JPH11168659A - Electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of false colors from occurring by correcting shading caused by the difference in charge storage time for each pixel of an image-pickup device of a light-shielding means. SOLUTION: The control over charge storage time of an image pickup device due to a light shielding means is performed by the operation of the light shielding means from an open state to a closed state, and a shading correcting means which corrects shading, that takes place from difference of the charge storage time of each pixel of the image-pickup device which is caused by the operation of the light shielding means, is provided. That is, although a first photographing 1 which obtains an image-pickup signal that has small exposure amount is performed by using an electronic shutter function of a CCD image- pickup device similarly to a conventional case, when a charge storage time T2 of the CCD image-pickup device for second photographing 2 to obtain an image-pickup signal which has large exposure amount is set to a time that is longer than time T0 (normally one vertical synchronizing signal interval) that is needed to read all pixels of the CCD image-pickup device, the image- pickup signal that has large exposure is produced by the use of the electronic shutter function of the CCD image-pickup device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic camera (referred to as a digital still camera) which obtains a wide dynamic range image by reading a plurality of image pickup signals having different exposure amounts from a single image pickup element and synthesizing them. Have been).

[0002]

2. Description of the Related Art Generally, television cameras, video cameras,
In an imaging device such as an electronic camera, a solid-state imaging device such as a CCD imaging device is used. However, there is a problem that the dynamic range of the solid-state imaging device is extremely narrow as compared with a silver halide photographic film.

Conventionally, in order to solve this problem, a method has been proposed in which two image pickup signals having different exposure amounts are read from a single image pickup device and synthesized to obtain an image having an enlarged dynamic range. For example, Japanese Unexamined Patent Publication No. 4-207581 discloses the following configuration.

[0004] That is, there is provided an image pickup device having a light receiving section composed of a plurality of light receiving elements for photoelectrically converting optical information, and means for transferring a signal from the light receiving section. Immediately after sending the signal by the first exposure to the transfer means, the second exposure having a longer exposure time than the first exposure is started, and after the signal by the first exposure is output from the image sensor, the second exposure is performed. A signal is sent to the transfer means so that a signal based on the second exposure is output from the image sensor, whereby a second exposure is performed during a period in which a signal based on the first exposure is output from the image sensor. A technique for reducing the time lag is disclosed. At this time, the first exposure time is controlled by an operation of sending a signal by exposure from the light receiving section to the transfer means, that is, controlled by an electronic shutter function, and the second exposure time is controlled by an exposure time of the image sensor. Control the second
There is also disclosed a device in which the exposure time can be controlled independently of the transfer operation of the first exposure signal.

As a method of synthesizing a wide dynamic range image by synthesizing two image pickup signals having different exposure amounts, Japanese Patent Application Laid-Open No. 6-141229 discloses a method as shown in FIG. ing. That is, CCD10
The signal of the short charge accumulation period CS1 read from the memory 1 is recorded in the memory 102, and the signal of the long charge accumulation period CL1 is
The data is read from the memory 102 at substantially the same timing as the data read from D101. The signal read from the memory 102 is multiplied by CL1 / CS 1 times, for example, 4
Multiply. By multiplying by this magnification, the signal level of the same subject with the signals having different charge accumulation periods is made the same in principle.

Next, a weight corresponding to the signal level is assigned by a level weighting means H105. The signal corresponding to the charge accumulation period CL1 is also weighted by the level weighting means L104. The characteristics of each weight are shown in FIG. 23. The horizontal axis is the input signal level, and the vertical axis is the weight coefficient assigned to the signal. The level weight L is set to 1 for 80% of the input signal level, linearly reduced from 80% to 100%, and set to 0 at the input level of 100%. On the other hand, the level weight H is 0 for up to 80% of the input signal level, is linearly increased from 80% to 100%, and the weight coefficient is 1 for 100% input level. For the input level of 100% or more, all the weighting factors are 1. In this manner, weighting is applied to image signals having different dynamic ranges,
The images are combined by the addition by the adder 106 to form one image. By this weighting, a portion having a good image state (S /
(Where N is good and not saturated) is extracted, and an image having a wide dynamic range is synthesized. The synthesized image is C
At the stage of reading the signal from the CD 101, the speed is twice as fast as usual, so that the speed converter 107 converts the scanning speed of the signal to 1/2 so as to correspond to the scanning of the standard television signal. Also, the signal level of the synthesized image can be up to 400
%, But the level is compressed to 100% by the level compression means 108. In FIG. 22, reference numeral 109 denotes a timing control unit.

As described above, the difference in signal level due to the difference in the charge accumulation period is corrected for two signals having different charge accumulation periods, and the signal is not saturated from these image signals and a sufficient S / N is maintained. Weighting the selected portion to smoothly combine the two image signals at the same time as selecting, compressing the signal with a wide dynamic range and large signal amplitude, converting it to a standard signal level, and outputting it Thus, an image having an expanded dynamic range is synthesized from two image signals in which the charge accumulation period of a CCD having a narrow dynamic range is controlled.

[0008]

By the way, Japanese Unexamined Patent Publication No. Hei 4-207581 discloses that an image having a small exposure amount is first used for an image pickup signal of two imaging signals having different exposure amounts by using an electronic shutter function of an image sensor. A technique is disclosed in which an image with a large amount of exposure is captured by controlling the charge accumulation time with a light-shielding unit (shutter). The open state is shifted to the closed state to control the charge accumulation time. In this case, the charge accumulation time differs depending on the position of the light receiving surface of the image sensor, and shading occurs. . However, regarding this point, nothing is taken into consideration in the above-mentioned publication, nor is any means taken to prevent shading from occurring. Further, there is a problem that the control of the accumulation period by the light-shielding means is not so accurate as compared with the electronic shutter of the image sensor.

Further, in the technique disclosed in the above publication, when two image pickup signals having different exposure amounts are obtained, no consideration is given to exactly setting the exposure amount ratio of the two image pickup signals. In addition, no consideration is given to the problem in the case of using flash light emitting means. Further, in a case where an imaging device such as an electronic camera includes an exposure setting unit (AE), a white balance setting unit (WB), a gain control unit, an aperture control unit, and the like, two imaging signals having different exposure amounts are output. When a wide dynamic range image is obtained by combining images, no consideration is given to how to correspond them.

Japanese Patent Application Laid-Open No. 6-141229 discloses a method of combining two image pickup signals having different exposure amounts to form a wide dynamic range image by changing a weighting coefficient and smoothly combining the two signals. However, no consideration is given to the problem of false color when a color image is synthesized, and there is no disclosure of a problem when a strobe is used.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem in a conventional imaging apparatus which forms a wide dynamic range image by combining a plurality of imaging signals having different exposure amounts. An object of the present invention is to provide an electronic camera capable of correcting shading that occurs when an image pickup signal having a large exposure amount is obtained by controlling the charge accumulation time of an image pickup device by a light shielding unit. According to the second aspect of the present invention, even when an image pickup signal is generated by controlling the charge accumulation time of the image pickup element by the light shielding unit,
An object of the present invention is to provide an electronic camera which does not generate shading. A third object of the present invention is to provide an electronic camera capable of controlling the charge storage time with high accuracy even when controlling the charge storage time of the image pickup device for a long time.

According to a fourth aspect of the present invention, an exposure amount of an image pickup signal can be controlled with high precision so that an exposure amount ratio corresponding to a preset exposure amount ratio in two photographing operations is obtained. It is an object of the present invention to provide an electronic camera.

According to a fifth aspect of the present invention, when two imaging signals having different exposure amounts are generated and combined by using a flash light emitting means to obtain a wide dynamic range image, the generation time difference between the two imaging signals is determined. It is an object of the present invention to provide an electronic camera capable of obtaining an image in which the difference between two imaging signals due to a difference in generation time is small, which is shortened. According to a sixth aspect of the present invention, even when the flash light emitting means is used, the exposure amount of the imaging signal can be controlled with high accuracy so that the exposure ratio corresponds to a preset exposure ratio. It is an object of the present invention to provide an electronic camera. It is another object of the present invention to provide an electronic camera capable of generating an image signal in which the influence of excess light emission when using a flash light emitting means is reduced.

