JPH06276413A - Image pickup device - Google Patents

Abstract

PURPOSE:To reduce deterioration in picture quality due to the blur of picture during a slow shutter operation. CONSTITUTION:The device is provided with a motion detection circuit 190, an aperture correction enhancer 120 and an enhancer control circuit 210 and the gain is controlled so as to increase a quantity of enhancement as the shutter speed is slower and a relative position deviation is higher by controlling the operation of the aperture correction enhancer 120 with motion information supplied from the motion detection circuit 190 thereby distinguishing an originally unsharpened edge resulting from a shape of an object from an edge unsharpened due to the blur of picture and applying proper enhancement to each edge.

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, for example, an image pickup device having a variable shutter speed, an image blur detection function for detecting a relative positional shift between the image pickup device and a subject, and an enhancer for improving image quality. It is suitable for use in an image pickup apparatus having an aperture correction).

[0002]

2. Description of the Related Art As is well known, an enhancer incorporated in an image pickup device for performing aperture correction converts an image signal into two.
This is intended to enhance the image quality by emphasizing the contour portion by performing the stepwise differentiation to extract a spatial high frequency component and adding it to the original image.

FIG. 3 shows a typical circuit configuration of a vertical enhancer (vertical aperture correction). In FIG. 3, the video signal input from the video signal input terminal 300 includes two 1-line delay lines (line memories) 310, 3
Given to 20. Then, these 1-line delay lines 3
With the functions of 10, 320, calculation can be performed on the current line g _i , the line g _{i-1 one} line time ago, and the line g _i-2 two line time ago.

Current line g _i and line g two lines before
_i-2 is added by the adder 330, and the coefficient unit 340 multiplies by 1/2 by bit shifting or the like. Then, the result of the above calculation is calculated by the subtracter 350 in the line g one line time before.
is subtracted from _i-1, calculation process, g _i-1 - expressed as _{(g i + g i-2} ) / 2 ... (1 type). Therefore, the line g one line time ago
_{Based on i-1} , the upper and lower lines are -1/2
This means that the reference line g _i-1 is multiplied by +1 and added.

This means that the image signal is subjected to vertical second-order differentiation (Laplacian), and spatial high-frequency components of the image such as contour components are extracted. Further, the high frequency component is multiplied by a constant α determined by the characteristics of the image pickup system in a multiplier 360, and an enhancement amount output terminal 370 is produced.
Is output from.

[0006] Further, a technique aiming at higher image quality is known. For example, when the image is very dark and the S / N is bad, on the contrary, when it is very bright, or when the contrast is very high and the enhancement of the high frequency component is unnecessary, the constant α is reduced to suppress the enhancement amount. Is widely known.

[0007]

However, in the above embodiment, the shutter speed of the image pickup device is slow (that is,
During slow shutter), and during that time (that is, during the charge accumulation time of the image sensor), camera shake of the photographer and movement of the subject,
Even when the image is blurred due to deformation or the like, the enhancement amount is added to the original signal with a constant gain, so that there is a problem that the image deterioration due to the image blur during the slow shutter is conspicuous.

In view of the above problems, it is an object of the present invention to reduce image quality deterioration due to image blurring during slow shutter.

[0009]

The image pickup device of the present invention is an image pickup device having an image pickup device for performing photoelectric conversion, and a shutter speed of the image pickup device and a relative positional deviation between the image pickup device and a subject. A control circuit for controlling the gain of the aperture correction enhancer according to the amount is provided.

[0010]

Since the present invention has the above-mentioned technical means, it is possible to control the gain of the enhancer according to the shutter speed of the image pickup device and the amount of relative displacement between the image pickup device and the object using the motion information of the image. This makes it possible to distinguish between an edge that is originally blunted as a shape of the subject and an edge that is blunted by image blurring, and to appropriately enhance each edge.

[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 configuration block diagram of an image pickup apparatus to which the present invention is applied. In FIG. 1, 10 is a subject, 20 is a photographic lens, and 30 is an image pickup device, which is composed of, for example, a two-dimensional CCD. Then 40 is 2
It is a sample hold (S / H) circuit that holds an output signal from an image pickup device such as a three-dimensional CCD.

Further, 50 is an automatic gain control (AGC) circuit, and 60 is an analog-digital (A / D) circuit.
Converter, 70 is image memory, 80 is Y / C separation circuit, 9
Reference numeral 0 is a color signal generation circuit, 100 is a color signal digital-analog (D / A) converter, and 110 is a color signal output terminal.

Further, 120 is an enhancer for emphasizing high frequency components of the luminance signal, 130 is a gamma corrector, 140 is a digital-analog (D / A) converter of the luminance signal, and 150.
Is a luminance signal (Y) output terminal.

Further, 160 is an input terminal for the shutter speed signal, 170 is a drive circuit for the image pickup device 30, and 180
Is a write / read control circuit for the image memory 70,
Reference numeral 190 is a motion detection circuit, 200 is a memory read address control circuit, and 210 is an enhancer gain control circuit.

Next, the operation of the image pickup apparatus shown in FIG. 1 will be described.
The optical image of the subject 10 is captured by the taking lens 20 to the image sensor 3
An image is formed on 0 and photoelectrically converted. The exposure time of the image pickup device 30 is determined by the shutter speed signal S1 input to the shutter speed input terminal 160 from the outside, and the drive circuit 170 controls the shutter speed, that is, the charge storage time, the signal output timing, and the like.

The sample hold 40 holds the output signal of the image pickup device 30, and the subsequent AGC circuit 50 automatically controls the gain of the signal. The A / D converter 60 converts the output signal of the AGC circuit 50 from analog to digital. A /
The digital signal converted by the D converter 60 is stored in the image memory 70.

