JP2009141702A - Imaging apparatus and control method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve definition of a still image while controlling exposure. <P>SOLUTION: An imaging apparatus obtains an image of proper exposure by using images of N frames consecutively photographed at a shutter speed that is 1/N (M is a square of 2) of the shutter speed required for photographing an image of proper exposure, comprising: a detection means for detecting a still region that has no movement, and a motion region that has movement, an addition means for adding data in the still regions among the images of the N frames and adding data in the motion regions among the images of the M frames if there is no movement; an amplification means for amplifying the data in the motion regions to be N-fold if data are not added, and for amplifying the data in the motion regions after addition to be N/M-fold in the case that the data in the motion regions in the images of the M frames are added by the addition means; and a production means which combines the added data in the still regions and the amplified data in the motion regions to produce image data. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and a control method for the imaging apparatus.

In an image pickup apparatus in which no mechanical shutter is provided between the lens and the image sensor and only an aperture is provided, the exposure is controlled by controlling the charge accumulation time of the charge by the image sensor and the aperture of the aperture.
Japanese Patent Laid-Open No. 2-179086

  In the imaging apparatus as described above, when the brightness of the subject becomes dark in a state where the aperture of the diaphragm is controlled to a fixed value, in order to control the exposure to an appropriate state, the charge accumulation time of charges by the imaging sensor is lengthened. It is necessary to slow down the shutter speed of the electronic shutter.

  When the shutter speed of the electronic shutter becomes slow, subject blur and camera shake due to the movement of the subject and the hand of the photographer tend to occur.

  An object of the present invention is to provide an imaging apparatus and an imaging apparatus control method capable of improving the quality of a still image while controlling exposure.

  The imaging apparatus according to the first aspect of the present invention is an image of N frames continuously captured at a shutter speed 1 / N (N is a power of 2) of a shutter speed necessary for capturing an image with appropriate exposure. Is used to detect a stationary region that does not move through the N frame image and a moving region that moves between at least two frames of the N frame image. When the data of the still area is added between the detection means and the N frame image, and there is no motion in the motion area of the M frame image (M is a natural number smaller than N) of the N frames. And adding means for adding the motion region data between the M frame images, and the motion region data is not added by the adding means. Amplifying means for amplifying area data by N times and amplifying the motion area data after addition by N / M times when the motion area data of the M frame image is added by the adding means And generating means for generating image data by synthesizing the data of the still area added by the adding means and the data of the motion area amplified by the amplifying means, To do.

  The control method of the image pickup apparatus according to the second aspect of the present invention is such that N is continuously captured at a shutter speed 1 / N (N is a power of 2) of the shutter speed necessary for capturing an image with appropriate exposure. A method of controlling an imaging apparatus that uses a frame image to obtain an image with appropriate exposure, wherein there is a motion between a static region where there is no movement through the N frame image and at least two frames of the N frame image. A detection step of detecting a motion region; adding the data of the still region between the images of the N frames; and the motion of an image of an M frame (M is a natural number smaller than the N) of the N frames An addition step of adding the data of the motion region between the images of the M frame when there is no motion in the region, and the data of the motion region in the addition step If not, the motion region data is amplified N times, and if the motion region data of the M frame image is added in the adding step, the motion region data after the addition is N Amplifying step for amplifying / M times, and a generating step for generating image data by combining the static region data added in the adding step and the motion region data amplified in the amplifying step It is characterized by comprising.

  According to the present invention, it is possible to improve the quality of a still image while controlling exposure.

  An imaging apparatus 1 according to a first embodiment of the present invention will be described. FIG. 1 is a configuration diagram of an imaging apparatus 1 according to the first embodiment of the present invention.

  The imaging apparatus 1 uses images of N frames continuously captured at a shutter speed 1 / N (N is a power of 2) of a shutter speed necessary for capturing an image with appropriate exposure, and uses an image with appropriate exposure. It is a device for obtaining. The imaging device 1 is, for example, a video camera having a still shooting function. The imaging apparatus 1 includes a lens group 100, a diaphragm 101, an imaging element (imaging unit) 102, a driver unit 103, and an AFE (Analog Front Nd) unit 104. The imaging apparatus 1 includes an image processing unit 105, a frame memory 106, a recording unit 107, and a CPU 108.