According to an eighth aspect of the present invention, when two imaging signals having different exposure amounts are generated and combined to obtain a wide dynamic range image, two imaging signals having the same depth of field can be obtained. It is an object of the present invention to provide an electronic camera. It is an object of each of the ninth, tenth, and eleventh aspects of the present invention to provide an electronic camera capable of obtaining an imaging signal with an equal depth of field and an optimal exposure.

According to a twelfth aspect of the present invention, when two imaging signals having different exposure amounts are generated and synthesized to obtain a wide dynamic range image, a synthesized image free from false colors due to a difference in white balance is obtained. It is an object of the present invention to provide an electronic camera that can be used. The invention according to claim 13 is
It is another object of the present invention to provide an electronic camera capable of preventing false colors from being generated in a wide dynamic range composite image with high accuracy. An object of the invention described in claim 14 is to provide an electronic camera capable of obtaining a wide dynamic range composite image with white balance correction with higher accuracy. It is an object of the present invention to provide an electronic camera capable of efficiently obtaining a white balance-corrected wide dynamic range composite image.

Another object of the present invention is to provide an electronic camera capable of efficiently obtaining a wide dynamic range composite image free from false colors due to a difference in white balance. It is an object of the present invention to provide an electronic camera capable of efficiently and accurately obtaining a wide dynamic range composite image free from false colors due to a difference in white balance. An object of each of the inventions described in claims 18 and 19 is to provide an electronic camera capable of efficiently and highly accurately obtaining a wide dynamic range composite image with white balance correction. It is an object of the present invention to provide an electronic camera capable of obtaining a wide dynamic range composite image with white balance correction more efficiently.

According to a twenty-first aspect of the present invention, there is provided an image forming apparatus having two different exposure amounts.
An object of the present invention is to provide an electronic camera capable of easily generating two image pickup signals that are adapted to a preset exposure ratio with high accuracy when generating and combining two image pickup signals to obtain a wide dynamic range image. And The invention according to claim 22 is
An electronic camera capable of easily generating two imaging signals that are highly accurate to the exposure ratio even when the shutter speed at the time of photographing cannot correspond to the preset exposure ratio with high accuracy. The purpose is to provide.

According to the twenty-third aspect of the present invention, the two exposures having different exposure amounts are provided.
An object of the present invention is to provide an electronic camera capable of easily generating two image pickup signals having different exposure amounts in the same charge accumulation time from an image pickup device when forming a wide dynamic range image by combining two image pickup signals. And The invention according to claim 24 provides an electronic camera capable of preventing generation of a false color caused by a difference in peripheral dimming when two image pickup signals having different exposure amounts are generated and combined depending on an aperture value. With the goal. According to the twenty-fifth aspect of the present invention, it is not necessary to control the amount of flash light emission when generating two imaging signals having different exposure amounts using the flash light emitting means, and the exposure amount ratio between flash light emission and ambient light is reduced. An object of the present invention is to provide an electronic camera that is made equal. The invention according to claim 26, when forming a color composite image of a wide dynamic range by combining a plurality of color image signals of different exposure amount,
It is an object of the present invention to provide an electronic camera provided with a color image synthesizing unit capable of forming a color synthesized image free from false colors and false contours.

[0019]

In order to solve the above-mentioned problems, the present invention is directed to a single image pickup device having an electronic shutter function capable of arbitrarily controlling an exposure amount by controlling a charge accumulation time. A light-shielding unit that shields a light-receiving surface of the image sensor, generates an image signal having a small exposure amount using an electronic shutter function of the image sensor, and controls the charge accumulation time of the image sensor by the light-shielding unit. In an electronic camera that generates a large amount of imaging signals and combines the two imaging signals to obtain an enlarged wide dynamic range image,
The control of the charge accumulation time of the image sensor by the light-shielding means is as follows:
A shading correction unit configured to correct shading that is performed by an operation of the light shielding unit from an open state to a closed state and that is caused by a difference in charge accumulation time of each pixel of the image sensor due to the operation of the light shielding unit. It is a feature. By providing such shading correction means, it is possible to correct shading caused by the difference in the charge accumulation time of the pixel at each position on the light receiving surface of the image sensor due to the opening → closing operation of the light shielding means, and the false color of the composite image can be corrected. Can be prevented from occurring.

According to a second aspect of the present invention, there is provided a single image sensor having an electronic shutter function capable of arbitrarily controlling the amount of exposure by controlling the charge accumulation time, and a light shielding means for shielding the light receiving surface of the image sensor. After generating an imaging signal with a small exposure amount using the electronic shutter function of the imaging device, controlling the charge accumulation time of the imaging device with a light shielding unit to generate an imaging signal with a large exposure amount, and combining the two imaging signals. In the electronic camera configured to obtain an enlarged wide dynamic range image, the light shielding unit includes a focal plane shutter, and the focal plane shutter is connected to the image sensor immediately after the electronic shutter operation of the image sensor ends. Shutter charge is performed with the charge accumulation operation of
After the shutter charge is completed, the charge storage operation of the image pickup device is started, and the control of the charge storage time is performed by a normal focal plane shutter operation. In this way, by operating the focal plane shutter as described above using the focal plane shutter, shading does not occur in the image signal obtained by controlling the charge accumulation time by the focal plane shutter operation. Even when it is used, it is possible to obtain a composite image without shading without providing a shading correction unit.

According to a third aspect of the present invention, there is provided a single image pickup device having an electronic shutter function capable of arbitrarily controlling an exposure amount by controlling a charge accumulation time, and a light shielding means for shielding a light receiving surface of the image pickup device. In an electronic camera configured to obtain an enlarged wide dynamic range image by reading two image pickup signals of the same subject having different exposure amounts from the image pickup device and performing synthesis, an image pickup signal having a large exposure amount is obtained. If the charge accumulation time of the image sensor is set shorter than the period required for reading all pixels of the image sensor,
After generating an imaging signal with a small exposure amount using the electronic shutter function of the imaging element, the light-shielding unit controls the charge accumulation time of the imaging element to generate an imaging signal with a large exposure amount, and an imaging with a large exposure amount is performed. If the charge accumulation time of the image sensor for obtaining a signal is set longer than the period required for reading out all pixels of the image sensor, the amount of exposure can be reduced by using the electronic shutter function of the image sensor instead of the light blocking means. It is configured to generate a large imaging signal. If the charge storage time of the image sensor for generating an image signal with a large exposure amount is set longer than the period required for reading all pixels of the image sensor, an electronic shutter may be used to set the charge storage time. In that case, by using an electronic shutter that is more accurate than the light blocking means,
The charge accumulation time can be controlled with high accuracy.

According to a fourth aspect of the present invention, an enlarged wide dynamic range is obtained by combining two image pickup signals obtained by photographing the same object twice with different exposure amounts using a single image pickup device. In an electronic camera having a function of obtaining an image, a photometric element separate from an image sensor is provided, and two preset photographing operations are performed based on an exposure amount measured by the photometric device during the first photographing. , The charge accumulation time of the image sensor at the time of the second shooting is set. By setting the charge accumulation time at the time of the second photographing based on the exposure amount at the time of the first photographing measured by the photometric element, the exposure amount ratio of the two image pickup signals is controlled with high accuracy. be able to.

According to a fifth aspect of the present invention, an enlarged wide dynamic range is obtained by synthesizing two image pickup signals obtained by photographing the same subject twice with different exposure amounts using a single image pickup device. An electronic camera having a function of obtaining an image, comprising a flash light emitting unit, wherein the flash light emitting unit is operated in the second half of the charge accumulation time of the image sensor at the time of the first shooting and the image sensor at the time of the second shooting. The light emission is performed at one or both timings in the first half of the charge accumulation time. With this configuration, it is possible to reduce the generation time difference when generating two imaging signals having different exposure amounts using the flash light emitting unit, and thereby to reduce the difference between the two imaging signals due to the generation time difference. Can be obtained.

