JP5381541B2 - Imaging device - Google Patents

Description

  The present invention relates to an imaging apparatus such as a digital camera or a video camera that captures continuous images, and more particularly to an imaging apparatus that can suppress an adverse effect on an image due to an external flash or the like.

  As a conventional signal processing device (imaging device) that suppresses an adverse effect on an image due to an external flash or the like, for example, there is a device described in Patent Document 1. FIG. 9 is a block diagram of a conventional imaging apparatus 900. Patent Document 1 describes a process of recording an image in a recording unit. Here, an example in which an image signal is externally output will be described.

  As shown in FIG. 9, the imaging apparatus 900 includes a CMOS sensor, a sensor driving circuit, and an analog / digital converter, which captures continuous images and performs digital sequential with vertical effective 720 lines, horizontal effective 1280 pixels, and frame frequency 60 Hz. An imaging unit 950 that outputs a scanning image signal and an image processing unit 951 that performs gamma processing and contour enhancement on the output of the imaging unit 950 are provided. In addition, the imaging apparatus 900 compares the output of the imaging unit 950 with continuous frame images and detects the presence or absence of external flash, and the output signal (flash detection signal) of the flash detection unit 952. An output control unit 953 that performs switching control of whether the image signal output from the image processing unit 951 is output as it is or whether the accumulated image is output.

  FIG. 10 shows a block diagram of the output control unit 953 in the conventional imaging apparatus 900. As shown in FIG. 10, the output control unit 953 is based on a memory circuit 954 that stores the image signal output from the image processing unit 951 for one frame, and an output signal (flash detection signal) of the flash detection unit 952. A switching circuit 955 that switches and outputs a signal output from the memory circuit 954 and an input signal from the image processing unit 951.

  The operation of the conventional imaging apparatus 900 configured as described above will be described.

  First, in the imaging unit 950, a drive signal is supplied from the sensor drive circuit to the CMOS sensor, and an optical signal (light from the subject) incident on the CMOS sensor is converted into an electrical signal by photoelectric conversion, and further acquired by photoelectric conversion. The electrical signal is converted into a digital progressive scanning image signal by analog / digital conversion. The digital progressive scanning image signal generated by the imaging unit 950 is output from the imaging unit 950. The digital progressive scanning image signal is supplied (output) to the image processing unit 951 and the flash detection unit 952.

  The image processing unit 951 performs gamma processing, contour enhancement processing, and the like on the input digital progressive scanning image signal, and the processed image signal is output to the output control unit 953.

  On the other hand, the flash detection unit 952 calculates an average luminance level for one frame with respect to the input digital progressive scanning image signal, and calculates the frame average luminance level of the input signal and the average luminance level of the previous frame. In comparison, when the average luminance level significantly increases, it is determined that the captured image is acquired by the imaging unit 950 in an environment where an external flash such as a flash exists. For example, when the frame average luminance level of the input signal is increased by 100% or more from the average luminance level of the previous frame, the flash detection unit 952 detects an external flash such as a flash (an environment in which an external flash exists). The signal value of the flash detection signal is set to “1”, and the flash detection signal is output. When the external flash is not detected, the flash detection unit 952 sets the signal value of the flash detection signal to “0” and outputs a flash detection signal. The flash detection signal and the image signal output from the image processing unit 951 are input to the output control unit 953.

  In the output control unit 953, the image signal output from the image processing unit 951 is input to the memory circuit 954. The memory circuit 954 writes and stores one frame of the image signal, delays it by a time corresponding to one frame, and outputs the image signal. When the signal value of the flash detection signal output from the flash detection unit 952 is “1”, that is, when flash is detected, the memory circuit 954 does not write a new image signal and does not write the previous frame. The image signal of the same frame is repeatedly output. The switching circuit 955 switches between the image signal output from the image processing unit 951 and the image signal output from the memory circuit 954 based on the flash detection signal. When the signal value of the flash detection signal output from the flash detection unit 952 is “1”, that is, when the flash detection signal indicates that the flash is detected, the switching circuit 955 is switched from the memory circuit 954. When the output image signal is selected and output, and the signal value of the flash detection signal output from the flash detection unit 952 is “0”, that is, the flash detection signal indicates that no flash is detected. The switching circuit 955 selects and outputs the image signal output from the image processing unit 951.

