JP4693602B2 - Imaging apparatus and image signal processing method - Google Patents

Description

The present invention relates to an imaging apparatus and an image signal processing method with an expanded dynamic range.

  Conventionally, when an image pickup device using a CCD or CMOS sensor is used to pick up an image from a bright subject to a dark subject, the dynamic range of the image pickup device is narrow. / N is bad, and there are drawbacks such as being swallowed by noise and not being visible.

  Therefore, in order to eliminate the above disadvantages, two images of a high-speed shutter image and a low-speed shutter image are taken out from the same imaging device, and by combining them, the dynamic range is expanded to reach from a bright part to a dark part. A method capable of clearly photographing has been proposed and put into practical use.

  In Non-Patent Document 1, by using a single imaging device to obtain a high-speed shutter image (low-sensitivity image) and a low-speed shutter (high-sensitivity image) in a time-sharing manner for each frame, The result of configuring a camera with a wide dynamic range has been reported.

  Non-Patent Document 2 describes an adaptive wide dynamic range technology that can efficiently acquire these high-speed shutter images and low-speed shutter images. That is, a bright part is selected and extracted from one screen of the subject, luminance information of this bright part is detected, and the electronic shutter speed for high-speed images is determined based on the magnitude of the luminance. On the other hand, a dark portion is selected and extracted from one screen including a subject, luminance information of the dark portion is detected, and the low-speed electronic shutter speed is determined based on the size.

  In this specific method, one screen including a subject is divided into 25 by 5 × 5, for example, and luminance information is detected in each region, and the images are arranged in order from brighter to darker. Therefore, for example, six areas are selected from the brighter side, luminance information in these areas is extracted, and the electronic shutter speed for high-speed images is determined. On the other hand, for example, five areas are selected from the dark side, luminance information in these areas is extracted, and the electronic shutter speed for low-speed images is determined.

  In this way, the electronic shutter time for each of the high-speed image and the low-speed image can be arbitrarily set as the situation where the subject is placed changes. This is called adaptive control, and Patent Document 1 introduces these detailed examples.

On the other hand, technologies for wide dynamic range have also been developed in image pickup devices, which are reported in Non-Patent Document 3, for example. This is intended to expand the dynamic range by changing the overflow gate voltage of the reset transistor within one frame period, thereby controlling the height of the potential barrier and discarding surplus charges to the overflow drain.
Sugi et al .: Adaptive wide dynamic range camera, 2001 Annual Conference of the Institute of Image Information and Television Engineers, 6.1, 55-56pp Sato et al .: Wide dynamic range color camera with electronic shutter, 1995 Annual Conference of the Television Society, 4.3, 63-64pp S. Decker: A 256 × 256 CMOS Imaging Array with Wide Dynamic Range Pixels and Column-Parallel Digital Output, IEEE Journal of Solid-State Circuits, Vol.33, No.12 Dec. 1998. JP 2003-250094 A

  However, in the prior art, it is extremely difficult to instantaneously set the high-speed shutter and the low-speed shutter to ideal values, and thus there is a drawback that it is difficult to obtain ideal high-speed shutter images and low-speed shutter images. In addition, when an imaging device using image synthesis is used, when a moving object is included in the subject, there is a problem that the portion becomes a double image, the outline is blurred, or the movement becomes unnatural.

The present invention has been made in view of such a problem, and has a wide dynamic range, and even when a captured object includes a moving object, a double image is formed or movement is unnatural. It is an object of the present invention to provide an imaging device and an image signal processing method that do not become a problem.

  An imaging apparatus according to the present invention is an imaging apparatus that obtains a first video signal imaged under a first exposure condition and a second video signal imaged under a second exposure condition. A luminance detector that detects the luminance of each of the second video signals; an exposure condition setting unit that independently sets the first exposure condition and the second exposure condition based on each luminance; and the first The comparison unit comparing the second exposure condition and the second exposure condition, and the comparison unit determine that the difference between the first exposure condition and the second exposure condition is less than or equal to a predetermined first threshold value. The first video signal or the second video signal is output as it is, and it is determined that the difference between the first exposure condition and the second exposure condition is larger than the predetermined first threshold value. The first video signal and the second video signal. Characterized in that it comprises an image synthesizing unit for outputting a third video signal form.

  The image signal processing method according to the present invention includes a step of imaging the first video signal and the second video signal according to the first exposure condition and the second exposure condition, respectively, the first video signal, Detecting the brightness of the second video signal; setting the first exposure condition and the second exposure condition based on the brightness; the first exposure condition and the second exposure condition; If the difference between the first exposure condition and the second exposure condition is equal to or less than a predetermined first threshold by the comparison, the first exposure condition and the second exposure condition The first exposure condition and the second exposure condition are corrected so as to be the same exposure condition, and an image is taken with the corrected first exposure condition and the corrected second exposure condition. The difference between the first exposure condition and the second exposure condition is If it is larger than the predetermined first threshold value, the image is captured under the first exposure condition and the second exposure condition without correcting with different exposure conditions, and the captured image is synthesized. And outputting it.

In addition, an imaging apparatus according to the present invention includes an imaging device that obtains a first image captured under a first exposure condition and a second image captured according to a second exposure condition, and an image from the imaging device. An image composition unit for outputting, and the imaging device detects a luminance of at least a partial region in the first image and a luminance of at least a partial region in the second image, and An exposure condition setting unit for independently setting or correcting the first exposure condition and the second exposure condition based on each luminance; a signal processing unit for obtaining a difference signal indicating a difference between the exposure conditions; and the first And an output unit for outputting the difference signal together with the second image and the second image, and when the difference signal is equal to or less than a predetermined threshold, the image synthesis unit is configured to output the first image or the second image. Any of the second images Outputs one, if the difference signal is larger than the threshold value, and outputs the synthesized image obtained by synthesizing the first image and the second image.

According to the present invention, an image pickup apparatus that has a wide dynamic range and does not form a double image or cause unnatural movement even when the picked-up image includes a moving object, and the image It is possible to provide a signal processing method.

  Embodiments of an imaging apparatus according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a functional block diagram of an imaging apparatus according to the first embodiment of the present invention. As illustrated in FIG. 1, the imaging apparatus 100 mainly includes an imaging unit 110, an analog signal processing unit 120 that performs processing from analog signals to digital conversion, a digital signal processing unit 130 that performs signal processing on the obtained digital signals, The control unit 140 executes control of the entire imaging apparatus 100 based on the digital signal subjected to the signal processing, and an image signal output terminal 150 that outputs an image to the outside.

  The imaging apparatus 100 captures a subject image with the imaging unit 110 and generates an image signal (analog signal). The generated analog image signal is converted from an analog signal to a digital signal (hereinafter referred to as A / D conversion) in the analog signal processing unit 120 and then output as a digital image signal. This digital image signal is branched into two, one of which is input to the digital signal processing unit 130 for signal processing. The digital image signal after the signal processing is converted from a digital signal to an analog signal (hereinafter referred to as D / A conversion) and output from the image signal output terminal 150.

