JPH08149342A - Surrounding monitor device - Google Patents

Abstract

(57) [Summary] [Purpose] Even if there are bright and dark parts in the visual field of the video camera, a monitor screen with good visibility is always obtained. A video camera 1 for capturing a surrounding image and generating a corresponding composite signal, a Y / C separation circuit 2 for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. When the level of the luminance signal separated in 2 is low, the contour emphasis circuit 3 which increases the degree of contour emphasis for the luminance signal, the brightness signal whose contour is changed by the contour emphasis circuit 3, and the Y / C separation circuit 2
And a Y / C synthesizing circuit 4 for synthesizing the color signals separated in step S1 to generate a new composite signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surrounding monitor device for monitoring a surrounding condition through a video camera, and particularly to a surrounding monitor device which always obtains a good visibility regardless of whether the monitored object is bright or dark. The present invention relates to a monitor device.

[0002]

2. Description of the Related Art Conventionally, as a device for improving the visibility of a screen, for example, as shown in FIG. 23, a contour correcting device described in Japanese Patent Laid-Open No. 6-46293 is known. .

In this contour correction device, a horizontal bandpass filter a and a vertical bandpass filter b extract high frequency components in the horizontal and vertical directions from an input video signal, and the horizontal and vertical high frequency components are added by an adder c. The absolute value amplifier d obtains the absolute value x of the addition result, the nonlinear processing circuit e selects the correction coefficient α based on the absolute value, the multiplier f multiplies the absolute value x by the correction coefficient α, and the nonlinear processing circuit For g, the correction coefficient β is selected based on the change in the input video signal level, and the result of multiplying the multiplication result of the multiplier f by the correction coefficient β by the multiplier h is added as an emphasis signal to the input video signal by the adder i. With this, the enhancement signal for appropriately enhancing the contour is added to the input video signal to improve the image quality of the display image.

[0004]

However, as shown in FIG.
In the case of the conventional device shown in FIG.
The purpose is to improve the image quality by improving the spatial characteristics and the like, and although good results are obtained from the viewpoint of faithful reproduction of the video signal obtained from the image pickup device, the video signal obtained from the image pickup device itself is Even if faithful reproduction is performed, it is not possible to improve the recognizability of obstacles, such as when it is unclear due to light or dark conditions, or when the difference in brightness between the obstacles and the background is small, etc. In consideration of the surrounding environment in 1), it is not immediately applicable to this type of surrounding monitor device. In other words, in consideration of the usage environment of this type of surrounding monitor device, even if the image data captured by the camera includes the image information of the obstacle, as shown in FIG. Alternatively, since it is saturated in a low region, this is not displayed, and there is a problem that the observer cannot recognize the obstacle.

The present invention has been made by paying attention to such conventional problems, and the purpose thereof is to:
Regardless of the brightness of the subject and the size of the contrast,
It is an object of the present invention to provide an ambient monitor device that can always obtain a screen with good visibility.

[0006]

According to the invention of claim 1 of the present application, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a luminance signal and a color signal are separately output from the composite signal. The Y / C separation circuit for performing the contour enhancement, the contour enhancement circuit that enhances the contour enhancement degree for the brightness signal when the luminance signal level separated by the Y / C separation circuit is low, and the contour enhancement circuit changes the contour. And a Y / C synthesizing circuit for synthesizing the luminance signal and the color signal separated by the Y / C separating circuit to generate a new composite signal.

According to a second aspect of the present invention, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. A contour enhancement circuit that increases the degree of contour enhancement for the luminance signal when the luminance signal level separated by the Y / C separation circuit is high; and a luminance signal whose contour is changed by the contour enhancement circuit and the Y signal. And a Y / C synthesizing circuit for synthesizing the color signals separated by the / C separating circuit to generate a new composite signal.