  Next, the operation of the imaging apparatus 900 will be described in detail with reference to FIG.

  FIG. 11 is a schematic diagram for explaining the adverse effect that an image (image captured by the image capture device 900) is subjected to by external flash in the conventional image capture device 900. FIG.

  (1) to (4) in FIG. 11 show continuous frames, and the timing at which the CMOS sensor receives light is shown on the basis of the vertical synchronization signal (the uppermost stage in FIG. 11).

  The “upper image” shown in FIG. 11 corresponds to an effective screen (a screen that is actually displayed when the image signal acquired by the imaging device is displayed on the display device (a screen excluding a portion such as a synchronization signal). It means the upper side of the screen. In the CMOS sensor, the first line of the effective screen receives light for the period indicated by the arrow in FIG. In the CMOS sensor, the light reception timing is slightly shifted for each line, so the 720th line is shifted by about 1/60 second with respect to the first line. Here, when there is an external flash at the timing indicated by the star in FIG. 11, the flash is received by the line constituting the lower screen of the frame (2) and the line constituting the upper screen of the frame (3). Will do. In such a situation, when the image signal acquired by the imaging unit 950 is displayed on the display device, a high-brightness horizontal band is generated over two consecutive frames on the display screen (video). The occurrence of this high-intensity horizontal band visually makes the user feel uncomfortable. Further, in a method of compressing using the correlation of consecutive frames, for example, in a process of compressing using the MPEG (Moving Picture Experts Group) method, block noise is generated when the image signal generated by the high luminance horizontal band is processed. Or the compression rate is reduced.

  Therefore, in the conventional imaging device 900 shown in FIG. 9, when an external flash is detected, the image of the frame that received the flash is not output, but the image of the immediately preceding frame is output. For this reason, in the imaging apparatus 900, generation | occurrence | production of a high-intensity horizontal band can be prevented.

JP 2007-306225 A

  However, in the conventional imaging device, when an external flash is detected over two consecutive frames, an image of the same frame is output over three frames, and there is a problem that continuity is lost as a moving image.

  For example, in the case of FIG. 11, a high-intensity horizontal band is generated by an external flash in two frames (frame (2) and frame (3)). The image of (1)) is repeatedly output. That is, since the imaging device 900 outputs the same image (an image corresponding to the frame (1)) over three frames, when the image (video) acquired by the imaging device 900 is displayed on the display device, It will be displayed as a still image temporarily, and a tingling sensation will occur as a moving image.

  In particular, when moving the subject or performing panning, tilting, and zooming operations on the camera, the conventional imaging device displays a part of the smooth video as a still image, resulting in smooth movement as a whole. However, it seemed to be tingling for a moment, and it became an uncomfortable image.

  The present invention solves the above-described conventional problems, suppresses the adverse effect of a high-brightness horizontal band caused by external flash, and reduces the tingling sensation as a moving image that appears prominently when there is movement in the image. An object of the present invention is to provide an imaging apparatus that outputs an image.

  In order to solve the above problems, an imaging apparatus according to the present invention includes an imaging unit that can capture a subject image and output a video signal in units of frames, a flash detection unit that detects an external flash, and the imaging unit that outputs 1 A video signal output from the imaging unit when an external flash is detected by the flash detection unit, and a frame averaging unit that adds the video signal of the frame and the video signal of at least one frame of the same number before and after the video signal And a selection unit that switches and outputs the video signal output by the frame averaging unit.

  According to the present invention, it is possible to suppress an adverse effect of a high luminance horizontal band caused by an external flash and to output an image with improved time continuity as a moving image.