According to a sixth aspect of the present invention, in the electronic camera according to the fifth aspect, a photometric element separate from the image sensor is provided, and the flash light emitting means emits light in both of two photographing operations. The configuration is such that the charge accumulation time of the image sensor at the time of the second shooting is set based on the light emission amount ratio of the two light emissions measured by the photometry means. By setting the charge accumulation time at the time of the second photographing based on the light emission amount ratio of the two light emissions measured by the photometer as described above, even when the flash light emitter is used, two electric charges can be obtained with high accuracy. The exposure amount ratio of the imaging signal can be controlled.

According to a seventh aspect of the present invention, in the electronic camera according to the fifth aspect, the image pickup device has an electronic shutter function that can control a charge accumulation time to arbitrarily control an exposure amount. The flash is configured to emit light in both shootings of the two shootings, and when the flash emission means emits a small amount of light, the stop timing of the small emission and the end timing of the electronic shutter operation of the image sensor. Are set to be the same.
Generally, the ratio of surplus light emission in the flash light emitting means increases as the amount of flash light emission decreases. Therefore, by setting the same timing as the stop timing of the small light emission of the flash light emitting means and the end timing of the electronic shutter operation of the image sensor, the influence of the excessive light emission at the time of the small light emission is eliminated, and the extra light when the flash light emitting means is used It is possible to obtain a high-accuracy image pickup signal having an exposure amount ratio with reduced influence of light emission.

According to the eighth aspect of the present invention, a wide dynamic range is obtained by combining two image pickup signals obtained by performing two shots of the same subject with different exposure amounts using a single image pickup device. An electronic camera having a function of obtaining an image, wherein the aperture value of the lens at the time of the two shootings is fixed. As described above, by fixing the aperture of the lens and photographing two times with different exposure amounts, two images having the same depth of field can be obtained.
One imaging signal can be obtained.

According to a ninth aspect of the present invention, in the electronic camera according to the eighth aspect, an exposure setting means is provided, and an aperture value and / or a shutter speed obtained by the exposure setting means prior to photographing are determined by adjusting an exposure amount The aperture value and / or shutter speed used during imaging to obtain a large imaging signal and at the time of imaging to obtain an imaging signal with a small amount of exposure are set in advance to two.
The setting is made so as to correspond to the exposure amount ratio in each photographing. According to a tenth aspect of the present invention, in the electronic camera according to the ninth aspect, the exposure setting means sets an exposure value based on a photometric output of a photometric element provided separately from the image sensor. It is. According to an eleventh aspect of the present invention, in the electronic camera according to the ninth aspect, the exposure setting means is configured to set an exposure value based on an image signal of an image sensor. By providing the exposure setting means in this way and fixing the aperture value obtained by the exposure setting means and using it for two shootings, it is possible to obtain an imaging signal having the same depth of field and the optimal exposure.

According to a twelfth aspect of the present invention, an enlarged wide dynamic range is obtained by combining two image pickup signals obtained by performing two different exposures of the same subject with a single image pickup device. In an electronic camera having a function of obtaining an image, white balance correction is performed by setting a white balance correction value equal to two image pickup signals having different exposure amounts before the synthesis. Things. As described above, the white balance correction value is set equal to the two image pickup signals having different exposure amounts before the synthesis, and the white balance correction is performed. A composite image of the range can be obtained.

According to a thirteenth aspect of the present invention, in the electronic camera according to the twelfth aspect, a white balance setting means is provided,
Prior to photographing, a white balance correction value obtained by the white balance setting means is used for the white balance correction. By using the white balance correction value obtained by the white balance setting means as described above, it is possible to obtain a composite image with higher accuracy and without generation of false colors due to a difference in white balance.

According to a fourteenth aspect of the present invention, in the electronic camera according to the twelfth aspect, the correction value used for the white balance correction is set based on an image pickup signal before the synthesis. It is. By setting the white balance correction value based on the image pickup signal before the synthesis in this way, it is possible to obtain a synthesized image whose white balance has been corrected with higher accuracy.

According to a fifteenth aspect of the present invention, in the electronic camera according to the twelfth aspect, the correction value used for the white balance correction is one of two image pickup signals having different exposure amounts before performing the combining. It is set based on a large image pickup signal. In general, white balance correction needs to be performed in a main part, but the main part is likely to be included in an imaging signal with a large exposure amount. Therefore, by setting a white balance correction value based on an imaging signal with a large amount of exposure, it is possible to efficiently obtain a composite image with white balance correction.

According to a sixteenth aspect of the present invention, the wide dynamic range is expanded by combining two image pickup signals obtained by performing two shots of the same subject with different exposure amounts using a single image pickup device. An electronic camera having a function of obtaining an image is configured to perform white balance correction on the synthesized wide dynamic range image. By performing the white balance correction on the composite image in this way, a wide dynamic range image free of false colors due to a difference in white balance can be efficiently obtained.

According to a seventeenth aspect of the present invention, in the electronic camera according to the sixteenth aspect, a white balance setting means is provided,
Prior to photographing, a white balance correction value obtained by the white balance setting means is used for the white balance correction. By using the white balance correction value obtained by the white balance setting means in this way, it is possible to efficiently and accurately obtain a composite image free from false colors due to a difference in white balance.

The invention according to claim 18 is the electronic camera according to claim 16, wherein the correction value used for the white balance correction is set based on the synthesized wide dynamic range image. The invention according to claim 19 is the electronic camera according to claim 16, wherein the correction value used for the white balance correction is set based on an image signal before performing the combining. Things. By setting the white balance correction value in this manner, a wide dynamic range composite image in which white balance is corrected efficiently and with high accuracy can be obtained.

According to a twentieth aspect of the present invention, in the electronic camera according to the nineteenth aspect, the correction value used for the white balance correction is one of two image pickup signals having different exposure amounts before performing the synthesis. It is set based on a large image pickup signal. By setting a white balance correction value based on an image pickup signal having a large exposure amount in this manner, a wide dynamic range composite image with white balance correction can be obtained more efficiently.

According to a twenty-first aspect of the present invention, an enlarged wide dynamic range is obtained by combining two imaging signals obtained by performing two different exposures of the same subject with a single imaging device. An electronic camera having a function of obtaining an image is provided with gain control means, wherein gain values of the two image pickup signals in the gain control means are set to different values. By setting the gain value corresponding to each imaging signal by the gain control means in this way, it is possible to easily generate two imaging signals that are highly accurately adapted to the exposure ratio.

According to a twenty-second aspect of the present invention, in the electronic camera according to the twenty-first aspect, a gain value for the two imaging signals corresponds to an exposure ratio in which an exposure ratio of the two imaging signals is set in advance. Is set as follows. With this configuration, even when the shutter speed at the time of photographing cannot correspond to the preset exposure ratio with high accuracy, two gains that are easily adjusted to the exposure ratio with high accuracy by adjusting the gain value are easily adjusted. An imaging signal can be generated.

According to a twenty-third aspect of the present invention, the wide dynamic range is expanded by combining two image pickup signals obtained by performing two shots of the same subject with different exposure amounts using a single image pickup device. An electronic camera having a function of obtaining an image, wherein an aperture control unit is provided, and two imaging signals having different exposure amounts are generated by changing an aperture value of a lens by the aperture control unit. It is. With this configuration, it is possible to easily generate two image pickup signals having different exposure amounts in the same charge accumulation time.

According to a twenty-fourth aspect of the present invention, in the electronic camera according to the twenty-third aspect, there is provided a vignetting correction means for a lens.
The present invention is configured to correct peripheral dimming generated based on the aperture values of different lenses for two image pickup signals having different exposure amounts generated by changing the aperture value of the lens by the aperture control unit. . If two imaging signals having different exposure amounts are generated by changing the aperture value of the lens by the aperture control means, different peripheral dimming occurs due to different aperture values,
A false color is generated in the composite image, but by providing a peripheral dimming correction means for the lens and correcting the peripheral dimming of a different lens, it is possible to obtain a composite image free of false color caused by a difference in the peripheral dimming. Can be.

