JP2011101208A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: a white band-shaped interference can not be properly corrected, the interference occurring in an imaging apparatus using a CMOS (Complementary Metal Oxide Semiconductor) imaging device under a flash of external light such as a flashing device. <P>SOLUTION: The imaging apparatus is equipped with: an imaging part 1 for imaging an object and outputting a video signal; a detecting part 5 which, for a video signal of one frame output by the imaging part 1, detects a video signal having a line position at which difference in line evaluation values of adjacent lines exceeds a predetermined value; a correction gain calculating part 8 which, for a video signal of one frame detected by the detecting part 5, calculates a correction gain amount by using average luminance levels before and after the line position and average luminance levels before and after a line position corresponding to the line position of a video signal one frame before the video signal of one frame detected by the detecting part; and a video signal correcting part 9 for correcting a video signal up to a line ahead of the line position of the video signal of one frame detected by the detecting part 5 or a video signal after the line position by using the calculated correction gain amount. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus such as a video camera, which can alleviate white belt-like interference that occurs when shooting a moving image by using a flash such as a still camera.

  2. Description of the Related Art In recent years, imaging apparatuses using CMOS (Complementary Metal Oxide Semiconductor) imaging elements having features such as small size, low power consumption, and high-speed imaging have made great progress in the fields of consumer video cameras and commercial video cameras.

  A CMOS image sensor has various features compared to a CCD (Charge Coupled Device). In a CMOS image sensor, the readout timing of a photodiode (Photo Diode: hereinafter referred to as PD) is not the same timing (so-called global shutter) in all pixels as in a CCD, but the readout timing is shifted in units of lines (pixels) ( Because of the so-called rolling shutter, a problem that does not exist in the CCD also occurs. This is because the readout timing is shifted and the timing of the accumulation period of each pixel is shifted.

  One of the problems is a phenomenon that white band-like interference occurs when an image of a subject in which flash light is blown, such as a still camera, is captured by a video camera of a CMOS image sensor. Here, white-band interference refers to a phenomenon in which only a part of a frame of a captured image is affected by flash light, and only the upper or lower part of the line is brightened.

  Hereinafter, this phenomenon will be described with reference to FIGS.

  FIG. 15 is a diagram showing a shooting scene where a video camera and a still camera are mixed, for example, a shooting scene such as a press conference.

  FIG. 15 shows a shooting scene composed of a video camera 100, a monitor 101 that displays an image pickup signal thereof, still cameras 102 and 103, and a subject 104. The video camera 100 uses a CMOS image sensor.

  When the still camera 102 or 103 is used in such a shooting scene, a white belt-like interference occurs on the screen of the monitor 101 that displays the image signal of the video camera 100. The principle will be described below.

  FIG. 16 is a diagram schematically showing the accumulation period (exposure period) and readout scanning period of the video camera 100. In FIG. 16, the charge accumulation period of each scanning line constituting the screen and the scanning period for reading out the charge are shown with the time axis as the horizontal axis. The total number of scanning lines is 1125 lines assuming an HD camera. The monitor screen 0 period is a period in which the imaging signal of frame 0 is output to the monitor screen or the like, and is 1/60 seconds here. The same applies to the monitor screen 1 period and the like.

For example, the line 1 which is the top line of the screen starts the PD accumulation of the frame 1 just at the start timing of the monitor screen 0 period, and ends the PD accumulation at the 1 frame period, that is, the end timing of the monitor screen 0 period. . The readout scan of the accumulated PD signal of line 1 is started immediately after this, and at the same time, the PD accumulation of the next frame 2 is started. The PD signal readout scanning period is 1/60 / 1125≈1.48 × 10 ⁻⁵ seconds because 1125 lines are scanned in one frame period (1/60 seconds).

  Next, line 2 starts PD accumulation in synchronization with the PD read scan period end timing for frame 0 of line 1. That is, the line 2 performs the PD accumulation and readout operation with a delay from the line 1 by the PD readout scanning period. The same applies to the line 3 and subsequent lines.

  Thus, in the rolling shutter system, the accumulation period of each line constituting one frame is slightly shifted from the top to the bottom as shown in FIG. Accordingly, the scanning period of each line, that is, the PD signal readout timing is immediately after the accumulation period of each line as shown in FIG. 16, and when the PD signal of line 1 is read out, the PD signal of line 2 is read out next. It is performed sequentially.

  Here, as shown in FIG. 16, when the flash is fired near the center of the monitor screen 1 period, bright light of the flash affects the accumulation period of the second half of the frame 1 and the accumulation period of the first half of the frame 2. As shown in FIG. 16, the flash lit during the period of the monitor screen 1 straddles the accumulation and readout timings of the frames 1 and 2 on the line X and the line Y. That is, in the frame 1, the portion of the line a1 before the line X is not affected by the flash light (the accumulation period has already ended). The line a2 portion in the period between the line X and the line Y is affected by the flash light in the frame 1, and the accumulated light quantity gradually increases. The portion of line a3 after line Y is affected by the total amount of flash light. On the contrary, in the frame 2, the portion of the line b 1 before the line X is affected by the total amount of flash light, and the portion of the line b 2 in the period between the lines X and Y is gradually less affected by the flash light. Become. Then, since the accumulation period has not yet started in the portion of the line b3 after the line Y, it is not affected by the flash light.

  Therefore, assuming that the flash light emission period is momentary and there is no transient period of the a2 and b2 portions, the monitor screen generally shows the monitor screen 1 (imaging signal of frame 1) as shown in the lower part of FIG. The lower half is bright, and the upper half of the monitor screen 2 (imaging signal of frame 2) is bright, and this is displayed as white-band interference. In the case of an imaging device using a CCD, unlike the CMOS, since the accumulation timing of all the lines constituting one frame is the same, such a problem does not occur. It was projected. As described above, the CMOS imaging device has a problem in that when an external flash light such as a flash light enters, a white belt-like interference occurs in the imaging signal.

  As a conventional imaging device that solves this problem, there is an imaging device described in Patent Document 1.

  FIG. 17 is a block diagram illustrating a configuration example of a conventional imaging device. This imaging apparatus is a digital still camera that mainly records so-called still images. 17, the imaging apparatus includes an imaging unit 113, an image processing unit 114, a recording / display processing unit 116, a buffer 117, an evaluation unit 120, a storage unit 121, and a control unit 123.

