JPH0678264A - Image picture device - Google Patents

Abstract

PURPOSE:To prevent the S/N from being deteriorated in the case of a still picture even when an image pickup element is made small resulting in deteriorating the S/N. CONSTITUTION:An adder circuit 9, a memory circuit 10 and a gate circuit 11 form a means accumulating picture data, the accumulation means accumulates picture data, a motion detection means compares two consecutive pictures to detect the presence of a motion of an object, and when no motion is detected, plural consecutive picture data accumulated by the accumulation means are divided by an accumulated number of times at a divider circuit 12 and the result is outputted, and when a motion of the object is detected on the other hand, the accumulation of the picture data is inhibited when the motion is detected and output data are initialized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device, and in particular,
The present invention relates to an imaging device having a function of capturing a still image.

[0002]

2. Description of the Related Art As is well known, an image pickup device having a function of picking up a still image is known. FIG. 6 is a block diagram showing a configuration of an image pickup apparatus conventionally used for inputting image processing and the like. In FIG. 6, 1 is a lens and 2 is a diaphragm. Further, 3 is a solid-state image sensor for converting the optical image formed by the lens 1 into an electric signal, and 4 is an A / D conversion circuit for converting the output of the solid-state image sensor 3 output as an analog signal into a digital signal. is there.

Reference numeral 5 is a signal processing circuit for converting the output format of the solid-state image sensor 3 converted into a digital signal by the A / D conversion circuit 4 into a required signal format (for example, RGB signal).

[0004]

The field of application of the image pickup apparatus configured as shown in FIG. 6 is not only for use as an apparatus for recording a moving image, but also for inputting a text or a microscope image. Can be considered. In these fields of application, there are many opportunities to image a stationary object as a subject.

On the other hand, the solid-state image pickup device 3 is shifting from 1/2 inch to 1/3 inch format.
Mainstream is moving toward miniaturization. Therefore, both the saturated charge amount and the signal charge amount tend to decrease. Although noise mixed in signal charges after photoelectric conversion can be improved by techniques such as correlated double sampling and dark current conversion, optical shot noise mixed in signal charges at the time of photoelectric conversion is reduced as the amount of signal charges decreases. The influence increases and the S / N tends to deteriorate.

By the way, the S / N ratio in the conventional image pickup apparatus
Was determined by the S / N of the solid-state image sensor 3, so that the S / N of the solid-state image sensor 3 deteriorates and the S / N of the image pickup apparatus decreases.
Also tended to deteriorate. In view of the above problems, it is an object of the present invention to prevent the S / N from deteriorating when the subject is a still image, even if the image pickup device is downsized and the S / N is degraded.

[0007]

An image pickup apparatus according to the present invention comprises image data cumulative addition means for cumulatively adding image data, and 2
Motion detection means for comparing two images to detect the presence or absence of movement of the subject in each image, and if the movement of the subject is not detected by the movement detection means, a plurality of consecutive images added by the cumulative addition means When the movement of the object is detected by the division means for dividing the data by the cumulative addition count and outputting the result, the cumulative addition of the image data is prohibited at the time when the movement is detected, and the output data is output. And initial setting means for initial setting.

Another feature of the present invention is that
The motion detecting means detects the motion of the subject by comparing image data between two consecutive frames.

Further, another feature of the present invention is that the motion detecting means compares one frame image data with data obtained by cumulatively adding a plurality of frame image data and dividing this by the number of additions. The motion of the subject is detected.

[0010]

With the miniaturization of the image pickup device, the presence or absence of the motion of the subject is detected, the image signals are cumulatively added until the motion is detected, and the average value of the cumulatively added image data is output for each pixel. The noise that increases as the S / N deteriorates is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image pickup apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an image pickup apparatus showing a first embodiment of the present invention. In addition, in FIG.
The same parts as those of the conventional example shown in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, 6 is a first memory circuit for storing the output of the signal processing circuit 5 for one frame, and 7 is a second memory for storing the signal of the first memory circuit 6 for delaying by 1 frame. Circuit.