According to a third aspect of the present invention, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. And a contour extraction circuit for extracting a contour signal from the luminance signal separated by the Y / C separation circuit, and a contour for increasing the degree of contour enhancement for the luminance signal when the contour signal level extracted by the contour extraction circuit is low. An enhancement circuit, and a Y / C synthesis circuit that synthesizes a luminance signal whose contour has been changed by the contour enhancement circuit and a color signal separated by the Y / C separation circuit to generate a new composite signal, It is characterized by including.

According to a fourth aspect of the present invention, an image pickup means for photographing a surrounding image and generating a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. And a luminance signal level discriminating circuit for comparing the luminance signal separated by the Y / C separating circuit with a predetermined threshold value, and the contour emphasizing control of the contour emphasizing level by the output of the luminance signal level judging circuit. A circuit and a Y / C synthesizing circuit for synthesizing the luminance signal whose contour is changed by the contour emphasizing circuit and the color signal separated by the Y / C separating circuit to generate a new composite signal. It is characterized by having.

According to a fifth aspect of the present invention, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. And a luminance signal level discriminating circuit for comparing the luminance signal separated by the Y / C separating circuit with a predetermined threshold, and a contour whose presence is controlled by the output of the luminance signal level discriminating circuit. An extraction circuit, a color signal phase shift circuit that changes the phase of the color signal based on the contour signal extracted from the contour extraction circuit;
And a Y / C synthesizing circuit for synthesizing the luminance signal separated by the C separating circuit and the color signal whose phase has been changed by the color signal phase circuit to generate a new composite signal. And

According to a sixth aspect of the present invention, in the invention according to the fourth aspect, in the contour emphasizing circuit, the luminance signal level determining circuit determines that the luminance signal is equal to or lower than a predetermined threshold level. It is characterized in that the contour enhancement is performed when it is determined that there is a failure.

According to a seventh aspect of the present application, in the invention according to the fourth aspect, in the contour enhancement circuit, the luminance signal level determination circuit determines that the luminance signal is equal to or higher than a predetermined threshold level. It is characterized in that the contour enhancement is performed when it is determined that there is a failure.

In the invention according to claim 8 of this application, in the invention according to claim 5, in the color signal phase shift circuit, the luminance signal is less than a predetermined threshold level in the luminance signal level determination circuit. It is characterized in that the phase of the color signal is changed when it is determined that

According to a ninth aspect of the present application, in the invention according to the fifth aspect, the luminance signal level discriminating circuit in the color signal phase shift circuit has a luminance signal equal to or higher than a predetermined threshold level. It is characterized in that the phase of the color signal is changed when it is determined that

According to a tenth aspect of the present invention, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. The brightness enhancement level is controlled by a brightness signal level determination circuit that compares the brightness signal separated by the Y / C separation circuit with a plurality of predetermined threshold values, and the output of the brightness signal level determination circuit. A contour enhancement circuit, a luminance signal whose contour has been changed by the contour enhancement circuit, and a color signal separated by the Y / C separation circuit are combined to generate a new composite signal Y /
And a C synthesizing circuit.

According to the eleventh aspect of the present invention, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. Presence or absence of contour extraction is controlled by a luminance signal level discriminating circuit that compares the luminance signal separated by the Y / C separating circuit with a plurality of predetermined threshold values, and the output of the luminance signal level discriminating circuit. A contour emphasizing circuit, and a color signal phase shifting circuit for changing the phase of the color signal by the contour signal extracted from the contour extracting circuit,
A Y / C synthesizing circuit for synthesizing the luminance signal separated by the Y / C separating circuit and the color signal whose phase has been changed by the color signal phase circuit to generate a new composite signal. It is characterized by

According to a twelfth aspect of the present invention, an image pickup means for photographing a surrounding image to generate a corresponding composite signal, and a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal. A contour enhancement circuit whose contour enhancement level is controlled by the output of the color signal level discrimination circuit; a luminance signal whose contour is changed by the contour enhancement circuit; and a color separated by the Y / C separation circuit. Y / which synthesizes the signal and a new composite signal
And a C synthesizing circuit.

