JP2000209492A - Imaging device - Google Patents

Abstract

(57) [Object] To provide an imaging device having a wide dynamic range capable of obtaining a sufficient contrast (gradation) even in a high luminance portion. Two different video signals, which are a bright first video signal imaged with the aperture 1-1 opened and a dark second video signal imaged with the aperture 1-1 narrowed, at a predetermined brightness or higher. Is an imaging device that adds a signal obtained by compressing the first video signal by a compression circuit 6 and the second video signal by an adder 11 to obtain a video signal having a wide dynamic range. A signal obtained by compressing the first video signal is attenuated by a predetermined attenuation coefficient by an attenuating circuit 7 from a signal having a predetermined brightness H2 (which can be determined from a second video signal captured by narrowing the aperture) or more. The second video signal, which is dark, is also multiplied by a predetermined coefficient in a multiplier circuit 10 from a signal having a predetermined brightness H2 or higher, and the attenuated signal and the multiplied signal are added to obtain a high-luminance portion. Get the key.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus having a wide dynamic range capable of imaging a subject from a dark part to a bright part without saturation by adding (synthesizing) images taken under different exposure conditions. It is.

[0002]

2. Description of the Related Art An imaging device such as a video camera is a CCD.
Processes video signals obtained from an image sensor that converts light into electrical signals, such as a Charge Coupled Device (KNE
E), gamma, detail, white balance, etc.)
Further, a final video signal is obtained by adding a synchronization signal or the like (for example, an NTSC video signal).

However, since an image pickup device such as a CCD generally has a narrow dynamic range, it is difficult to faithfully image a subject having a large luminance difference from a dark portion to a bright portion. In order to solve such a problem, there has been known a method of realizing an imaging device capable of obtaining a wide dynamic range by adding (synthesizing) two types of images obtained by imaging a subject under different exposure conditions.

FIG. 3 is a block diagram showing the configuration of a conventional imaging device. As shown in FIG. 3, an optical signal (a signal from a subject) set to a predetermined exposure amount by an aperture (iris adjusting means) 1-1 is converted into an electric signal by the image pickup device 1 and is converted into a sample-and-hold circuit (hereinafter, referred to as an "sample / hold circuit"). (S / H circuit) 2. The S / H circuit 2 samples and holds the electric signal for each pixel generated by the photoelectric conversion in the image sensor 1 using a clamp pulse to extract a signal portion. The extracted signal component is converted into a digital signal by the A / D converter 3 and then supplied to the memory 5 or the subtractor 8 via the switch circuit 4. The output terminal a or b of the switch circuit 4 is switched by the control signal S1 of the control circuit 15 at the same timing as the exposure amount of the aperture 1-1 is switched. The first video signal captured with an increased exposure amount (that is, a bright video signal captured with the aperture 1-1 open) is YS, and the second video signal captured with a reduced exposure amount (that is, an aperture 1). Dark video signal captured with -1 set down)
Is YF, and the aperture from the image sensor 1 by the control circuit 15 is
By the switching control of 1-1, the first and second video signals YS, Y
Output in the order of F.

When the diaphragm 1-1 is open, the switch circuit 4
Is connected to the output terminal a, so that the first video signal YS imaged with the aperture open is written to the memory 5 as delay means, from which the first video signal YS is transmitted to the second video signal YS. It is read at the input timing of the video signal YF.
Writing to and reading from the memory 5 is performed by a control signal S2 from the control circuit 15. The memory 5 is provided so that the adder 11 at the subsequent stage adjusts the time of the two added signals, that is, the first and second video signals. The compression circuit 6 obtains a signal YS2 that has been level-compressed so that a signal having a predetermined signal level (100%) or more has a constant signal level.

On the other hand, since the switch circuit 4 is connected to the output terminal b when the aperture 1-1 is stopped down, the second video signal YF imaged with the aperture stopped down is supplied to the subtractor 8 and supplied from the terminal 9. The signal YF2 is obtained by subtracting the reference level Yref. Then, the adder 11 adds (combines) the YS2 and the YF2. After the addition (combination), the signal processing circuit 12 performs signal processing such as knee, gamma, and detail processing to obtain a high luminance portion (100% or more). Is compressed, converted to an analog video signal by a D / A converter 13, and
Various signals such as a synchronization signal are added after being TSC-encoded and output.

