JPH0774987A - Video camera - Google Patents

Abstract

PURPOSE:To improve the photographing picture quality of a video camera by providing the video camera with a contour compensating signal generating part and a compensation variable adjusting part, adding an output signal from the adjusting part to a photographed video signal to compensate a contour. CONSTITUTION:A horizontal contour compensation signal obtained after adjusting a compensation variable is supplied from an amplifier circuit 7 to an adder circuit 5 to add the contour compensation signal to a video signal. An output signal from the circuit 5 is supplied to a vertical compensation signal generating circuit 9 in a contour compensation signal generating part 2 and a vertical side adder circuit 10 in a compensation adding part 4. A vertical contour compensation signal from the circuit 9 is supplied to a vertical side variable amplifier circuit 11 in a compensation variable adjusting part 6. A compensation variable adjusted vertical contour compensation signal from the circuit 11 is supplied to the circuit 10 and added to the output signal of the circuit 5 by the circuit 10 and the vertical emphasis of the contour part is applied to the video signal. Consequently a sense of uniform resolution is obtained over the whole compensated screen based upon an output signal from the circuit 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera used as a surveillance camera or the like.

[0002]

2. Description of the Related Art Conventionally, a video camera used as a surveillance camera or the like performs contour enhancement correction in order to improve the sense of resolution of a captured image. Conventionally, this enhancement correction is performed as follows.

That is, the subject through the taking lens is C
An image is picked up by an image pickup device such as a CD, and a picked-up image signal of this device and a signal obtained by delaying this signal in both horizontal and vertical directions are used to extract a contour component signal of the picked-up image signal to form a contour correction signal. . Then, this contour correction signal is added to the photographed video signal to enhance and correct the contour of the video signal.

[0004]

In the case of the above-mentioned conventional video camera, since a certain amount of contour correction determined by the brightness of the photographed image or the like is applied to any position on the photographing screen, the resolution of the photographing lens is reduced. There is a problem in that a sense of uniform resolution cannot be obtained over the entire screen of the captured image based on the difference between the central portion and the peripheral portion.

That is, the photographing lens has a characteristic that the resolution is lowered toward the peripheral portion, and particularly in the case of an inexpensive and low-grade lens used for a surveillance camera or the like, the resolution of the peripheral portion is largely deteriorated (deteriorated).

Therefore, if the same correction amount enhancement correction is applied to the central portion and the peripheral portion of the photographic screen, the corrected photographic screen has the resolution of the peripheral portion based on the difference between the central portion and the peripheral portion of the resolution of the lens. The feeling deteriorates from the central part, and it is not possible to obtain a uniform sense of resolution over the entire screen. An object of the present invention is to obtain a uniform sense of resolution over the entire shooting screen.

[0007]

To achieve the above object, in a video camera of the present invention, a contour correction signal generator for extracting a contour component of a photographed video signal to form a contour correction signal, and a photographing operation. Adds the output signal of the correction amount adjustment unit to the captured video signal, and the correction amount adjustment unit that variably amplifies and outputs the contour correction signal with a larger gain in the peripheral part of the shooting screen by gain control of the parabolic wave signal synchronized with the video signal. And a correction addition unit that corrects the contour of the captured video signal.

[0008]

In the case of the video camera of the present invention configured as described above, the contour correction signal of the contour correction signal generating section obtained by extracting the contour component of the photographed video signal is the parabolic wave signal by the correction amount adjusting section. It is variably amplified based on the gain control. By this variable amplification, the contour correction signal is adjusted so that the correction amount increases toward the peripheral portion of the screen.

Then, the correction addition unit adds the contour correction signal adjusted by the correction amount adjustment unit to the picked-up video signal, and by this addition, the contour of the picked-up video signal is emphasized and corrected with a characteristic that the correction amount increases toward the peripheral portion of the screen. To be done. Therefore, the captured image based on the captured video signal after correction by the correction addition unit is subjected to contour correction so as to cancel the difference between the central portion and the peripheral portion of the resolution of the photographing lens, and as a result, a uniform resolution over the entire photographing screen. You can get a feeling.