  In the conventional imaging apparatus, with such a configuration, for example, when a still image or a moving image is captured by the imaging unit 113 in accordance with a user operation, the captured image is processed by the image processing unit 114 with predetermined image processing. Is applied to the record display processing unit 116 and the evaluation unit 120. The recording display processing unit 116 buffers this image in the buffer 117, and the evaluation unit 120 generates an evaluation value for this image by the detection circuit and supplies it to the control unit 123, and the control unit 123 stores the evaluation value in the storage unit 121. Memorize temporarily. The arithmetic circuit of the control unit 123 calculates a difference value between the evaluation value and the evaluation value already stored in the storage unit 121, that is, the evaluation value generated from the image one frame before. If the difference value is greater than or equal to a preset reference value, it is determined that the image has been adversely affected by the external flash, and if the difference value is less than the reference value, it is determined that the image is not affected by the external flash. In response to the result, the control unit 123 controls each unit of the imaging device, and if it is determined that the image has been adversely affected by the external flash, the image is excluded. By outputting an image, the problem of white band interference caused by an external flash is solved.

JP 2007-306225 A

  In the conventional imaging device, when it is determined that the captured image is adversely affected by the external flash, the image is replaced with an image that has not been affected by the external flash captured in the past, and the external flash is used. The correction is realized by eliminating the frame itself including white belt-like interference.

  However, with this method, the past frame is frozen for at least two frames, and when the moving image is shot, the video is uncomfortable and stops moving for a moment.

  In addition, in order to eliminate all images affected by external flash, it contains a brightened image that should be present in the output video even though the scene where the external flash was emitted was captured. It will be unnatural and the image will be unnatural.

  The present invention solves the above-described conventional problems, and can capture the influence of an external flash emitted at an arbitrary timing on an imaging signal without leaving a sense of incongruity while leaving information included in the original image. An object is to provide an apparatus.

  In order to solve the above problems, an imaging apparatus according to the present invention provides a difference in line evaluation values of adjacent lines between an imaging unit that captures a subject image and outputs a video signal, and a one-frame video signal output by the imaging unit. A detection unit that detects a video signal having a line position exceeding a predetermined value, and at least an average luminance level up to a line before the line position for the one-frame video signal detected by the detection unit, after the line position The average luminance level of the video signal, the average luminance level up to the line before the line position corresponding to the line position in the video signal one frame before the video signal, and the line position in the video signal one frame before the video signal. A correction gain calculation unit that calculates a correction gain amount using any one of the average luminance levels after the corresponding line position, and the correction gain. Using down amount, and a video signal correction unit that corrects the video signal of the video signal from the line position to the front of the line, or after the line position in the video signal of one frame detected by the detection unit.

  With the above configuration, the correction gain amount is calculated from the ratio of the average brightness level before and after being affected by the external flash with respect to the external flash emitted at an arbitrary timing, and the external flash is calculated using the gain coefficient. By correcting the influence of the image, the video is not frozen, so that the natural image including the image brightened by the external flash should be acquired without missing the information included in the original image. .

FIG. 3 is a diagram illustrating a schematic configuration of an imaging device according to Embodiment 1. FIG. 3 is a diagram illustrating a schematic configuration of a line determination unit of the imaging device according to Embodiments 1 and 2. FIG. 4 is a diagram illustrating a schematic configuration of a block addition average calculation unit of the imaging apparatus according to Embodiments 1 and 3; Flowchart showing the operation of the imaging apparatus in the first to fourth embodiments FIG. 6 is a diagram for explaining the operation of the gain adjustment unit of the imaging device according to the first and second embodiments. The figure explaining the influence on the image pick-up signal by the external flash in the image pick-up device using a CMOS image sensor FIG. 6 is a diagram illustrating a schematic configuration of an imaging device according to Embodiment 2. FIG. 10 is a diagram illustrating a schematic configuration of a block addition average calculation unit of an imaging apparatus according to Embodiment 2. FIG. 6 is a diagram illustrating a schematic configuration of an imaging device according to Embodiment 3. FIG. 5 is a diagram illustrating a schematic configuration of a line determination unit of an imaging apparatus according to Embodiments 3 and 4 FIG. 6 is a diagram for explaining the operation of the gain adjustment unit of the imaging apparatus according to Embodiments 3 and 4; FIG. 6 is a diagram illustrating a schematic configuration of an imaging device according to Embodiment 4. FIG. 10 is a diagram illustrating a schematic configuration of a block addition average calculation unit of an imaging apparatus according to Embodiment 4. The figure explaining the influence on the image pick-up signal by the external flash in the image pick-up device using a CMOS image sensor The figure explaining the photography scene which can interfere with an image pick-up signal by an external flash The figure explaining the principle of white-band interference caused by an external flash in an imaging device using a CMOS image sensor The figure which shows schematic structure of the conventional imaging device

  Hereinafter, embodiments will be described with reference to FIGS.

(Embodiment 1)
(1-1. Configuration of Imaging Device)
FIG. 1 is a diagram illustrating a schematic configuration of the imaging apparatus according to the first embodiment.

  The imaging apparatus shown in FIG. 1 includes an imaging unit 1, a frame memory 2, a first line addition average calculation unit 3, a second line addition average calculation unit 4, a first line determination unit 5, and a first line determination unit 5. 1 block addition average calculation unit 6, second block addition average calculation unit 7, first gain calculation unit 8, and first gain adjustment unit 9.

  The imaging unit 1 includes an imaging element (not shown), a correlated double sampling (CDS) circuit, an A / D (Analog / Digital) circuit, a signal generator (SG), and a timing generator (TG), and captures an image of the subject. Output the image.

  The image sensor is composed of, for example, a CMOS sensor or a CCD, and outputs an image signal as an electric signal by receiving light from an incident subject and performing photoelectric conversion. The imaging device is composed of a plurality of pixels that accumulate charges according to the amount of received light, which are laid out in a flat pattern in a grid-like arrangement, and a horizontal drive signal and a vertical drive signal supplied from a timing generator Accordingly, light is received for a predetermined exposure time. A charge corresponding to the amount of received light is accumulated in each pixel of the image sensor, and the image sensor supplies the charge as an analog image signal to the CDS circuit.

  The CDS circuit removes the noise component of the analog image signal supplied from the image sensor by performing correlated double sampling. The CDS circuit supplies the image signal from which the noise component has been removed to the A / D circuit.

  The A / D circuit performs A / D conversion on the analog image signal from the CDS circuit, and outputs the resulting digital image data as the first imaging signal. The signal generator generates a horizontal synchronization signal and a vertical synchronization signal based on control of a control unit (not shown), and outputs them to the timing generator. The timing generator generates a horizontal drive signal and a vertical drive signal for driving the image pickup device based on the horizontal synchronization signal and the vertical synchronization signal supplied from the signal generator, and supplies them to the image pickup device.

  The frame memory 2 delays the first imaging signal output from the imaging unit 1 by one frame and outputs it as a second imaging signal.

  The first line addition average calculation unit 3 calculates the addition average value of the luminance levels for each line of the first imaging signal in each frame, and calculates a first line evaluation value L1x (x is a line position).