Next, the operation of FIG. 3 will be described with reference to FIGS. 4 (a) to 4 (d). For example, an image picked up by the image sensor 1 under different exposure conditions (by changing the exposure amount to the image sensor 1) using the aperture 1-1 is converted into an electric signal, passed through the S / H circuit 2, and converted into an A / D converter. In step 3, it is converted to a digital signal. FIG.
FIG. 4A shows a characteristic example of the output (vertical axis) of the image sensor 1 with respect to the input level (horizontal axis) of the image sensor 1 when the image is captured with the aperture opened. FIG. 4 shows an example of characteristics of an output (vertical axis) of the image sensor 1 with respect to an input level (horizontal axis) of the image sensor 1 when an image is captured in a state where the aperture is stopped down. That is, FIGS. 4A and 4B show characteristic examples in the case where the first and second video signals YS and YF from the image sensor 1 are converted into the dynamic range of the image pickup apparatus. At the same time, FIG. 4A shows the output of the compression circuit 6 with respect to the input level (horizontal axis) of the image sensor 1 using hatching, and FIG. 4B shows the output with respect to the input level (horizontal axis) of the image sensor 1. The output of the subtracter 8 is shown using satin.

As shown in FIGS. 4 (a) and 4 (b), a fixed signal level after compression of the first video signal YS (set to 100% of the standard level in the present embodiment) And imaging device 1
The aperture is adjusted so that the difference (D2) between the level (e.g., 400% in this embodiment) and the difference (D2) between the second video signal YF and the reference brightness level Yref are equal. And

The first video signal YS is input to the memory 5 and read out from the memory 5 at the same timing as when the second video signal YF is obtained. As shown in FIG. A signal YS2 which has been level-compressed to a certain signal level for a signal having a predetermined brightness (100%) or more is obtained. On the other hand, as for the second video signal YF,
As shown in FIG. 4B, the reference level Yref is subtracted to obtain YF
It becomes 2.

Then, the YS2 and the YF2 are added (combined) by an adder 11, and YS2 + shown in FIG.
YF2 is obtained. After the addition (synthesis), the high luminance portion (100% or more) is compressed as shown in FIG. 4D through knee, gamma processing and the like of the signal processing circuit 12 (in this embodiment, a maximum of 12%).
The signal Y2 (compressed to 0%) is converted to an analog signal by the D / A converter 13 and
C encoded.

As described above, the conventional image pickup apparatus adds (synthesizes) images picked up at different brightnesses while changing the exposure condition, so that an image of a high-brightness portion saturated with a normal aperture can be obtained. By adding (synthesizing) non-saturated images by narrowing down the aperture, it is possible to capture an image of a subject from a dark portion to a bright portion without saturating the image without losing the luminance gradation of the subject.

However, in the above-mentioned conventional apparatus, there is a drawback that although the gradation of the high luminance portion is obtained, the final video signal is largely compressed by knee, gamma processing and the like, so that the image becomes whitish with little contrast. Was.

[0013]

As described above, in the conventional apparatus, although the gradation of the high-luminance portion can be obtained, the final video signal is largely compressed by knee, gamma processing, etc., so that a whitish video with little contrast is obtained. There was a problem that would be.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide an image pickup apparatus having a wide dynamic range capable of obtaining a sufficient contrast even in a high luminance portion. is there.

[0015]

According to the first aspect of the present invention,
What is claimed is: 1. An imaging apparatus capable of capturing an image with a wide dynamic range by changing the amount of exposure to an image sensor in multiple stages and capturing an image with a wide dynamic range. Compression means for level-compressing a first video signal imaged with an increased amount for a signal whose input level to the image sensor is equal to or more than a first predetermined value; and a level-compressed signal from the compression means. Attenuating means for attenuating a signal whose input level to the image sensor is equal to or more than a second predetermined value with a predetermined attenuation coefficient, and a second video signal imaged with a reduced amount of exposure to the image sensor. Multiplying means for multiplying a signal having an input level equal to or higher than the second predetermined value by a predetermined coefficient; adding a signal from the attenuating means to a signal from the multiplying means; Range video signal Those provided with the adding means for outputting.