1 is a block diagram of an imaging apparatus according to a first embodiment. Block diagram of a flash correction unit according to the first embodiment Block diagram of a flash detection unit according to the first embodiment Schematic diagram for explaining the operation of the imaging apparatus according to the first embodiment. Schematic diagram illustrating the effect of correction of the imaging apparatus according to the first embodiment Block diagram of a flash correction unit according to the second embodiment Block diagram of a flash detection unit according to the second embodiment Schematic diagram illustrating the operation of the imaging apparatus according to the second embodiment Block diagram of a conventional imaging device Block diagram of output control unit of conventional imaging device Schematic diagram for explaining the adverse effect of an image caused by external flash in a conventional imaging device

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

(First embodiment)
<1.1: Configuration of Imaging Device>
FIG. 1 is a block diagram illustrating a main part of the imaging apparatus 100 according to the first embodiment.

  As shown in FIG. 1, the imaging apparatus 100 includes an imaging unit 1, a flash correction unit 2, a flash detection unit 3 that detects the occurrence of external flash light, and a signal processing unit 4.

  The imaging unit 1 includes an imaging device and an analog / digital conversion unit, converts light from the subject into an electrical signal by photoelectric conversion, and outputs the signal as a digital image signal to the flash correction unit 2 and the flash detection unit 3. A CMOS sensor (CMOS type image sensor) is used as the imaging device, but is not limited thereto. The imaging unit 1 captures continuous images and outputs, for example, a digital sequential scanning image signal having a vertical effective 720 lines, a horizontal effective 1280 pixels, and a frame frequency of 60 [Hz].

  Based on the flash detection signal from the flash detection unit 3, the flash correction unit 2 switches and outputs the image signal of the odd-numbered frame (this time will be described as 3 frames) to an averaged signal (details will be described later).

  The flash detection unit 3 calculates the average luminance level of the lower portion of the screen from the image signal from the imaging unit 1, and detects whether or not an external flash has occurred due to a change between the frames (details will be described later).

  The signal processing unit 4 performs gamma processing, contour enhancement processing, matrix processing, and the like on the output of the flash correction unit 2 and outputs the result as an image output that conforms to the video standard.

  An example of a specific configuration of the flash correction unit 2 is shown in FIG.

  As shown in FIG. 2, the flash correction unit 2 includes a first frame memory 20, a second frame memory 21, a frame averaging processing unit 22, and a selector processing unit 23.

  The image signal from the imaging unit 1 is input to the first frame memory 20 and the frame averaging processing unit 22 as a 0V delay signal. The first frame memory 20 writes and stores one frame of the image signal, and outputs it to the second frame memory 21, the frame averaging processing unit 22 and the selector processing unit 23 as a 1V delay signal after one frame delay. Is done. Similarly to the first frame memory 20, the second frame memory 21 writes and stores one frame of the 1V delay signal, and further outputs it to the frame averaging processing unit 22 as a 2V delay signal after one frame delay. Is done.

  The frame averaging processing unit 22 adds and averages the input 0V delay signal, 1V delay signal, and 2V delay signal, and outputs a flash correction signal.

  The selector processing unit 23 switches and outputs the 1V delay signal output from the first frame memory 20 and the flash correction signal output from the frame averaging processing unit 22 in accordance with the flash detection signal from the flash detection unit 3. That is, when no external flash is generated, a 1V delay signal is output, and when an external flash is generated, a flash correction signal is output.

  An example of a specific configuration of the flash detection unit 3 is shown in FIG.

  As shown in FIG. 3, the flash detection unit 3 includes a screen lower average luminance level calculation unit 30, an average luminance level change determination unit 31, and a flash detection signal generation unit 32.

  The screen lower average luminance level calculation unit 30 calculates the average luminance level of the lower screen portion of the input image signal and outputs it to the average luminance level change determination unit 31.

  The average brightness level change determination unit 31 compares the screen lower part average brightness level of the current frame with the screen lower part average brightness level of the immediately preceding frame, and determines that external flashing has started when it significantly increases. For example, when the screen lower part average luminance level of the current frame is increased by 100% or more from the screen lower part average luminance level of the previous frame, it is determined that an external flash has occurred, and the luminance level change determination signal is set to “1”. If the difference in average luminance level between frames is less than 100%, it is determined that no external flash has occurred, and the luminance level change determination signal remains “0”. Further, once the luminance level change determination signal becomes “1”, it is determined that the external flash frame is completed when the difference between the lower average screen luminance level and the previous frame is decreased. For example, when the average luminance level at the lower part of the screen of the current frame is reduced by 100% or more from the average luminance level at the lower part of the screen of the previous frame as in the case of the external flash, it is determined that the external flash frame has ended, and the luminance level When the change determination signal is “0” and does not decrease by 100% or more, it is determined that the external flash is continuously generated and remains “1”. Further, it may be determined that the external flash frame has ended when the average luminance level before the external flash is generated when the external flash is generated is the same level.