  Similarly, the second line addition average calculation unit 4 calculates the addition average value of the luminance levels for each line of the second imaging signal in each frame, and calculates the second line evaluation value L2x (x is the line position). .

  The first line determination unit 5 receives the first line evaluation value, and the line evaluation value of the current line is greater than or equal to a predetermined amount set in advance compared to the previous line evaluation value due to the influence of external flash. A changing line m (m is a line position) is detected, and the line position m is temporarily stored.

  FIG. 2 is a diagram showing a schematic configuration of the first line determination unit 5 of FIG.

  The line determination unit illustrated in FIG. 2 includes an evaluation value shift register unit 51, an evaluation value determination unit 52, a line counter 53, and a line position storage unit 54.

  The evaluation value shift register unit 51 is a shift register composed of a flip-flop or the like, and the first line evaluation value L1x (x is a line position) of each line calculated by the first line addition average calculation unit 3 of FIG. ) Is input and transferred to the next-stage register line by line in accordance with the horizontal synchronization pulse. The evaluation value determination unit 52 generates a trigger pulse if it is larger than a predetermined amount by comparison with the line evaluation value of one line before each line. The line counter 53 counts the number of lines according to the horizontal synchronization pulse. The line position storage unit 54 temporarily stores the counter value of the line counter 53 according to the trigger pulse generated by the evaluation value determination unit 52, that is, the line position m where the line m satisfies the above-described condition.

  In FIG. 1, the first block addition average calculation unit 6 performs a line position m stored in the first line determination unit 5 from a line m of the (N−1) th frame to a line n (n is the last line). The value obtained by adding the first line evaluation values L1m to L1n up to the line position) is divided by nm + 1 to obtain the first average value of the first line evaluation values from line m to line n. The block addition average value Bm, n is calculated.

  Similarly, the second block addition average calculating unit 7 applies the line m to the line n (n is the line of the last line) with respect to the line position m stored in the first line determination unit 5. The value obtained by adding the second line evaluation values L2m to L2n up to (position) is divided by n−m + 1 to obtain the addition average value of the second line evaluation values from line m to line n. The block addition average value Am, n is calculated.

  FIG. 3 is a diagram showing a schematic configuration of the first block addition average calculation unit 6 and the second block addition average calculation unit 7 in FIG.

  The block addition average calculation unit illustrated in FIG. 3 includes a line counter 61, counter value comparison units 63 and 65, a delay unit 66, a line evaluation value addition unit 67, and a block addition average value storage unit 69.

  Hereinafter, the case of the first block addition average calculation unit 6 will be described as an example.

  The line counter 61 counts the number of lines according to the horizontal synchronization pulse. The counter value comparison units 63 and 65 have the counter values of the line counter 61 set to m and n (n is the line position of the final line) with respect to the line position m stored in the first line determination unit 5 in FIG. A trigger pulse is generated at the timing. The delay unit 66 receives the line evaluation value Lx (x is the line position) of each line calculated by the first line addition average calculation unit 3 in FIG. 1, and the line m is input by the first line determination unit 5 as described above. The line evaluation value is delayed according to the horizontal synchronization pulse so that the line evaluation value Lm of the line m is input to the line evaluation value adding unit 67 after the timing when the line position m satisfying the condition is stored. The line evaluation value adding unit 67 sets the input line evaluation value to 0 at the timing when the counter value comparing unit 63 generates a trigger pulse, that is, when the line evaluation value Lm of the line m is input to the line evaluation value adding unit 67. In other cases, a value obtained by adding the total value of the line evaluation values so far to the input line evaluation value is output according to the horizontal synchronization pulse. The block addition average value storage unit 69 receives the value output from the line evaluation value addition unit 67, takes it in at the timing when the counter value comparison unit 65 generates a trigger pulse, and divides and stores it by n−m + 1. That is, the block addition average value storage unit 69 divides the addition value of the line evaluation values from the line m to the line n calculated by the line evaluation value addition unit 67 by n−m + 1 and averages the first block addition value. The average value Bm, n (second block addition average value Am, n in the case of the second block addition average calculation unit 7) is stored.

  The first gain calculation unit 8 receives the second block addition average value Am, n and the first block addition average value Bm, n and calculates a gain coefficient k (k = Bm, n / Am, n). Remember. That is, the gain coefficient k represents the ratio of the average luminance level before and after the luminance level of the area under the image affected by the external flash increases.

  The first gain adjusting unit 9 corrects the gain of the first image pickup signal output from the frame memory 2 at an appropriate timing using the gain coefficient k.

(1-2. Operation of Imaging Device)
Hereinafter, the operation of the imaging apparatus according to the first embodiment will be described with reference to the flowchart of FIG. 4 and FIGS. 5 and 6.

  FIG. 6 is a diagram illustrating an influence on an imaging signal and a display image when an external flash such as a flash of a still camera is emitted during imaging.

  As shown in FIG. 6, when an external flash is emitted during imaging of the Nth frame, the imaging signal output from the imaging unit 1 includes the lower part of the image of the N−1th frame and A white belt-like disturbance occurs at the top of the image of the Nth frame. In FIG. 6, in the (N-1) th frame, it is not affected by the external flash until the (m-1) th line, and is affected by the external flash in the mth and subsequent lines. Is affected by an external flash, and is not affected by an external flash after the m-th line.

  The imaging unit 1 images a subject and outputs it as a first imaging signal (step 401). First, the case where the imaging unit 1 outputs the imaging signal of the frame N-1 will be described.

  The first line addition average calculation unit 3 calculates an addition average value of luminance levels for each line of the first imaging signal, and calculates a first line evaluation value L1x (x is a line position). The first line determination unit 5 receives the first line evaluation value, and the line evaluation value of the current line is greater than or equal to a predetermined amount set in advance compared to the previous line evaluation value due to the influence of external flash. When an increasing line m (m is a line position) is detected, it is determined that a white band has occurred, and the line position m is temporarily stored (Yes in step 402).

  It is confirmed whether or not the calculated gain coefficient exists for the imaging signal one frame before (in this case, the frame N-2). If it does not exist (No in step 403), the following processing is executed.

  The first block addition average calculation unit 6 adds the line evaluation values from the line position m in the first image pickup signal to the line position n that is the final line of the frame, and divides the addition value by n−m + 1. The averaged value is calculated as the first block addition average value Bm, n (step 404).

  Similarly, the second block addition average calculation unit 7 performs line evaluation from the line position m to the line position n stored above for the second image pickup signal which is the image pickup signal one frame before the first image pickup signal. The value is added, and the value obtained by dividing and averaging the added value by nm + 1 is stored as the second block addition average value Bm, n (step 405).