According to a second aspect of the present invention, there is provided an image pickup apparatus capable of picking up an image with a wide dynamic range by changing the amount of exposure to an image pickup element in multiple steps.
Means for adjusting the exposure amount to the image sensor in two stages, a first video signal captured with the increased exposure amount and a second video signal captured with the reduced exposure amount, 2
Switch means for sequentially switching in accordance with the stepwise exposure amount switching, control means for performing the two-stage exposure amount switching in the adjusting means for a predetermined time and switching the switch means, and sequentially output from the switch means. Delay means for adjusting the time of the first and second video signals, and applying the time-aligned first video signal to a signal whose input level to the image sensor is equal to or greater than a first predetermined value. Compression means for performing level compression, attenuating means for attenuating a signal whose level has been compressed from the compression means with respect to a signal whose input level to the image sensor is equal to or more than a second predetermined value, by a predetermined attenuation coefficient, Multiplying means for multiplying a signal whose input level to the image sensor is equal to or more than the second predetermined value by the time-aligned second video signal by a predetermined coefficient; And signals, by adding the signals from said multiplying means, those provided with the adding means for outputting a video signal of wide dynamic range.

According to a third aspect of the present invention, in the imaging apparatus according to the first or second aspect, the predetermined attenuation coefficient in the attenuation means is set to be larger as the subject is brighter and the input level to the imaging device is higher. The predetermined coefficient in the multiplying means is set to be larger as the subject is brighter and the input level to the image sensor is higher.

According to a fourth aspect of the present invention, in the image pickup apparatus according to the first or second aspect, for a signal whose input level to the image sensor is equal to or more than a second predetermined value, the amount of attenuation by the attenuation means is determined. , The increment by the multiplying means is set to be equal.

In the image pickup apparatus according to the present invention, a signal obtained by compressing the first video signal imaged by increasing the exposure amount is determined by a predetermined brightness or more (from the second video signal imaged by reducing the exposure amount). Attenuated by a predetermined attenuation coefficient from the level of “can be achieved”, and the second video signal captured with a reduced exposure amount is also determined to be equal to or higher than a predetermined brightness (based on the second video signal captured with a reduced exposure amount). ) Is multiplied (amplified) by a predetermined coefficient, and the attenuated signal and the multiplied (amplified) signal are added (combined).

In this way, the second video signal obtained by reducing the amount of exposure in the bright portion of the subject in the video signal after addition (combining) (i.e., does not saturate even if bright but faithfully reproduces the gradation of the subject) By increasing the ratio of the signal reproduced in the above, it is possible to obtain a gradation of a high luminance portion which has been compressed and almost crushed by signal processing (knee, gamma processing, etc.) in the past. That is, the contrast of the high luminance portion can be improved.

The means for adjusting the exposure amount in two stages may be constituted by means for varying the aperture amount or shutter speed, or may be constituted by means for controlling the charge accumulation time of the image sensor. It is possible, or it is also possible to comprise an optical filter arranged before the image sensor.

[0022]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of an imaging device according to an embodiment of the present invention. The same parts as those in FIG. 3 (conventional example) will be described with the same reference numerals.

FIG. 1 differs from FIG. 3 in that the level-compressed signal is attenuated by a predetermined attenuation coefficient with respect to a signal whose input level to the image sensor 1 is equal to or higher than a predetermined value at a stage subsequent to the compression circuit 6. A multiplication circuit 10 is provided downstream of the subtractor 8 in which the attenuation circuit 7 is provided and a subtraction output is multiplied (amplified) by a predetermined coefficient with respect to a signal whose input level to the image sensor 1 is equal to or higher than a predetermined value. That is. And the control circuit 15
A is provided with a control function for causing the attenuating operation of the attenuating circuit 7 and the multiplying operation of the multiplying circuit 10 to be performed on a signal whose input level to the image sensor 1 is equal to or more than a predetermined value. The function of performing the attenuating operation of the attenuating circuit 7 and the multiplying operation of the multiplying circuit 10 on a signal having a predetermined value or more of the input level to the image sensor 1 is independent of the control of the control circuit 15A. 7 and the multiplication circuit 10.