According to a thirteenth aspect of the present invention, in the twelfth aspect of the invention, the contour emphasizing circuit has the level of the color signal which is below a predetermined threshold value by the color signal level discriminating circuit. The feature is that the contour is emphasized when is discriminated.

According to a fourteenth aspect of the present invention, in the invention according to any one of the first, second, third, fourth, sixth, seventh, tenth, twelfth and thirteenth aspects, the contour emphasis level in the contour emphasis circuit is set. Is characterized by changing periodically.

The invention of claim 15 of this application is the same as the invention of any one of claims 5, 8, 9 and 11,
The phase shift level of the color signal phase circuit is periodically changed.

The invention of claim 16 of this application is the same as that of claim 1.
The invention according to any one of 1 to 15 is characterized in that the image pickup means photographs a situation around the vehicle and generates a corresponding composite signal.

[0022]

According to the invention of claim 1 of this application, the image pickup means shoots a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit extracts a luminance signal and a color signal from the composite signal. Separately output, and the contour emphasis circuit outputs Y /
When the luminance signal level separated by the C separation circuit is low, the degree of contour enhancement for the luminance signal is increased, and the Y / C synthesis circuit separates the luminance signal whose contour is changed by the contour enhancement circuit from the Y / C separation signal. A new composite signal is generated by synthesizing the color signals separated by the circuit.

According to the invention of claim 2 of this application, the image pickup means captures a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit separates and outputs a luminance signal and a color signal from the composite signal. , The contour enhancement circuit is the Y / C
When the level of the luminance signal separated by the separation circuit is high, the degree of contour enhancement for the luminance signal is increased, and the Y / C synthesis circuit and the luminance signal whose contour is changed by the contour enhancement circuit and the Y / C separation circuit. A new composite signal is generated by synthesizing the color signals separated by.

According to the invention of claim 3 of this application, the image pickup means shoots a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit extracts a luminance signal and a color signal from the composite signal. Separately output, the contour extraction circuit extracts a contour signal from the luminance signal separated by the Y / C separation circuit, and the contour emphasis circuit outputs a contour for the luminance signal when the contour signal level extracted by the contour extraction circuit is low. The degree of enhancement is high, and the Y / C synthesizing circuit outputs the luminance signal whose contour is changed by the contour enhancing circuit and the Y / C.
A new composite signal is generated by synthesizing the color signals separated by the separation circuit.

According to the invention of claim 4 of this application, the image pickup means shoots a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit extracts a luminance signal and a color signal from the composite signal. Separately output, the luminance signal level discrimination circuit compares the luminance signal separated by the Y / C separation circuit with a predetermined threshold value, and the contour emphasizing circuit outputs the contour signal emphasizing level by the output of the luminance signal level discrimination circuit. The Y / C synthesis circuit synthesizes the luminance signal whose contour has been changed by the contour enhancement circuit and the color signal separated by the Y / C separation circuit to generate a new composite signal.

According to the invention of claim 5 of this application, the image pickup means shoots a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit extracts a luminance signal and a color signal from the composite signal. Separately output, the luminance signal level discrimination circuit compares the luminance signal separated by the Y / C separation circuit with a predetermined threshold value, and the contour extraction circuit outputs the contour signal by the output of the luminance signal level discrimination circuit. The presence / absence of the color signal is controlled, the color signal phase shift circuit changes the phase of the color signal according to the contour signal extracted from the contour extraction circuit, and the Y / C synthesis circuit detects the luminance signal separated by the Y / C separation circuit. A new composite signal is generated by synthesizing the color signal whose phase has been changed by the color signal phase circuit.

According to the invention of claim 6 of this application, in the invention of claim 4, the contour emphasis circuit is
When the brightness signal level determination circuit determines that the brightness signal has become equal to or lower than a predetermined threshold level, contour enhancement is performed.

