Imaging device and control method thereof

Abstract

This reduces the unnatural appearance of the live view display when using still images. [Solution] When continuous shooting is not instructed to take multiple frames of the second image in succession, the system is controlled to take multiple frames of the first image and display the taken first image on the display unit at a predetermined interval. When continuous shooting is instructed, the system is controlled to take multiple frames of the second image in succession without taking the first image during continuous shooting, and to display at least some of the frames of the second image taken in succession on the display unit at a predetermined interval.

Description

Technical Field

[0001] The present invention relates to an imaging device and a control method thereof.

Background Art

[0002] In recent years, in imaging devices such as digital cameras, cameras that enable both continuous shooting of still images for recording and display of live view images have been proposed. Patent Document 1 discloses a technique for reducing the exposure difference between a live view image and a still image for recording by synthesizing images of a plurality of frames output from an imaging element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, there is a problem that a sense of incongruity occurs in the live view image due to the timing at which the image signal is read from the imaging element and the timing at which the live view image is displayed when continuously shooting still images for recording.

[0005] An object of the present invention is to provide an imaging device that reduces the sense of incongruity in live view display caused by the timing at which an image signal is read from an imaging element and the timing at which a live view image is displayed when continuously shooting still images for recording.

Means for Solving the Problems

[0006] To achieve the above objective, the present invention provides an imaging device comprising: an image sensor; a display unit that displays a live view image captured by the image sensor; and a control unit that, before performing continuous shooting of multiple still images, captures multiple live view images with the image sensor and controls the display unit to display the captured live view images at predetermined intervals; and during the execution of continuous shooting, continuously captures multiple still images with the image sensor without capturing the live view images, and controls the display unit to display at least some of the still images from the multiple still images as the live view image at predetermined intervals. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an imaging device that reduces the discrepancy in live view display caused by the timing of when the image signal is read out from the image sensor and the timing of when the live view image is displayed when continuously shooting still images for recording. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the overall configuration of the imaging device in the embodiment. [Figure 2] This figure shows the configuration of the image sensor and surrounding area in the embodiment. [Figure 3] This figure shows the operation flow of image signal readout from the image sensor and live view display in the embodiment. [Figure 4] This figure shows the configuration of the image sensor and surrounding area in the embodiment. [Figure 5] This diagram shows the operation flow of image signal readout from the image sensor and live view display in the embodiment. [Figure 6] This is a flowchart showing the flow of changing the continuous shooting method in the embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, preferred embodiments of the present invention will be described in detail based on the accompanying drawings.

[0010] (Example 1) FIG. 1 is a diagram schematically showing the overall configuration of the imaging device in Example 1 of the present invention.

[0011] The lens 102 forms an optical image incident thereon on the imaging element 100.

[0012] The imaging element 100 converts the optical image formed by the lens 102 into an image signal and outputs the converted image signal to the signal processing circuit 101.

[0013] The signal processing circuit 101 performs predetermined processing on the image signal output from the imaging element 100 to generate photographed image data and focus detection image data.

[0014] The lens operation unit 103 performs zoom control, focus control, aperture control, etc. of the lens 102.

[0015] The CPU 104 performs various controls of the imaging element 100, the signal processing circuit 101, and the lens control unit 103.

[0016] The memory 105 is used to temporarily record image data processed by the signal processing circuit 101.

[0017] The recording unit 106 records image data processed by the signal processing circuit 101 in a semiconductor memory (not shown), or reads out image data from the semiconductor memory.

[0018] The display unit 107 displays the photographed live view image, recording image, or various information such as exposure conditions.

[0019] The operation unit 108 is composed of operation buttons, dials, etc., and can perform various settings of the imaging device. Also, during the display of the live view image, it is possible to instruct high-speed continuous shooting of recording still images.

[0020] FIG. 2 is a diagram showing the overall configuration of the imaging device 100 in Embodiment 1 of the present invention.