  The other of the image signals output from the analog signal processing unit 120 is input to the control unit 140. The control unit 140 generates a control signal and controls the imaging unit 110, the analog signal processing unit 120, and the digital signal processing unit 130. With these controls of the control unit 140, the imaging apparatus 100 can perform imaging capable of expressing a wide luminance region (wide dynamic range) even for a subject having a wide luminance difference.

  The imaging unit 110 includes an imaging lens 111 that collects light from a subject and an imaging element, for example, a CCD 112.

  In the imaging unit 110, light from the subject is collected by the imaging lens 111 and imaged on the light receiving surface of the CCD 112. The exposure condition of the CCD 112 is determined by adjusting the electronic shutter speed. The CCD 112 performs photoelectric conversion and accumulates an amount of charge corresponding to the amount of image light in the CCD 112. An image signal corresponding to the accumulated charge amount is output from the CCD 112.

  At the time of imaging a subject, the electronic shutter of the CCD 112 provided in the imaging unit 110 alternately repeats imaging at two different shutter speeds. That is, imaging is performed at a low shutter speed and a high shutter speed. Image signals that are alternately output from the CCD 112 are output from the imaging unit 110 and input to the analog signal processing unit 120.

  The analog signal processing unit 120 sets an AGC circuit 121 that sets the gain of an analog image signal picked up by alternately inputted low-speed shutter speed and high-speed shutter speed, and A performs conversion from an analog signal to a digital signal. / D conversion circuit 122.

  The analog image signal input to the analog signal processing unit 120 is sequentially transmitted to the AGC circuit 121 and the A / D conversion circuit 122 for signal processing. With the control signal from the control unit 140, the AGC circuit 121 can change the gain for each analog image signal.

  The A / D conversion circuit 121 converts an analog image signal into a digital image signal. The converted image signal, that is, the digital image signal imaged at the low shutter speed and the high shutter speed is alternately output from the analog signal processing unit 120 and is input to the digital signal processing unit 130 alternately.

  The digital signal processing unit 130 includes an image signal processing execution unit 131, an addition circuit 132, and a D / A conversion circuit 133 that performs conversion from the synthesized digital image signal to an analog image signal.

The image signal processing execution unit 131 is a low-speed shutter signal processing unit 131a that processes a digital image signal captured by a low-speed shutter, and a high-speed shutter signal processing unit 131b that processes a digital image signal captured at a high-speed shutter speed. With. Each of the low-speed shutter signal processing unit 131a and the high-speed shutter signal processing unit 131b includes a memory circuit, a switching circuit, and a characteristic conversion circuit. That is, the low speed shutter signal processing unit 131a includes a memory circuit 131a ₁ for low speed shutter, a switching circuit 131a ₂ for the low-speed shutter, and a low-speed shutter characteristic conversion circuit 131a _3, On the other hand, the signal processing unit for high-speed shutter 131b includes a memory circuit 131b ₁ for high-speed shutter, a switching circuit 131b ₂ for high-speed shutter, a high-speed shutter characteristic conversion circuit 131b _3.

  Next, image signal processing performed by the image signal processing execution unit 131 will be described with reference to FIGS.

  FIG. 2 is an operation explanatory diagram illustrating the operation of the imaging apparatus 100.

  FIG. 2A shows a vertical synchronization signal, and the imaging device 100 operates in synchronization with this cycle. During a period in which the image is captured by the CCD 112 and an image signal is output (one vertical synchronization period), A01 is an image signal output period on the low-speed shutter side (hereinafter referred to as a low-speed shutter period), and A02 is an image signal output period on the high-speed shutter side ( A03 is a low-speed shutter period, A04 is a high-speed shutter period, and A05 is a low-speed shutter period.

  FIG. 2B shows the electronic shutter operation of the CCD 112. The electronic shutter operation of the CCD 112 causes a delay of one vertical period due to the relationship between the charge accumulation of the CCD 112 and the readout time. Therefore, with respect to the vertical synchronization signal as shown in FIG. 2A, the electronic shutter operation has a high shutter speed period B01 and a low shutter speed period B02, and so on. The operation period of B03, B04, and B05 is repeated.

  FIG. 2C shows the operation of the AGC circuit 121. The AGC circuit 121 operates independently during the low-speed shutter operation period and the high-speed shutter operation period. C01 is an operation period for a low-speed shutter, C02 is an operation period for a high-speed shutter.

  FIG. 2D shows an image signal output from the CCD 112. D01 is a low-speed shutter image signal, D02 is a high-speed shutter image signal, and D03, D04, and D05 are repeated in the same manner.

  The output characteristics of the low-speed shutter image signal and the high-speed shutter image signal output from the CCD 112 in FIG. 2D will be supplemented with reference to FIG.

  FIG. 3 is an explanatory diagram showing the imaging characteristics of the CCD 112. The horizontal axis indicates the luminance (brightness), and the vertical axis indicates the video output, that is, the output level of the image signal with respect to the incident light amounts of the low speed shutter and the high speed shutter. In FIG. 3, the output characteristic of the image signal by the low-speed shutter is 3a, and the saturation point of the low-speed shutter output is 3b. On the other hand, the image output characteristic of the high-speed shutter is 3c, and the saturation point of the high-speed shutter output is 3d.

  Referring to FIG. 3, the low-speed shutter image signal has a small amount of incident light that reaches saturation and quickly reaches saturation. On the other hand, the high-speed shutter image signal has a large amount of incident light that reaches saturation and slows to reach saturation. Therefore, in the characteristic of the image output signal in FIG. 2D, D01 (low-speed shutter image signal) is saturated within one vertical synchronization period, and the output reaches a peak. On the other hand, in D02 (high-speed shutter image signal), there is no saturation within one vertical synchronization period, and the output gradually increases.

  FIG. 2E shows an output from the A / D conversion circuit 122 of the analog signal processing unit 120 shown in FIG. 1 in response to the signal input of FIG. That is, FIG. 2E is the digital signal of FIG.

  In FIG. 2E, E01 is a low-speed shutter image signal, E02 is a high-speed shutter image signal, and image signals E03, E04, and E05 are output in the same manner. According to FIG. 2E, the low-speed shutter image signal and the high-speed shutter image signal are both intermittent signals. As shown in the figure, the low-speed shutter image signal is formed by E01, E03, and E05, and the high-speed shutter image signal is formed by E02 and E04.