[0010]

EXAMPLES Examples will be described with reference to FIGS. 1 to 4. (Embodiment 1) First, an embodiment in which contour components in both horizontal and vertical directions are extracted and contours are corrected will be described with reference to FIGS.

As shown in FIG. 1, a photographed video signal of an image pickup device such as a CCD is supplied from an input terminal 1 to a horizontal correction signal generation circuit 3 of a contour correction signal generation unit 2 and a horizontal side addition circuit 5 of a correction addition unit 4. To be done. The generating circuit 3 is configured as shown in FIG. 2, and delays the input signal Sa by a fixed amount τ in the horizontal direction by delay devices 3a and 3b to obtain delayed signals Sb and Sc.
To form.

Further, the adder 3c adds the input signal Sa and the delay signal Sc, and the output signal of the adder 3c is multiplied by-(1/2) by the coefficient unit 3d to be halved to invert the polarity. Then, the adder 3e adds the output signal of the coefficient unit 3d to the delay signal Sb to obtain the edge component of the input signal Sa,
That is, the contour component in the horizontal direction is extracted, and the output signal Sf as the contour correction signal in the horizontal direction is formed.

In order to simplify the description, assuming that the input signal Sa of one horizontal line is the signal shown in FIG. 3A, the signals Sb to Sf are shown as (b) to (f) in FIG. As shown. The output signal Sf is formed without considering the position on the shooting screen, and the correction amount does not depend on the position on the shooting screen.

The horizontal contour correction signal of the generation circuit 3 is supplied to the horizontal variable amplification circuit 7 of the correction amount adjustment section 6. The gain of the amplifier circuit 7 is controlled by the horizontal parabolic wave signal of the horizontal parabolic wave generation circuit 8 synchronized with the picked-up video signal so that the amplification degree at the left and right ends of each horizontal line becomes larger than that at the central part. Based on the control, the horizontal contour correction signal is adjusted non-linearly so that the correction amount becomes large on the left and right end sides of the photographing screen.

Further, the horizontal contour correction signal after the correction amount adjustment of the amplifier circuit 7 is supplied to the adding circuit 5, and the horizontal contour correction signal after the correction amount adjustment is added to the photographed video signal of the input terminal 1. It At this time, the photographed video signal is delayed and added so that the timing matches the horizontal contour correction signal after the correction amount adjustment.

By this addition, the captured video signal is emphasized in the horizontal direction of the contour. Further, the output signal of the addition circuit 5 is supplied to the vertical correction signal generation circuit 9 of the contour correction signal generation unit 2 and the vertical side addition circuit 10 of the correction addition unit 4.

The generation circuit 9 is formed, for example, by setting the delay amounts of the delay units 3a and 3b of the generation circuit 3 to one or several lines, and based on the input signal and the signal obtained by delaying this signal, The contour component in the vertical direction is extracted, and FIG.
A vertical contour correction signal similar to the output signal Sf of (f) is formed. Note that, like the contour correction signal of the generation circuit 3, this contour correction signal does not depend on the position of the photographing screen for its correction amount.

Then, the vertical contour correction signal of the generation circuit 9 is supplied to the vertical side variable amplification circuit 11 of the correction amount adjustment section 6. The gain of the amplifier circuit 11 is controlled by the vertical parabolic wave signal of the vertical parabolic wave generation circuit 12 synchronized with the captured video signal so that the amplification degree at the upper and lower ends of each field or frame becomes larger than that at the central part. Based on this gain control, the contour correction signal in the vertical direction is adjusted non-linearly so that the correction amount becomes large on the upper and lower end sides of the photographing screen.

Further, the vertical contour correction signal after the correction amount adjustment of the amplifier circuit 11 is supplied to the adding circuit 10, and the vertical contour correction signal after the correction amount adjustment is added to the output signal of the adding circuit 5. The outline of the captured image signal is vertically emphasized. The output signal of the adder circuit 5 is delayed and added so that the timing coincides with the vertical contour correction signal after the correction amount adjustment.