[0021] In the pixel group 200, pixels 201 are arranged in a matrix. Each of the pixels 201 has a photoelectric conversion unit, a transistor, and the like. Here, each of the pixels 201 may have a plurality of photoelectric conversion units. For example, by comparing the output signals of the plurality of photoelectric conversion units to perform phase difference detection, focus detection of the subject can be performed. In addition, an addition signal obtained by adding the output signals of the plurality of photoelectric conversion units can be used for generating a captured image.

[0022] The vertical scanning circuit 202 supplies a drive signal for controlling a transistor (not shown) included in each of the pixels 201 to each row of pixels in the pixel group 200. The column signal lines 203 are provided at least one by one for each pixel column in the pixel group 200, and transfer the output signals of the read pixels 201 to the column circuit 204.

[0023] The column circuit 204 performs various processes such as analog / digital conversion (A / D conversion) on the output signals of the pixels 201 transferred from the column signal lines 203. The clock generation circuit 205 generates a control signal for the column circuit 204 based on the clock signal supplied from the timing generator 209 and supplies it to the column circuit control unit 206.

[0024] The column circuit control unit 206 controls each of the column circuits 204 based on the control signal supplied from the clock generation circuit 205. The horizontal scanning circuit 207 transfers the output signals of the pixels 201 processed by the column circuit 204 to the signal processing circuit 101.

[0025] The register group 208 stores settings of each operation mode transmitted from an external control device such as the CPU 104. The timing generator 209 operates the vertical scanning circuit 202, the clock generation circuit 205, and the horizontal scanning circuit 207 based on the settings stored in the register group 208.

[0026] Next, Figure 3 is a diagram showing the operation flow of reading the image signal from the image sensor 100 and displaying the live view image on the display unit 107. Here, we will explain how to read the image signal from the image sensor 100 when high-speed continuous shooting is instructed and how to use the still images captured at high-speed continuous shooting for live view display. It is assumed that the live view image is displayed on the display unit 107 at a predetermined display period T (predetermined period).

[0027] For each vertical synchronization signal VD supplied from the CPU 104, an image signal is read from the pixel group 200 of the image sensor 100. The image signal read from the image sensor 100 is subjected to predetermined processing such as various correction and development processes in the signal processing circuit 101, and is displayed on the display unit 107 as a live view image in synchronization with the display vertical synchronization signal LVVD supplied from the CPU 104.

[0028] Figure 3(A) is a timing chart showing the case where the start timing of reading out the image signal from the image sensor 100 coincides with the start timing of display on the display unit 107.

[0029] At time t1, since high-speed continuous shooting of still images is not instructed (before high-speed continuous shooting is performed), the normal live view image display operation is performed. The live view image based on the live view image signal read from the image sensor 100 is displayed on the display unit 107.

[0030] When high-speed continuous shooting of still images is instructed between time t1 and time t2, the CPU 104 transmits the settings for still image shooting operation to the image sensor 100.

[0031] At time t2, the normal live view display operation is performed as at time t1, and the live view image based on the live view image signal read from the image sensor 100 is displayed on the display unit 107. At this time, the period from time t1 to time t2 (the VD period of live view), which is the readout period of the live view image signal from the image sensor 100, coincides with the display period T (a predetermined period). Therefore, the readout of the live view image signal and the display of the live view image on the display unit 107 are synchronized, resulting in a live view image display that does not feel unnatural. In other words, a display that does not feel unnatural can be achieved when the following equation (1) is satisfied when the live view image signal is displayed on the display unit 107. Readout period for LV operation = display period T... Equation (1)

[0032] Next, the imaging device switches to still image capture mode to perform high-speed continuous shooting of the instructed still images. To perform high-speed continuous shooting of still images, the accumulation of the still image signal for the first frame begins between time t2 and time t3. The still image pixel signals that begin to be read out at time t3 are corrected and developed by the signal processing circuit 101 before being recorded in memory 105 or storage unit 106. Since the period from time t2 to time t3 is shorter than the display cycle T (predetermined cycle), the display vertical synchronization signal LVVD is not supplied, and the still image signals read out from time t3 are not used for live view display.