According to a twenty-fifth aspect of the present invention, in the electronic camera according to the twenty-third aspect or the twenty-fourth aspect, a flash light emitting means is provided, and the same amount of flash light is emitted during the two shootings with different exposure amounts, and the aperture control By changing the aperture value of the lens by means, two imaging signals having different exposure amounts are generated. With this configuration, it is not necessary to control the flash light emission amount, and it is possible to make the flash light emission amount and the ambient light exposure amount ratio equal.

According to a twenty-sixth aspect of the present invention, there is provided an electronic camera comprising a color image synthesizing means for synthesizing a plurality of color image signals having different exposure amounts to form a color image having a wide dynamic range. Weighting means for weighting corresponding to each signal level, and means for adding a plurality of weighted color image signals, the weighting means, for each color signal in the plurality of color image signals And the same weighting factor is set for each. By setting the same weighting factor for each color signal in a plurality of color image signals and performing weighted addition, a color composite image with a wide dynamic range free from false colors and false contours can be formed. .

[0042]

Next, an embodiment will be described. First, a basic overall configuration of an electronic camera to which the present invention is applied will be described based on a block configuration diagram shown in FIG. In FIG. 1, reference numeral 1 denotes a single-chip color CCD image sensor for photoelectrically converting an optical signal into an electric signal, which has an electronic shutter function.
The subject light is input through the aperture / shutter mechanism 3. The output of the CCD image sensor 1 is amplified by an amplifier 4 after noise is removed by a correlated double sampling circuit or the like. An A / D converter 5 converts the output of the amplifier 4 which is analog data into digital data.
Reference numeral 6 denotes a camera signal processing circuit that processes a signal from the CCD image sensor 1 as video data. Reference numeral 7 denotes an image pickup signal or the like from the CCD image pickup device 1 prior to the original photographing.
AF detection circuit that extracts AF information to control focus, AE that extracts AE information to control exposure
AWB for setting detection circuit and white balance
This is an AWB detection circuit that extracts information.
The output signals from the E and AWB detection circuits 7 are transmitted through the CPU 8 to the AF information to the lens 2 and to the aperture / shutter mechanism 3 by the A signal.
The A information is supplied to the camera signal processing circuit 6 with the E information.

9 is a compression circuit (J) for compressing the data amount.
PEG), the image data compressed by the compression circuit 9 is recorded on the memory card 15 via the memory card I / F 14. Reference numeral 10 denotes a memory controller, and reference numeral 11 denotes a DRAM, which is used as a working memory when performing color processing of video data and the like. Reference numeral 12 denotes a display circuit, and 13 denotes an LCD display unit, which reads out and displays data recorded on the memory card 15 and is used for checking a shooting state and the like. Reference numeral 16 denotes a personal computer I / F used to transfer data recorded on the memory card 15 to the personal computer 17. In FIG. 1, reference numeral 18 denotes a timing generator which generates a timing pulse for driving the CCD 1 and drives the CCD 1 under the control of the CPU 8. Reference numeral 19 denotes a flash mechanism, which is controlled via the CPU 8 by AE information. Reference numeral 20 denotes an input key of the CPU, which can set various photographing modes, drive a trigger switch, and the like.

Next, a specific method according to the present invention in a method of obtaining an enlarged wide dynamic range image by reading and synthesizing two image pickup signals having different exposure amounts in the electronic camera configured as described above. A first embodiment will be described. In the conventional example disclosed in Japanese Patent Laid-Open No. 4-207581 described above, as shown in FIG. 2, the first photographing for obtaining an imaging signal with a small exposure amount is performed by an electronic shutter of a CCD imaging device. The second photographing for obtaining an image pickup signal with a large exposure amount is performed using a light shielding means (shutter). In FIG. 2, the first photographing,
The second shooting, VD is a vertical synchronizing signal, T ₂ indicates the charge accumulation time of the second shooting.

On the other hand, in the first embodiment of the present invention, as shown in FIG. 3, the first photographing for obtaining an image pickup signal with a small exposure amount is performed by the CCD as in the conventional example.
It is performed using the electronic shutter function of the imaging device, the charge storage time T ₂ of the CCD image sensor of the second imaging for obtaining a large imaging signal of the exposure amount, the time required for the all-pixel reading CCD image pickup device (usually 1 If is set longer than the vertical synchronizing signal period) T ₀ (as the setting is performed in accordance with aspects of the subject), to generate a large imaging signal of the exposure amount using the electronic shutter function of the CCD image sensor Make up.

That is, at the end of the charge accumulation time of the CCD image pickup device for obtaining the imaging signal with a large exposure amount, the reading operation of the imaging signal with a small exposure amount has been completed. The electronic shutter function can be used to set the charge storage time for obtaining a signal. By using the electronic shutter function in this way, the charge storage time can be controlled with higher precision than in the case of using the light shielding means. This makes it possible to accurately set the exposure ratio of the two imaging signals. The above CCD
The operations of the image pickup device and the light shielding means are all controlled by control signals from the CPU.

Next, a second embodiment will be described. When the electronic camera is provided with the light-shielding means, the light-shielding means is normally used with the light-shielding means in an open state. When the charge accumulation time is set for photographing, the light-shielding means is closed to set the accumulation time. Like that. Note that the start of the charge storage time is the same as that of the electronic shutter.
This is performed by applying a shutter pulse to the D imaging element, discharging unnecessary charges, and starting photoelectric conversion. Therefore, when the focal plane shutter is used as the light shielding means, only the rear curtain operates to set the charge accumulation time. However, the movement of the rear curtain causes the CCD to move as shown in FIG.
In the light receiving surface 21 of the image sensor, the charge accumulation time of each pixel differs depending on the position (for example, the front end and the rear end), and accordingly, the shading 22 having a constant inclination is unavoidable in the image signal. In FIG. 4, the shutter positions A and B indicate the positions of the leading end of the rear curtain.

In the present embodiment, in order to solve this problem, shading correction means having the characteristic of the reciprocal of the inclination is provided to perform shading correction.
The shading correction means is provided in a camera signal processing circuit or the like, and performs shading correction by signal processing.

Next, a third embodiment will be described. In this embodiment, shading is prevented from occurring when a focal plane shutter is used as a light shielding means for setting a charge accumulation time. That is, as shown in FIG. 5, first, a first imaging with a small exposure amount is performed using the electronic shutter function of the CCD imaging device, and a first imaging signal is generated. Then, immediately after the end of the electronic shutter operation, the operation of accumulating electric charge in the CCD image sensor is temporarily stopped. This is performed, for example, by continuing the operation of discharging unnecessary charges. The stop period t ₁ of the charge accumulation, in order to ready for use both curtains of the front curtain and rear curtain of the focal plane shutter, charge the shutter of the focal plane shutter. After the completion of the shutter charge, the charge accumulation operation of the CCD image pickup device is started, and then the normal shutter operation of the focal plane shutter in which both curtains are operated is performed, so that the exposure time (actual charge accumulation time) t ₂ Is performed to perform a second photographing, and a second image pickup signal is generated. Since the second image signal is obtained by a normal focal plane shutter operation, no shading occurs, and therefore, no shading correction means is required. In FIG. 5, A and B indicate the positions of the leading end of the rear curtain (the positions corresponding to A and B in FIG. 4).

Next, a fourth embodiment will be described. In this embodiment, as shown in FIG. 6, a photometric device 31 separate from the CCD image sensor 1 is disposed near the CCD image sensor 1, and the actual measurement measured by the photometric device 31 during the first photographing is performed. The charge accumulation time of the CCD image pickup device 1 at the time of the second shooting is set so as to correspond to a preset exposure amount ratio of the two shootings based on the exposure amount.