  The lens group 100 converges incident light and forms an image on the imaging surface of the imaging element 102. The lens group 100 incorporates an AF mechanism and a zoom mechanism.

  The diaphragm 101 is provided between the lens group 100 and the image sensor 102 and limits the amount of light guided from the lens group 100 to the image sensor 102.

  The imaging element 102 converts an image of a subject formed on a pixel array (imaging surface) in which a plurality of pixels are arrayed into an image signal. Each pixel of the pixel array accumulates a signal corresponding to light and generates an image signal. The image sensor 102 reads out the image signal from the pixel array and outputs it. The image sensor 102 is, for example, a CCD or a CMOS sensor.

  The driver unit 103 generates a driving pulse for driving the image sensor 102. The drive signal is, for example, a vertical scanning pulse, a horizontal transfer pulse, and an electronic shutter. The vertical scanning pulse is a pulse for selecting a predetermined row by scanning the pixel array in the vertical direction. The horizontal transfer pulse is a pulse for scanning the pixel array in the horizontal direction and sequentially outputting the signals of each column to the subsequent stage. The electronic shutter is a pulse for resetting each pixel of the pixel array.

  The AFE unit 104 receives an image signal (analog signal) from the image sensor 102, performs CDS (Correlated Double Sampling) processing, amplification processing, A / D conversion, and the like to generate an image signal (digital signal).

  The image processing unit 105 receives an image signal (digital signal) from the AFE unit 104, and performs various image processing such as gamma correction, contour enhancement processing, white balance, and color balance on the image signal to generate image data.

  The image processing unit 105 includes a generation unit (generation unit) 105a, an image comparison unit (detection unit) 105b, an addition unit (addition unit) 105c, an amplification unit (amplification unit) 105d, and a determination unit (determination unit) 105e. The generation unit 105a receives an image signal from the image sensor 102 via the AFE unit 104, and generates image data in units of frames. The image comparison unit 105b detects a motion area and a still area in the image data. The adder 105c adds data of at least a part of the image data to other frames. The amplifying unit 105d amplifies data in at least a part of the image data. The determination unit 105e determines an amplification factor for the amplification unit 105d to amplify the data.

  The frame memory 106 receives image data from the image processing unit 105 and temporarily stores the image data. The frame memory 106 is, for example, an SDRAM.

  The recording unit 107 receives image data from the image processing unit 105 and records the image data for storage or the like. The recording unit 107 is, for example, a recording tape for recording in the DV format or a recording card for recording in the JPEG format.

  The CPU 108 is connected to the diaphragm 101, the driver unit 103, the AFE unit 104, and the image processing unit 105, and controls the diaphragm 101, the driver unit 103, the AFE unit 104, and the image processing unit 105 as a whole.

  The CPU 108 includes an exposure control unit (exposure control means) 108a. The exposure control unit 108 a receives information related to the luminance component of the image data from the image processing unit 105. The exposure control unit 108a controls the charge accumulation time of the image sensor 102 via the driver unit 103 and the opening degree of the diaphragm 101 according to the information on the luminance component. Thereby, the exposure control unit 108 a controls the exposure amount of the image sensor 102. That is, the exposure control unit 108a performs AE (automatic exposure control) processing that automatically controls exposure according to the brightness of the subject.

  Next, the operation of the imaging apparatus 1 when preparation for still image shooting is performed will be described.

  First, when the CPU 108 of the imaging apparatus 1 recognizes that a power button (not shown) is turned on, it sets the operation mode to the initial operation mode. The CPU 108 controls each unit to perform a predetermined initial operation in response to the initial operation mode. When completing the initial operation, the CPU 108 of the imaging apparatus 1 switches the operation mode from the initial operation mode to the monitor mode. The monitor mode is a mode in which an image of a subject imaged by the image sensor 102 is displayed on a display panel (not shown) such as an LCD.

  The exposure control unit 108a controls the charge accumulation time of the image sensor 102 and the opening of the diaphragm 101 to predetermined initial values in accordance with the monitor mode.