One of the low-speed shutter image signals output from the A / D conversion circuit 122 of the analog signal processing unit 120 shown in FIG. 1 passes through the low-speed shutter memory circuit 131a ₁ to the low-speed shutter switching circuit 131a ₂ . is input, the other is directly input to the switching circuit 131a ₂ for the low-speed shutter. The low-speed shutter switching circuit 131a ₂ switches the image signal between the input from the low-speed shutter memory circuit 131a ₁ side and the input from the A / D conversion circuit 122 side of the analog signal processing unit 120 every vertical period. Thus, the intermittent signal is a continuous signal.

FIG. 2F shows a low-speed shutter image signal that is a continuous signal. Incidentally, the signal code M are assigned in FIG. 2 (F) shows an image signal input from the memory circuit 131a ₁ for low speed shutter. In FIG. 2F, the input from the low-speed shutter memory circuit 131a ₁ is switched to the memory of the low-speed shutter memory circuit 131a ₁ during the periods E02 and E04 that are intermittent in FIG. It is generated by inputting the accumulated low-speed shutter image signal.

  On the other hand, the high-speed shutter image signal is shown in FIG. The process for converting a high-speed shutter image signal into a continuous signal is the same as that for a low-speed shutter image signal. Therefore, the description of the high-speed shutter image signal is omitted.

In the low speed shutter switching circuit 131a ₂ and the high-speed shutter switching circuit 131b ₂ low-speed shutter image signal and the high speed shutter image signal becomes continuous signal, characteristic for the characteristic conversion circuits 131a ₃ and the high-speed shutter for low-speed shutter shown in FIG. 1 in the conversion circuit 131b _3, for example, characteristic conversion is performed to obtain a gamma characteristic. The low-speed shutter image signal and the high-speed shutter image signal after the characteristic conversion correspond to FIGS. 2 (H) and 2 (I), respectively.

Adder circuit as an image synthesizing unit shown in FIG. 1 132, the image signal processing for the low-speed shutter characteristic provided in execution unit 131 converting circuit 131a ₃ and characteristics in a high speed shutter characteristic conversion circuit 131b ₃ converted low speed shutter image signal The high-speed shutter image signal is added under a predetermined condition to obtain one composite digital image signal. As will be described later, this addition is performed when the difference between the low shutter speed and the light shutter speed is greater than a predetermined threshold. Also, image composition is not always necessary, and it is possible to output them separately depending on how they are used.

  FIGS. 2J and 2K are explanatory diagrams showing that the low-speed shutter image signal and the high-speed shutter image signal after the characteristic conversion are added. FIG. 2 (K) is an analog representation of FIG. 2 (J). Reference numeral 3e in FIG. 3 shows details of the output characteristic signal in each of the periods K01 to K05 in FIG. 2 (K). The output characteristic 3e of the image signal is obtained by synthesizing the low-speed shutter image signal characteristic 3a and the high-speed shutter image signal characteristic 3c, and has an intermediate signal characteristic. That is, the luminance output of the image is optimally adjusted. The synthesis ratio is determined by a synthesis ratio control signal generation unit 526 included in the microcomputer circuit 142 described later.

  The D / A conversion circuit 133 shown in FIG. 1 converts the image signal synthesized by the adder circuit 132 from a digital signal to an analog signal, and outputs an analog image signal. The analog image signal output by the D / A conversion circuit 133 is output from the image signal output terminal 150 as an output of the imaging device 100.

  The control unit 140 includes an image signal information acquisition unit 141 that calculates luminance from image signal information, a microcomputer circuit (hereinafter referred to as a microcomputer circuit) 142, and an electronic shutter circuit 143 that controls and drives the shutter speed of the CCD. Prepare.

  The control unit 140 acquires image signal information from the low-speed shutter image signal and the high-speed shutter image signal by the image signal information acquisition unit 141, and controls the imaging device 100 based on the acquired image signal information (low-speed / high-speed shutter). A speed control signal) is generated by the microcomputer circuit 142. Of the control signals generated by the microcomputer circuit 142, a control signal for controlling the imaging unit 110 is input to the electronic shutter circuit 143, and a control signal for controlling the electronic shutter of the CCD 112 provided in the imaging unit 110 is output.

  First, the image signal information acquisition unit 141 divides a captured image signal for one screen in order to acquire image signal information. The image signal information acquisition unit 141 captures a luminance integrated value circuit 141a that integrates luminance as image signal information, a luminance peak value detection circuit 141b that detects a luminance peak value, and 1 And a gate waveform generation circuit 141c that divides the image signal for the screen.

  First, the image signal information acquisition unit 141 divides an image signal for one screen obtained by imaging in order to calculate a divided image luminance integrated value and a divided image luminance peak value.

  FIG. 4 is an explanatory diagram in which an image signal for one screen is divided and the screen is divided. In FIG. 4, the image signal for one screen of the captured entire screen 11 is divided into a plurality of areas such as 25 divisions, and a set of image signals of 25 divided screens 12 is obtained. This screen division is executed using the gate signal generated by the gate waveform generation circuit 141c provided in the image signal information acquisition unit 141.

  The gate waveform generation circuit 141c generates a gate signal using a horizontal synchronization pulse (hereinafter referred to as HD pulse), a vertical synchronization pulse (hereinafter referred to as VD pulse), and a clock pulse (hereinafter referred to as CLK pulse). This gate signal is transmitted to a luminance integrated value circuit 141a that integrates luminance and a luminance peak value detection circuit 141b that detects a peak value of luminance, and divides 25 image signals for one screen of the entire screen 11 that has been imaged. Divide into screens 12.

  FIG. 5 is a functional block diagram of the luminance integrated value circuit 141 a provided in the image signal information acquisition unit 141.

  The luminance integrated value circuit 141a shown in FIG. 5 calculates the luminance integrated value for each image signal of one screen of the divided screen 12. The luminance integrated value circuit 141a inputs the image signal output from the analog signal processing unit 120 and the gate signal generated by the gate waveform generation circuit 141c to the gate circuit 201, and outputs the image signal of the set screen range of the divided screen 12 To gate. The gated image signal is subjected to luminance integration by the integration processing unit 202, and an integrated output control circuit 203 outputs an integrated luminance value by an output control signal from the microcomputer circuit 142 shown in FIG. The output luminance integrated value is input to the microcomputer circuit 142.

  The luminance integration executed by the integration processing unit 202 is performed for each pixel in the gated image signal, and is performed by the integration circuit 202a and the one-pixel holding circuit 202b provided in the integration processing unit 202. The integration circuit 202a adds the luminance value of the input image signal for one pixel and the luminance value of the image signal for pixels for which integration processing has already been completed, and inputs the added luminance value to the one-pixel holding circuit 202b. The one-pixel holding circuit 202b stores the input luminance value, feeds back the stored luminance value to the integrating circuit 202a, repeats addition with the luminance value of the image signal input to the integrating circuit 202a, and gated image signal The integrated value of the luminance is calculated. The calculated luminance integrated value is received by the integrated output control circuit 203 from the one-pixel holding circuit 202b in response to an output control signal from the microcomputer circuit 142 shown in FIG. The received luminance integrated value is output from the integrated output control circuit 203 and transmitted to the microcomputer circuit 142.