That is, the exposure amount ratio in the two photographings is set in advance to, for example, 1: 8 or 1:16. Therefore, 1/8 or 1 / of the AE value obtained prior to shooting
The charge accumulation time is set so that the exposure amount becomes 16, and the first imaging is performed as shown in FIG. 7 to generate the first imaging signal. At this time, the actual exposure amount is measured by the photometric element 31. Then, based on the measured exposure amount, an exposure amount ratio (for example, 1:
8 or 1:16), the charge accumulation time of the CCD image sensor at the time of the second imaging is set, the second imaging is performed, and the second imaging signal is generated. And 2
The two imaging signals are combined to form a wide dynamic range image. In this case, since the charge accumulation time in the second photographing is set based on the actually measured exposure amount measured by the photometric element, the actual exposure amount ratio of the two imaging signals can be controlled with high accuracy. it can.

Next, a fifth embodiment will be described. In this embodiment, the strobe light emission timing when photographing is performed with the use of a strobe is appropriately set so that the generation of a false color in a composite image can be suppressed as much as possible. That is, as shown in FIG. 8, the timing of the first half t ₄ of the charge accumulation time of the charge accumulation time of the second half t ₃ of the timing and the second shooting strobe during the first shooting, in either or both of the timing It is configured to emit light.

As a result, it is inevitable that a time difference occurs between the two photographing operations, but this time difference can be minimized, and the occurrence of false colors in the composite image can be reduced as much as possible.
In addition, by reducing the time difference, the influence of camera shake can be reduced.

Next, a sixth embodiment will be described. Also in this embodiment, two image pickup signals having different exposure amounts are generated by using the strobe light emission. However, since the actual strobe light emission amount varies, the light emission amount ratio is actually measured using a photometric element. The exposure ratio is set in accordance with the light emission ratio. That is, as shown in FIG. 9, a photometric device 31 is provided near the CCD image sensor 1, and the strobe mechanism 19 emits light in both shootings during two shootings. The two flash emission amounts are set so as to be a preset exposure amount ratio, for example, 1: 8 or 1:16, and as shown in FIG. It is emitted at the first half of the timing of the second shooting. However, since the actual flash emission varies, the light emission element ratio is measured twice by the photometric element 31, and the charge accumulation time at the time of the second photographing is set to correspond to the actually measured flash emission ratio. Set. This makes it possible to control the exposure ratio with high accuracy in correspondence with the strobe light emission ratio even if there are variations in the strobe light emission, even in the case of generating two image pickup signals having different exposure amounts using the strobe light emission. it can. In this case, the combining process of the two image pickup signals is performed based on the exposure amount ratio corresponding to the measured light emission amount ratio.

Next, a seventh embodiment will be described. In general, flash emission is accompanied by surplus light emission. That is, as shown in FIG. 11 (A), the strobe light emission has a mountain-like shape with extra light emission even after the stop of the light emission, and when this is expressed by an integral value, it becomes saturated as shown in FIG. 11 (B). It becomes the shape which goes. The error of the light emission amount due to the surplus light emission has a larger ratio as the light emission amount is smaller. Therefore, in the present embodiment, the emission stop timing (timing of the emission stop signal) and the end timing of the electronic shutter operation of the CCD image sensor are set to be the same during the first small emission of the two emission operations. In order to eliminate the influence of excess light emission on the setting of the exposure amount ratio.

Next, an eighth embodiment will be described. In this embodiment, when two imaging signals with different exposure amounts are generated, the aperture value of the lens is kept constant during two shootings, and an imaging signal with the same depth of field is obtained. . As a result, it is possible to prevent a false color caused by combining an in-focus image and an out-of-focus image.

As the aperture value, the optimal aperture value and the aperture value at the shutter speed obtained by the exposure setting means before photographing are used. The optimal aperture value and the shutter speed are used when capturing an imaging signal with a large exposure amount, and when capturing an imaging signal with a small exposure amount, the same aperture value is used and the shutter speed is set to a predetermined exposure speed. Set according to the quantity ratio.

The photometry for obtaining the optimum aperture value and shutter speed in the exposure setting means may be performed by using a CCD image sensor, or by using an external photometric device provided separately from the CCD image sensor. May go.

Next, a ninth embodiment will be described. In this embodiment, when image pickup signals of two different exposure amounts are generated and combined, white balance correction is performed on two photographing signals before the combination using the same white balance correction value. is there. This can prevent the generation of false colors in the composite image.

As the correction value used for the white balance correction, the white balance correction value obtained by the white balance setting means prior to photographing is used, and the white balance correction is performed on the two imaging signals before the synthesis. I do. The white balance correction value is
The setting may be made based on two image signals actually obtained.

In general, it is necessary to set the white balance in the portion of the image that is to be the main subject, and it is highly possible that the portion of the image that is to be the main subject is included in the imaging signal with a large exposure amount. Therefore, by obtaining the white balance correction value based on the imaging signal of the large exposure amount among the two imaging signals, the white balance correction value can be efficiently obtained, and the white balance of the main subject is optimized. A combining process can be performed.

Next, a tenth embodiment will be described. In this embodiment, the white balance is not corrected for the two image pickup signals having different exposure amounts before the synthesis processing is performed, but the white balance is corrected for the image after the synthesis processing. It is configured. As a result, the white balance can be corrected efficiently. Also, the white balance correction value used in this case may be a white balance correction value obtained by the white balance setting means prior to photographing, or may be a value obtained based on an image after performing synthesis. In addition, the white balance correction value may be set based on two image signals before synthesis, and in this case, the white balance correction value may be set based on the image signal with a large exposure amount among the two image signals before synthesis. May be set.

Next, an eleventh embodiment will be described. Normally, two imaging signals having different exposure amounts are subjected to the synthesis process with a fixed gain. In an electronic camera that performs the synthesis process, two imaging signals are generated by, for example, shooting at an exposure amount ratio of 1: 8. In this case, a shutter speed ratio of 1/4: 1/32 is required.
4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/25
It has a shutter speed of 0, 1/500
If the shutter speed is set to 4: 1/30, an image signal with an accurate exposure amount ratio cannot be generated.

Therefore, in the present embodiment, as shown in FIG.
35 is provided so that different gain values can be set for two imaging signals having different exposure amounts. Then, at this time, a gain value for the two imaging signals is set such that the exposure ratio of the two imaging signals corresponds to a preset exposure ratio (image combining ratio). Accordingly, even when the shutter speed cannot be accurately adapted to the exposure amount ratio, for example, in the above example, the gain value of the imaging signal photographed at the shutter speed of 1/30 is changed and the photographing is performed at the shutter speed of 1/32. Thus, it is possible to obtain an image signal equivalent to the above case, and it is possible to generate two image signals set to the exposure amount ratio with high accuracy.

Next, a twelfth embodiment will be described. In this embodiment, when two imaging signals with different exposure amounts are generated, the charge accumulation time is kept constant, and the aperture value of the lens is changed to generate imaging signals with different exposure amounts. Things. This makes it possible to obtain an imaging signal with a preset exposure ratio without controlling the charge accumulation time with high accuracy.

At this time, by changing the aperture value of the lens, the degree of vignetting (a phenomenon that the illuminance decreases in proportion to the fourth power of the COS of the angle of view) changes. In order to remove the vignetting, as shown in FIG. 13, a vignetting correction circuit 42 for correcting the vignetting corresponding to the diaphragm control by the diaphragm control circuit 41 is provided. Thereby, it is possible to correct the vignetting caused by the change in the lens aperture value.

Also, as shown in FIG. 13, even when two imaging signals with different exposure amounts are generated using strobe light emission, two flashes with the same light emission amount are performed, and the aperture value of the lens is changed. To generate imaging signals having different exposure amounts. Accordingly, it is not necessary to control the amount of light emission of the strobe with high accuracy, and the ratio of the amount of light emission of the strobe and the ratio of the amount of exposure of ambient light can be set to be equal.

Next, a thirteenth embodiment will be described. This embodiment relates to a method of synthesizing an image when a synthetic image having a wide dynamic range is formed by synthesizing two imaging signals having different exposure amounts.