  The image sensor 102 receives light that has passed through the lens group 100 and the diaphragm 101, accumulates a signal corresponding to the light with an initial charge accumulation time, and generates an image signal. The image signal is supplied from the image sensor 102 to the AFE unit 104, subjected to analog signal processing by the AFE unit 104, and then supplied to the image processing unit 105. The image processing unit 105 generates image data corresponding to the supplied image signal. The exposure control unit 108 a receives information regarding the luminance component of the image data from the image processing unit 105. The exposure control unit 108a controls the exposure by controlling the charge accumulation time Te of the image sensor 102 and the opening of the diaphragm 101 according to the information of the luminance component of the image data.

  For example, the exposure control unit 108a performs control so that the opening degree of the diaphragm 101 increases when the subject becomes dark. The exposure control unit 108a controls the charge accumulation time Te of the image sensor 102 to be longer when the subject is further darkened and the aperture of the diaphragm 101 is maximized.

  As described above, the image sensor 102 repeatedly generates an image signal, and the charge accumulation time (exposure time) of the image sensor 102 and the opening degree (aperture value) of the diaphragm 101 according to the luminance component of the image data corresponding to the image signal. And are controlled so as to be an appropriate value. Thereby, AE processing for automatically controlling exposure is performed.

  Note that the exposure control unit 108a may further control the exposure by controlling the gain in the amplification process of the AFE unit 104 according to the information of the luminance component of the image data.

  Next, the operation of the imaging apparatus 1 when still image shooting is performed will be described with reference to FIG. FIG. 2 is a flowchart illustrating the operation of the imaging apparatus 1 when still image shooting is performed.

  In step S200, when a user presses a shutter button (not shown), the shutter button accepts a still image shooting command. The CPU 108 receives the still image shooting command from the shutter button, and switches the operation mode from the monitor mode to the still image shooting mode in accordance with the still image shooting command.

  In step S201, the exposure control unit 108a obtains a temporary charge accumulation time Ttmp of the image sensor 102 according to the opening of the diaphragm 101 so that the exposure amount of the image sensor 102 becomes a predetermined exposure value. For example, the exposure control unit 108a sets the value of the charge accumulation time obtained immediately before in the monitor mode as the temporary charge accumulation time Ttmp in response to the opening degree of the diaphragm 101 being the value controlled immediately before in the monitor mode. be able to.

  In step S202, the exposure control unit 108a compares the temporary charge accumulation time Ttmp with the first threshold (maximum exposure time) Tmax, and determines whether or not the temporary charge accumulation time Tetmp exceeds the first threshold Tmax. Determine whether. The first threshold value (maximum exposure time) Tmax starts to cause subject blur and camera shake in a subject image when a subject of a predetermined size moving at a predetermined speed at a predetermined distance is imaged at a predetermined angle of view. This is the time when it begins to be recognized with the naked eye. The subject shake and camera shake are caused by the movement of the subject and the movement of the photographer's hand. The first threshold Tmax is obtained in advance through experiments or simulations.

  For example, assuming that the temporary charge accumulation time Ttmp = 1/50 [s] and the first threshold Tmax = 1/100 [s], the exposure control unit 108a determines that the temporary charge accumulation time Ttmp is the first threshold. It is determined that Tmax is exceeded.

  If the exposure control unit 108a determines that the provisional charge accumulation time Ttmp exceeds the first threshold Tmax, the process proceeds to step S204, where the provisional charge accumulation time Ttmp does not exceed the first threshold Tmax. If YES, the process proceeds to step S203.

  In step S <b> 203, the imaging apparatus 1 performs normal imaging processing in response to the provisional charge accumulation time Ttmp not exceeding the first threshold Tmax.

  That is, the exposure control unit 108a determines the temporary charge accumulation time Ttmp as the control charge accumulation time Te. The exposure control unit 108a controls the image sensor 102 via the driver unit 103 so as to perform the charge accumulation operation with the charge accumulation time Te. The image sensor 102 receives light that has passed through the lens group 100 and the diaphragm 101, accumulates a signal corresponding to the light with an initial charge accumulation time, and generates an image signal. The image signal is supplied from the image sensor 102 to the AFE unit 104, subjected to analog signal processing by the AFE unit 104, and then supplied to the image processing unit 105. The image processing unit 105 generates image data corresponding to the supplied image signal. The recording unit 107 receives image data from the image processing unit 105 and records the image data for storage or the like.