[0033] At time t4, the instruction for high-speed continuous shooting of still images is still in effect (high-speed continuous shooting is in progress), so the same operations for still image shooting are performed as at time t3. At this time, since the period from time t2 to time t4 coincides with the display cycle T (predetermined cycle), the vertical synchronization signal VD and the display vertical synchronization signal LVVD are supplied at the same timing at time t4. Therefore, by displaying the still image signal read out from time t4 as the live view image on the display unit 107, the reading of the still image signal and the display of the live view image are synchronized, and a live view image display without any sense of incongruity can be achieved. In other words, at least some of the multiple still images are displayed as the live view image.

[0034] In this way, the still image signal is read out at the same time as the display vertical synchronization signal LVVD is supplied, similar to the readout operation of the live view image signal. By using the readout still image signal for display, it is possible to achieve a seamless display with synchronized image signal readout and live view image display.

[0035] Furthermore, the image signal used to display the live view image on the display unit 107 may be not only the still image signal read from time t4, but also an image signal obtained by adding together still image signals from multiple frames read at other times. In this case, even if the exposure period of the live view image signal and the exposure period of the still image signal are different, they can be matched, and the blur and brightness of the subject will also be matched, further reducing any unnatural appearance in the display.

[0036] Alternatively, the exposure center of gravity of the live view image can be aligned by limiting or weighting the frames of the still image signal to be added. This makes it possible to more accurately match the display of the live view image generated from the live view image signal with the display of the live view image generated from the still image signal in terms of reducing subject blur.

[0037] Furthermore, at time t4, the live view image displayed on the display unit 107 is switched from an image based on the live view image signal to an image based on the still image signal. This enables seamless switching of the live view image display without causing frame stops or blackouts. In order to read out the still image signal from the image sensor 100 at intervals of the live view image display period T (predetermined period), the still image readout period must be an integer multiple of the display period T (predetermined period) as shown in equation (2) if the still image readout period is constant. Readout period for still image signal = N × display period T (where N is any positive integer) ... Equation (2)

[0038] Here, the readout period for the still image signal (for example, the interval between time t3 and time t4) is the reciprocal of the frame rate of the set high-speed continuous shooting. In Figure 3(A), the readout period for the still image signal is twice the display period T (predetermined period) of the live view image (N=2). Since two frames of still image signals can be read out for one frame of the live view image display period, an image signal that is not used for displaying the live view image is read out once every two frames, such as the still image signal read out from time t3.

[0039] At time t5, the instruction for high-speed continuous shooting continues, so the readout operation for the still image signal is performed. Since the period from time t4 to time t5 is shorter than the display period T (predetermined period) of the live view image, the display vertical synchronization signal LVVD is not supplied during that period, and the still image signal readout from time t5 is not used for displaying the live view image.

[0040] From time t6 to time t8, the still image signal read from time t6 is displayed as a live view image at the same time as from time t4 to time t6, when the display vertical synchronization signal LVVD and the vertical synchronization signal VD coincide. This enables a seamless live view image display with synchronized readout of the still image signal and display of the live view image.

[0041] Next, when the instruction for high-speed continuous shooting is canceled between time t7 and time t8, the CPU 104 sends the setting for live view image capture operation to the image sensor 100.

[0042] At time t8, the image signal for still images is read out, and then between time t8 and time t9, the accumulation of the image signal for live view images begins. The image signal for live view images, which is read out at time t9, undergoes correction and development processing in the signal processing circuit 101, and is displayed on the display unit 107 as a live view image in synchronization with the vertical synchronization signal LVVD for display.

[0043] From time t9 onward, the still image signal is not read out, and the reading of the live view image signal and the display of the live view image are repeated in the same manner as from time t1 to time t2. In this way, at time t9, the live view image displayed on the display unit 107 is switched again from an image based on the still image signal to an image based on the live view image signal. This enables seamless switching of the live view image display without causing frame stops or blackouts.

[0044] As described above, in Figure 3(A), the intervals between the display vertical synchronization signal LVVD and the vertical synchronization signal VD, which reads the image signal of the frame used for the live view image, are matched during the readout operation of the image signal for the live view image and the readout operation of the image signal for the still image. By doing so, a live view display without any sense of incongruity can be achieved.