As described above, JP-A-6-14122
The image synthesis method disclosed in Japanese Patent Application Laid-Open No. 9-29904 basically replaces a saturated portion in an imaging signal having a large exposure amount with an imaging signal having a small exposure amount, and performs gain correction based on an exposure amount ratio upon the replacement. It is intended to obtain a composite image signal with a linear and wide dynamic range,
At the time of the synthesizing process, a smooth switching such as overlapping is performed by giving a slope weighting coefficient.

However, when this method is simply applied to a color image signal, the following problems occur. That is, as shown in FIG. 14, when there are G and R signals having different output levels with respect to the luminance, and when the level of 100% is determined and synthesized with the above weighting factors, actually, Due to variations in the elements, a linear composite output cannot be obtained in many cases even when the composite processing is performed in accordance with the exposure amount ratio. In FIG. 14, the solid line indicates the combined image data of the G and R signals, and in the case shown in the figure, indicates that the actual level of the image data with a small exposure amount is smaller than the exposure amount ratio. In such a case, since the ratio of the G signal to the R signal changes in the range α of the portion where the linearity is lost, the color is not correctly reproduced and appears as a false color. In the above publication, no consideration is given to this point.

On the other hand, in Japanese Patent Application Laid-Open No. Hei 7-131708, the synthesis ratio of an imaging signal having a large exposure amount and an imaging signal having a small exposure amount at the time of actual synthesis is obtained from actual image data. A technique for synthesizing using the technique disclosed in Japanese Patent Application Laid-Open No. 6-141229 is basically solved by applying this technique.

However, Japanese Patent Application Laid-Open No.
In the case where strobe light emission is applied to the combining method disclosed in Japanese Patent Publication No. 8 (1994), the following problems occur. That is,
Here, as a scene of flash emission shooting, as shown in FIG. 15, when there is a wall on the left side of the room and the flash is emitted to the wall, the front is brighter with respect to the flash light and the darker as it goes farther. Consider an aspect in which a gradation of luminance occurs. In such an embodiment, the ambient light is assumed to be at a constant level, and when the flash is fired and a long-time exposure (large exposure) is taken, the state of the level of the image data with respect to the position is as shown in FIG. It is represented as shown in the schematic diagram. On the other hand, when a short exposure (small exposure) is performed while changing the ratio of the exposure amount and the strobe light emission amount (for example, 1: 4), image data as indicated by a dotted line in FIG. The result of the gain correction (for example, four times) of the image data is represented by a solid line.

The gain-corrected ambient light level is shown in FIG.
(A) is the same as the ambient light level in the long-time exposure. However, it is actually difficult to emit strobe light at an accurate ratio (for example, 1: 4), which causes variation. This illustrated example shows a case where the amount of strobe light emission in short-time exposure is large. When the long-time exposure imaging signal and the short-time exposure imaging signal shown in FIGS. 16A and 16B are combined, as shown in FIG. Although the images are correctly synthesized, in a portion where the strobe light gradation occurs, a luminance step is generated in the synthesized image as shown in the figure due to the variation in the light emission amount ratio. A pseudo contour occurs at this step,
There is a problem that even if the luminance changes smoothly on a wall or the like, the image is synthesized so as to have an outline.

Therefore, in the present embodiment, an attempt is made to solve such a problem, and any one of the R, G, and B color signals in an image pickup signal of a long-time exposure (large exposure amount) is used. When saturation occurs and a state of replacing with a signal of short exposure (small exposure amount) occurs, the same replacement is performed on all the color signals at the same time. The replacement is performed by performing an addition process while performing the same weighting.

That is, as shown in FIG. 18, for example, when the G signal of the long-time exposure reaches a saturation level of 100%, it is replaced with a signal of the short-time exposure whose gain has been corrected by weighting addition. At the same time, the R signal is also switched to a short-time exposure signal whose gain has been corrected using the same weighting coefficient. At this time, even if there is some error, the switching is performed using the same weighting coefficient for all the color signals, so that the problem that a false color occurs at the switching point is solved. Then, the weighting coefficient is calculated by using
The weighting factors disclosed in Japanese Patent Application Laid-Open No.
As in the case of FIG. 19, the synthesized signal is smoothly changed and changed so as to overlap at the switching portion, and the long-time exposure signal is replaced with the short-time exposure signal. The luminance gradually changes, and the generation of a false contour can be prevented even when strobe light emission is used.

As a specific synthesizing circuit, as shown in FIG. 20, an image signal from the CCD image sensor 1 is A / D converted by an A / D converter 5, and a synthesizing process is performed by a synthesizing circuit 51.
Any configuration may be used as long as the compression circuit 52 performs a compression process and performs an operation to match the dynamic range of the output system. Then, for example, as shown in FIG. 21, the synthesizing circuit outputs the color signals R _L ,
A maximum value detection circuit 61 for outputting the maximum (luminance) of G _L and B _L , and a weight coefficient corresponding to the luminance of the color signal having the maximum value output through the maximum value detection circuit 61 And a weight coefficient generating circuit 62 for generating
The same weighting factor set in step 62 is used for each color signal R _L , G _L , _{BL of the long-} time exposure color imaging signal and each color signal R _S , G _S , B _{S of the} short-time exposure color imaging signal.
And multipliers 63 and 64 for multiplying each of the color signals, and adders 65 for adding each of the color signals multiplied by the weight coefficient for each color signal.
It is composed of The color signals R _s , G _s , and B _s are signals obtained by correcting a difference in signal level due to a difference in charge accumulation time with a ratio of charge accumulation times or a coefficient obtained from actual image data.

In the synthesizing circuit configured as described above, the maximum value detection circuit 61 detects and outputs the one having the maximum value among the color signals R _L , G _L , and B _L of the color image pickup signal of the long exposure. A weighting factor generator 62 generates a weighting factor for each of the long-exposure and short-time exposure color signals in accordance with the luminance value of the detected and output maximum-value color signal. The signals R _L , G _L , B _L and the color signals R _S , G _S , B _{S of the} short-time exposure imaging signal are respectively multiplied by the same weighting coefficient by the multipliers 63, 64, and then weighted. The added color signals are added by an adder 65 to generate R, G, B combined signals having a wide dynamic range. In this embodiment, R, G,
Although the description has been made using the B signal, the present invention is not limited to this, and can be similarly applied to other color signals such as a complementary color system.

[0078]

As described above with reference to the embodiment, according to the first aspect of the present invention, two image pickup signals having different exposure amounts are generated using the electronic shutter function of the image pickup device and the light shielding means. In an electronic camera that forms a wide dynamic range image by combining images, a shading correction unit is provided, so that shading caused by the operation of the light blocking unit can be corrected, and generation of a false color can be prevented.
According to the second aspect of the present invention, a focal plane shutter is used as the light blocking means, and the charge operation is performed by stopping the charge accumulation operation immediately after the end of the electronic shutter operation.
Since the shutter operation is started after the charge accumulation operation is started, a composite image without shading can be obtained without providing a shading correction unit. According to the third aspect of the present invention, when the charge accumulation time for obtaining an imaging signal with a large exposure amount is set to be longer than the time required for reading out all pixels, an image is taken using the electronic shutter function. With this configuration, it is possible to control the charge accumulation time at the time of imaging with a large exposure amount with high accuracy.

According to the fourth aspect of the present invention, the charge accumulation time for the second photographing is set based on the exposure amount at the first photographing measured by the photometric element. Therefore, it is possible to control the exposure ratio of the two imaging signals with high accuracy. According to the invention described in claim 5,
Since the flash light emission unit is configured to emit light at one or both of the timing of the second half of the charge accumulation time at the time of the first imaging and the timing of the first half of the charge accumulation time at the time of the second imaging, two imaging signals are provided. To reduce the time difference between
An image in which the difference between the two imaging signals due to the generation time difference is small can be obtained. According to the invention described in claim 6, the flash light emitting unit emits light in both of the two photographing operations,
Since the second charge accumulation time is set based on the light emission amount ratio measured by the photometry means, even when the flash light emission means is used, the exposure amount ratio of the two imaging signals can be accurately determined. Can be controlled. According to the invention of claim 7, since the stop timing of the small light emission of the flash light emitting means and the end timing of the electronic shutter operation of the image sensor are set to be the same, the influence of the excess light emission in the small light emission is eliminated. The exposure ratio of the imaging signal can be controlled with high accuracy.