According to the invention of claim 7 of this application, in the invention of claim 4, the contour emphasis circuit is
When the brightness signal level determination circuit determines that the brightness signal has exceeded a predetermined threshold level, contour enhancement is performed.

According to the invention of claim 8 of this application, in the invention of claim 5, the color signal phase shift circuit is configured such that the brightness signal level determination circuit determines that the brightness signal has a predetermined threshold value. When it is determined that the level is below the level, the phase of the color signal is changed.

According to the invention of claim 9 of this application, in the invention of claim 5, the color signal phase shift circuit is configured such that the luminance signal level determining circuit determines that the luminance signal has a predetermined threshold value. When it is determined that the level is exceeded, the phase of the color signal is changed.

According to the invention of claim 10 of this application, the image pickup means shoots a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit extracts a luminance signal and a color signal from the composite signal. Separately output, the luminance signal level discrimination circuit compares the luminance signal separated by the Y / C separation circuit with a plurality of predetermined threshold values, and the contour emphasizing circuit outputs the contour by the output of the luminance signal level discrimination circuit. The enhancement level is controlled, and the Y / C synthesizing circuit synthesizes the luminance signal whose contour is changed by the contour enhancing circuit and the color signal separated by the Y / C separating circuit to generate a new composite signal. To do.

According to the invention of claim 11 of this application, the image pickup means shoots a surrounding image to generate a corresponding composite signal, and the Y / C separation circuit extracts a luminance signal and a color signal from the composite signal. Separately output, the luminance signal level discrimination circuit compares the luminance signal separated by the Y / C separation circuit with a plurality of predetermined threshold values, and the contour emphasizing circuit outputs the contour by the output of the luminance signal level discrimination circuit. The presence / absence of extraction is controlled, and the color signal phase shift circuit changes the phase of the color signal according to the contour signal extracted from the contour extraction circuit.
The C synthesis circuit synthesizes the luminance signal separated by the Y / C separation circuit and the color signal whose phase is changed by the color signal phase circuit to generate a new composite signal.

According to the twelfth aspect of the present invention, the image pickup means photographs the surrounding image and generates a corresponding composite signal, and the Y / C separation circuit extracts the luminance signal and the color signal from the composite signal. Separately output, the contour emphasizing circuit controls the contour emphasizing level by the output of the color signal level discriminating circuit, and the Y / C synthesizing circuit and the Y / C luminance signal whose contour is changed by the contour emphasizing circuit. A new composite signal is generated by synthesizing the color signals separated by the separation circuit.

According to the invention of claim 13 of this application, in the invention of claim 12, the contour emphasizing circuit determines whether the level of the color signal is equal to or lower than a predetermined threshold value by the color signal level determining circuit. The contour is emphasized when it is determined that the stroke has occurred.

Invention of claim 14 of this application In the invention of any one of claims 1, 2, 3, 4, 6, 7, 10, 12, and 13, the contour enhancement level in the contour enhancement circuit is set to a cycle. Change.

According to the invention of claim 15 of this application, in the invention of any one of claims 5, 8, 9 and 11, the phase shift level of the color signal phase circuit is periodically changed.

According to the invention of claim 16 of this application, in the invention according to any one of claims 1 to 15,
The image pickup means photographs the situation around the vehicle and generates a corresponding composite signal to be used as a surrounding monitor device for the vehicle.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
A first embodiment of the present invention is shown in FIG.

The ambient monitor device of this embodiment is for a vehicle, and includes a video camera 1, a Y / C separation circuit 2, an edge enhancement circuit 3, a Y / C synthesis circuit 4, and a luminance signal level determination circuit 5. It has and.

The video camera 1 is mounted on a vehicle and is used for photographing the surroundings of the vehicle, for example, left and right sides, rear, overhead, front, etc. The video camera 1 corresponds to the light and dark conditions of the subject. A composite color video signal (hereinafter, simply referred to as a composite signal) is output.