Reference numeral 8 is a motion detection circuit for comparing the signals of two consecutive frames stored in the first memory circuit 6 and the second memory circuit 7, respectively, and detecting the presence or absence of motion of the subject. Furthermore, 9, 10 and 11 are components provided to perform cumulative addition of image data for each frame,
Reference numeral 9 is an adder circuit, 10 is a third memory circuit that stores the output of the adder circuit 9 for one frame, and 11 is a third memory circuit 1
It is a gate circuit that gates one input of the adder circuit 9 from the output of 0. Next, 12 is a division circuit, which is provided to divide the output of the third memory circuit 10 by the cumulative addition count.

In the image pickup apparatus of this embodiment having such a configuration, the output of the signal processing circuit 5 is temporarily stored in the first memory circuit 6 and then stored in the second memory circuit 7, and then the first memory circuit 7 is stored. The content stored in the memory circuit 6 is delayed by one frame. Data of two consecutive frames stored in the first memory circuit 6 and the second memory circuit 7 are compared by the motion detection circuit 8 to detect the presence or absence of motion of the subject.

As a result of the motion detection of the motion detection circuit 8, the gate circuit 11 is opened while the motion is not detected, and one frame of data stored in the third memory circuit 10 and the first memory circuit 6 are stored. And one frame of data is added. Then, while no motion is detected by the motion detection circuit 8, the cumulative addition count is incremented, and the division circuit 12 divides the data of the third memory circuit 10 by the cumulative addition count and outputs the result.

Next, the operation of the image pickup apparatus of the present invention will be described in more detail. FIG. 2 is a diagram illustrating an example of image data block division of one frame. As in the example shown in FIG. 2, image data of two consecutive frames of the first memory circuit 6 and the second memory circuit 7 is divided into small blocks of, for example, 16 pixels in the horizontal and 16 horizontal pixels, and each block is divided into blocks. Be compared.

FIG. 3 is a flow chart for explaining the operation of the first embodiment. First, in step P1, the data in the first memory circuit 6 is set as the initial values of the third memory circuit 10 and the second memory circuit 7, and in step P2, the contents of the first memory circuit 6 are updated. To do.

Next, in step P3, the sum of squares S of the differences between the first memory data and the second memory data is calculated for each block. If the pixel at row i and column j in the block of data stored in the first memory circuit 6 is x _1ij and the pixel at row i and column j in the block of the second field is x _2ij , the sum of squares S is Indicated by.

[0019]

[Equation 1]

In step P4, it is judged whether or not there is a block in which the sum of squared differences S exceeds a preset threshold value.
If there is a block that exceeds the threshold value, it is determined that the subject has moved, and the gate of the gate circuit 11 is closed to prohibit the cumulative addition operation. In this case, the process returns to step P1 and the data of the first memory circuit 6 is transferred to the third memory circuit 1
Initialize to 0 and reset the cumulative addition count to 1.

As a result of the judgment in step P4, the sum of squared differences S
If there is no block whose threshold value exceeds the preset threshold value, the process proceeds to step P5 and the gate of the gate circuit 11 is opened, so that the first memory circuit 6 and the third memory circuit 1
The data of 0 is added. Further, the contents of the first memory circuit 6 are copied to the second memory circuit 7 (step P6), and the contents of the first memory circuit 6 are updated (step P7). At this time, the cumulative addition count is incremented by 1.

By the operation described above, the averaging operation by cumulative addition is performed on the image data unless a motion is detected in the subject, and an extremely low noise image signal is obtained.

FIG. 4 is a block diagram of an image pickup apparatus which is another embodiment of the present invention. In FIG. 4, reference numeral 6 denotes a first memory circuit that stores the output of the signal processing circuit 5 for one frame,
Reference numerals 7, 8 and 9 are components for performing cumulative addition of image data for each frame, 7 is an addition circuit, 8 is a second memory circuit that stores the output of the addition circuit for one frame, and 9 is a second memory circuit. 8 is a gate circuit that uses the output of 8 as the gate and one input of the addition circuit 7 as a gate.