According to the eighth aspect of the present invention, since two shots with different exposure amounts are performed with the lens aperture fixed, two image pickup signals having the same depth of field are generated. It is possible to prevent a false color caused by combining the obtained and out-of-focus images. According to the ninth, tenth, and eleventh aspects of the present invention, since the photographing is performed twice while fixing the aperture value obtained by the exposure setting means, the optimum depth of field is equal. An exposure imaging signal is obtained.

Further, according to the twelfth aspect of the present invention, the white balance correction value is set to be equal for two image pickup signals having different exposure amounts before the combination, so that the difference in white balance is different. Thus, it is possible to obtain a composite image having a wide dynamic range in which false colors do not occur. According to the invention of claim 13, since the white balance correction value obtained by the white balance setting means is used, it is possible to obtain a composite image with higher accuracy and no generation of false colors due to a difference in white balance. Can be.
According to the invention as set forth in claim 14, since the white balance correction value is set based on the image pickup signal before performing the synthesis, it is possible to obtain a white balance corrected composite image with higher accuracy. it can. According to the invention of claim 15, since the white balance correction value is set based on the image pickup signal having a large exposure amount, it is possible to efficiently obtain a white balance corrected composite image.

According to the sixteenth aspect of the present invention, since the white balance correction is performed on the synthesized image, the wide dynamic range synthesis without the occurrence of false colors due to the difference in white balance can be efficiently performed. Images can be obtained. According to the seventeenth aspect of the present invention, the white balance is corrected using the white balance correction value obtained by the white balance setting means for the composite image, so that the white balance can be efficiently and accurately corrected. Thus, it is possible to obtain a composite image free of false colors due to the difference in According to each of the inventions described in claims 18 and 19, the white balance correction is performed on the composite image using the composite image or the white balance correction value set based on the imaging signal before performing the composite. Because
It is possible to efficiently and highly accurately obtain a composite image whose white balance has been corrected. According to the invention as set forth in claim 20, since the white balance correction is performed using the white balance correction value obtained based on the imaging signal having a large exposure amount for the composite image, more efficient A composite image with white balance corrected can be obtained.

According to the twenty-first aspect of the present invention, since the gain control means sets the gain value corresponding to each image pickup signal, an image pickup signal suitable for the exposure ratio with high accuracy can be easily obtained. Can be generated. According to the invention of claim 22, since the gain value for the two imaging signals is set such that the exposure ratio of the two imaging signals is equal to a preset exposure ratio,
Even when the shutter speed at the time of photographing cannot correspond to a preset exposure amount ratio with high accuracy, it is possible to easily generate an image signal that is highly accurate to the exposure amount ratio by adjusting the gain value.

According to the twenty-third aspect, the aperture value of the lens is changed by changing the aperture value of the lens by the aperture control means.
Since the configuration is such that one imaging signal is generated, it is possible to easily generate imaging signals having different exposure amounts in the same accumulation time. According to the invention described in claim 24, the peripheral dimming correction means of the lens performs different peripheral dimming corrections on two image pickup signals having different exposure amounts generated by changing the aperture value. Therefore, even if two imaging signals generated by changing the aperture value are combined, a combined image free of false color can be obtained. According to the twenty-fifth aspect of the present invention, by changing the aperture value, two imaging signals having different exposure amounts are generated with the same flash light emission, so that it is not necessary to control the flash light emission amount, and the flash light emission is not required. And the ambient light exposure ratio can be made equal.

According to the twenty-sixth aspect, when two color image signals having different exposure amounts are combined to form a color composite image having a wide dynamic range, two color image signals having different exposure amounts are used. Since the same weighting coefficient is set for each color signal and weighted addition is performed, false colors do not occur, and the occurrence of false contours can be prevented even when flash light emission is used. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic overall configuration of an electronic camera to which the present invention is applied.

FIG. 2 is a timing chart for explaining a mode of generating two image pickup signals having different exposure amounts using a conventional electronic shutter function and a light shielding unit.

FIG. 3 is a timing chart for explaining a mode of generating two image pickup signals having different exposure amounts in the electronic camera according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining a problem when a light shielding unit is used when two image pickup signals having different exposure amounts are generated.

FIG. 5 is a timing chart for explaining a mode of generating two image pickup signals having different exposure amounts in the third embodiment of the present invention.

FIG. 6 is a schematic block diagram showing a configuration of a main part of a fourth embodiment of the present invention.

FIG. 7 is a timing chart for explaining an operation in the fourth embodiment shown in FIG. 6;

FIG. 8 is a timing chart for explaining a mode of generating two image pickup signals having different exposure amounts in the fifth embodiment of the present invention.

FIG. 9 is a schematic block diagram illustrating a configuration of a main part according to a sixth embodiment of the present invention.

10 is a timing chart for explaining the operation of the sixth embodiment shown in FIG.

FIG. 11 is an explanatory diagram for explaining a mode of surplus light emission of a strobe.

FIG. 12 is a schematic block diagram illustrating a configuration of a main part of an eleventh embodiment of the present invention.

FIG. 13 is a schematic block diagram illustrating a configuration of a main part according to a twelfth embodiment of the present invention.

FIG. 14 is an explanatory diagram for describing a problem that occurs when a wide dynamic range combined image is generated by combining color image signals having different exposure amounts using a conventional image combining method.

FIG. 15 is an explanatory diagram for explaining an aspect in which gradation occurs when strobe light is emitted to a wall surface.

16 is a diagram illustrating a change in the level of image data with respect to a position and a mode of gain correction when a strobe is fired with a change in the amount of light emission in the mode illustrated in FIG. 15;

17 is an explanatory diagram for describing a problem in a case where a combined image is generated by combining the image data illustrated in FIG. 16;

FIG. 18 is a diagram illustrating a form of each color signal obtained by synthesizing a color synthesized image in the thirteenth embodiment of the present invention.

19 is a diagram illustrating a color composite image signal when a strobe light is emitted in the wall surface space in the mode illustrated in FIG. 15 and the composite process is performed according to the thirteenth embodiment.

FIG. 20 is a schematic block diagram illustrating a configuration for realizing a combining process according to a thirteenth embodiment of the present invention.

21 is a circuit configuration diagram illustrating a configuration example of a synthesis circuit in FIG. 20.

FIG. 22 is a circuit configuration diagram of a conventional synthesis processing unit that forms a wide dynamic range image by synthesizing two imaging signals having different exposure amounts.

23 is a diagram illustrating characteristics of weights with respect to input levels in the combining processing unit of FIG. 22.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CCD image sensor 2 Lens 3 Aperture / shutter mechanism 4 Amplifier 5 A / D converter 6 Camera signal processing circuit 7 AE, AF, AWB detection circuit 8 CPU 9 Compression circuit 10 Memory controller 11 DRAM 12 Display circuit 13 LCD 14 Memory card I / F 15 Memory card 16 Personal computer I / F 17 Personal computer 18 Timing generator 19 Strobe mechanism 21 Light receiving surface of CCD image sensor 22 Shading with constant inclination 31 Photometric element 35 Gain control means 41 Aperture control circuit 42 Peripheral dimming correction circuit 51 Synthesis Circuit 52 Compression circuit 61 Maximum value detection circuit 62 Weight coefficient generation circuit 63, 64 Multiplier 65 Adder

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Osamu Inagaki 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd.