  The first gain calculation unit 8 calculates a gain coefficient k (k = Bm, n / Am, n) using the second block addition average value Am, n and the first block addition average value Bm, n. (Step 406).

  The first gain adjustment unit 9 corrects the second imaging signal output from the frame memory 2 using the gain coefficient k (step 407). The gain coefficient k is a value calculated using the luminance level up to the final line position n of the first imaging signal of the frame N-1. Therefore, when the gain coefficient k is calculated, the imaging unit 1 starts outputting the imaging signal of the next frame, frame N, as the first imaging signal. The first gain adjustment unit 9 outputs the image pickup signal of the frame N as the first image pickup signal from the image pickup unit 1, and outputs the second image pickup signal of the frame N−1 delayed by one frame output from the frame memory 2. On the other hand, correction is performed.

  The correction performed by the first gain adjustment unit 9 will be described with reference to FIG. As shown in FIG. 5A, the first gain adjustment unit 9 performs the luminance level of the imaging signal from line m to line n, where the luminance level increases due to the influence of the external flash, as shown in FIG. Is 1 / k times to correct an image including a white band generated by the influence of the external flash in the (N-1) th frame.

  In the first embodiment, an image that is not affected by the external flash is obtained by multiplying the luminance level of the imaging signal from line m to line n by 1 / k, where the luminance level is increased due to the external flash. However, by multiplying the luminance level of the imaging signal from line 1 to line m−1 that is not affected by the external flash by k, an image in which the entire surface is lit white by the influence of the external flash is obtained. You may correct | amend as follows.

  Next, the case where the imaging unit 1 outputs an imaging signal of the next frame, which is a frame N, will be described.

  The first line addition average calculation unit 3 calculates an addition average value of luminance levels for each line of the first imaging signal, and calculates a first line evaluation value L1x (x is a line position). The first line determination unit 5 receives the first line evaluation value, and the line evaluation value of the current line is greater than or equal to a predetermined amount set in advance compared to the previous line evaluation value due to the influence of external flash. If a decreasing line m (m is a line position) is detected, it is determined that the white belt has ended, and the line position m is temporarily stored (step 402).

  It is checked whether or not the calculated gain coefficient exists for the image signal one frame before (in this case, frame N-1) (step 403). Since the gain coefficient k calculated for the frame N-1 exists (Yes in Step 403), the process proceeds to Step 407 without newly calculating the gain coefficient k.

  The first gain adjustment unit 9 outputs the image pickup signal of the next frame, frame N + 1, as the first image pickup signal by the first image pickup unit 1, and the second gain of the frame N delayed by one frame by the frame memory 2. Correction is performed at the timing when the imaging signal is output (step 407). For the frame N, the first gain adjustment unit 9 increases the luminance level of the imaging signal from line m to line n immediately after the influence of the external flash is finished, as shown in FIG. Thus, it is possible to correct an image including a white band caused by the influence of the external flash of the Nth frame.

  In the first embodiment, the luminance level of the imaging signal from line m to line n immediately after the influence of the external flash is finished is multiplied by k times, so that the entire Nth frame is affected by the external flash. An image that has been corrected to be a white-lighted image, but is not affected by the external flash by multiplying the luminance level of the imaging signal from line 1 to line m-1 affected by the external flash by 1 / k. You may correct | amend so that it may become.

  In the first embodiment, in step 403, it is confirmed whether or not the calculated gain coefficient exists for the imaging signal one frame before, and if it exists, the form using the gain coefficient has been described. A mode may be employed in which gain coefficients are calculated for all frames and correction is performed using the calculated gain number.

  In addition, although the imaging apparatus, the line determination unit, and the block addition average calculation unit of the first embodiment have been described with reference to FIGS. 1, 2, and 3, other configurations are appropriately configured without departing from the gist of the invention. Needless to say, it can be taken.

  In the first embodiment, the evaluation value of each line is set as the luminance level of the imaging signal. However, the line evaluation value for determining the presence or absence of the influence of the external flash by the first line determination unit 5 is the external flash. Other signal components and values such as color components, frequency components and SN ratio (Signal to Noise Ratio) of the imaging signal may be used as evaluation values as long as they change depending on the presence or absence of the influence of. In addition, if the block addition average value calculated by the first block addition average calculation unit 6 and the second block addition average calculation unit 7 changes in proportion to the luminance level, other signal components and values are evaluated. It does not matter as a value.

  As described above, according to the first embodiment, a steep change in the evaluation value in the line direction is first detected, and the average luminance level of the area affected by the external flash in the screen and the outside of the same area are detected. By calculating the gain coefficient from the ratio to the average brightness level before being affected by the flash, and correcting using the gain coefficient, any line affected by the timing of the external flash is corrected. It is possible, and by making use of the information of the original image without freezing the normal image at the time of correction, the movement of the subject does not become unnatural, and the image that has been corrected should be bright. Since the image is also included, the influence of the external flash can be corrected without a sense of incongruity.

(Embodiment 2)
FIG. 7 is a diagram illustrating a schematic configuration of the imaging apparatus according to the second embodiment.

  The imaging apparatus illustrated in FIG. 7 includes an imaging unit 1, a frame memory 2, a first line addition average calculation unit 3, a second line addition average calculation unit 4, a first line determination unit 5, and a first line determination unit 5. 3 block addition average calculation unit 60, fourth block addition average calculation unit 70, second gain calculation unit 80, and first gain adjustment unit 9.

  The imaging unit 1, the frame memory 2, the first line addition average calculation unit 3, the second line addition average calculation unit 4, the first line determination unit 5, and the first gain adjustment unit 9 are the same as those in the first embodiment. Since it is the same as that of an apparatus, description is abbreviate | omitted.

  From the line position m stored in the first line determination unit 5, the third block addition average calculation unit 60 extends from the line m of the (N−1) th frame to the line n (n is the line position of the last line). The first block evaluation average of the first line evaluation values from line m to line n is obtained by dividing the value obtained by adding the first line evaluation values L1m to L1n by n−m + 1. A value Bm, n is calculated, and a value obtained by adding the first line evaluation values L11 to L1m-1 from the line 1 to the line m-1 is divided by the m-1, thereby dividing the line 1 to the line m. The average addition value of the first line evaluation values up to −1 is calculated as the third block addition average value B1, m−1.

  Similarly, the fourth block addition average calculating unit 70 applies the line m to the line n (n is the line of the last line) with respect to the line position m stored in the first line determination unit 5. The value obtained by adding the second line evaluation values L2m to L2n up to (position) is divided by n−m + 1 to obtain the addition average value of the second line evaluation values from line m to line n. The block addition average value Am, n is calculated, and the value obtained by adding the second line evaluation values L21 to L2m-1 from line 1 to line m-1 is divided by m-1 to obtain line 1 To the line m−1 is calculated as a fourth block addition average value A1, m−1.