Then, the output signal of the adding circuit 10 is supplied as a contour-corrected photographed video signal to the subsequent circuit section, and at this time, the photographed video signal is subjected to the horizontal and vertical edge enhancements to resolving the resolution of the photographing lens. The contour portion is enhanced and corrected in a non-linear manner so that the edge portion is emphasized in a lower range.
Therefore, the contour correction is performed so as to cancel the decrease in the resolution of the photographing lens, and the corrected photographing screen based on the output signal of the adding circuit 10 has a uniform sense of resolution over the entire screen.

(Other Embodiments) Next, an embodiment in which only the horizontal contour component is extracted and corrected will be described with reference to FIG. In the figure, reference numeral 13 denotes a contour correction signal generating section, which is formed by a horizontal correction signal generating circuit similar to the generating circuit 3 of FIG. 1 and extracts and generates a horizontal contour component of the captured video signal of the input terminal 1. A horizontal contour correction signal similar to the output signal of the circuit 3 is formed.

Reference numeral 14 denotes a correction amount adjusting section, which is the same as the generating circuits 8 and 12 in FIG.
5, 16 and an adder circuit 17 for adding the horizontal and vertical parabolic wave signals of both generation circuits 15, 16 and the adder circuit 1
7 and a variable amplification circuit 18 whose gain is controlled by the output signal of FIG. 7, the amplification circuit 18 causes the contour correction signal of the generation unit 13 to be increased in correction amount on the left, right, upper, and lower end sides. Adjust non-linearly.

Reference numeral 19 denotes a correction addition unit, which adds the contour correction signal after the correction amount adjustment of the addition circuit to the picked-up video signal of the input terminal 1 to emphasize and correct the contour portion of the picked-up video signal, and after correction. The captured video signal is supplied to the subsequent circuit section.

Therefore, the photographic image signal of this embodiment is also non-linearly contour-corrected so that the peripheral portion where the resolution of the photographic lens is lowered is emphasized, and the photographic image screen after correction based on the output signal of the correction adder 10 is A uniform sense of resolution is obtained over the entire screen. In the case of this embodiment, since simple correction is performed without using the vertical contour component, 1
There is an advantage that the structure is cheaper and simpler than the case of the embodiment.

[0025]

Since the present invention is configured as described above, it has the following effects. The contour correction signals of the contour correction signal generators 2 and 13 obtained by extracting the contour component of the captured video signal are variably amplified by the correction amount adjusters 6 and 14 based on the gain control of the parabolic wave signal, and this variable amplification is performed. Thus, the contour correction signal is adjusted so that the correction amount increases toward the peripheral portion of the screen.

Then, the correction addition units 4 and 19 add the contour correction signals adjusted by the correction amount adjustment units 6 and 14 to the photographed video signal, and the addition increases the correction amount of the photographed video signal toward the periphery of the screen. The contour is enhanced and corrected by the characteristic. Therefore, the captured image based on the captured video signal after correction by the correction addition units 4 and 19 is contour-corrected so as to cancel the difference between the central portion and the peripheral portion of the resolution of the photographing lens, and as a result,
A uniform sense of resolution can be obtained over the entire shooting screen, and the shooting quality of various video cameras such as surveillance cameras can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a video camera of the present invention.

FIG. 2 is a detailed connection diagram of a part of FIG.

3A to 3F are timing charts for explaining the operation of FIG.

FIG. 4 is a block diagram of another embodiment of the present invention.

[Explanation of symbols]

 2,13 Contour correction signal generation unit 4,19 Correction addition unit 6,14 Correction amount adjustment unit

Claims (1)

[Claims] 1. A contour correction signal generator that extracts a contour component of a captured video signal to form a contour correction signal, and a gain control of a parabolic wave signal that is synchronized with the captured video signal to increase the gain in the peripheral portion of the captured screen. And a correction amount adjusting unit that variably amplifies and outputs the contour correction signal, and a correction adding unit that adds the output signal of the correction amount adjusting unit to the captured video signal to perform contour correction of the captured video signal. A video camera that is characterized.