  The luminance level change determination signal is output to the flash detection signal generation unit 32. The flash detection signal generation unit 32 generates a signal obtained by delaying the falling position of the luminance level change determination signal by one frame and outputs it as a flash detection signal.

<1.2: Operation of Imaging Device>
The operation of the imaging apparatus 100 configured as described above will be described. Here, a case where a CMOS sensor of a type in which the light receiving timing is slightly shifted for each line as a result of sequentially reading for each line will be described.

  First, the imaging unit 1 photoelectrically converts an optical signal incident on the CMOS sensor, and further performs analog / digital conversion to output a digital sequential scanning image signal. Since the CMOS sensor sequentially outputs from the upper side of the screen and the light reception timing is slightly shifted for each line, the light reception timing is shifted by about 1/60 second between the first line and the 720th line.

  Considering the case where an external flash occurs, the image becomes brighter from the line read immediately after the time when the external flash occurs, and a dark image is output again from the line of the next frame.

  FIG. 4 is a schematic diagram for explaining the operation when an external flash is generated immediately before 360 lines are read.

  For example, if an external flash has occurred just before the 360th line of frame (2) is read, since the previous 359th line is already being read, the external flash has an effect when reading the 359th line of the next frame. That is, a bright image is obtained at the 359th line of the next frame (3) after approximately 1/60 seconds. In the 360th line of the frame (2), an external flash is generated immediately before reading, so an image in which the external flash is received is output. That is, a bright image is obtained. In the 361st line of the frame (2), an external flash is generated slightly before reading, so that a bright image is similarly obtained. Since this is the same thereafter, the result is a bright image from the 360th line of the frame (2) to the 359th line of the next frame (3). Therefore, when frames (1) to (4) before and after the occurrence of the external flash are displayed by frame advance, the dark frame (1), the top 1 to 359 lines on the screen are dark, and the 360 to 720 lines on the bottom of the screen are bright. The frame (2), the upper 1 to 359 lines of the screen are bright, the lower 360 to 720 lines of the screen are dark (3), the entire frame is dark (4), and the frames (2) and (3) are bright horizontal bands Is generated.

  When an external flash occurs, an image signal having a bright horizontal band in the frames (2) and (3) is output from the imaging unit 1 to the flash correction unit 2 and the flash detection unit 3.

  The flash detection unit 3 calculates the average luminance level of the lower portion of the screen from the image signal from the imaging unit 1, and detects whether or not an external flash has occurred due to a change between the frames. That is, the screen lower average luminance level calculation unit 30 calculates the average luminance level. Further, the average luminance level change determination unit 31 compares the average luminance levels of the lower screen portions of the frames (1) and (2) at the timing of the frame (3), and as a result, the average luminance level change determination unit 31 significantly increases. It is determined that an external flash has occurred, and “1” is output as a luminance level change determination signal. Furthermore, the average luminance level change determination unit 31 compares the average luminance levels of the lower screen portions of the frames (2) and (3) at the timing of the next frame (4), and as a result, decreases. It is determined that the external flash has ended, and the luminance level change determination signal is set to “0” and output. The flash detection signal generation unit 32 generates a signal obtained by delaying the falling position of the luminance level change determination signal by one frame and outputs it as a flash detection signal.

  In the flash correction unit 2, a 1V delay signal and a flash correction signal are generated from the image signal from the imaging unit 1 by the first frame memory 20, the second frame memory 21, and the frame averaging processing unit 22, and selector processing is performed. To the unit 23. In the selector processing unit 23, in accordance with the flash detection signal, the output images of the frames (2) and (3) of the 1V delay signal are converted into the average images of the frames (1) to (3) and the frames (2) to (4), respectively. By switching to the average image, the horizontal band image is corrected.