  FIG. 8 is a diagram showing a schematic configuration of the third block addition average calculation unit 60 and the fourth block addition average calculation unit 70 in FIG.

  The block addition average calculation unit shown in FIG. 8 includes a line counter 61, counter value comparison units 62, 63, and 65, a delay unit 66, a line evaluation value addition unit 67, and block addition average value storage units 68 and 69. Have

  Hereinafter, the case of the third block addition average calculation unit 60 will be described as an example.

  The line counter 61 counts the number of lines according to the horizontal synchronization pulse. The counter value comparison units 62, 63, and 65 have a counter value of 1, m, and n (n is the final line) for the line position m stored in the first line determination unit 5 of FIG. The trigger pulse is generated at the timing of (line position). The delay unit 66 receives the line evaluation value Lx (x is the line position) of each line calculated by the first line addition average calculation unit 3 in FIG. 7, and the first line determination unit 5 sets the line m to the above-described line evaluation value Lx. The line evaluation value is delayed according to the horizontal synchronization pulse so that the line evaluation value Lm of the line m is input to the line evaluation value adding unit 67 after the timing when the line position m satisfying the condition is stored. The line evaluation value adding unit 67 is input at the timing when the counter value comparing units 62 and 63 generate the trigger pulse, that is, at the timing when the line evaluation values L1 and Lm of the line 1 and line m are input to the line evaluation value adding unit 67. In this case, a value obtained by adding the total value of the line evaluation values so far to the input line evaluation value is output in accordance with the horizontal synchronization pulse. The block addition average value storage units 68 and 69 receive the values output from the line evaluation value addition unit 67, and the counter value comparison units 63 and 65 take in at the timing when the trigger pulse is generated, respectively, at m−1 and n−m + 1. Divide and store. That is, the block addition average value storage unit 68 divides the addition value of the line evaluation values from the line 1 to the line m−1 calculated by the line evaluation value addition unit 67 by m−1 and averages the third value. Stored as the block addition average value B1, m-1 (fourth block addition average value A1, m-1 in the case of the fourth block addition average calculation unit 70). The block addition average value storage unit 69 divides the addition value of the line evaluation values from the line m to the line n calculated by the line evaluation value addition unit 67 by n−m + 1 and averages the third block. The addition average value Bm, n (fourth block addition average value Am, n in the case of the fourth block addition average calculation unit 70) is stored.

  The second gain calculation unit 80 includes the fourth block addition average value A1, m-1, the fourth block addition average value Am, n, the third block addition average value B1, m-1, and the third block addition. Using the average value Bm, n as an input, the gain coefficient k (k = (Bm, n × A1, m−1) / (Am, n × B1, m−1)) is calculated and stored.

  The operation of the imaging apparatus in the second embodiment is the same as the flowchart of the first embodiment shown in FIG. Hereinafter, differences from the first embodiment will be described. In the second embodiment, when calculating the gain coefficient k, Bm, n / Am, n are the same as those in the first embodiment, but the ratio of A1, m−1 / B1, m−1 is further increased. It is included. This is the ratio of the average luminance level of the area above the image that is not affected by the external flash, and can be considered to represent a change in luminance level due to an iris change between two frames. That is, the gain coefficient k is an average luminance level before and after the luminance level of the lower region of the image affected by the external flash is increased, taking into account changes due to imaging conditions such as iris that are not related to the emission of the external flash. Will represent the ratio.

  The first gain adjustment unit 9 uses the gain coefficient k to correct the second imaging signal output from the frame memory 2 by adjusting the gain at an appropriate timing, as in the first embodiment. The imaging signal of each frame is output sequentially.

  In addition, although the imaging apparatus, the line determination unit, and the block addition average calculation unit according to the second embodiment have been described with reference to FIGS. 7 and 8, other configurations can be appropriately employed without departing from the gist of the invention. Needless to say.

  In the second embodiment, the evaluation value of each line is used as the luminance level of the imaging signal. However, the line evaluation value for determining the presence or absence of the influence of the external flash in the first line determination unit 5 is the external flash. Other signal components and values such as color components, frequency components and SN ratio (Signal to Noise Ratio) of the imaging signal may be used as evaluation values as long as they change depending on the presence or absence of the influence of. In addition, if the block addition average value calculated by the third block addition average calculation unit 60 and the fourth block addition average calculation unit 70 changes in proportion to the luminance level, other signal components and values are evaluated. It does not matter as a value.

  As described above, according to the second embodiment, first, a steep change in the evaluation value in the line direction is detected, and the average luminance level of the area affected by the external flash in the screen and the outside of the same area are detected. Changes in shooting conditions such as iris settings are taken into account by calculating the gain coefficient from the ratio of the average brightness level before being affected by the flash and the ratio of the average brightness level of the area not affected by the external flash in each frame. By calculating a more accurate gain coefficient and correcting using the gain coefficient, it is possible to correct any line affected by the timing of external flash emission. By using the information of the original image without freezing the normal image, the movement of the subject does not become unnatural, and the corrected image includes a brightened image that should exist originally. Flash It is possible to correct the influence.

(Embodiment 3)
FIG. 14 is a diagram showing an influence on an image signal and a display image when an external flash such as a still camera flash is emitted during imaging. In the third embodiment, a case will be described in which light emission of an external flash is not instantaneous but continues for a certain period.

  As shown in FIG. 14, when an external flash is emitted during imaging of the Nth frame, the imaging signal output from the imaging unit 1 includes the lower part of the image of the (N−1) th frame and A white belt-like disturbance occurs at the top of the image of the Nth frame. In FIG. 14, in the (N-1) th frame, there is almost no influence from the external flash until the (m-1) th line, and from the (m + a) th line, it is influenced by almost the total light quantity of the external flash, and the line between them is the external flash. Depending on the light emission period, it is a transient period in which the accumulated light quantity increases almost linearly as the line number increases. In the Nth frame, up to the (m-1) th line, it is affected by almost the total light intensity of the external flash, and after the m + a line, it is hardly affected by the external flash, and the line between them is almost linear as the line number increases. The transient period during which the accumulated light quantity decreases.

  FIG. 9 is a diagram illustrating a schematic configuration of the imaging apparatus according to the third embodiment.

  The imaging apparatus shown in FIG. 9 includes an imaging unit 1, a frame memory 2, a first line addition average calculation unit 3, a second line addition average calculation unit 4, a second line determination unit 50, 5 block addition average calculation unit 600, sixth block addition average calculation unit 700, first gain calculation unit 8, and second gain adjustment unit 90.