  In step S <b> 204, the imaging apparatus 1 performs a multiple exposure shooting process in response to the provisional charge accumulation time Ttmp exceeding the first threshold Tmax. Specifically, the imaging apparatus 1 performs steps S205 to S209.

  In step S205, the exposure control unit 108a determines the number of frames of image data to be acquired (the number of frames to be captured) N. That is, the exposure control unit 108a determines the number N of frames of image data to be acquired based on the result of dividing the temporary charge accumulation time Ttmp by the reference charge accumulation time (minimum exposure time) Tmin. The reference charge accumulation time (minimum exposure time) Tmin is a time used as a reference when determining the number N of frames of image data to be acquired, and is determined in advance to a value equal to or less than half of the first threshold value Tmax. .

  For example, if the temporary charge accumulation time Ttmp is divisible by the reference charge accumulation time Tmin, the exposure control unit 108a sets the quotient as the number N of frames of image data to be acquired. Here, assuming that the provisional charge accumulation time Ttmp = 1/50 [s] and the reference charge accumulation time Tmin = 1/200 [s], the exposure control unit 108a has the Ttmp / Tmin = 1/50/1. Let / 200 = 4 be the number N of frames of image data to be acquired.

  For example, when the temporary charge accumulation time Ttmp is not divisible by the reference charge accumulation time Tmin, the exposure control unit 108a sets the value obtained by adding 1 to the quotient as the number N of frames of image data to be acquired.

  For example, when the temporary charge accumulation time Ttmp is not divisible by the reference charge accumulation time Tmin, the exposure control unit 108a adjusts the reference charge accumulation time Tmin to be divisible. The exposure control unit 108a sets the quotient obtained by dividing the temporary charge accumulation time Ttmp by the adjusted reference charge accumulation time Tmin as the number N of frames of image data to be acquired.

  For example, when the temporary charge accumulation time Ttmp is not divisible by the reference charge accumulation time Tmin, the exposure control unit 108a controls the opening degree of the aperture 101 (and the gain of the AFE unit 104) so as to be divisible. The charge accumulation time Tetmp is adjusted. The exposure control unit 108a sets the quotient obtained by dividing the adjusted temporary charge accumulation time Ttmp by the reference charge accumulation time Tmin as the number N of frames of image data to be acquired.

  In step S206, the exposure control unit 108a controls the image sensor 102 so as to accumulate a signal with a divided accumulation time Td obtained by dividing the temporary charge accumulation time Ttmp by the number of N frames.

  For example, when the temporary charge accumulation time Ttmp is divisible by the reference charge accumulation time Tmin or is adjusted to be divisible, the exposure control unit 108a sets the reference charge accumulation time Tmin as the divided accumulation time Td.

  For example, when the value obtained by adding 1 to the quotient obtained by dividing the temporary charge accumulation time Ttmp by the reference charge accumulation time Tmin is set to the number of frames N of the image data, the exposure control unit 108a sets the temporary charge accumulation time Ttmp as the image data. The value divided by the number N of frames is defined as the divided accumulation time Td.

  The driver unit 103 receives information about the number of frames N and the divided accumulation time Td from the exposure control unit 108a, and generates a start pulse as shown in FIG. In FIG. 3, the driver unit 103 starts counting a value for generating a vertical scanning pulse in accordance with the start pulse falling timing 300. The driver unit 103 selects a predetermined row of the pixel array of the image sensor 102 via the vertical scanning pulse.

  The driver unit 103 resets pixels in a predetermined row selected via the vertical scanning pulse at timings 301 to 302 by an electronic shutter. The driver unit 103 releases the reset at timing 302 and does not reset until timing 303 after the lapse of the divided accumulation period Td, so that the pixels in a predetermined row selected through the vertical scanning pulse are divided into the divided accumulation period Td. Charge accumulation operation is performed.

