JP3284584B2 - Multiple exposure camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiple exposure camera capable of performing multiple exposures such that a plurality of exposure screens are projected one upon another.

[0002]

2. Description of the Related Art In a camera-integrated VTR, a multi-exposure VTR capable of projecting a plurality of exposure screens in order to obtain a special video effect has been developed. In a conventional camera-integrated VTR capable of multiple exposure,
A multi-exposure screen is formed by simply accumulating screens of a plurality of fields.

[0003]

However, in such conventional multiple exposure, the signal level difference between a stationary portion on the screen such as the background and a moving moving portion becomes large as the number of exposures increases. For example, when the moving part is not bright, there is a problem that the result of the multiple exposure may not be exhibited.

[0004] That is, as shown in FIG.
Assume that multiple exposure is performed on a screen in which the moving object 52 is located at 1.
Then, as shown in FIG. 2B, the signal level of the stationary portion 51 at this time is V _A1 , and the signal level of the moving body 52 is V _B1 .

When such a screen is exposed, for example, three times, a multiplexed screen as shown in FIG. 3A is obtained. At this time, the signal level _VA2 of the stationary portion 51 and the signal level _VB2 of the moving body portion are as shown in FIG. 3B. That is, when the screen is exposed three times, the level V _A2 of the still part becomes three times the signal level V _A1 of the still part of one screen, and (V _A2
= 3V _A1 ). In contrast, in the body portion, the signal level is not deposited be multiplexed, the signal level when the multiplex V _B2 is substantially equal to the signal level V _B1 before multiplexing.

As described above, in the stationary portion, the signal level increases each time the exposure is repeated, whereas in the moving portion, the signal level hardly changes even when the exposure is repeated. Therefore, each time exposure is repeated, the signal level difference between the stationary part and the moving part increases.

Accordingly, it is an object of the present invention to provide an optimum multiplexing process irrespective of the movement or brightness of a subject, because the signal level difference between a moving body portion and a stationary portion does not increase when multiple exposure is performed. It is an object of the present invention to provide a multi-exposure camera.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an image pickup device on which object image light is formed, and a moving object based on an output signal of the image pickup device.
Discriminating means for discriminating between a portion and a stationary portion;
Is more sensitive to the output signal of the image sensor than the moving part.
Control means for controlling the gain so as to reduce the gain
And gain control means that the gain of the stationary part is
The output of the image sensor whose gain is controlled so as to be lower than
Multiple exposure means for accumulating signals to form multiple exposure signals;
Is a multi-exposure camera.

[0009]

The difference between the signal levels of the stationary part and the moving part is almost eliminated by discriminating the stationary part and the moving part, weighting the stationary part and the moving part, and forming a multiple exposure signal. Therefore, even when multiple exposures are performed a plurality of times, there is almost no difference in signal level between the stationary part and the moving part. Therefore, optimal multiplexing processing can be performed irrespective of the movement and brightness of the subject.

[0010]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, subject image light having passed through a lens 1 is formed on a light receiving surface of a CCD image sensor 2. This C
The output of the CD image sensor 2 is the sample-and-hold circuit 3, AG
The signal is supplied to the signal processing circuit 5 via the C circuit 4. In the signal processing circuit 5, the imaging signal of the CCD imaging device 2 is, for example, NT
It is converted to an SC video signal. The video signal from the video signal processing circuit 5 is supplied to the terminal 6A of the switch circuit 6.
And supplied to the A / D converter 7.

The switch circuit 6 is supplied with a switch control signal from a setting circuit 18. The setting circuit 18 is supplied with a terminal multiplexing number k from the terminal 19 when performing multiple exposure. The switch circuit 6 is set on the terminal 6A side during normal photographing. When performing multiple exposure, the switch circuit 6
It is set on the terminal 6B side. The output of the switch circuit 6 is output from the output terminal 8.

The A / D converter 7 digitizes the video signal from the signal processing circuit 5. The digitized video signal is supplied to a field memory 9 and a subtraction circuit 10. In the field memory 9, the video signal is delayed by one field. The output of the field memory 9 is supplied to a subtraction circuit 10.
At the same time, the output of the field memory 9 is supplied to the terminal 11A of the switch circuit 11, and is also supplied to the terminal 11B of the switch circuit 11 via the multiplication circuit 12.
The coefficient of the multiplication circuit 12 is set to, for example, (1 / k), where k is the number of exposures. For example, when performing triple exposure, the coefficient of the multiplication circuit 12 is set to (1/3).