  The imaging unit 1, the frame memory 2, the first line addition average calculation unit 3, and the second line addition average calculation unit 4 are the same as those of the imaging apparatus according to the first embodiment, and thus description thereof is omitted.

  The second line determination unit 50 receives the first line evaluation value as an input, and the line evaluation value of the line m + a is greater than a predetermined amount set in advance by comparison with the line evaluation value of the line m−1 due to the influence of the external flash. The line position m and the line position m + a are increased so that the line evaluation value increases in line with the line m, the line m + 1,. Detect and store temporarily. In the case of FIG. 14, the line position m and the line position m + a are detected and stored at the timing when the first image pickup signal output from the image pickup unit 1 is the image pickup signal of the (N−1) th frame. .

  FIG. 10 is a diagram showing a schematic configuration of the second line determination unit 50 of FIG.

  The line determination unit illustrated in FIG. 10 includes an evaluation value shift register unit 501, an evaluation value determination unit 502, a line counter unit 53, and a line position storage unit 504.

  The evaluation value shift register unit 501 is a shift register composed of a flip-flop or the like, and the first line evaluation value L1x (x is a line position) of each line calculated by the first line addition average calculation unit 3 in FIG. ) Is input and transferred to the next-stage register line by line in accordance with the horizontal synchronization pulse. The evaluation value determination unit 502 is larger than a predetermined amount for each line compared with the line evaluation value before the line a + 1, and the line evaluation value does not change much before and after the line evaluation value. If it is detected that the line evaluation value increases linearly, a trigger pulse is generated. In the case of FIG. 10, the line evaluation value Lm + a is larger than the line evaluation value Lm−1 before the a + 1 line by a predetermined amount or more, Lm−2 is Lm−1, Lm + a + 1 is substantially equal to Lm + a, Lm−1, When it is detected that the line evaluation value increases almost linearly as Lm,..., Lm + a−1, Lm + a, a trigger pulse is generated. The line counter 53 counts the number of lines according to the horizontal synchronization pulse. The line position storage unit 504 temporarily stores the counter value of the line counter 53, that is, the line position m and the line position m + a when the above-described conditions are satisfied, according to the trigger pulse generated by the evaluation value determination unit 502. Here, the value of a is such that the change in the line evaluation value from the first line to the (m-1) th line is smaller than a predetermined amount, and the change in the line evaluation value from the m + a line to the nth line is from the predetermined amount. The difference between the line evaluation values of the (m−1) -th line and the (m + a) -th line is larger than a predetermined amount, and it may be determined by judging from the line evaluation value profile during which the line evaluation value changes linearly. An appropriate value may be determined as a fixed value in advance. In the latter case, the number of lines in which the line evaluation value changes linearly is smaller than the a + 2 line between the m-1 line and the m + a line, depending on the actual value of the external flash emission, with respect to the set value of a. In some cases, however, the luminance level in the transient period can be corrected in a step-by-step manner compared to the case where the luminance level changes in one line, so that more natural correction is possible. Become.

  For the line position m + a stored in the second line determination unit 50, the fifth block addition average calculation unit 600 performs from the line m + a of the (N−1) th frame to the line n (n is the line position of the last line). A value obtained by adding the first line evaluation values L1m + a to L1n is divided by n− (m + a) +1 to obtain an average addition value of the first line evaluation values from the line m + a to the line n. The block addition average value Bm + a, n is calculated.

  Similarly, for the line position m + a stored in the second line determination unit 50, the sixth block addition average calculation unit 700 uses the line m + a to the line n (n is the line of the last line). The value obtained by adding the second line evaluation values L2m + a to L2n up to (position) is divided by n− (m + a) +1 to obtain the addition average value of the second line evaluation values from line m + a to line n. The sixth block addition average value Am + a, n is calculated.

  The fifth block addition average calculation unit 600 and the sixth block addition average calculation unit 700 are the same as those in the first block addition average calculation unit 6 and the second block addition average calculation unit 7 of the first embodiment shown in FIG. Since this is the same as when the line position m + a is input instead of the line position m, the description is omitted.

  The first gain calculation unit 8 receives the sixth block addition average value Am + a, n and the fifth block addition average value Bm + a, n, and calculates a gain coefficient k (k = Bm + a, n / Am + a, n). Remember. That is, the gain coefficient k represents the ratio of the average luminance level before and after the luminance level in the region excluding the transient period under the image affected by the external flash increases.

  Using the gain coefficient k, the second gain adjustment unit 90 corrects the second imaging signal output from the frame memory 2 by adjusting the gain at an appropriate timing.

  The operation of the imaging apparatus in the third embodiment is the same as the flowchart in the first embodiment shown in FIG. Hereinafter, differences from the first embodiment will be described.

  FIG. 11 is a diagram for explaining the operation of the second gain adjusting unit 90 in FIG.

  At the timing when the first image pickup signal is the image pickup signal of the (N-1) th frame and the second image pickup signal is the image pickup signal of the (N-2) th frame, the second line determination unit 50 detects the line position m and the line position. m + a is detected, and the fifth block addition average calculation unit 600 and the sixth block addition average calculation unit 700 calculate the fifth block addition average value Bm + a, n and the sixth block addition average value Am + a, n, respectively. The first gain calculation unit 8 calculates the gain coefficient k. The second gain adjuster 90 increases the luminance level after one frame, that is, at the timing when the second imaging signal is the (N−1) th frame imaging signal, due to the influence of the external flash as shown in FIG. The luminance level of the imaging signal from the line m + a to the line n is 1 / k times. On the other hand, for the line m to line m + a−1, which is a transient period, individual gain adjustment is performed for each line. That is, assuming that the luminance level increases in proportion to the increase of the line number due to the influence of the external flash, the line m is (a + 2) / (2 × k) times, and the line m + 1 is (a + 2) / (3 × k) times, line m + 2 is (a + 2) / (4 × k) times,..., Line L is (a + 2) / ((L−m + 2) × k) times (L is line position),. The line m + a−1 is (a + 2) / ((a + 1) × k) times, and adjustment is performed by changing the gain amount stepwise. Accordingly, the N-1th frame is corrected so as to be an image not affected by the external flash. Further one frame later, that is, at the timing when the second imaging signal is the N-th frame imaging signal, as shown in FIG. 11, the imaging signals from line m + a to line n immediately after the influence of the external flashing ends. Is set to k times. On the other hand, for the line m to line m + a−1, which is a transient period, individual gain adjustment is performed for each line. That is, assuming that the luminance level decreases in proportion to the increase of the line number due to the influence of the external flash, the luminance level from line m to line m + a-1 is multiplied by k / (a + 1) times, and the line m is multiplied by k / (a + 1) times. m + 1 is k / a times, line m + 2 is k / (a-1) times,..., line L is k / (a-L + m + 1) times (L is a line position),. Adjustment is made by changing the gain amount step by step to k / 2 times. As a result, the Nth frame is corrected so as to be an image in which the entire surface shines white due to the influence of the external flash. For frames other than those described above, the second gain adjustment unit 90 does not perform correction, but sequentially outputs the imaging signals of each frame.