  Similarly, at timings 303 to 304, timings 305 to 306, timings 307 to 308, and timings 307 to 308, the driver unit 103 activates the electronic shutter and resets each pixel in the pixel array of the image sensor 102. The driver unit 103 causes the selected row of pixels to perform the charge accumulation operation in the divided accumulation period Td at timings 304 to 305, timings 306 to 307, and timings 308 to 309.

  Further, the driver unit 103 sequentially outputs the pixel signals acquired at timings 302 to 303, timings 304 to 305, timings 306 to 307, and timings 308 to 309 to the subsequent stage via the horizontal transfer signal (FIG. 3).

  The generation unit 105a receives image signals for N frames generated by signals accumulated by the image sensor 102 at the division accumulation time Td via the AFE unit 104, and sequentially receives temporary image data for N frames A to D. Generate (see FIG. 3). The generation unit 105 a stores temporary image data of N frames A to D in the frame memory 106.

  In step S207, the image comparison unit 105b compares the temporary image data of the N frames A to D, and detects the motion area and the still area in the images of the N frames A to D. Then, the image comparison unit 105b determines whether there is a motion region in the N frames A to D based on the detected result.

  For example, the image comparison unit 105b calculates a difference in luminance level for each pixel constituting the temporary image data between the frame A and the frame B, and detects a pixel position (Dxy) that is equal to or greater than a certain threshold value. When the detected pixel position Dxy having a large difference exists continuously for a plurality of pixels in the X direction or the Y direction, the image comparison unit 105b detects the region as a motion region. Further, the image comparison unit 105b detects an area other than the motion area in the image data as a still area. In this manner, the image comparison unit 105b detects the motion area and the still area in the frame A image and the frame B image. In this case, the image comparison unit 105b has a region surrounded by the maximum and minimum values of the X position and the maximum and minimum values of the Y position where Dxy is continuously distributed (for example, a region 400, indicated by a solid line in FIG. 4). 401) is stored as a temporary motion area.

  Similarly, the image comparison unit 105b compares the temporary image data of the frame B and the frame C, and detects a temporary motion region in the image of the frame B and the image of the frame C. The image comparison unit 105b compares the temporary image data of the frame C and the frame D, and detects a temporary motion area in the image of the frame C and the image of the frame D.

  In this way, the image comparison unit 105b calculates a logical sum of temporary motion areas between the images of the frames A and B, between the images of the frames B and C, and between the images of the frames C and D. The motion regions 500, 501 and the like (indicated by broken lines in FIG. 4) in the images of. In addition, the image comparison unit 105b detects a region other than the motion regions 500, 501 and the like in the N frames A to D as a still region. When detecting the motion area in the N frames A to D, the image comparison unit 105b determines that there is a motion area in the images of the N frames A to D.

  Note that the image comparison unit 105b may detect the subject area of each frame and detect the motion area and the still area in each frame from the difference in the position of the subject area of each frame.

  If the image comparison unit 105b determines that there is a motion region in the N frames A to D, the process proceeds to step S209. If the image comparison unit 105b determines that there is no motion region in the N frames A to D, the process proceeds to step S208. .

  In step S208, the adding unit 105c generates the image data by adding the temporary image data of N frames A to D to each other.

  In step S209, the adding unit 105c adds the data of the still areas in the N frames A to D to each other. As a result, the data of the added still area becomes a luminance level when the moving area in the temporary image data is imaged by the image sensor 102 during the temporary charge accumulation time Ttmp.

  For example, consider a case where temporary image data of each of the N frames A to D is obtained by imaging with a divided storage time Td≈ (temporary charge storage time Ttmp) / 4. In this case, the brightness level of the still area in each of the frames A to D is about ¼ of the brightness level of the still area when the image is captured in the temporary charge accumulation time Ttmp. On the other hand, since the data of the still area is added between the images of the four frames A to D (see FIG. 5), the luminance level of the data of the added still area is imaged during the temporary charge accumulation time Ttmp. In this case, the brightness level of the data in the still area is equivalent.

  On the other hand, the determination unit 105e causes the amplification unit 105d to amplify the data in the motion region so that the luminance level is obtained when the motion region in the temporary image data is captured with the temporary charge accumulation time Ttmp by the imaging element 102. The first amplification factor is determined. The amplification unit 105d receives information about the determined first amplification factor from the determination unit 105e. The amplification unit 105d multiplies the data of the motion regions 500, 501,... In any one of the N frames A to D by the first amplification factor N determined by the determination unit 105e (amplifies the data by N times).