Claims (26)

[Claims] 1. A single image pickup device having an electronic shutter function capable of arbitrarily controlling an exposure amount by controlling a charge accumulation time, and a light shielding means for shielding a light receiving surface of the image pickup device. After using the shutter function to generate an imaging signal with a small exposure amount, the light shielding unit controls the charge accumulation time of the imaging device to generate an imaging signal with a large exposure amount, and combine the two imaging signals to enlarge the widened image. In the electronic camera configured to obtain a dynamic range image, the control of the charge accumulation time of the image sensor by the light-shielding unit is performed by an operation from an open state to a closed state of the light-shielding unit, and the image sensor by the operation of the light-shielding unit. An electronic camera comprising a shading correction unit for correcting shading caused by a difference in charge accumulation time of each pixel. 2. An image pickup device comprising: a single image pickup device having an electronic shutter function capable of arbitrarily controlling an exposure amount by controlling a charge accumulation time; and a light shielding means for shielding a light receiving surface of the image pickup device. After using the shutter function to generate an imaging signal with a small exposure amount, the light shielding unit controls the charge accumulation time of the imaging device to generate an imaging signal with a large exposure amount, and combine the two imaging signals to enlarge the widened image. In an electronic camera adapted to obtain a dynamic range image, the light shielding means is constituted by a focal plane shutter, and the focal plane shutter stops a charge accumulation operation to the image sensor immediately after the electronic shutter operation of the image sensor is completed. After the shutter charge is completed, the charge storage operation of the image pickup device is started, and the control of the charge storage time is performed in a normal form. An electronic camera, wherein the electronic camera is configured to be operated by a local plane shutter operation. 3. A single image pickup device having an electronic shutter function capable of arbitrarily controlling an exposure amount by controlling a charge accumulation time, and a light shielding means for shielding a light receiving surface of the image pickup device. In an electronic camera configured to obtain an enlarged wide dynamic range image by reading and combining two image pickup signals having different exposure amounts of a subject, a charge accumulation time of an image pickup device for obtaining an image pickup signal with a large exposure amount Is set to be shorter than the period required for reading out all the pixels of the image sensor, an image signal having a small exposure amount is generated by using the electronic shutter function of the image sensor, and then the charge storage time of the image sensor by the light shielding unit is generated. Is controlled to generate an imaging signal with a large exposure amount, and the charge accumulation time of the imaging device for obtaining an imaging signal with a large exposure amount is determined by reading all pixels of the imaging device An electronic camera characterized in that an image signal having a large exposure amount is generated by using an electronic shutter function of an image sensor instead of the light-shielding means when the period is set longer than a period required for output. 4. An enlarged wide dynamic range image is obtained by synthesizing two image pickup signals obtained by photographing the same subject twice with different exposure amounts using a single image pickup device. In an electronic camera having a function, a photometric element separate from an image sensor is provided, and based on an exposure amount measured by the photometric element at the time of the first photographing, corresponding to a preset exposure ratio in two photographings. An electronic camera configured to set a charge accumulation time of an image sensor at the time of a second photographing. 5. An enlarged wide dynamic range image is obtained by synthesizing two image pickup signals obtained by performing two shots of the same subject with different exposure amounts using a single image pickup device. An electronic camera having a function, comprising a flash light emitting means, wherein the flash light emitting means is provided with the timing of the latter half of the charge accumulation time of the image sensor at the time of the first photographing and the former half of the charge accumulation time of the image sensor at the time of the second photographing. An electronic camera configured to emit light at one or both of the above timings. 6. A light-metering device separate from an image pickup device, wherein said flash light-emitting means emits light in both of two photographing operations, and a light emission amount ratio of the two light-emissions measured by said light-measuring device is provided. 6. The electronic camera according to claim 5, wherein a charge accumulation time of the image sensor at the time of the second photographing is set based on the second time. 7. The image pickup device has an electronic shutter function capable of arbitrarily controlling an exposure amount by controlling a charge accumulation time,
The flash light emitting means is configured to emit light in both of the two photographing operations,
6. The electronic camera according to claim 5, wherein, when a small light emission is performed among the light emission times, the stop timing of the small light emission and the end timing of the electronic shutter operation of the image sensor are set to be the same. 8. An enlarged wide dynamic range image is obtained by synthesizing two image pickup signals obtained by photographing the same subject twice with different exposure amounts using a single image pickup device. An electronic camera having a function, wherein an aperture value of a lens at the time of the two photographing operations is fixed. 9. An exposure setting means, wherein an aperture value and / or a shutter speed obtained by the exposure setting means prior to photographing are used at the time of photographing to obtain an imaging signal having a large exposure amount, 9. The electronic camera according to claim 8, wherein an aperture value and / or a shutter speed at the time of photographing for obtaining a small image pickup signal are set so as to correspond to a preset exposure ratio in two photographings. . 10. The electronic camera according to claim 9, wherein the exposure setting unit is configured to set an exposure value based on a photometric output of a photometric device provided separately from the image sensor. . 11. The electronic camera according to claim 9, wherein the exposure setting unit is configured to set an exposure value based on an imaging signal of an imaging device. 12. An enlarged wide dynamic range image is obtained by combining two image pickup signals obtained by performing two shots of the same subject with different exposure amounts using a single image pickup device. An electronic camera having a function, wherein white balance correction is performed by equally setting a white balance correction value for two image pickup signals having different exposure amounts before performing the combining. 13. The electronic camera according to claim 12, further comprising a white balance setting unit, wherein a white balance correction value obtained by the white balance setting unit before photographing is used for the white balance correction. 14. The electronic camera according to claim 12, wherein a correction value used for the white balance correction is set based on an image pickup signal before performing the combining. 15. A correction value used for the white balance correction is set based on an imaging signal having a large exposure amount among two imaging signals having different exposure amounts before performing the combining. 15. The electronic camera according to claim 14, wherein: 16. An enlarged wide dynamic range image is obtained by synthesizing two image pickup signals obtained by photographing the same subject twice with different exposure amounts using a single image pickup device. An electronic camera having a function, wherein white balance correction is performed on the synthesized wide dynamic range image. 17. The electronic camera according to claim 16, further comprising white balance setting means, wherein a white balance correction value obtained by the white balance setting means is used for the white balance correction prior to photographing. 18. The electronic camera according to claim 16, wherein a correction value used for the white balance correction is set based on the synthesized wide dynamic range image. 19. The electronic camera according to claim 16, wherein a correction value used for the white balance correction is set based on an image signal before performing the combining. 20. A correction value used for the white balance correction is set based on an imaging signal having a large exposure amount among two imaging signals having different exposure amounts before performing the combining. 20. The electronic camera according to claim 19. 21. An enlarged wide dynamic range image is obtained by synthesizing two image pickup signals obtained by photographing the same subject twice with different exposure amounts using a single image sensor. An electronic camera having a function, comprising a gain control means, wherein the gain values of the two image pickup signals in the gain control means are set to different values. 22. The gain value according to claim 21, wherein a gain value for the two imaging signals is set such that an exposure ratio of the two imaging signals corresponds to a preset exposure ratio. Electronic camera. 23. An enlarged wide dynamic range image is obtained by synthesizing two image pickup signals obtained by photographing the same subject twice with different exposure amounts using a single image pickup device. An electronic camera having a function, comprising an aperture control means, wherein the aperture control means changes an aperture value of a lens to generate two image pickup signals having different exposure amounts. 24. A lens peripheral dimming correction unit, wherein two imaging signals having different exposure amounts generated by changing the aperture value of the lens by the aperture control unit are generated based on different lens aperture values. 24. The electronic camera according to claim 23, wherein the electronic camera is configured to perform correction of vignetting. 25. A flash light emitting means for emitting flash light of the same light emission amount at the time of photographing two times with the different exposure amounts, and changing the aperture value of the lens by the aperture control unit to obtain two different light amounts. 25. The electronic camera according to claim 23, wherein the electronic camera generates an imaging signal. 26. An electronic camera including a color image synthesizing unit that forms a color image with a wide dynamic range by synthesizing a plurality of color image signals having different exposure amounts, wherein each of the plurality of color image signals has a corresponding signal. Weighting means for weighting in accordance with the level; and means for adding a plurality of weighted color image signals, wherein the weighting means has the same weighting factor for each color signal in the plurality of color image signals. An electronic camera characterized by setting the following.