  FIG. 6 is a functional block diagram of the luminance peak value detection circuit 141 b provided in the image signal information acquisition unit 141.

  The luminance peak value detection circuit 141b shown in FIG. 6 detects the peak value of the luminance value for each image signal of one screen of the divided screen 12. Similarly to the luminance integrated value circuit 141a, the luminance peak value detection circuit 141b supplies the image signal output from the analog signal processing unit 120 and the gate signal generated by the gate waveform generation circuit 141c to the luminance peak value detection gate circuit 301. Input and gate the image signal of the set screen range of the divided screen 12. The luminance peak value detection gate circuit 301 outputs the gated image signal pixel by pixel.

  The luminance peak value detection circuit 141b detects the luminance peak value of the gated image signal. The detection of the luminance peak value is performed after adding the luminance for two consecutive pixels. This is because when the optical color filter of the CCD 112 is a complementary color mosaic, the magnitude of the signal changes in units of pixels. By adding the luminance for two pixels, the influence of the difference in color filter is eliminated.

  To add the luminance for two pixels, the input current signal and the signal delayed by one pixel by the luminance peak value detection one-pixel holding circuit 302, that is, the signal one pixel before the current signal are obtained. The luminance addition circuit 303 adds the values. The added luminance values for two pixels are subjected to peak value detection processing as one unit and input to the two-pixel holding circuit 304. The two-pixel holding circuit 304 receives a signal from the two-pixel holding signal generation circuit 305 and generates a luminance value signal with the luminance value for two pixels as one unit.

  The luminance value signal including the current signal output from the two-pixel holding circuit 304 is input to the comparison circuit 306 and compared with the luminance value signal including the signal two pixels before the current signal. The comparison circuit 306 compares the two luminance value signals, generates a selection signal for selecting the higher luminance value, and supplies the selection signal to the switching circuit 307. Based on the selection signal from the comparison circuit 306, the switching circuit 307 selects one of the current signal and the luminance value signal including the signal two pixels before the current signal having the larger luminance value. The selected signal is input to and held in the luminance value signal holding circuit 308.

  The luminance value signal held in the luminance value signal holding circuit 308 is fed back to the comparison circuit 306, and the comparison process with the luminance value signal from the two-pixel holding circuit 304 is repeated. This comparison processing is performed until the output of the image signal output from the luminance peak value detection gate circuit 301 is completed. After the comparison processing is completed, the peak value output control circuit 309 receives the output of the luminance value signal holding circuit 308, that is, the output of the luminance peak value signal, by the output control signal from the microcomputer circuit 142 shown in FIG. The luminance peak value signal whose output has been accepted is output from the peak value output control circuit 309 and transmitted to the microcomputer circuit 142.

  FIG. 7 is a functional block diagram of the gate waveform generation circuit 141 c provided in the image signal information acquisition unit 141.

  As shown in FIG. 7, the gate waveform generation circuit 141c includes a vertical direction setting unit 401 and a horizontal direction setting unit 402 that set a gated range, and a synthesis circuit 403 that generates a gate signal. The gate waveform generation circuit 141c generates and outputs a gate signal in which an area to be gated is set from the three signals of the input VD pulse, HD pulse, and CLK pulse.

  The vertical direction gate range is set by the vertical direction setting unit 401. The VD pulse input to the vertical direction setting unit 401 is first input to the vertical synchronization reset signal generation circuit 401a. The vertical synchronization reset signal generation circuit 401a generates a reset signal, and the generated reset signal is input to the vertical direction start position setting circuit 401b. The vertical start position setting circuit 401b counts HD pulses and determines a vertical start point. If the start point in the vertical direction is determined, from this start point, the vertical width setting circuit 401c can count HD pulses and set the vertical width. The vertical width set by the vertical width setting circuit 401c is input to the synthesis circuit 403 as a vertical width signal.

  On the other hand, the horizontal direction gate range is set by the horizontal direction setting unit 402. The HD pulse input to the horizontal direction setting unit 402 is first input to the horizontal synchronization reset signal generation circuit 402a. The horizontal synchronization reset signal generation circuit 402a generates a reset signal, and the generated reset signal is input to the horizontal start position setting circuit 402b. The horizontal start position setting circuit 402b counts CLK pulses and determines a horizontal start point. When the horizontal start point is determined, the horizontal width setting circuit 402c can count the CLK pulse from the start point to determine the horizontal width. The horizontal width set by the horizontal width setting circuit 402 c is output as a horizontal width signal and input to the synthesis circuit 403.

  The vertical width signal and the horizontal width signal obtained from the vertical direction width setting circuit 401 c and the horizontal direction width setting circuit 402 c are combined by the combining circuit 403. This synthesized signal becomes a gate signal and is output from the gate waveform generation circuit 141c.

  FIG. 8 is a circuit block diagram of the microcomputer circuit 142 included in the control unit 140.

  The microcomputer circuit 142 mainly includes a luminance average value calculation unit 510 that calculates a luminance average value based on the luminance integration value and the luminance peak value, and a control signal generation unit 520 that outputs a shutter speed control signal based on the luminance average value. It is composed of

  The microcomputer circuit 142 receives the integrated luminance value and the peak value from the luminance integrated value circuit 141a and the luminance peak value detecting circuit 141b included in the image signal information acquisition unit 141 as image signal information. The input luminance integrated value and peak value are input to the luminance average value calculation unit 510, and the luminance average value is calculated. The calculated luminance average value is input to the control signal generation unit 520, and first, the electronic shutter speed is calculated. Next, a control signal for controlling each unit of the imaging apparatus 100 is generated so that an appropriate captured image can be obtained from the calculation result of the electronic shutter speed.

  An example in which data referred to by the microcomputer circuit 142 is visually represented is shown in FIG. The luminance average value calculation processing of the luminance average value calculation unit 510 included in the microcomputer circuit 142 will be described with reference to FIG.

  The luminance average value calculation unit 510 includes a luminance integrated value (hereinafter referred to as a low-speed luminance integrated value) of the low-speed shutter image signal obtained from the luminance integrated value circuit 141a and a low-speed shutter image obtained from the luminance peak value detection circuit 141b. Based on the luminance peak value of the signal (hereinafter referred to as the low-speed luminance peak value), the divided screen 12 has an area where the luminance is saturated (hereinafter referred to as luminance saturated area) 13 and an area where the luminance is not saturated (hereinafter referred to as luminance). Divided into 14).