As shown in FIG. 1, an optical signal (signal from a subject) set to a predetermined exposure amount by an aperture (iris adjusting means) 1-1 is converted into an electric signal by an image pickup device 1 and is subjected to S / H. Input to the circuit 2. The S / H circuit 2 samples and holds the electric signal for each pixel generated by the photoelectric conversion in the image sensor 1 using a clamp pulse to extract a signal portion. The extracted signal component is converted into a digital signal by the A / D converter 3 and then supplied to the memory 5 or the subtractor 8 via the switch circuit 4. Switch circuit 4
Is such that the output terminal a or b is switched at the same timing as the exposure amount switching of the aperture 1-1 by the control signal S1 of the control circuit 14A. The first video signal captured with an increased exposure amount (that is, a bright video signal captured with the aperture 1-1 open) is converted to YS, and the second video signal captured with a reduced exposure amount (aperture 1-1). A dark video signal picked up in a state in which 1 is stopped down) is defined as YF, and the first and second video signals YS and YF are output from the image sensor 1 in the order of the first and second video signals YS by the switching control of the stop 1-1 by the control circuit 15A. And

During the period when the first video signal YS is output, the switch circuit 4 is connected to the output terminal a and the first video signal Y
S is written into the memory 5 and is read from the memory 5 at the input timing of the second video signal YF. Writing to and reading from the memory 5 is performed by a control signal S2 from the control circuit 15A. The compression circuit 6 outputs a signal which is level-compressed so that a signal whose input level to the image sensor 1 is equal to or higher than a predetermined value (100%) becomes a constant signal level. Then, the output signal of the compression circuit 6 is input to the attenuation circuit 7, and the signal is output at a predetermined gradient from a level of a predetermined brightness H2 or more (after exceeding the saturation level of the image sensor 1 of 400% in this embodiment). Is attenuated to obtain YS1.

On the other hand, during the period when the second video signal YF is output, the switch circuit 4 is connected to the output terminal b, the second video signal YF is input to the subtractor 8, and the second video signal YF is subtracted. The reference level Yref from the terminal 9 is subtracted by the switch 8. The output of the subtracter 8 is multiplied (amplified) by a predetermined coefficient from a level higher than a predetermined brightness H2 (after exceeding the saturation level of 400% which is the saturation level of the imaging device 1 in this embodiment) by a multiplication circuit 10. .

The control circuit 15A generates a control signal S1 for switching the exposure amount of the diaphragm 1-1 and for switching the switch circuit 4, and a control signal for writing and reading the first video signal YS to and from the memory 5. S2 is generated, and a control signal S3 for causing the attenuating circuit 7 and the multiplying circuit 10 to perform an attenuating operation and a multiplying operation on a signal having a predetermined value H2 or more of the input level to the image sensor 1 is generated.

The adder 11 calculates the YS2 and the Y
F2 is added (synthesized), and the signal after addition (synthesis) is subjected to signal processing such as knee, gamma, and detail processing in the signal processing circuit 12 to compress the high luminance portion (100% or more).
The signal is converted into an analog video signal by the / A converter 13, NTSC encoded by the encoder 14, added with various signals such as a synchronization signal, and output.

Next, the operation of FIG. 1 will be described with reference to FIGS. 2 (a) to 2 (d). For example, an image picked up by the image sensor 1 under different exposure conditions (by changing the exposure amount to the image sensor 1) using the aperture 1-1 is converted into an electric signal, passed through the S / H circuit 2, and converted into an A / D converter. In step 3, it is converted to a digital signal. FIG.
FIG. 2A shows an example of the characteristic of the output (vertical axis) of the image sensor 1 with respect to the input level (horizontal axis) of the image sensor 1 when the image is captured with the aperture opened. FIG. 4 shows an example of characteristics of an output (vertical axis) of the image sensor 1 with respect to an input level (horizontal axis) of the image sensor 1 when an image is captured in a state where the aperture is stopped down. That is, FIGS. 2A and 2B show characteristic examples when the first and second video signals YS and YF from the image sensor 1 are converted into the dynamic range of the image pickup apparatus. At the same time, FIG. 2A shows the output of the attenuation circuit 7 with respect to the input level (horizontal axis) of the image sensor 1 using hatching, and FIG. 2B shows the output level with respect to the input level (horizontal axis) of the image sensor 1. The output of the multiplication circuit 10 is shown using satin.

As shown in FIGS. 2 (a) and 2 (b), a fixed signal level of the first video signal YS after being compressed by the compression circuit 6 (in the present embodiment, the standard level of 100). %) And the level at which the image sensor 1 is saturated (in the present embodiment,
400%) and the difference (D2) between the second video signal YF and the reference brightness level Yref is made equal to the stop 1-1.