  For example, consider a case where temporary image data of each of the N frames A to D is obtained by imaging with a divided storage time Td≈ (temporary charge storage time Ttmp) / 4. In this case, the brightness level of the still area in each of the frames A to D is about ¼ of the brightness level of the still area when the image is captured in the temporary charge accumulation time Ttmp. On the other hand, the determination unit 105e determines the first amplification factor N to be “4” in response to the number of frames of image data to be acquired being “4”. The amplifying unit 105d selects the motion regions 500, 501 in the frame B to be synthesized from the motion regions 500, 501,... In the N frames A to D. The amplification unit 105d amplifies the data of the motion regions 500 and 501 in the selected frame B with the first amplification factor N = “4”. As a result, the luminance level of the data in the motion region amplified four times becomes equal to the luminance level of the data in the still region when the image is captured in the temporary charge accumulation time Ttmp.

  Note that the amplifying unit 105d may select a motion region to be synthesized from frames other than the frame B, or may select a plurality of motion regions from different frames. Further, the image processing unit 105 may perform more advanced image analysis on each motion region of each frame, and the amplification unit 105d may select a motion region with less motion in response to the result.

  The generation unit 105a combines the data of the motion regions 500 and 501 of the frame B amplified by the amplification unit 105d with the first amplification factor and the data of the still region added by the addition unit 105c, thereby generating image data. Is generated.

  For example, as illustrated in FIG. 5, the generation unit 105a replaces the temporary image data with the data of the motion areas 500 and 501 amplified by the amplification unit 105d and the data of the still area added by the addition unit 105c. Are combined to generate image data.

  As described above, in the temporary image data of N frames acquired by imaging with each divided accumulation time, addition or so as to obtain a luminance level equivalent to the case of imaging with the temporary charge accumulation time Ttmp Amplification is performed. Thereby, even if it is a case where it image | photographs by division | segmentation accumulation | storage time, the image data by which the exposure value was adjusted appropriately can be obtained. That is, the exposure can be controlled so that a predetermined appropriate exposure value is obtained.

  In addition, since the data of the still area in the N frame is added to each other and the data of the motion area in any of the N frames is amplified N times, the image quality of the still area can be improved and the subject blur in the motion area can be improved. Camera shake can be prevented. Thereby, the quality of the obtained still image can be improved.

  Therefore, the quality of the still image can be improved while controlling the exposure.

  Next, an imaging apparatus 1a according to a second embodiment of the present invention will be described. Below, it demonstrates centering on a different part from 1st Embodiment, and abbreviate | omits description of the same part.

  The basic configuration of the imaging apparatus 1a is the same as that of the first embodiment, but its operation is different from that of the first embodiment as shown in FIG. FIG. 6 is a flowchart showing the operation of the imaging apparatus 1a according to the second embodiment when still image shooting is performed.

  In step S604, the imaging apparatus 1a performs the multiple exposure photographing process in response to the provisional charge accumulation time Ttmp exceeding the first threshold value Tmax. Specifically, the imaging device 1a performs the processes of steps S205 to S611.

  In step S610, the image comparison unit 105b detects that the motion amount is less than the second threshold in the motion region of the image of M frames (M is a natural number smaller than N) among the N frames A to D. That is, the image comparison unit 105b detects that there is no motion in the motion region of the M frame image among the N frames A to D.

  For example, the image comparison unit 105b compares the motion region 707 of the frame A and the motion region 700 of the frame B, so that the motion amount between the motion region 707 and the motion region 700 is less than the second threshold. Is detected. That is, the image comparison unit 105b detects that the amount of motion is less than the second threshold in the motion regions 707 and 700 of the M frames A and B among the N frames A to D.

  For example, the image comparison unit 105b compares the motion region 704 of the frame C and the motion region 706 of the frame D so that the motion amount between the motion region 704 and the motion region 706 is less than the second threshold. Is detected. That is, the image comparison unit 105b detects that the amount of motion is less than the second threshold in the motion regions 704 and 706 of the M frames C and D among the N frames A to D.