The Y / C separation circuit 2 converts a composite signal into a luminance signal (hereinafter referred to as Y signal) and a color signal (hereinafter referred to as Y signal).
(Referred to as C signal), and its specific configuration may be, for example, the filter system shown in FIG. 2A and the delay line system shown in FIG. 2B. .

The circuit of the filter system shown in FIG. 2A is composed of a color signal trap circuit 21, a color signal high-pass filter 22 and a clamp circuit 23. The color signal trap circuit 21 and the color signal high-pass filter 22 are used by the camera. Y signal and C from composite signal output from 1
It is designed to separate signals. Furthermore, separated Y
The DC level of the signal is fixed by the clamp circuit 23.

On the other hand, in the case of the delay line type circuit shown in FIG. 2B, a delay line constituted by a comb filter is used. That is, after the composite signal is branched into three systems, one of them is delayed by 1H by the 1H delay circuit 24, which is further added by the adder 2
5 and the subtracter 21 add / subtract with the other two systems,
The C signal is obtained from the subtractor 21, and the Y signal is obtained from the adder 25. This Y signal is D by the clamp circuit 25.
The C component is made constant.

The contour emphasizing circuit 3 is a circuit for emphasizing the contour of the Y signal. Specifically, for example, the differentiation method shown in FIG. 3A and the frequency shown in FIG. 3B are used. A variable characteristic type is considered. The contour-enhancement circuit of the differentiation method shown in FIG. 3A amplifies a differentiation circuit 31 that differentiates an input Y signal and a differentiation signal obtained from the differentiation circuit 31, and at the same time, makes its gain variable by a control signal. A voltage-controlled variable gain amplifier circuit 32,
The output of the voltage-controlled variable gain amplifier circuit 32 and the original Y
And an adder circuit 33 for adding the signals. or,
The frequency characteristic variable contour emphasis circuit shown in FIG. 3B has a function of amplifying the Y signal, and the frequency characteristic of the voltage control filter 34 is variable by a control signal given from the outside. It is composed by.

As shown in FIG. 4, the Y / C synthesizing circuit 4 is composed of an adding circuit for adding the Y signal and the C signal to generate a composite signal.

The luminance signal level discrimination circuit 5 outputs the Y signal output from the Y / C separation circuit 2 to a predetermined threshold voltage V.
It is composed of a comparison circuit that performs discrimination binarization based on ref, and the output of this comparison circuit is supplied to the contour emphasis circuit 3 as a contour emphasis ON / OFF signal (control signal). The threshold voltage Vref may be a variable voltage source so that an arbitrary value can be set, and the voltage can be switched depending on the monitor used. For example, when a monitor having a luminance display characteristic as shown in FIG. 5 is used, the value shown in FIG.
You can set it to f.

Next, the operation of the first embodiment will be described.

The video camera 1 outputs a composite signal corresponding to the light and dark conditions of the subject. Y / C
The separation circuit 2 converts the composite signal output from the video camera 1 into a luminance signal (Y signal) and a color signal (C signal).
Extract only. The luminance signal level determination circuit 5 is Y / C
The Y signal extracted by the separation circuit 2 is set to the threshold voltage V
Binarization is performed by comparing with ref, and Y signal is threshold voltage V
"L" when lower than ref, "H" when higher
Is output to the contour emphasis circuit 3 as a control signal which is a contour emphasis on / off signal. In the contour emphasizing circuit 3, when the contour emphasizing ON / OFF signal given from the luminance signal level discriminating circuit 5 is received and the Y signal inputted from the Y / C separating circuit 2 is lower than a predetermined threshold voltage Vref. If the brightness is less than a certain set value, the contour enhancement operation is performed. Then, the Y signal subjected to the contour enhancement in the contour enhancement circuit 3 and the C signal separated in the Y / C separation circuit 2 are Y / C.
The image is synthesized in the synthesizing circuit 4 and sent to the monitor device as a video output, and an image in which only the low-luminance portion is edge-enhanced is displayed on the screen of the monitor device. A timing chart of these actions is shown in FIG.