  Here, the average image of the frames (1) to (3) and the average image of the frames (2) to (4) to be output in place of the frame (2) and the frame (3) which are horizontal band images will be described in detail. .

  The horizontal band phenomenon of the frames (2) and (3) occurs because the external flash generated immediately before the 360 line affects different frames depending on the line. That is, 360 to 720 lines are output to frame (2), and 1 to 359 lines are output to frame (3). However, since the combined light amounts of the frame (2) and the frame (3) are substantially the same, the lateral band phenomenon disappears when the image signals of the frames (2) and (3) are added.

  Therefore, the average image of the frames (1) to (3) is an image having no horizontal band phenomenon because the frames (2) and (3) are added. Similarly, the average images of the frames (2) to (4) are also images having no horizontal band phenomenon because the frames (2) and (3) are added.

  In other words, the output image of the flash correction unit 2 can suppress the adverse effect of a high luminance horizontal band caused by external flash.

  FIG. 5 is a schematic diagram schematically showing an output image for explaining the effect of correction. The horizontal bands of the frames (2) and (3) are corrected.

  A notable feature of the imaging apparatus 100 is that the temporal center of the switching image and the original image is equal.

  That is, the average image of frames (1) to (3) has a temporal center at frame (2), and the average image of frames (2) to (4) has a temporal center at frame (3). is there.

  Accordingly, the horizontal center of the horizontal band image of the frame (2) and the average center of the average images of the frames (1) to (3) being switched are equal, and the horizontal band image of the frame (3) and the switching output are respectively. The temporal centers of the average images of the frames (2) to (4) are equal.

  The effect of performing switching output with images having the same temporal center appears remarkably, for example, when the flash detector 3 erroneously detects an external flash even though no external flash has occurred.

  For example, when the flash detection unit 3 erroneously detects an external flash when taking an image of a moving subject or when the camera is in panning, tilting, or zooming, a conventional imaging device uses a frame Since the image of the frame (1) that is temporally different is output in the portions (2) and (3), the operation seems to be jerky for a moment and a sense of incongruity occurs.

  However, when switching between the average image of the frames (1) to (3) and the average image of the frames (2) to (4) of the imaging apparatus 100, the temporal center is equal, so that the user feels a sense of discomfort that seems to be jerky for a moment. Can be improved.

  As described above, in the imaging apparatus 100 according to the present embodiment, an external flash is particularly effective by suppressing an adverse effect of a high luminance horizontal band caused by an external flash and outputting an image with improved time continuity as a moving image. It is possible to improve a sense of incongruity that causes a momentary flicker when an erroneous detection occurs.

  In the above description, the odd frames averaged by the flash correction unit 2 are described as three frames. However, the odd number of frames may be used, and five frames may be used.

  In the above description, the flash detection unit 3 has been described as being configured to detect the occurrence of external flash based on a change in the average luminance level below the screen. However, any configuration may be used as long as external flash can be detected. The structure which has etc. may be sufficient.

(Second Embodiment)
The imaging apparatus according to the second embodiment distinguishes between the case where the external flash is only one frame and the case where the external flash is continuously generated for two or more frames. In the case of switching output and when the signals are continuously generated for two frames or more, the five-frame average signal is switched and output. In other words, it is possible to switch and output only three types of delayed signal, three frame average signal, and five frame average signal, and to switch and output three types according to the second flash detection signal. The configuration of the imaging apparatus is the same as that of the imaging apparatus according to the first embodiment, and the internal configurations of the flash correction unit and the flash detection unit are changed.

<2.1: Configuration of imaging apparatus>
An example of a specific configuration of the flash correction unit according to the second embodiment is shown in FIG.

  As shown in FIG. 6, the flash correction unit 5 of the second embodiment includes a first frame memory 20, a second frame memory 21, a third frame memory 52, a fourth frame memory 53, 2 frame averaging processing section 54 and second selector processing section 55, and a simple 2V delay signal and 3 frame average signal (average of 1V delay signal, 2V delay signal and 3V delay signal) and 5 frames Three types of average signals (average of 0V delay signal, 1V delay signal, 2V delay signal, 3V delay signal, 4V delay signal) are always generated and switched and output by the second flash detection signal.