  In step S611, the adding unit 105c adds the data of the still areas in the N frames A to D to each other. As a result, the data of the added still area becomes a luminance level when the moving area in the temporary image data is imaged by the image sensor 102 during the temporary charge accumulation time Ttmp.

  In addition, the adding unit 105c adds the data of the motion area, in which the amount of motion is detected to be less than the second threshold value in step S610, between the M frame images.

  For example, the adding unit 105c adds the data in the motion area 707 in frame A and the data in the motion area 700 in frame B. That is, the adding unit 105c adds the data of the motion areas 707 and 700 in the M frames A and B to each other.

  For example, the adding unit 105c adds the data in the motion area 704 in frame C and the data in the motion area 706 in frame D. That is, the adding unit 105c adds the data of the motion areas 704 and 706 in the M frames C and D to each other.

  On the other hand, the determination unit 105e causes the amplification unit 105d to amplify the data in the motion region so that the luminance level is obtained when the motion region in the temporary image data is captured with the temporary charge accumulation time Ttmp by the imaging element 102. The second amplification factor (second amplification factor; N / M) is determined. The amplification unit 105d receives information on the second amplification factor from the determination unit 105e. The amplifying unit 105d amplifies the data of the motion region added by the adding unit 105c with the second amplification factor N / M (amplifies the data by N / M times).

  For example, consider a case where temporary image data of each of the N frames A to D is obtained by imaging with a divided storage time Td≈ (temporary charge storage time Ttmp) / 4. In this case, the brightness level of the still area in each of the frames A to D is about ¼ of the brightness level of the still area when the image is captured in the temporary charge accumulation time Ttmp. On the other hand, in response to the number of frames of the image data to be acquired being “4” and the number of frames of the added image data being “2”, the determination unit 105e causes the amplification unit 105d to A gain (second amplification factor) for multiplying the data is determined to be 4/2 = 2. The amplification unit 105d amplifies the data of the motion regions 707 and 700 added in the two frames A and B with the second amplification factor “2”. Further, the amplification unit 105d amplifies the data of the motion regions 704 and 706 added in the two frames C and D with the second amplification factor “2”. As a result, the luminance level of the data in the motion region that has been added and amplified is equivalent to the luminance level of the data in the still region when the image is captured in the temporary charge accumulation time Ttmp.

  The generation unit 105a generates image data by combining the motion region data amplified by the amplification unit 105d with the second amplification factor N / M and the still region data added by the addition unit 105c. .

  For example, as illustrated in FIG. 8, the generation unit 105a uses the data of the motion regions 707 and 700 and the data of the motion regions 704 and 706 amplified by the second amplification factor N / M, and N frames by the addition unit 105c. The data of the still area added between the images is synthesized. Thereby, the generation unit 105a generates image data.

  As described above, in the motion region of N frames, the motion region data with less motion are added and amplified, so that the image quality of the motion region can be improved while preventing blurring and blurring of the motion region. As a result, the quality of the obtained still image can be further improved.

1 is a configuration diagram of an imaging apparatus 1 according to a first embodiment of the present invention. 6 is a flowchart showing the operation of the imaging apparatus 1 when still image shooting is performed. The timing chart which shows the drive pulse which a driver part produces | generates. The figure which shows the temporary image data acquired. The figure which shows the image data synthesize | combined. The flowchart which shows operation | movement of the imaging device 1a which concerns on 2nd Embodiment at the time of still image photography. The figure which shows the temporary image data acquired. The figure which shows the image data synthesize | combined.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a Image pick-up device 101 Aperture 102 Imaging element 105a Generation part 105b Image comparison part 105c Addition part 105d Amplification part 105e Determination part 108a Exposure control part

Claims (7)