[0045] However, in the control shown in Figure 3(A), if there is a large time difference between the reading of one frame of the live view image signal and the reading of one frame of the still image signal, the following occurs: The difference between the reading timing of the last pixel row of the live view image signal and the display timing of the live view image, and the difference between the reading timing of the last pixel row of the still image signal and the display timing of the live view image, becomes large.

[0046] Therefore, if there is a large difference in the time required to read out one frame of the image signal between the readout operation for the live view image and the readout operation for the still image, the control should be as shown in Figure 3(B). In other words, the interval between the display vertical synchronization signal LVVD and the vertical synchronization signal VD is controlled separately for when the live view image is displayed based on the live view image signal and when the live view image is displayed based on the still image signal.

[0047] In Figure 3(B), compared to Figure 3(A), the centroid (median value of the readout time) of the still image signal is controlled to coincide with the start timing of the live view image display. This control reduces the difference between the readout timing of the last pixel row of the live view image signal and the display timing of the live view image, and between the readout timing of the last pixel row of the still image signal and the display timing of the live view image.

[0048] As described above, the intervals of the display vertical synchronization signal LVVD and the vertical synchronization signal VD are controlled separately depending on whether the live view image display operation is based on the image signal for the live view image or on the image signal for the still image. This control makes it possible to achieve a live view image display that is as natural as possible.

[0049] According to the embodiment described above, when continuous shooting is instructed and the continuously captured still images are used to display the live view image, it is possible to achieve a seamless and uninterrupted display of the live view image.

[0050] (Example 2) Figure 4 shows the overall configuration of the image sensor 100 in Embodiment 2 of the present invention.

[0051] The image sensor 100 shown in Figure 4 differs from the configuration of Embodiment 1 shown in Figure 2 only in that a resizing circuit 400 (resized image generation unit) is added to generate a resized image by downsampling the image signal read from the pixel group 200 in the row or column direction. The configuration other than the resizing circuit 400 is exactly the same as in Figure 2, so its explanation is omitted here.

[0052] The resize circuit 400 receives the image signal output from the column circuit 204, resizes the input image signal by downsampling it in the row or column direction to generate a resized image, and transmits it to the signal processing circuit 104 located downstream of the image sensor 100. Alternatively, the resize circuit 400 may resize the image signal by adding the image signals of multiple pixel rows or multiple pixel columns.

[0053] Furthermore, the resizing circuit 400 is designed to allow switching between the presence or absence of resizing operation and the settings for resizing operation, depending on the set shooting mode and shooting conditions. Specifically, it switches between the number of rows to be thinned out in the row direction or the number of columns to be thinned out in the column direction, and the number of rows to be added to the image signal in the row direction or the number of columns to be added to the image signal in the column direction.

[0054] Furthermore, a path is provided to transmit the image signal output from the column circuit 204 to the signal processing circuit 101 without passing through the resizing circuit 400. This makes it possible to transmit both the resized image signal (resized image signal) and the unresized image signal to the signal processing circuit 101 with a single image signal readout.

[0055] Next, Figure 5 shows the operation flow of image signal readout from the image sensor 100 and live view image in Figure 3(A) described in Example 1, with the operation sequence of the resize circuit 400 added. Referring to Figure 5, an example of the relationship between image signal readout from the image sensor 100 and the display of the live view image when the resize circuit 400 is used will be explained.

[0056] The resize circuit 400 is assumed to be operational when the control signal transmitted from the CPU 104 to the image sensor 100 is HIGH, and inoperable when it is LOW. The differences from Figure 3(A) will be explained below.

[0057] The resize circuit 400 is used when high-speed continuous shooting is instructed and the still image signal is used for displaying a live view image, but the correction and development processing for the still image signal cannot be completed within a predetermined time due to insufficient data processing capacity of the signal processing circuit 101.

[0058] The resizing circuit 400 reduces the amount of data by downsampling or adding to the still image signal in the row or column direction, thereby lowering the resolution to a level comparable to that of the live view image signal. The resized still image signal (resized image signal) is used to display the live view image during high-speed continuous shooting.