  In addition, although the imaging apparatus, the line determination unit, and the block addition average calculation unit of the third embodiment have been described with reference to FIGS. 9 and 10, other configurations can be appropriately employed without departing from the gist of the invention. Needless to say.

  In the third embodiment, the evaluation value of each line is used as the luminance level of the imaging signal. However, the line evaluation value used by the second line determination unit 50 to determine whether or not there is an external flash influence is the external flash. Other signal components and values such as color components, frequency components and SN ratio (Signal to Noise Ratio) of the imaging signal may be used as evaluation values as long as they change depending on the presence or absence of the influence of. Further, if the block addition average value calculated by the fifth block addition average calculation unit 600 and the sixth block addition average calculation unit 700 changes in proportion to the luminance level, other signal components and values are evaluated. It does not matter as a value.

  As described above, according to the third embodiment, first, a steep change in the evaluation value in the line direction is detected, and the average luminance level of the region excluding the transient period of the region affected by the external flash in the screen The gain coefficient is calculated from the ratio of the average brightness level before being affected by the external flash in the same area, and the gain coefficient is used to correct the gain coefficient. If the image is corrected, it is possible to correct the image, and the image of the subject is not unnatural by using the information of the original image without freezing the normal image at the time of correction. Bright images that should originally exist are also included, so there is no sense of incongruity, and for the transient period, by changing the gain amount appropriately and correcting, the vicinity of the boundary line that switches whether correction is performed is stepwise The influence of the Department flash can be corrected.

(Embodiment 4)
FIG. 12 is a diagram illustrating a schematic configuration of the imaging apparatus according to the fourth embodiment.

  The imaging device shown in FIG. 12 includes an imaging unit 1, a frame memory 2, a first line addition average calculation unit 3, a second line addition average calculation unit 4, a second line determination unit 50, 7 block addition average calculation unit 601, eighth block addition average calculation unit 701, second gain calculation unit 80, and second gain adjustment unit 90.

  The imaging unit 1, the frame memory 2, the first line addition average calculation unit 3, the second line addition average calculation unit 4, the second line determination unit 50, and the second gain adjustment unit 90 are the same as those in the third embodiment. Since it is the same as that of the apparatus, the description is omitted.

  The seventh block addition average calculation unit 601 performs the line position m and the line position m + a stored in the second line determination unit 50 from the line m + a to the line n (n is the last line). The sum of the first line evaluation values from line m + a to line n is obtained by dividing the value obtained by adding the first line evaluation values from L1m + a to L1n up to line position) by n− (m + a) +1. Is calculated as the seventh block addition average value Bm + a, n, and the value obtained by adding the first line evaluation values L11 to L1m−1 from line 1 to line m−1 is divided by m−1. Thus, the addition average value of the first line evaluation values from line 1 to line m−1 is calculated as the seventh block addition average value B1, m−1.

  Similarly, the eighth block addition average calculating unit 701 performs the line m + a to the line n (n is the n−2th frame) for the line position m and the line position m + a stored in the second line determination unit 50. The value of the second line evaluation value from the line m + a to the line n is divided by n− (m + a) +1 by dividing the value obtained by adding the second line evaluation value from the second line evaluation value (the line position of the last line) to L2n by n− (m + a) +1. The addition average value is calculated as the eighth block addition average value Am + a, n, and a value obtained by adding the second line evaluation values L21 to L2m−1 from line 1 to line m−1 is m−1. Then, the addition average value of the second line evaluation values from line 1 to line m−1 is calculated as the eighth block addition average value A1, m−1.

  FIG. 13 is a diagram showing a schematic configuration of the seventh block addition average calculation unit 601 and the eighth block addition average calculation unit 701 in FIG.

  13 includes a line counter 61, counter value comparison units 62, 63, 64, and 65, a delay unit 66, a line evaluation value addition unit 67, a block addition average value storage unit 68, and 69.

  Hereinafter, the case of the seventh block addition average calculation unit 601 will be described as an example.

  The line counter 61 counts the number of lines according to the horizontal synchronization pulse. The counter value comparison units 62, 63, 64, and 65 have the counter values of the line counter 61 of 1, m, respectively, with respect to the line position m and the line position m + a stored in the second line determination unit 50 in FIG. A trigger pulse is generated at the timing of m + a and n (n is the line position of the last line). The delay unit 66 receives the line evaluation value Lx (x is a line position) of each line calculated by the first line addition average calculation unit 3 in FIG. 12, and the second line determination unit 50 sets the line m + a to the above-described line m + a. The line evaluation value is delayed according to the horizontal synchronization pulse so that the line evaluation value Lm + a of the line m + a is input to the line evaluation value adding unit 67 after the timing at which the line position m + a satisfying the condition is stored. The line evaluation value adding unit 67 is input at the timing when the counter value comparing units 62 and 64 generate the trigger pulse, that is, at the timing when the line evaluation values L1 and Lm + a of the line 1 and the line m + a are input to the line evaluation value adding unit 67. In this case, a value obtained by adding the total value of the line evaluation values so far to the input line evaluation value is output in accordance with the horizontal synchronization pulse. The block addition average value storage units 68 and 69 receive the values output from the line evaluation value addition unit 67, and the counter value comparison units 63 and 65 take in the timing at which the trigger pulse is generated, respectively, and m−1 and n− ( m + a) Divide by +1 and store. In other words, the block addition average value storage unit 68 divides the addition value of the line evaluation values from the line 1 to the line m−1 calculated by the line evaluation value addition unit 67 by m−1 and averages the seventh value. Stored as the block addition average value B1, m-1 (in the case of the eighth block addition average calculation unit 701, the eighth block addition average value A1, m-1). Further, the block addition average value storage unit 69 divides the addition value of the line evaluation values from the line m + a to the line n calculated by the line evaluation value addition unit 67 by n− (m + a) +1 and averages the value. 7 as the block addition average value Bm + a, n (in the case of the eighth block addition average calculation unit 701, the eighth block addition average value Am + a, n).

  The second gain calculation unit 80 includes the eighth block addition average value A1, m−1 and the eighth block addition average value Am + a, n, the seventh block addition average value B1, m−1, and the seventh block addition. Using the average value Bm + a, n as an input, a gain coefficient k (k = (Bm + a, n × A1, m−1) / (Am + a, n × B1, m−1)) is calculated and stored. Here, Bm + a, n / Am + a, n is the same as in the third embodiment, but further includes a ratio of A1, m−1 / B1, m−1. This is the ratio of the average luminance level of the area above the image that is not affected by the external flash, and can be considered to represent a change in luminance level due to an iris change between two frames. That is, the gain coefficient k takes into account changes due to imaging conditions such as iris that are unrelated to the emission of the external flash, and before and after the increase of the luminance level in the region excluding the transient period under the influence of the external flash. It represents the ratio of the average luminance level.