Next, 10 is a division circuit for dividing the output of the second memory circuit 8 by the cumulative addition count. 11 is the first
This is a motion detection circuit for detecting the presence or absence of motion of the subject by comparing the data of the memory circuit 6 and the data of the division circuit 10.

FIG. 5 is a flow chart for explaining the operation of the second embodiment. First, in step P1, the data of the first memory circuit 6 is set as the initial value of the second memory circuit 8, and in step P2, the content of the first memory circuit 6 is updated. Next, in step P3, the sum of squares S of the difference between the data stored in the first memory circuit 6 and the data obtained by dividing the second memory data by the cumulative addition count is the same as in the first embodiment. Calculate for each block. Note that the cumulative addition count is reset to 1 at the time of this initial setting.

Next, at step P4, it is judged if the sum of squared differences S exceeds a preset threshold value. As a result of this determination, if there is a block in which the sum of squared differences S exceeds a preset threshold value, it is determined that the subject has moved, and the process returns to step P1 to close the gate of the gate circuit 9 to perform the cumulative addition operation. The first memory circuit 6
Data is initialized in the second memory circuit 8 and the cumulative addition count is reset to 1.

If the result of determination in step P4 is that there is no block that exceeds the preset threshold value, the gate of the gate circuit 9 is opened to open the first memory circuit 6
The cumulative addition operation is performed by adding the data of 1 to the data of the second memory circuit 8 (step P5). In addition, the cumulative addition count is incremented by 1 (step P
6), the contents of the first memory circuit 6 are updated (step P7).

[0028]

As described above, according to the present invention, when the subject is a stationary object, the averaging is automatically performed to reduce the noise.
It became possible to obtain a good image even when N deteriorated.
Further, since the exposure charge amount is increased by lengthening the accumulation time, an image with a good S / N can be obtained even if an image sensor having a small saturated charge amount that cannot be taken as a means for improving the S / N is used. be able to. Further, even if the image is taken under an illumination condition in which a sufficient exposure amount cannot be obtained, a good S / N can be obtained. In addition, even if you narrow down to obtain a sufficient depth of field, S
Since / N does not deteriorate, there is also an effect that shooting becomes very easy.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an image pickup apparatus of the present invention.

FIG. 2 is a diagram illustrating block division of image data of one frame.

FIG. 3 is a flowchart illustrating an operation of the image pickup apparatus according to the first embodiment.

FIG. 4 is a block diagram of an image pickup apparatus showing another embodiment of the present invention.

FIG. 5 is a flowchart illustrating an operation of the image pickup apparatus according to the second embodiment.

FIG. 6 is a block diagram of an image pickup apparatus generally used as an input for image processing and the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 lens 2 diaphragm 3 solid-state image sensor 4 A / D conversion circuit 5 signal processing circuit 6 first memory circuit 7 second memory circuit 8 motion detection circuit 9 adder circuit 10 third memory circuit 11 gate circuit 12 division circuit

Claims (3)

[Claims] 1. An image data cumulative addition means for accumulatively adding image data, a motion detection means for comparing two images to detect the presence or absence of a motion of the object in each image, and a motion of the object by the motion detection means. If not detected, a dividing means for dividing and outputting a plurality of consecutive image data added by the cumulative adding means by the cumulative addition number of times, and if the motion of the subject is detected by the motion detecting means, An image pickup apparatus, comprising: an initial setting unit that prohibits cumulative addition of image data when a motion is detected and initializes output data. 2. The image pickup apparatus according to claim 1, wherein the motion detecting means compares the image data between two consecutive frames to detect the motion of the subject. 3. The motion detecting means detects the motion of a subject by comparing one frame image data with data obtained by cumulatively adding a plurality of frame image data and dividing the result by the number of additions. The image pickup apparatus according to claim 1.