  The separation of the luminance saturated area 13 and the luminance unsaturated area 14 is performed by first obtaining the luminance average value of the low-speed shutter image signal (hereinafter referred to as the low-speed luminance average value) from the low-speed luminance integrated value for each divided screen 12. .

  FIG. 9A is an explanatory diagram of the divided screen 12 showing the low-speed luminance integrated value. In this case, for example, when the luminance level is 8 bit width, the low-speed luminance average value is 200. Then, an area having a low-speed luminance average value of 200 or more is extracted. The extracted area that is equal to or higher than the low-speed luminance average value is an area surrounded by a broken line in FIG.

  Next, an area in which the luminance peak value obtained from the same low-speed shutter image signal is the maximum value of 8 bit width is extracted. FIG. 9B is an explanatory diagram of the divided screen 12 showing the low-speed luminance peak value. In FIG. 9B, the area where the extracted low-speed luminance peak value is the maximum is the area surrounded by the broken line in FIG.

  Next, an area is extracted in which the low-speed luminance average value is 200 or more and the low-speed luminance peak value is the maximum value of 8 bit width. FIG. 9C is an explanatory diagram for calculating the luminance saturation area 13 from the low-speed luminance integrated value and the low-speed luminance peak value in the divided screen 12 showing the low-speed luminance integrated value. The area where the low-speed luminance average value is 200 or more and the low-speed luminance peak value is extracted as the maximum value of the 8-bit width is an area where the areas surrounded by the broken lines in FIGS. 9A and 9B overlap. In FIG. 9C, the area is surrounded by a broken line. An area surrounded by a broken line in FIG. 9C is a luminance saturation area 13, and other areas are luminance unsaturated areas 14. The luminance saturation area 13 is an object to be imaged by the high-speed shutter.

  After the low-speed shutter image signal is divided into the luminance saturated area 13 and the luminance unsaturated area 14, the low-speed luminance average value is calculated from the luminance unsaturated area 14 of the low-speed shutter image signal.

  For the high-speed shutter image signal, the luminance average value of the high-speed shutter image signal (hereinafter referred to as the high-speed luminance average value) is calculated from the luminance saturation area 13 in the same manner as the low-speed shutter image signal. FIG. 9D is an explanatory diagram for calculating the high-speed luminance average value from the luminance unsaturated area 14 of the luminance integrated value of the high-speed shutter image signal.

  The control signal generation unit 520 includes a calculation processing unit 521 that calculates a shutter speed and a shutter speed ratio. The calculation processing unit 521 includes a low-speed shutter calculation processing unit 522 that processes a low-speed luminance average value and a high-speed shutter calculation processing unit 523 that processes a high-speed luminance average value. The low-speed shutter calculation processing unit 522 and the high-speed shutter calculation processing unit 523 control the electronic shutter circuit 143 and the AGC circuit 121 for the low-speed shutter image and the high-speed shutter image, and the electronic shutter speed and the gain of the image signal are controlled. By varying the value, an appropriate captured image can be obtained.

  In addition to the calculation processing unit 521, the control signal generation unit 520 compares the low-speed shutter speed with the high-speed shutter speed and corrects the shutter speed, and the characteristic conversion that controls the characteristic conversion of the image signal. A control signal generation unit 525 and a synthesis ratio control signal generation unit 526 that controls the image synthesis ratio of the two image signals are provided.

  The low-speed shutter calculation processing unit 522 included in the calculation processing unit 521 includes a low-speed shutter speed control signal generation unit 522a, a low-speed AGC circuit control signal generation unit 522b, and a low-speed shutter fine adjustment processing unit 522c. A control signal and an AGC control signal are generated.

  The low-speed shutter speed control signal generation unit 522a generates a low-speed shutter control signal for changing the electronic shutter speed of the CCD 112 shown in FIG. 1 from the input low-speed luminance average value. When the input low-speed luminance average value exceeds the appropriate range, the electronic shutter speed is changed roughly with a large width (hereinafter referred to as rough adjustment). When the input low-speed luminance average value is within the appropriate range, the electronic shutter speed is changed finely with a small width (hereinafter referred to as fine adjustment). That is, the electronic shutter speed is adjusted in two steps. Based on this control result, a low-speed shutter speed control signal is generated so that the low-speed luminance average value gradually becomes the center of the appropriate range. The generated low-speed shutter speed control signal is input to the electronic shutter circuit 143, and a signal for driving the shutter of the CCD 112 is output.

  The low-speed AGC circuit control signal generation unit 522b generates an AGC control signal for controlling the AGC circuit 121 shown in FIG. The generated AGC control signal is transmitted to the AGC circuit 121, and the AGC circuit 121 is controlled.

  The low-speed shutter fine adjustment processing unit 522c performs processing for compensating for long-period screen luminance fluctuations. When the luminance variation of the illumination light source, for example, the frequency of the fluorescent lamp flicker and the frame frequency of the CCD 112 are very close to each other by a natural number, a very long period of screen luminance variation due to aliasing distortion occurs. The screen brightness fluctuation is detected by the low-speed shutter fine adjustment processing unit 522c, and processing is performed so as to suppress the fluctuation.

  The high-speed shutter calculation processing unit 523 included in the calculation processing unit 521 includes a high-speed shutter speed control signal generation unit 523a, a high-speed AGC circuit control signal generation unit 523b, and a high-speed shutter fine adjustment processing unit 523c. A shutter speed control signal and an AGC control signal are generated. The constituent elements of the high-speed shutter calculation processing unit 523 are the same as those obtained by replacing the low-speed shutter function of the low-speed shutter calculation processing unit 523 with the high-speed shutter, and thus the description thereof is omitted.

The comparison unit 524 compares the high-speed shutter speeds t _H and t _L based on the low-speed shutter speed control signal and the high-speed shutter speed control signal input from the low-speed shutter speed control signal generation unit 522a and the high-speed shutter speed control signal generation unit 523a. . Comparison of the shutter speed t _H and t _L calculates the difference between the high-speed shutter speed t _H and the low speed shutter speed t _L, the difference is to perform the comparison at or less than a predetermined threshold value [delta]. If the difference is less than or equal to a predetermined threshold value δ, the low-speed shutter speed control signal and the high-speed shutter speed control signal are changed so that the high-speed shutter speed t _H and the low-speed shutter speed t _L are corrected to the same speed. If it is large, the low shutter speed control signal and the high shutter speed control signal are output to the electronic shutter circuit 143 as they are without correcting the high shutter speed t _H and the low shutter speed t _L.

The characteristic conversion control signal generation unit 525 receives the low-speed shutter speed control signal and the high-speed shutter speed control signal corrected by the comparison unit 524. A characteristic conversion control signal generation unit 525 generates a characteristic conversion control signal from the input shutter speed control signal. If low-speed shutter speed control signal is input to the characteristic conversion control signal generation unit 525, the low speed characteristic conversion control signal for controlling the low speed shutter characteristic conversion circuit 131a ₃ shown in FIG. 1 is obtained.