As shown in FIG. 7A, when there are a high brightness area and a low brightness area in the photographed screen,
A low-luminance region usually sinks in black, and the visibility of an object in this region is low. However, FIG.
As shown in (b), according to the first embodiment, the area with high brightness becomes an image equivalent to a normal screen, whereas the contour enhancement is performed only in the area with brightness lower than the set value. It is possible to obtain an image in which obstacles are easily recognized.

In the first embodiment described above, the contour emphasizing circuit 3 whose degree of emphasis can be switched between two levels in accordance with the contour emphasizing ON / OFF signal from the luminance signal level discriminating circuit 5 is shown. However, in addition to this, as the contour emphasizing circuit 3, it is also possible to use a circuit in which the degree of contour emphasizing is continuously variable. In this case, as the luminance signal level determination circuit 5, an operational amplifier circuit that outputs a difference voltage between the Y signal and the threshold voltage Vref may be used. In this case, the contour emphasizing operation is performed in inverse proportion to the level of the Y signal.

Further, by changing the threshold voltage Vref, for example, when the monitor characteristic is likely to be blackened in a low luminance region, the threshold voltage Vref is changed.
If the value is set to a high value, the recognizability can be further improved. As shown in the first embodiment, by setting a plurality of threshold voltages Vref according to the type of monitor, the optimum threshold voltage Vref can be selected and the recognizability of obstacles can be improved. it can.

Next, a second embodiment of the present invention is shown in FIG. In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The feature of the second embodiment is that the polarity on the input side of the comparator constituting the luminance signal level discriminating circuit 5a is inverted and becomes "L" when the Y signal is higher than the threshold voltage Vref. This is because a logic signal that becomes "H" when it is low is output. Then, this logic signal is supplied to the above-mentioned contour emphasis circuit 3 as a contour emphasis on / off signal. Although the threshold voltage Vref is fixed, it can be set to a variable type or a selection type as in the first embodiment. For example, the threshold voltage Vref may be set to the value shown in FIG. 9 when the monitor having the brightness characteristics shown in FIG. 9 is used.

Next, the operation of the second embodiment will be described. The Y / C separation circuit 2 extracts the Y signal and the C signal from the composite signal output from the video camera 1. When the Y signal is higher than the threshold voltage Vref, the brightness signal level discrimination circuit 5a outputs a contour emphasis ON / OFF signal corresponding to the contour emphasis ON, whereby the contour emphasis circuit 3 captures an image. In the screen, the edge enhancement function is performed only in a portion whose brightness is higher than a certain value, and thereafter, as in the first embodiment, Y /
From the C synthesizing circuit 4, a video output on which contour enhancement has been performed is obtained. These actions are shown in FIG.

Therefore, according to the second embodiment, in the photographed screen, the low-luminance region becomes an image equivalent to the normal screen, and the contour is emphasized only in the region where the luminance is higher than the set value. . Therefore, for example, even if there is a light-colored obstacle near the white wall as shown in FIG. 11 and the brightness of the entire screen is high, it is possible to obtain an image in which the obstacle is easily recognized.

A third embodiment of the invention is shown in FIG.
In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The feature of the third embodiment is that the degree of contour enhancement of the contour enhancement circuit 3 is
This is because the Y signal itself is used for control.

That is, the contour emphasizing circuit 3a of this embodiment.
3 uses a variable frequency characteristic type shown in FIG. 3B. Therefore, when the level of the Y signal changes, the voltage control type filter 3 that constitutes the contour emphasis circuit 3a is used.
By controlling the frequency characteristic of No. 4 and increasing the gain in the high frequency band, the contour enhancement of the image is performed.

