data imaged by the imaging device 2 is copied to a personal computer via a memory card or an interface cable.

  Note that the present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired.

It is a block diagram which shows the structure of one Embodiment of a digital camera. It is a figure which shows the specific example of a multiple exposure setting screen. It is a figure which shows the specific example of the RAW data memorize | stored in the image memory. FIG. 4 is a flowchart showing a process flow in the digital camera 100.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shooting lens 2 Image pick-up element 3 A / D conversion circuit 4 Timing generator 5 Image memory 6 Image processing circuit 7 Compression circuit 8 Display circuit 9 Display apparatus 10 Memory 11 Recording medium 12 CPU
13 Input device

Claims (7)

Storage means for storing a plurality of images captured by the image sensor when the multiple exposure shooting mode is set;
Combining means for combining the plurality of images stored in the storage means to generate a multiple exposure photographed image;
Recording control for recording, on the recording medium, the original image before composition stored in the storage unit together with the multiple-exposure photographed image when performing processing for recording the multiple-exposure photographed image synthesized by the synthesizing unit. And a digital camera. The digital camera according to claim 1, wherein
When performing the process of recording the multiple-exposure photographed image on the recording medium, a first recording mode for recording only the multiple-exposure photographed image and a second recording mode for recording the multiple-exposure photographed image and the original image A digital camera, further comprising recording selection means for selecting. The digital camera according to claim 2,
A gain applying unit that applies a gain determined so that the sum is 1 based on the number of multiple-exposure shots to a plurality of captured images;
The digital camera is characterized in that the synthesizing unit generates a multiple-exposure photographed image by synthesizing the plurality of images after the gain is applied by the gain applying unit. The digital camera according to claim 3, wherein
At the time of image synthesis by the synthesizing means, a gain is given by the gain giving means, and then a first synthesis mode for synthesizing the plurality of images to generate a multiple exposure photographed image, and gain is given by the gain giving means. In addition, the digital camera further includes a combination selection unit that selects a second combination mode in which the plurality of images are combined to generate a multiple exposure photographed image. The digital camera according to claim 4, wherein
When the second recording mode is selected by the recording selection means,
The synthesizing unit synthesizes the plurality of images and combines the plurality of images after applying gain to the original image by the gain applying unit even when the second synthesis mode is selected by the synthesis selecting unit. Produces
The digital camera according to claim 1, wherein the recording control unit records the original image without the gain on the recording medium together with the multiple exposure photographed image. The digital camera according to claim 1, wherein
A gain applying unit that applies a gain determined so that the sum is 1 based on the number of multiple-exposure shots to a plurality of captured images;
The digital camera is characterized in that the synthesizing unit generates a multiple-exposure photographed image by synthesizing the plurality of images after the gain is applied by the gain applying unit. The digital camera according to claim 6, wherein
At the time of image synthesis by the synthesizing means, a gain is given by the gain giving means, and then a first synthesis mode for synthesizing the plurality of images to generate a multiple exposure photographed image, and gain is given by the gain giving means. In addition, the digital camera further includes a combination selection unit that selects a second combination mode in which the plurality of images are combined to generate a multiple exposure photographed image.

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