On the other hand, when a high-speed shutter speed control signal is input, a high-speed characteristic conversion control signal for controlling the high-speed shutter characteristic conversion circuit 131b ₃ shown in FIG. 1 is obtained. It generated a low speed characteristic conversion control signal and the high-speed characteristic conversion control signal is transmitted to the low-speed shutter characteristic conversion circuit 131a ₃ and a high speed shutter characteristic conversion circuit 131b _3.

The low-speed characteristic conversion control signal and the high-speed characteristic conversion control signal are used to combine the low-speed shutter image and the high-speed shutter image to construct a so-called dynamic range expansion image expressed from low luminance to high luminance. This is a control signal for realizing the control. Slow characteristic conversion control signal and the high-speed characteristic conversion control signal is used to control the low-speed shutter characteristic conversion circuit 131a ₃ and a high speed shutter characteristic conversion circuit 131b _3.

  Problems that occur during image composition: Simply adding two images increases the enlargement ratio and causes nonlinear distortion in the tone characteristics of the composite screen, resulting in an image that cannot be contrasted. There is. Therefore, before adding the two images, the characteristics of the video signal are converted in accordance with a dynamic range expansion rate, which will be described later, and nonlinear distortion is suppressed to improve contrast reduction.

The characteristic conversion control of the low-speed shutter characteristic conversion circuit 131a ₃ and the high-speed shutter characteristic conversion circuit 131b ₃ will be described.

  First, the dynamic range expansion rate is calculated from the following equation.

  Dynamic range expansion ratio = low-speed shutter control signal / high-speed shutter control signal

  The dynamic range expansion ratio calculated here is the dynamic range expansion ratio after setting the exposure conditions.

  The value of the dynamic range expansion rate is calculated by the calculation processing unit 521, and the calculation results are output as a low speed characteristic conversion control signal and a high speed characteristic conversion control signal.

The low-speed shutter characteristic conversion circuit 131a ₃ and the high-speed shutter characteristic conversion circuit 131b ₃ have tables of X ^{1 to} X ^0.7 and log ₁₀ 1 to ₁₀ as input X-output Y characteristics, and expand the dynamic range. The table is switched according to the rate to improve the non-linear distortion with respect to the image signal. The relationship of the table selection to the dynamic range expansion rate is shown below.

Dynamic range expansion factor <16 when ...... ^{X 1} selection table 64 when ...... ^{X 0.7} Selection Table 16 ≦ dynamic range expansion factor ≦ 64 <case of dynamic range expansion factor ...... ^{X 1} of table choose

Characteristic conversion control signal generation unit 525 generates the result of the above conditions as a slow characteristic conversion control signal and the high speed characteristic conversion control signal, the table switching for the low speed shutter characteristic conversion circuit 131a ₃ and the high-speed shutter characteristic conversion circuit 131b ₃ Performed automatically.

  Based on the low-speed shutter speed control signal and the high-speed shutter signal control signal corrected by the comparison unit 524, the combination ratio control signal generation unit 526 generates a combination ratio control signal that controls the combination ratio of the two image signals. The generated synthesis ratio control signal is transmitted to the addition circuit 132 shown in FIG.

  The purpose of the composition ratio control is to optimize the composition of the low-speed shutter image and the high-speed shutter image and increase the contrast of the composite image, as in the characteristic conversion control. As a problem at the time of image composition, there is a problem that when the dynamic range is increased, the image becomes white and the contrast is deteriorated.

  The reason for the deterioration of the contrast is that most of the low-speed shutter image is a saturated area, and the signal of the high-speed shutter image is on the saturation signal. In order to improve the contrast degradation, the composition ratio of the high-speed shutter image is increased with the enlargement ratio, and the contrast reduction is corrected by suppressing the whitening of the image. In particular, it is highly effective to improve the contrast of the composite image by performing the composite ratio control simultaneously with the characteristic conversion control.

  The operation of the synthesis ratio control signal generation unit 526 calculates a dynamic range expansion ratio in the same manner as the characteristic conversion control signal generation unit 525, and generates a synthesis ratio control signal for switching the image synthesis ratio of the low speed shutter and the high speed shutter from the calculation result. Generate. This synthesis ratio control signal is sent to the addition circuit 132 as an image signal synthesis unit shown in FIG. 1 to automatically control the synthesis distribution of two images, that is, the synthesis ratio.

  The relationship of the composition ratio control based on the dynamic range expansion ratio is as follows.

When dynamic range expansion ratio = 1 ... L100%: H0%
1 <Dynamic range expansion ratio <6 ... L94%: H6%
When 6 ≦ Dynamic range expansion rate ≦ 8: L88%: H12%
When 8 <Dynamic range expansion rate: L75%: H25%
However, the above synthesis ratio is an example, and may be changed as necessary.

  Next, with reference to FIG. 10, control up to image output of the imaging apparatus according to the first embodiment of the present invention will be described with reference to a flowchart. Hereinafter, “S” in FIGS. 10 and 11 means “STEP”.

First, light from the detection object is received by the CCD 112 and divided into the luminance saturated area 13 and the luminance unsaturated area 14 as described above, and the luminance of the image in each of the areas 13 and 14 is detected (STEP 101). ). Then, the average luminance value calculation unit 510 in the microcomputer circuit 142 calculates the average amplitude value of the luminance signal in each of the divided areas 13 and 14 (STEP 102). Then, the calculation processing unit 521 determines the high shutter speed t _H and the low shutter speed t _L based on the average amplitude value of the luminance signal (STEP 103).

Next, the high-speed shutter speed t _H and the low-speed shutter speed t _L calculated by the calculation processing unit 521 are input to the comparison unit 524. The comparison unit 524 determines whether or not the difference between the high shutter speed t _H and the low shutter speed t _L is equal to or less than a predetermined threshold δ (STEP 104). Hereinafter, the symbol t _H ′ represents the corrected high-speed shutter speed, and the symbol t _L ′ represents the corrected low-speed shutter speed. If the difference between the shutter speeds of the high shutter speed t _H and the low shutter speed t _L is larger than the predetermined threshold δ (STEP 104, No), t _H and t _L are determined as t _H ′ and t _L ′ without correction. Is done. When this is represented by a code, t _H ′ = t _H and t _L ′ = t _L (STEP 105). Although the shutter speeds t _H and t _L calculated by the calculation processing unit 521 constantly change, the shutter speeds t _H ′ and t _L ′ sent to the electronic shutter circuit 143 after correction are set to constant values. .