  An example of a specific configuration of the flash detection unit according to the second embodiment is shown in FIG.

  As shown in FIG. 7, the flash detection unit 6 according to the second embodiment includes a screen lower average luminance level calculation unit 30, an average luminance level change determination unit 31, a frame length determination unit 60, and a second flash detection. A signal generation unit 61.

  Since the screen lower average luminance level calculation unit 30 and the average luminance level change determination unit 31 are the same as the flash detection unit 3 according to the first embodiment, detailed description thereof is omitted.

  The frame length determination unit 60 determines the frame length of the luminance level change determination signal, and the second luminance level change determination determined as three types of no external flash, one external flash, and two or more continuous external flashes. Output a signal.

  In the second flash detection signal generation unit 61, the falling position of the second luminance level change determination signal that has determined that there is no external flash, one frame of external flash, and two or more consecutive external flashes is set to one frame. A delayed signal is generated and output as a second flash detection signal.

<2.2: Operation of Imaging Device>
The operation of the image pickup apparatus according to the second embodiment configured as described above will be described in detail particularly about the operation of the image pickup apparatus when the second flash detection signal is generated.

  FIG. 8A shows the generation process of the second flash detection signal when the external flash is only one frame, and FIG. 8B shows the generation process of the second flash detection signal when the external flash is continuous for two frames. The schematic diagram explaining is shown.

  The operation of the imaging apparatus when an external flash is generated only once in the frame (3) will be described with reference to FIG.

  When the external flash occurs only once in the frame (3), the imaging unit 1 outputs the frames (3) and (4) in which the horizontal band is generated. Similar to the imaging device in the first embodiment, when the average luminance level of the lower part of the screen in the output of the imaging unit 1 is calculated and the luminance level change determination signal is generated, the luminance level of H is only in one frame period of the frame (4). A change determination signal is obtained.

  The frame length determination unit 60 delays the input luminance level change determination signal by one frame period, and determines whether or not the H period is continuous for two frames or more from the luminance level change determination signal before and after the delay. The second luminance level change determination signal is output.

  That is, the frame length determination unit 60 delays the input luminance level change determination signal by one frame period, and in the case of L, “0” indicating no external flash is displayed, and in the case of H, there is only one frame. Controls to output “1” indicating an external flash of one frame, and “2” indicating an external flash of two or more frames when two or more frames are continuous, and outputs a second luminance level change determination signal To do. In the case of FIG. 8A, since the period of H is only one frame, “1” is output. The second flash detection signal generation unit 61 shapes the falling position of the second luminance level change determination signal into a signal delayed by one frame and outputs it as a second flash detection signal. In the flash correction unit 5 of the second embodiment, switching control by the second flash detection signal is performed, and the frames (3) and (4) where the horizontal band is generated are switched and output as average images of three frames, respectively. The

  Similarly, the operation of the imaging apparatus when an external flash is generated twice consecutively in frames (3) and (4) will be described with reference to FIG.

  When the external flash occurs twice in frames (3) and (4), the imaging unit 1 outputs the frame (3), the frame (4), and the frame (5) in which the horizontal band is generated. . Similarly, a waveform that becomes H in frames (4) and (5) is obtained as the luminance level change determination signal.

  The frame length determination unit 60 delays the input luminance level change determination signal by one frame period, and determines whether or not the H period is continuous for two frames or more from the luminance level change determination signal before and after the delay. The second luminance level change determination signal is output.

  That is, in the case of FIG. 8B, the frame length determination unit 60 delays the input luminance level change determination signal by one frame period, and in the case of L, “0” indicating no external flash is set. In the H period, “2” indicating an external flash of 2 frames or more is output.

  The second flash detection signal generation unit 61 shapes the falling position of the second luminance level change determination signal into a signal delayed by one frame and outputs it as a second flash detection signal. In the flash correction unit 5 of the second embodiment, switching control is performed by the second flash detection signal, and the frames (3), (4), and (5) in which the horizontal band is generated are each averaged by 5 frames. To output.