The image memory 70 may be, for example, a field memory or a frame memory depending on the purpose. The timing of reading and writing of the image memory 70 is also external from the shutter speed input terminal 160.
Is determined by the shutter speed signal S1 input to
It is controlled by the memory write / read control circuit 180.

The motion detection circuit 190 includes an A / D converter 60.
The digital signal which is the output of the above is processed to detect the relative image shift amount between the previous image and the current image. Such a motion detection circuit is disclosed in USP 3896402 and JP-B-60.
It may be configured by a circuit based on the spatiotemporal gradient method described in the publication No. -46878. In addition, information processing Vol. 17, No. 7, p. 634-640Jul
y (1976), a circuit based on a matching operation may be used.

By the way, in this embodiment, it is necessary to use a detection method that can be processed in real time. That is, the amount of image shift detected by the motion detection circuit 190 is input to the memory address control circuit 200 and the enhancer gain control circuit 210.

The memory address control circuit 200 indicates to the image memory 70 the start address of the area to be output from the image memory 170 according to the amount of image shift, and continuously outputs the area output on the previous screen from the current screen. Control to compensate for image blur. As a result, the output image output to the viewfinder of the recording video camera, the recording system, or the like becomes a stable image free from image blur such as camera shake.

The output signal of the image memory 70 is separated into a color signal and a luminance signal by the Y / C separation circuit 80. The color signal is given to the color signal generation circuit 90, and the color signal generation circuit 90 is provided.
Is converted into a regular color signal such as RGB. Then, it is converted into an analog signal by the subsequent D / A converter 100 and output from the color signal output terminal 110.

On the other hand, the luminance signal is given to the enhancer 120, and in the enhancer 120, a process for emphasizing a high frequency component such as an edge of a subject is performed in order to improve image quality. At this time, the gain of the enhance component added to the original signal is determined by the enhancer gain control circuit 210.

The gamma correction circuit 130 provided at the next stage of the enhancer 120 is for preventing saturation in the highlight portion and expanding the dynamic range. The luminance signal that has undergone the above processing is converted into an analog signal by the D / A converter 140 and output from the luminance signal output terminal 150.

Next, the operation principle of the enhancer gain control circuit 210 will be described. 4 and 5 show an edge moving to the right in the drawings at a constant speed. 4 and 5
4 (a) → FIG. 4 (b) → FIG. 5 (a) → FIG.
The shutter speed is slower in the order of (b), and the edge portion is blunted in that order.

Also, the broken line in the figure shows the edge after the enhancement processing with a constant gain. As is clear from these figures, the sharper the edge, the greater the enhancement amount,
The amount of enhancement decreases as it dulls. Therefore, in the enhancer gain control circuit 210, the gain is controlled to increase the enhancement amount as the shutter speed is slower and the relative positional displacement amount between the imaging device and the subject is larger.

Here, if the shutter speed is Δt, the relative positional deviation amount between the image pickup device and the subject is v, and α and β are appropriate constants, the enhancer gain G is given by the following equation: G = β × v It can be expressed by × Δt + α (Equation 2).

Further, an appropriate threshold value is given to the shutter speed Δt and the movement amount v, and, for example, when the shutter speed exceeds the above threshold value, the gain of the enhancer is changed according to the movement amount.
On the contrary, when the amount of movement exceeds the threshold value, one of the switches may be used as the other switch, such as changing the gain of the enhancer according to the shutter speed.

Next, a second embodiment of the image pickup apparatus of the present invention will be described with reference to FIG. In the first embodiment, the amount of image shift is obtained by signal processing, but an external sensor may be used to detect the amount of movement of the image pickup apparatus main body. As is apparent from FIG. 2, in the case of the second embodiment, the motion detection circuit 190 in the image pickup apparatus of FIG. 1 is replaced with the sensor 195.

As such an external sensor, a type in which the angular velocity is detected by utilizing the inertial force of an object is well known. However, when the external sensor is used, the image pickup device is stationary, and it cannot deal with the case where the subject is moving.

[0030]

As described above, according to the present invention, the gain of the aperture correction enhancer is controlled by using the motion information of the image, so that the original edge of the object and the image It is possible to reliably distinguish and control an edge blunted by a blur. Therefore, each edge can be appropriately enhanced, and a high-quality image can be provided under all photographing conditions.

[Brief description of drawings]

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

FIG. 2 is a block diagram of an image pickup apparatus showing another embodiment of the present invention.

FIG. 3 is a block diagram showing a general aperture correction enhancer.

FIG. 4 is a diagram showing an operation of a conventional aperture correction enhancer.

FIG. 5 is a diagram showing an operation of a conventional aperture correction enhancer.

[Explanation of symbols]

 10 subject 20 shooting lens 30 image sensor 40 sample hold circuit 50 auto gain control circuit 60 analog-digital converter 70 image memory 80 Y / C separation circuit 90 color signal generation circuit 100 digital-analog circuit 110 color signal output terminal 120 enhancer 130 Gamma correction circuit 140 Digital-analog converter 150 Luminance signal output terminal 160 Shutter speed input terminal 170 Image sensor drive circuit 180 Image memory write / read control circuit 190 Motion detection circuit 195 Sensor 200 Memory address control circuit 210 Enhancer gain control circuit

Claims (1)

[Claims] 1. An image pickup device having an image pickup device for performing photoelectric conversion, wherein the gain of an aperture correction enhancer is controlled according to a shutter speed of the image pickup device and a relative positional deviation amount between the image pickup device and a subject. An imaging device comprising a control circuit.