  The second gain adjustment unit 90 uses the gain coefficient k to correct the second imaging signal output from the frame memory 2 by adjusting the gain at an appropriate timing, as in the third embodiment. The imaging signal of each frame is output sequentially.

  In addition, although the imaging device, the line determination unit, and the block addition average calculation unit of the fourth embodiment have been described with reference to FIGS. 12 and 13, other configurations can be appropriately employed without departing from the gist of the invention. Needless to say.

  In the fourth embodiment, the evaluation value of each line is used as the luminance level of the imaging signal. However, the line evaluation value for determining the presence or absence of the influence of the external flash by the second line determination unit 50 is the external flash. Other signal components and values such as color components, frequency components and SN ratio (Signal to Noise Ratio) of the imaging signal may be used as evaluation values as long as they change depending on the presence or absence of the influence of. Also, if the block addition average value calculated by the seventh block addition average calculation unit 601 and the eighth block addition average calculation unit 701 changes in proportion to the luminance level, other signal components and values are evaluated. It does not matter as a value.

  As described above, according to the fourth embodiment, first, a steep change in the evaluation value in the line direction is detected, and the average luminance level of the region excluding the transient period in the region affected by the external flash in the screen Iris setting, etc. by calculating the gain coefficient from the ratio of the average brightness level of the same area before being affected by the external flash and the average brightness level of the area not affected by the external flash of each frame By calculating a more accurate gain coefficient that takes into account changes in shooting conditions and correcting using the gain coefficient, it is possible to correct any line affected by the timing of external flash emission. Also, by making use of the information of the original image without freezing the normal image during correction, the movement of the subject does not become unnatural, and the brightened image that should originally exist in the corrected image Without discomfort because it contains further by correcting properly changing the amount of gain for transient period, the border lines around switching the presence or absence of correction can correct stepwise influence of an external flash.

  The imaging apparatus according to the present embodiment has a white belt-like shape generated by photographing a subject with a flash or the like, which is peculiar to an imaging apparatus using a CMOS image sensor that has recently been used in video cameras. It is useful as an imaging device that detects and corrects interference.

DESCRIPTION OF SYMBOLS 1,113 Image pick-up part 2 Frame memory 3, 4 line addition average calculation part 5, 50 Line determination part 6, 7, 60, 70, 600, 601, 700, 701 Block addition average calculation part 8, 80 Gain calculation part 9, 90 Gain adjustment unit 51, 501 Evaluation value shift register unit 52, 502 Evaluation value determination unit 53, 61 Line counter 54, 504 Line position storage unit 62, 63, 64, 65 Counter value comparison unit 66 Delay unit 67 Line evaluation value addition Unit 68, 69 Block addition average value storage unit 100 Video camera 101 Monitor 102, 103 Still camera 104 Subject 114 Image processing unit 116 Recording display processing unit 117 Buffer 120 Evaluation unit 121 Storage unit 123 Control unit

Claims (9)

An imaging unit that captures a subject image and outputs a video signal;
A detection unit for detecting a video signal having a line position in which a difference in line evaluation values of adjacent lines exceeds a predetermined value for one frame of video signal output by the imaging unit;
For one frame of video signal detected by the detection unit, at least the average luminance level up to the line before the line position, the average luminance level after the line position, and the line position in the video signal one frame before the video signal Correction gain amount using either of the average luminance level up to the line before the line position corresponding to, and the average luminance level after the line position corresponding to the line position in the video signal one frame before the video signal A correction gain calculation unit for calculating
A video signal correction unit that corrects a video signal up to the line before the line position in the video signal of one frame detected by the detection unit, or a video signal after the line position, using the correction gain amount;
An imaging apparatus comprising: The correction gain calculator is
The ratio between the average luminance level after the line position and the average luminance level after the line position corresponding to the line position in the video signal one frame before the video signal for one frame of video signal detected by the detection unit The imaging device according to claim 1, wherein the correction gain amount is calculated on the basis of the information. The correction gain calculator is
For the video signal of one frame detected by the detection unit, the average luminance level up to the line before the line position and the line before the line position corresponding to the line position in the video signal one frame before the video signal The imaging apparatus according to claim 2, wherein a ratio with the average luminance level up to and including the ratio is calculated in consideration of the ratio. The correction gain calculator is
When the correction gain amount calculated in the video signal one frame before the video signal exists as the correction gain amount for the video signal of one frame detected by the detection unit, the correction gain amount that exists is used. The imaging device according to claim 1. An imaging unit that captures a subject image and outputs a video signal;
A detection unit that detects a video signal in which a difference in line evaluation values of adjacent lines changes stepwise for one frame of video signal output by the imaging unit;
Regarding the one-frame video signal detected by the detection unit, the average luminance level of the one-frame video signal detected by the detection unit up to the line before the start line position at which the average luminance level changes at least in steps. The average luminance level after the end line position of the change, the average luminance level up to the line before the line position corresponding to the start line position in the video signal one frame before the video signal, and one frame before the video signal A correction gain calculation unit that calculates a correction gain amount using any one of the average luminance levels after the line position corresponding to the end line position in the video signal;
Using the correction gain amount, at least a video signal to a line before the start line position in a video signal of one frame detected by the detection unit, a video signal to the end line position after the start line position, and A video signal correction unit for correcting any of the video signals after the end line position;
An imaging apparatus comprising: The video signal correction unit is
The imaging apparatus according to claim 5, wherein a video signal from the start line position to the end line position is corrected using a correction gain amount obtained by changing the correction gain amount in a stepwise manner. The correction gain calculator is
For an image signal of one frame detected by the detection unit, an average luminance level after the end line position, and an average luminance level after the line position corresponding to the end line position in the video signal one frame before the video signal, The imaging device according to claim 5, wherein the correction gain amount is calculated based on a ratio of The correction gain calculator is
For the video signal of one frame detected by the detection unit, the average luminance level up to the line before the start line position and the line position corresponding to the start line position in the video signal one frame before the video signal. The imaging device according to claim 7, wherein a ratio with an average luminance level up to a line is calculated, and the correction gain amount is calculated in consideration of the ratio. The correction gain calculator is
When the correction gain amount calculated in the video signal one frame before the video signal exists as the correction gain amount for the video signal of one frame detected by the detection unit, the correction gain amount that exists is used. The imaging device according to claim 5.

Images