[0059] This makes it possible to display a live view image based on a still image signal at a display rate equivalent to that of a normal live view image, even when the amount of data in the still image signal output from the pixel group 200 of the image sensor 100 is large. Note that this resizing circuit 400 does not necessarily need to be located inside the image sensor 100; for example, it may be built into the signal processing circuit 101.

[0060] Next, I will explain the operations at each time point.

[0061] From time t1 to time t2, the live view image is displayed based on the normal live view image display signal, so the resize circuit 400 does not operate.

[0062] Between times t2 and t4, the camera performs still image capture operations based on the instruction for high-speed continuous shooting. However, the image signal for the first frame of the still image is not used for displaying the live view image, so the resize circuit 400 does not operate at this time either.

[0063] Between times t4 and t5, the resize circuit 400 is operated to either thin out or add the second frame of still image signals read out in the row or column direction. The resized image based on the resized still image signals is then displayed as a live view image on the display unit 107. The still image signals that have not been resized are corrected and developed by the signal processing circuit 101 before being recorded in the memory 105 or the recording unit 106.

[0064] From this point forward, if the still image signal captured while high-speed continuous shooting is instructed is used to display the live view image, the resize circuit 400 is activated. After time t9, the still image signal is not read out, and the reading of the live view image signal and the display of the live view image are repeated as in time t1 to time t2, so the resize circuit 400 does not operate.

[0065] As explained above, according to this embodiment, even when displaying a live view image based on a still image signal with a large amount of data read out during high-speed continuous shooting, the display of the live view image can be updated at the display cycle T while recording the original still image data that was captured. Furthermore, even if the frame rate of the still images being shot at high speed is higher than the display frame rate of the live view image, the live view image can be displayed without interruption and without any sense of unnaturalness, similar to Embodiment 1.

[0066] (Example 3) Example 3 describes an example in which, when high-speed continuous shooting of still images as described in Examples 1 and 2 is instructed, the system switches between prioritizing the continuous shooting speed of still images or prioritizing reducing the sense of discomfort when displaying the live view image, depending on the set shooting conditions.

[0067] Figure 6 is a flowchart illustrating the operation of the imaging device in Example 3.

[0068] In step S100, the power is turned on and the imaging device is started.

[0069] In step S101, it is determined whether the shooting mode previously set in the imaging device is the "continuous shooting speed priority mode" for high-speed continuous shooting. Note that the setting of the shooting mode does not necessarily have to be determined based on user instructions; the imaging device may be configured to determine it automatically.

[0070] If it is determined in step S101 that the imaging device is set to "continuous shooting speed priority mode", the process proceeds to step S102. If it is determined that the imaging device is not set to "continuous shooting speed priority mode", the process proceeds to step S103.

[0071] In step S102, the imaging device is set to operate in "continuous shooting speed priority mode". In "continuous shooting speed priority mode", when high-speed continuous shooting of still images is instructed, the continuous shooting speed of still images is prioritized, and synchronization of the vertical sync signal VD and the display vertical sync signal LVVD is not performed. Therefore, since the continuous shooting speed of still images (period of the vertical sync signal VD) does not depend on the display period T (predetermined period), any continuous shooting speed can be set.

[0072] In step S103, the imaging device is set to operate in "display priority mode". In "display priority mode", when high-speed continuous shooting of still images is instructed, the vertical sync signal VD and the display vertical sync signal LVVD are synchronized as described in Examples 1 and 2. Therefore, the continuous shooting speed of still images (period of the vertical sync signal VD) is controlled to depend on the display period T (predetermined period), which reduces the sense of incongruity when displaying live view images.

[0073] Once the shooting mode setting is completed in step S102 or step S103, the process proceeds to step S104 to terminate the shooting mode setting process.

[0074] According to the embodiment 3 described above, it is possible to switch between "continuous shooting speed priority mode" and "display priority mode". When high-speed continuous shooting of still images is instructed, it is possible to provide an imaging device that balances the continuous shooting speed of still images and the display of live view images to meet the user's needs.

[0075] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0076] This embodiment includes the following configuration.