Next, the operation of the third embodiment will be described.
In the voltage control type filter 34 in the contour emphasizing circuit 3a, when the level of the Y signal externally supplied as the control signal is lowered, the gain in the high frequency band is increased, and as a result, the high luminance region and the low luminance region are low in the captured screen. When a region exists, a high-luminance region has an image equivalent to that of a normal screen, whereas a low-luminance region has an emphasized contour, which makes it possible to obtain an image in which obstacles and the like are easily recognized. .

A fourth embodiment of the present invention is shown in FIG.
In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the same figure, the contour extraction circuit 3b has a differentiating circuit 35 as shown in FIG.
The contour signal is generated by differentiating the Y signal.

The emphasis level calculation circuit 6 is composed of a square calculation circuit composed of, for example, an operational amplifier, and performs a square calculation on the contour signal output from the contour extraction circuit 3b.

The division circuit 7 is configured to divide the contour signal extracted by the contour extraction circuit 3b by the output of the emphasis level calculation circuit 6.

The adder circuit 8 adds the Y signal obtained from the Y / C separation circuit 2 and the signal obtained from the division circuit 7,
This is supplied to the Y / C synthesis circuit 4.

Next, the operation of the fourth embodiment will be described. From the video camera 1, image information corresponding to the photographed subject is converted into a composite signal and output. The Y / C separation circuit 2 extracts only the luminance signal (Y signal) and the color signal (C signal) from the composite signal output from the camera. The contour extraction circuit 3b differentiates the Y signal separated by the Y / C separation circuit 2 and outputs it as a contour signal. The emphasis level calculation circuit 6 performs, for example, a square calculation, and thereby the contour extraction circuit 3b.
The contour signal obtained from is subjected to a squaring process. Then
The contour signal obtained from the contour extraction circuit 3b is slowed down by the squared signal from the emphasis level calculation circuit 6, and its output is added to the original Y signal separated by the Y / C separation circuit 2 in the addition circuit 8. Thereafter, the output luminance signal of the adder circuit 8 and the C signal extracted from the Y / C separation circuit 2 are Y / C.
They are combined in the combining circuit 4 and sent to the monitor as a video output. In the third embodiment, since the contour emphasis level is emphasized in inverse proportion to the contour level, the contour emphasizing is performed on a signal whose contour is not clear. Therefore, for example, even if there are multiple obstacles at a distance and it is difficult to focus all the objects, and even if the focus is deviated, the contour of only the deviated region is emphasized, and therefore the obstacle is obstructed. It is possible to obtain an image in which objects can be easily recognized.

FIG. 15 shows a fifth embodiment of the present invention.
In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, the contour extraction circuit 3b has the same configuration as that of the above-described fourth embodiment, that is, is constituted by a simple differentiating circuit 35 as shown in FIG.

The color signal phase shift circuit 9 is composed of a circuit as shown in FIG. That is, the transistor Tr
1, a transistor resistor R4, an emitter resistor R3, a bleeder resistor R1 and R2
It receives the C signal via the coupling capacitor C1. After this C signal is amplified by the transistor Tr1,
The output is split into two systems, the collector side and the emitter side. The output of both these systems is the capacitor C2.
And a transistor Tr that functions as a resistor and are combined, and then output as a phase-shifted C signal. On the other hand, the resistance value of the transistor Tr2 functioning as a resistance changes in magnitude depending on a control signal given from the outside,
Thus, the degree of phase shift of the C signal is adjusted according to the value of the control signal voltage. Also, the phase shift on /
When the transistor Tr3 is turned on by the off signal, Tr2 is turned on accordingly and the phase shift action is stopped.