On the other hand, the object of high luminance and low luminance not mixed in the subject, the brightness difference of the object is small, high-speed shutter speed t _H and the low speed shutter speed t _L becomes close values. When the difference between the shutter speeds is equal to or less than the threshold value δ (STEP 104, Yes), correction is performed so that the average value of the high-speed shutter speed t _H and the low-speed shutter speed t _L is obtained for each of t _H ′ and t _L ′. Is made. That is, the shutter speed t _H ′ = t _L ′ = (t _H + t _L ) / 2 is set (STEP 106). As the correction value when the difference between the shutter speeds t _H and t _L is small, an average value obtained by averaging the high-speed shutter speed t _H and the low-speed shutter speed t _L may be used, or the high-speed shutter t _H or it may be used either the value of the low speed shutter t _L.

As described above, when the luminance difference of the subject is small, the state of t _H ′ = t _L ′ is continuously maintained. However, the difference between the luminance difference it opens fast shutter speed t _H and the low speed shutter speed t _L between the divided image conditions of an object is changed is becomes large. In such a case, when the comparison unit 524 exceeds the threshold value δ, the same shutter speed is stopped, and separate shutter speeds t _H ′ and t _L ′ are output without correction.

If the luminance difference of the subject is large, a high-speed shutter image at a high shutter speed t _H ′ and a low-speed shutter image at a low shutter speed t _L ′ are respectively captured by the CCD 112 (STEP 107). Based on the output from the generation unit 526, addition is performed (image synthesis) in the adder circuit 132 (STEP 109), and an image having a wide dynamic range is output (STEP 110). On the other hand, when the luminance difference of the subject is reduced and the high shutter speed t _H and the low shutter speed t _L are corrected to the same shutter speed, the images obtained by the imaging (STEP 110) are added (synthesized). Without being output (STEP 109).

That is, when the brightness difference of the object is reduced, since the high-speed shutter speed t _H in the captured high-speed shutter image t _H and the low-speed shutter speed t _L in the captured low-speed shutter image is missing is little difference, even by adding The dynamic range improvement effect cannot be expected so much. Rather, a temporal LPF is applied due to the addition of images, which causes a problem that a subject moving at high speed is blurred.

In the present embodiment, when the brightness difference between the high shutter speed t _H and the low shutter speed t _L becomes small in this way, the two shutter speeds t _H and t _L are converted into the same shutter speed t _H by the comparator 524. Since the image obtained by imaging is output without being added (synthesized) by the adder circuit 132 after being corrected to “, t _L ”, it has a great effect that the object moving at high speed is not blurred. .

(Second Embodiment)
Next, an image pickup apparatus according to a second embodiment of the present invention will be described. Note that the configuration of the imaging apparatus of the second embodiment is the same as that in FIGS. 1 and 5 to 8, and the processing performed in the comparison unit 524 is different.

In the first embodiment, the condition for canceling the same shutter speed t _H ′ = t _L ′ = (t _H + t _L ) / 2 determined by the correction is set to exceed the threshold δ. However, in the first embodiment, when the luminance difference of the subject changes with a value close to the threshold δ, the same shutter speed t _H ′ = t _L ′ = (t _H + t _L ) / 2 and the separate shutter speed t. _H ′ = t _H , t _L ′ = t _L , which may change little by little, and the image continuity may not be maintained, and the image may be difficult to view. Therefore, in the second embodiment, as a countermeasure for eliminating the above-described concern, a threshold value δ ₁ (δ <δ ₁ ) larger than the threshold value δ is set as a release condition for the same shutter speed. That is, when the difference between the high shutter speed t _H and the low shutter speed t _L becomes larger than the threshold δ ₁ after t _H ′ and t _L ′ are corrected to the same shutter speed, the correction to the same shutter speed is performed. (T _H '= t _L ') is set to be released. As a result, a predetermined hysteresis effect occurs, and the above problem is solved.

This process will be described in detail as a flowchart shown in FIG. First, through the same steps as in the first embodiment (STEP 201 to STEP 202), the high-speed shutter time t _H and the low-speed shutter time t _L are calculated (STEP 203). Subsequently, it is determined whether or not the same shutter speed is corrected (STEP 204). If it is determined that the same shutter speed is not corrected (t _H '≠ t _L ') (STEP 204, No), it is then determined whether (t _H -t _L ) ≤δ. (STEP 205). On the other hand, if it is determined that the same shutter speed is corrected (t _H '= t _L ') (STEP 204, Yes), it is then determined whether t _H -t _L > δ ₁ or not. (STEP 206).

STEP 205 is the same as STEP 104 in the first embodiment, and subsequent steps STEP 207 to STEP 212 are also the same as STEP 105 to STEP 110 in the first embodiment. In STEP206, the difference between the high-speed shutter speed _{t H} and the low speed shutter speed _{t L} is greater than the threshold value [delta] _1, at STEP 207, the correction of the same shutter speed is released. On the other hand, when the difference between the high-speed shutter speed t _H and the low speed shutter speed t _L is the threshold value [delta] ₁ below, are the state of being corrected at the same shutter speed at STEP 208.

As described above, the second embodiment includes the processing steps of STEP 204 and STEP 206 that are not provided in the first embodiment, so that the continuity of images can be maintained, and a natural image can be obtained. Moreover, although it has been described that the same shutter speed t _H ′ = t _L ′ = (t _H + t _L ) / 2, it can be unified to the low shutter speed t _L. In this way, the low-speed shutter image becomes a natural image without discontinuity. Similarly, it is possible to unify to the high shutter speed t _H.

  Thus, according to the imaging device according to the first and second embodiments of the present invention, as shown in FIG. 12, in a situation where the luminance difference between subjects is large, for example, indoors and outdoors, FIG. As shown in a), an image (low-speed shutter image) in which the shutter speed is adjusted with respect to the indoor 1000 having a low luminance, which is mainly a person, is taken. As shown in FIG. If images with high shutter speeds (high-speed shutter images) are captured against a high outdoor 2000, they can be combined as shown in FIG. 12C to output an optimal image with a wide dynamic range. It is. Therefore, a clear image can be obtained even in a scene including both bright and dark portions. On the other hand, in a situation where the luminance difference of the subject is small, imaging is performed at one shutter speed, so that even if there is an object moving at high speed, a double image is produced or the movement becomes unnatural. There is a great effect that a natural image without a sense of incongruity can be obtained. When this image signal is directly displayed on the monitor and used for observation, a natural and easy-to-see image can be obtained. In this case, image composition is not necessarily required unless the image is displayed on the monitor, and can be output separately. When image processing is performed using these signals, there is an advantage that the processing is easier if the signals are output separately without being synthesized.

  In addition, when this image signal is passed through a signal processing circuit and various image processing is to be performed, accurate and accurate processing can be performed, so that processing is easy and processing without errors can be performed. There is.