An imaging device that obtains an image with an appropriate exposure using images of N frames continuously captured at a shutter speed of 1 / N (N is a power of 2) of the shutter speed required for capturing an image with an appropriate exposure. There,
Detecting means for detecting a stationary region that does not move through the N frame image and a moving region that moves between at least two frames in the N frame image;
Adding means for adding the data of the still area between the images of the N frames;
Amplifying means for amplifying the motion area data N times when the motion area data is not added by the adding means;
Generating means for generating image data by combining the data of the still area added by the adding means and the data of the motion area amplified by the amplifying means;
An imaging apparatus comprising: Imaging means for generating an image signal corresponding to the light received by each pixel during the charge accumulation time;
An aperture for adjusting the amount of light received by the imaging means;
Exposure control means for controlling the charge accumulation time and the aperture of the diaphragm to control the exposure amount of the imaging means;
Further comprising
The exposure control means obtains a temporary charge accumulation time corresponding to the aperture of the diaphragm so that the exposure amount becomes a predetermined exposure value, and the temporary charge accumulation time exceeds a first threshold value. And when the provisional charge accumulation time exceeds the first threshold value, the image pickup means uses the divided accumulation time obtained by dividing the provisional charge accumulation time by N as the charge accumulation time. Control
The generation means receives the image signals for the N frames generated by the imaging means using the divided accumulation time as the charge accumulation time, and generates temporary image data for the N frames,
The detection means compares the temporary image data of the N frames, detects the motion region and the still region for the image of the N frames,
The adding means adds the data of the still area detected by the detecting means between the images of the N frames,
The imaging apparatus according to claim 1, wherein the amplification unit amplifies the data of the motion region detected by the detection unit N times. The detecting means detects that there is no motion in the motion region of an image of an M frame (M is a natural number smaller than N) of the N frames;
The adding means adds the data of the motion area between the images of the M frames,
The amplifying unit amplifies the data of the motion region after the addition by N / M times when the data of the motion region of the M frame image is added by the adding unit. The imaging device according to claim 1. Imaging means for generating an image signal corresponding to the light received by each pixel during the charge accumulation time;
An aperture for adjusting the amount of light received by the imaging means;
Exposure control means for controlling the charge accumulation time and the aperture of the diaphragm to control the exposure amount of the imaging means;
Further comprising
The exposure control means obtains a temporary charge accumulation time corresponding to the aperture of the diaphragm so that the exposure amount becomes a predetermined exposure value, and the temporary charge accumulation time exceeds a first threshold value. If the provisional charge accumulation time exceeds the first threshold value, the imaging means is configured to use the divided accumulation time obtained by dividing the provisional charge accumulation time by the N as the charge accumulation time. Control
The generation means receives the image signals for the N frames generated by the imaging means using the divided accumulation time as the charge accumulation time, and generates temporary image data for the N frames,
The detection means compares the provisional image data of the N frames to detect the motion region and the still region with respect to the N frame image, and between the M frame images of the N frames. And detecting that the amount of motion in the motion region is less than a second threshold,
The adding means adds the data of the still area detected by the detecting means between the images of the N frames, and the detecting means detects that the amount of movement is less than the second threshold value. Adding motion area data between the M frame images;
4. The imaging apparatus according to claim 3, wherein the amplifying unit amplifies the data of the motion region added by the adding unit by N / M times. The said exposure control means determines the said N so that the said division | segmentation accumulation | storage time may become the reference | standard charge accumulation | storage time predetermined as half or less of the said 1st threshold value or, 5. The imaging device according to 4. The amplifying unit determines an amplification factor for amplifying the data in the motion region so that the luminance level is obtained when the motion region in the temporary image data is captured in the temporary charge accumulation time by the imaging unit. The imaging apparatus according to claim 2, further comprising a determination unit. An imaging apparatus that obtains an image with an appropriate exposure using images of N frames continuously captured at a shutter speed of 1 / N (N is a power of 2) of the shutter speed necessary for capturing an image with an appropriate exposure. A control method,
A detection step of detecting a stationary region having no motion through the N frame image and a motion region having a motion between at least two frames of the N frame image;
When the data of the still region is added between the images of the N frames, and there is no motion in the motion region of the images of M (M is a natural number smaller than the N) of the N frames, the M frames An addition step of adding the motion region data between the images of
When the motion region data is not added in the addition step, the motion region data is amplified N times, and when the motion region data of the M frame image is added in the addition step. An amplification step of amplifying the motion region data after the addition by N / M times;
A step of generating image data by combining the data of the still region added in the adding step and the data of the motion region amplified in the amplification step;
An image pickup apparatus control method comprising:

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