The first video signal YS is input to the memory 5 and read out from the memory 5 at the same timing as when the second video signal YF is obtained. As shown in FIG. For a signal having a predetermined brightness H1 (100%) or more, a signal whose level has been compressed so as to have a certain signal level is obtained. The output signal of the compression circuit 6 is input to the attenuation circuit 7 and has a predetermined brightness H2 or more (in the present embodiment, the image pickup device 1).
YS1 is obtained by attenuating the signal at a predetermined slope from the level (after exceeding the saturation level of 400%). That YS
The input / output characteristics of No. 1 (the output characteristics of the attenuation circuit 7 with respect to the input level to the image sensor 1) are shown by the hatched portions in FIG. The output attenuation at the maximum brightness input (that is, the dynamic range of the imaging device) that can be expressed by the imaging device is -D1 from the standard level.

On the other hand, as shown in FIG. 2B, the second video signal YF is subtracted from the reference level Yref and further multiplied by a predetermined coefficient to obtain YF1. The output of the subtracter 8 is multiplied (amplified) by a predetermined coefficient from a level higher than a predetermined brightness H2 (after exceeding the saturation level of 400% which is the saturation level of the image pickup device 1 in this embodiment) by a multiplication circuit 10. The input / output characteristics (the output characteristics of the multiplying circuit 10 with respect to the input level to the image sensor 1) are shown by the satin portions in FIG. After the multiplication, the output increase at the maximum brightness input that can be expressed by the image pickup apparatus (that is, the dynamic range of the image pickup apparatus) is set to be D1. By setting the attenuation D1 equal to the increase D1 in this manner, the signal YS1 + YF1 after addition (combination) in the adder 11 is obtained.
As shown in FIG. 2C, input / output characteristics (natural gradation characteristics) similar to those of the conventional example can be obtained. FIG.
(c) shows the output characteristic of the adder 11 with respect to the input level (horizontal axis) of the image sensor 1. The respective coefficients of attenuation and multiplication (amplification) are preferably set so as to have optimal characteristics for the imaging device according to the dynamic range of the imaging device, the S / N of the YF signal, and the like. The predetermined attenuation coefficient in the attenuation circuit 7 is set to be higher as the subject is brighter and the input level to the image sensor 1 is higher, and the predetermined coefficient in the multiplication circuit 10 is set as the subject is brighter and the input level to the image sensor 1 is higher. It is preferable that the larger the value, the larger the value.

After the addition (synthesis), the signal processing circuit 1
As shown in FIG. 2D, the signal Y1 whose high-luminance portion (100% or more) is compressed (in this embodiment, compressed to a maximum of 120%) through knee / gamma processing is D / A Converter 1
3 and converted into an analog signal, and further encoded by an NTSC encoder 14. FIG. 2D shows the output characteristics of the signal processing circuit 12 with respect to the input level (horizontal axis) of the image sensor 1.

In general, the second video signal YF is
Is multiplied (i.e., amplified) by a predetermined coefficient. However, since the signal is compressed by knee and gamma processing in the signal processing circuit 12 at the subsequent stage (Y1 in FIG. 2D), an increase in noise is not so noticeable. , High brightness part (more than 100% especially 400%
The effect of obtaining the gradation of the portion close to () is greater.

According to the imaging apparatus of the embodiment of the present invention described above with reference to FIG. 1, a signal obtained by compressing a first video signal captured by increasing an exposure amount is converted into a signal having a brightness of a subject equal to or higher than a predetermined brightness. , And a second video signal imaged with a reduced amount of exposure is also multiplied (amplified) by a predetermined coefficient from a level higher than a predetermined brightness,
The signal attenuated by the previous era and the multiplied (amplified) signal are added (synthesized), and a video signal obtained by reducing the amount of exposure in a bright portion of the subject in the added (synthesized) video signal (that is, even if the video signal is bright) By increasing the ratio of a signal that faithfully reproduces the gradation of the subject without being saturated, a gradation of a high-luminance portion that has been compressed and almost crushed in the conventional signal processing (knee, gamma processing, etc.) is obtained. be able to. That is, the contrast of the high luminance portion can be improved.

In the above-described embodiment, the case where the aperture 1-1 is used as a means for adjusting the exposure amount has been described. However, the means for adjusting the exposure amount is not limited to a means for varying the aperture amount. Instead, it may be constituted by means for varying the shutter speed, or may be constituted by means for controlling the charge accumulation time of the image sensor 1, or an ND filter or the like disposed in front of the image sensor 1. It is also possible to configure with an optical filter.