  Further, in a situation where the luminance difference is small, the same shutter speed is obtained, so that there is a great effect that a change in the image is reduced for each frame and a natural image can be obtained. Further, if the subject does not change with time, the two types of image signals do not change, and the signal processing system is improved.

Furthermore, when the luminance difference of the subject increases with time, an image having a wide dynamic range can be obtained immediately. Also, the determination of whether the shutter speed is approached determines the difference, for example, as _{t H -t L ≦ δ = 1} / 250s compares the fast shutter speed _{t H} and the low speed shutter speed _{t L.} However, if it changes minutely in this vicinity, a composite image may be obtained, or it may become a single image or change like chattering. In order to avoid this, the hysteresis characteristic is changed by changing the threshold value such as δ ₁ = 1/250 s when changing from a composite image to a single image and δ ₁₂ = 1/100 s when returning from a single image to a composite image. By providing this, it becomes possible to obtain a more natural image without fine chattering and change.

  Although the embodiments of the invention have been described above, the present invention is not limited to these embodiments, and various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention. For example, the combination of each block is arbitrary, and it is also possible to use a CMOS sensor instead of the CCD 112 as an image sensor. The image device need not be a single device, and may be a combination of a plurality of devices. For example, the control unit 140 may be a general-purpose personal computer.

It is a functional block diagram of the imaging device concerning a 1st embodiment of the present invention. It is a figure explaining operation of an imaging device concerning a 1st embodiment of the present invention in time series. It is a figure which shows the imaging characteristic and signal processing output characteristic of the image pick-up element of the imaging device which concerns on one Embodiment of this invention. It is a figure which shows the example of a division | segmentation of a captured image. 2 is a functional block diagram of a luminance integrated value circuit in FIG. 1 of the imaging apparatus according to an embodiment of the present invention. FIG. It is a functional block diagram of the luminance peak value detection circuit of FIG. 1 of the imaging apparatus according to an embodiment of the present invention. It is a functional block diagram of the gate waveform generation circuit of FIG. 1 of the imaging device according to an embodiment of the present invention. It is a functional block diagram of the microcomputer circuit of FIG. 1 of the imaging device which concerns on one Embodiment of this invention. It is a figure explaining the processing content of the screen-divided image of the imaging device which concerns on 1st Embodiment of this invention. It is a figure which shows the flowchart which sets the shutter conditions of the imaging device which concerns on 1st Embodiment of this invention, and performs imaging. It is a figure which shows the flowchart which sets the shutter conditions of the imaging device which concerns on 2nd Embodiment of this invention, and performs imaging. It is a figure which shows the example of the image adjustment using the imaging device by 1st Embodiment and 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Imaging device, 110 ... Imaging part, 111 ... Imaging lens, 112 ... CCD, 120 ... Analog signal processing part, 121 ... AGC circuit, 122 ... A / D conversion circuit, 130 ... Digital signal processing part, 131 ... Image signal Processing execution unit, 131a ... low-speed shutter signal processing unit, 131a ₁ ... low-speed shutter memory circuit, 131a ₂ ... low-speed shutter switching circuit, 131a ₃ ... low-speed shutter characteristic conversion circuit, 131b ... high-speed shutter signal processing unit, 131b ₁ ... High-speed shutter memory circuit, 131b ₂ ... High-speed shutter switching circuit, 131b ₃ ... High-speed shutter characteristic conversion circuit, 132 ... Adder circuit, 133 ... D / A conversion circuit, 140 ... Control unit, 141 ... Image signal Information acquisition unit, 141a ... luminance integrated value circuit, 141b ... luminance peak value detection circuit, 141c ... gate Form generating circuit, 142 ... microcomputer circuit, 143 ... electronic shutter circuit, 150 ... image signal output terminal.

Claims (7)

In an imaging device that obtains a first video signal imaged under a first exposure condition and a second video signal imaged under a second exposure condition,
A luminance detector for detecting the luminance of each of the first video signal and the second video signal;
An exposure condition setting unit that independently sets the first exposure condition and the second exposure condition based on each luminance;
A comparison unit for comparing the first exposure condition and the second exposure condition;
When the comparison unit determines that the difference between the first exposure condition and the second exposure condition is less than or equal to a predetermined first threshold, the first video signal or the second video signal is If the difference between the first exposure condition and the second exposure condition is determined to be greater than the predetermined first threshold, the first video signal and the second video signal are output as they are. An image synthesizing unit that synthesizes and outputs as a third video signal. The comparison unit performs the same exposure on the first exposure condition and the second exposure condition when a difference between the first exposure condition and the second exposure condition is equal to or less than the predetermined first threshold value. Corrected to the conditions,
When the difference between the first exposure condition and the second exposure condition is larger than the predetermined first threshold value, the first exposure condition and the second exposure condition are not corrected. The imaging device according to claim 1.   The imaging apparatus according to claim 2, wherein the same exposure condition is an average value of the first exposure condition and the second exposure condition.   The imaging apparatus according to claim 2, wherein the same exposure condition is one of the first exposure condition and the second exposure condition.   The comparison unit corrects the first exposure condition and the second exposure condition to the same exposure condition, and then determines that the difference between the first exposure condition and the second exposure condition is the first exposure condition. The imaging apparatus according to claim 2, wherein the correction to the same exposure condition is canceled when the second threshold value is greater than a second threshold value. Imaging a first video signal and a second video signal respectively according to a first exposure condition and a second exposure condition;
Detecting the luminance of the first video signal and the second video signal;
Setting the first exposure condition and the second exposure condition based on the luminance;
Comparing the first exposure condition and the second exposure condition;
If the difference between the first exposure condition and the second exposure condition is equal to or less than a predetermined first threshold by the comparison, the first exposure condition and the second exposure condition are set as the same exposure condition. As described above, the first exposure condition and the second exposure condition are corrected, and the first exposure condition and the corrected second exposure condition are imaged and output, and the first exposure condition is corrected. If the difference between the exposure condition and the second exposure condition is larger than the predetermined first threshold, the first exposure condition and the second exposure condition are not corrected without changing the exposure conditions. An image signal processing method, and a step of synthesizing and outputting the captured image. An imaging device that obtains a first image imaged under a first exposure condition and a second image imaged under a second exposure condition ;
An image composition unit that outputs an image from the imaging device;
The imaging device is:
A luminance detector that detects the luminance of at least a partial region in the first image and the luminance of at least a partial region in the second image;
An exposure condition setting unit for independently setting or correcting the first exposure condition and the second exposure condition based on each luminance;
A signal processing unit for obtaining a difference signal indicating a difference between the exposure conditions;
An output unit for outputting the difference signal together with the first image and the second image ;
The image synthesizing unit outputs either the first image or the second image when the difference signal is equal to or less than a predetermined threshold, and when the difference signal is larger than the threshold. Outputs a composite image obtained by combining the first image and the second image.
An imaging apparatus characterized by that .