The output of the subtraction circuit 10 is supplied to one input terminal of a comparator 13. A predetermined level is supplied from the terminal 14 to the other input terminal of the comparator 13. The output of the comparator 13 is supplied to the switch circuit 11 as a switch control signal.

The output of the switch circuit 11 is supplied to an adder circuit 15. The output of the adding circuit 15 is the field memory 1
6. The output of the field memory 16 is supplied to the addition circuit 15 and also to the D / A converter 17. The output of the D / A converter 17 is supplied to the terminal 6B of the switch circuit 6.

When performing normal photographing, the switch circuit 6
Is set on the terminal 6A side. For this reason, the imaging signal from the CCD imaging device 2 is signal-processed by the signal processing circuit 5, and
The signal is output from the output terminal 8 via the switch circuit 6.

When performing multiple exposure, the switch circuit 6
Is set on the terminal 6B side. Therefore, the image signal from the CCD image sensor 2 is signal-processed by the signal processing circuit 5, digitized by the A / D converter 7, supplied to the subtraction circuit 10, and delayed by one field by the field memory 9. Then, it is supplied to the subtraction circuit 10. The pixel of the video signal at this time and the pixel delayed by one field via the field memory 9 are supplied to the subtraction circuit 10, and the subtraction circuit 10 calculates the difference between the pixels in one field. From the difference value of the pixels in one field,
It can be determined whether it is a stationary part or a moving part.

That is, in the stationary portion, since the signal level hardly changes between the fields, the output of the subtraction circuit 11 has a small value. On the other hand, in the moving object part, the change in the signal level between each field is large,
The output of the subtraction circuit 13 is higher than a predetermined level.

In the stationary portion, the output of the comparator 13 is at a low level. When the output of the converter 13 is at a low level, the switch circuit 11 is set to the terminal 11B side. Therefore, in the stationary part, the level of the video signal from the field memory 9 is changed by the multiplication circuit 12 to (1
/ K) and output from the switch circuit 11.

In the moving part, the output of the comparator 13 becomes high level. When the output of the comparator 13 is at a high level, the switch circuit 11 is set to the terminal 11A side. Therefore, the video signal from the field memory 9 is output from the switch circuit 11 as it is.

The output of the switch circuit 11 is accumulated by the field memory 16 and the adder circuit 15 for a predetermined number of times of multiplexing. The multiplexed video signal is D /
The terminal 6B of the switch circuit 6 via the A converter 17
Supplied to Then, it is output from the output terminal 8.

As described above, when performing multiple exposure, a stationary portion and a moving object portion are determined from the output of the subtraction circuit 10, and the signal of the stationary portion is multiplied by the multiplication circuit 12 (1 / k).
Therefore, even when multiple exposures are performed a plurality of times, there is almost no difference in signal level between the stationary part and the moving part.

[0022]

According to the present invention, when performing multiple exposure, a stationary portion and a moving portion are determined from the output of the subtraction circuit 10, and the signal of the stationary portion is multiplied by (1/1 /
k). Therefore, even when multiple exposures are performed a plurality of times, there is almost no difference in signal level between the stationary part and the moving part. Therefore, optimal multiplexing processing can be performed irrespective of the movement and brightness of the subject.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a schematic diagram used for describing a conventional multiple exposure camera.

FIG. 3 is a schematic diagram used for describing a conventional multiple exposure camera.

[Explanation of symbols]

 2 CCD image sensor 6,11 switch circuit 12 multiplication circuit

Claims (1)

(57) [Claims] An image pickup device on which object image light is formed, and a moving body portion and a stationary portion are determined from an output signal of the image pickup device.
A differentiating means, and the above-mentioned imaging element is compared with the moving part in the stationary part.
The gain is controlled so that the gain for the
Gain control means for controlling, and the gain of the stationary portion is controlled by the gain control means.
The above-mentioned shooting with the gain controlled to be lower than the moving part
A multi-exposure signal is formed by accumulating the output signals of the image elements.
A multi-exposure camera including a double exposure unit .