  The lateral band phenomenon of frames (3), (4), and (5) when external flashes are generated twice in succession causes the external flash generated in frame (3) to affect different frames depending on the line. 3) and (4), and similarly, the external flash generated in frame (4) affects different frames depending on the line, and extends over frames (4) and (5). It is caused by the combination. Therefore, the light amounts of all the frames (3), (4), and (5) are almost the same, and when the image signals of the frames (3), (4), and (5) are added, the lateral band phenomenon disappears. .

  The five-frame average images output by switching to the frames (3), (4) and (5) are the frames (1) to (5), (2) to (6) and (3) to (7), respectively. Therefore, in any case, the image includes frames (3), (4), and (5) and has no horizontal band phenomenon. Further, the temporal center of each 5-frame average image coincides with the frames (3), (4) and (5) before switching. Therefore, for example, when the flash detection 3 erroneously detects an external flash, for example, when an image of a moving subject is being photographed, or when the camera is in a panning, tilting, or zooming operation, this phenomenon occurs remarkably. It is possible to improve the feeling of strangeness that can be felt for a moment.

  A remarkable feature of the imaging apparatus 100 according to the second embodiment is that the lateral band phenomenon is corrected with a correction image that is most suitable for both the case where the external flash occurs only for one frame and the case where it occurs twice consecutively. Is that you can. That is, in the imaging apparatus according to the first embodiment, if the number of frames to be averaged is 5 frames, it is possible to deal with external flashes generated twice in succession. There is a problem that an image that can be corrected with an image is corrected with an average image of five frames, and the afterimage feeling of the corrected image may increase. On the other hand, the imaging device 100 according to the second embodiment can solve this problem.

  As described above, the imaging apparatus according to the second embodiment optimally suppresses the adverse effect of a high-intensity horizontal band caused by an external flash that occurs only for one frame and an external flash that occurs twice consecutively, and a moving image. By outputting an image with improved time continuity as described above, it is possible to improve a sense of discomfort such as a momentary tingling that becomes noticeable particularly when an external flash is erroneously detected in a moving image.

  In the above description, the flash detection unit 6 has been described as being configured to detect the occurrence of an external flash based on a change in the average luminance level below the screen, but an external flash that occurs only one frame and an external flash that occurs continuously twice or more. Any configuration may be used as long as the flash can be detected, and a configuration having a light amount sensor or the like may be used.

  The imaging apparatus according to the present invention can output a continuous image as a moving image, excluding a high-brightness horizontal band caused by an external flash, and thus a digital camera, a video camera, or the like that captures a continuous image Can be applied to and useful.

DESCRIPTION OF SYMBOLS 1,950 Image pick-up part 2, 5 Flash correction | amendment part 3, 6 Flash detection part 4 Signal processing part 20 1st frame memory 21 2nd frame memory 22 Frame averaging process part 23 Selector process part 30 Bottom average brightness level calculation Unit 31 average luminance level change determination unit 32 flash detection signal generation unit 52 third frame memory 53 fourth frame memory 54 second frame averaging processing unit 55 second selector processing unit 60 frame length determination unit 61 second Flash detection signal generation unit 100, 900 imaging device 951 image processing unit 952 flash detection unit 953 output control unit 954 memory circuit 955 switching circuit

Claims (3)

An imaging unit capable of capturing a subject image and outputting a video signal in units of frames;
A flash detector for detecting external flashes;
A frame averaging unit that adds one frame of video signal output by the imaging unit and at least one frame of video signal of the same number before and after the video signal;
A selection unit that switches between a video signal output by the imaging unit and a video signal output by the frame averaging unit when an external flash is detected by the flash detection unit;
An imaging apparatus comprising: The frame averaging unit includes:
The imaging device according to claim 1, wherein the number of the same number of frames before and after the addition is changed according to a period in which the external flash detected by the flash detection unit continues. The frame averaging unit includes:
When the external flash detected by the flash detection unit is a period corresponding to one frame, the video signal of one frame is added before and after,
The imaging apparatus according to claim 2, wherein in a period corresponding to two or more frames, video signals of two frames are added to the front and rear, respectively.