[0037]

As described above, according to the present invention, it is possible to realize an imaging apparatus having a wide dynamic range capable of obtaining a sufficient contrast even in a high-luminance portion.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an imaging apparatus according to an embodiment of the present invention.

FIG. 2 is an input / output characteristic diagram illustrating the operation of the device of FIG.

FIG. 3 is a block diagram showing a conventional imaging apparatus.

FIG. 4 is an input / output characteristic diagram illustrating the operation of the device of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Image sensor 1-1 ... Aperture (exposure amount adjustment means) 2 ... Sample hold circuit 3 ... A / D converter 4 ... Switch circuit 5 ... Memory (delay means) 6 ... Compression circuit 7 ... Attenuation circuit 8 ... Subtraction Unit 9 Terminal 10 Multiplying circuit 11 Adder 12 Signal processing circuit 13 D / A converter 14 Encoder 15A Control circuit YS A / D output signal imaged with the aperture open YF A / D output signal imaged in the squeezed state YS1 ... output signal of attenuation circuit YF1 ... output signal of multiplication circuit Y1 ... output signal of signal processing circuit

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tetsuo Sakurai 3-3-9 Shimbashi, Minato-ku, Tokyo F-term in Toshiba Abu E Co., Ltd. 5C022 AB12 AB13 AB17 AB19 AB68 AC42 AC55 AC56 AC69 5C024 AA01 CA15 CA17 EA02 EA08 FA01 GA11 HA17 HA24

Claims (7)

[Claims] An image pickup apparatus capable of capturing an image with a wide dynamic range by changing an exposure amount to an image pickup element in two steps and imaging the image pickup element in at least two steps. Adjusting means; adjusting means for compressing a first video signal imaged by increasing the exposure amount for a signal whose input level to the image sensor is equal to or higher than a first predetermined value; Attenuating means for attenuating the level-compressed signal from a signal having an input level to the image sensor equal to or higher than a second predetermined value with a predetermined attenuation coefficient, and a second image captured with a reduced exposure amount Multiplying means for multiplying a signal by a predetermined coefficient to a signal whose input level to the image sensor is equal to or greater than the second predetermined value; adding a signal from the attenuating means and a signal from the multiplying means By doing so, Imaging apparatus characterized by comprising an adding means for outputting a video signal of the dynamic range. 2. An image pickup apparatus capable of picking up an image with a wide dynamic range by changing an exposure amount to an image pickup element in two stages, wherein the exposure amount to the image pickup element is changed in at least two steps. Adjusting means for sequentially switching the first video signal captured with the increased exposure amount and the second video signal captured with the reduced exposure amount in accordance with the two-step exposure amount switching Switch means; control means for performing the two-stage exposure amount switching in the adjusting means for a predetermined time and switching the switch means; and switching the first and second video signals sequentially output from the switch means. Delay means for performing time adjustment; and a pressure for level-compressing the time-aligned first video signal with respect to a signal whose input level to the image sensor is equal to or greater than a first predetermined value. Means for attenuating the level-compressed signal from the compression means with respect to a signal whose input level to the image sensor is equal to or higher than a second predetermined value by a predetermined attenuation coefficient; A multiplying means for multiplying the video signal of the second image signal by a predetermined coefficient to a signal having an input level to the image sensor equal to or more than the second predetermined value; a signal from the attenuating means; and a signal from the multiplying means. And an adder for outputting a video signal having a wide dynamic range by adding 3. A predetermined damping coefficient in said damping means is:
The larger the brightness of the subject and the higher the input level to the image sensor, the larger the value.
3. The image pickup apparatus according to claim 1, wherein the setting is made larger as the subject is brighter and the input level to the image pickup device is higher. 4. A signal whose input level to said image pickup device is equal to or higher than a second predetermined value is set so that an amount of attenuation by said attenuation means and an amount of increase by said multiplication means are equal. The imaging device according to claim 1 or 2, wherein 5. The image pickup apparatus according to claim 1, wherein said means for adjusting the exposure amount in two stages comprises a means for varying an aperture amount or a shutter speed. 6. The imaging apparatus according to claim 1, wherein said means for adjusting the exposure amount in two stages comprises means for controlling a charge accumulation time of said imaging device. apparatus. 7. An image pickup apparatus according to claim 1, wherein said means for adjusting the exposure amount in two stages comprises an optical filter disposed before said image pickup device. apparatus.