[0077] (Composition 1) Image sensor and A display unit that displays a live view image captured by the aforementioned image sensor, Before executing continuous shooting of multiple still images, the image sensor captures multiple live view images, and the captured live view images are controlled to be displayed on the display unit at predetermined intervals. A control unit controls the image sensor to continuously capture multiple still images without capturing the live view image during the execution of the continuous shooting, and to display at least some of the still images from the multiple still images as the live view image on the display unit at a predetermined interval. An imaging device characterized by having the following features.

[0078] (Configuration 2) The imaging apparatus according to configuration 1, characterized in that the control unit controls the display unit to display an image obtained by combining multiple frames of still images as the live view image.

[0079] (Composition 3) The system further includes an image generation unit that generates a resized image by resizing the aforementioned still image, The imaging apparatus according to configuration 1 or 2, characterized in that the control unit controls the display unit to display the resized images of multiple frames as the live view image.

[0080] (Composition 4) The imaging apparatus according to claim 3, characterized in that the control unit controls the display unit to display an image obtained by combining the resized images of multiple frames as the live view image.

[0081] (Composition 5) The image sensor generates a resized image by resizing the still image, The imaging apparatus according to claim 1, characterized in that the control unit displays the resized image as the live view image on the display unit.

[0082] (Composition 6) The imaging apparatus according to claim 5, characterized in that the control unit controls the display unit to display an image obtained by combining the resized images of multiple frames as the live view image.

[0083] (Method 1) A control method for an imaging device having an image sensor and a display unit that displays a live view image captured by the image sensor, A control method for an imaging device, characterized by having a control step of: before performing continuous shooting of multiple frames of still images, taking live view images of multiple frames with the image sensor, and controlling the device to display the taken live view images on the display unit at a predetermined interval; and during the execution of the continuous shooting, taking multiple frames of still images in succession with the image sensor without taking the live view images, and controlling the device to display at least some of the frames of the multiple frames of still images as the live view images on the display unit at a predetermined interval.

[0084] (Composition 7) A program characterized by causing a computer to execute the control method described in Method 1.

[0085] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its gist. [Explanation of symbols]

[0086] 100 image sensors 101 Signal Processing Circuit 104 CPU 107 Display section

Claims

1. Image sensor and A display unit that displays a live view image captured by the aforementioned image sensor, Before executing continuous shooting of multiple still images, the image sensor captures multiple live view images, and the captured live view images are controlled to be displayed on the display unit at predetermined intervals. A control unit controls the image sensor to continuously capture multiple still images without capturing the live view image during the execution of the continuous shooting, and to display at least some of the still images from the multiple still images as the live view image on the display unit at a predetermined interval. An imaging device characterized by having the following features.

2. The imaging apparatus according to claim 1, characterized in that the control unit controls the display unit to display an image obtained by combining multiple frames of still images as the live view image.

3. The system further includes an image generation unit that generates a resized image by resizing the aforementioned still image, The imaging apparatus according to claim 1, characterized in that the control unit controls the display unit to display the resized images of multiple frames as the live view image.

4. The imaging apparatus according to claim 3, characterized in that the control unit controls the display unit to display an image obtained by combining the resized images of multiple frames as the live view image.

5. The image sensor generates a resized image by resizing the still image, The imaging apparatus according to claim 1, characterized in that the control unit displays the resized image as the live view image on the display unit.

6. The imaging apparatus according to claim 5, characterized in that the control unit controls the display unit to display an image obtained by combining the resized images of multiple frames as the live view image.

7. A control method for an imaging device having an image sensor and a display unit that displays a live view image captured by the image sensor, A control method for an imaging device, characterized by having a control step of: before performing continuous shooting of multiple frames of still images, taking live view images of multiple frames with the image sensor, and controlling the device to display the taken live view images on the display unit at a predetermined interval; and during the execution of the continuous shooting, taking multiple frames of still images in succession with the image sensor without taking the live view images, and controlling the device to display at least some of the frames of the multiple frames of still images as the live view images on the display unit at a predetermined interval.

8. A program characterized by causing a computer to execute the control method described in claim 7.

Images