Next, the operation of the fifth embodiment will be described. The video camera 1 outputs a composite signal corresponding to the situation of the subject, and the Y / C separation circuit 2 extracts the Y signal and the C signal from the composite signal. The brightness signal level determination circuit 5f compares the brightness signal extracted by the Y / C separation circuit 2 with the threshold voltage Vref, and becomes “H” when the Y signal is lower than the threshold voltage Vref, and when the Y signal is higher than the threshold voltage Vref. Logic signal that goes low
The phase shift on / off signal is output to the transistor Tr3 of the color signal phase shift circuit 9. The contour extraction circuit 3b uses Y / C
A contour signal is generated by differentiating the Y signal separated by the separation circuit 2, and this is supplied to the color signal phase shift circuit 9 as a control signal. The color signal phase shift circuit 9 is supplied with the contour signal from the contour extraction circuit 3b as the phase shift control signal and the discrimination output from the luminance signal level discrimination circuit 5 as the phase shift on / off signal. The phase shift of the color signal is modulated according to the contour signal when the level is low.
After that, the C signal output from the color signal phase shift circuit 9 and Y /
The Y signal obtained from the C separation circuit 2 is combined in the Y / C combination circuit 4 and given to the monitor as a video output.

Therefore, according to the fifth embodiment, when there are a high-luminance region and a low-luminance region, the high-luminance region becomes an image equivalent to a normal screen, and only the region where the luminance is lower than the set value. A color change is added to the contour of the image, and when the object to be photographed is as shown in FIG. 7A as in the first embodiment, it is possible to obtain an image in which an obstacle or the like can be easily recognized.

In the fifth embodiment, the color change is applied to the outline of the low brightness area. However, as in the second embodiment shown in FIG. It is also possible to invert the input polarity and give a color change only to the outline of the high brightness area. In this case, similarly to the second embodiment, it is possible to improve the recognizability of the obstacle in the case of the photographing target as shown in FIG.

Next, FIG. 17 shows a sixth embodiment of the present invention. In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The feature of this embodiment is that a flushing effect is given to the contour of a predetermined area on the monitor screen.

In the figure, the counter circuit 10 is composed of an oscillator circuit and a general-purpose digital IC, and outputs a pulse train having a predetermined duty as a flicker signal.

The switch circuit 11 is composed of a transistor circuit or a general-purpose digital IC, and in response to the flicker signal given from the counter circuit 10, the signal path from the luminance signal level discriminating circuit 5 to the contour emphasizing circuit 3 is cyclical. It is designed to be intermittent.

Next, the operation of the sixth embodiment will be described.
Similar to the first embodiment, from the luminance signal discrimination circuit 5, the contour emphasis ON / OFF signal for turning on the contour emphasis circuit 3 only during the period when the Y signal is lower than the predetermined threshold voltage Vref. Is output. On the other hand, the switch circuit 11
As described above, the flicker signal output from the counter circuit 10 is received, and the contour emphasis on / off signal is periodically interrupted. Next, the C signal obtained from the Y / C separation circuit 2 and the contour-emphasized luminance signal intermittently obtained from the contour enhancement circuit 3 are synthesized in the Y / C synthesis circuit 4 and sent to the monitor as a video output. To be

According to the sixth embodiment, the same image as that of the first embodiment can be obtained, and in particular, since the emphasis level of the contour periodically changes, the contour seems to be flushing. The effect can be given to the image.

Also in the sixth embodiment, it is needless to say that if the input polarity in the luminance signal level discriminating circuit 5 is inverted, the contour of the bright area can have a flushing effect.

Next, a seventh embodiment of the present invention is shown in FIG. In the figure, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, the counter circuit 12 is configured as a counter that repeatedly counts a fixed time, and the count time value is supplied to the D / A conversion circuit 13 as digital data.

The D / A conversion circuit 13 includes the counter circuit 12
Periodic ramp waveform voltage is output by digital-to-analog conversion of the time data given by the above, and this is supplied to the reference input side of the luminance signal level determination circuit 5 as the variable threshold voltage Vref '.

Therefore, in the comparison circuit which constitutes the luminance signal discrimination circuit 5, the Y signal is discriminated based on the variable threshold voltage, so that a long-time contour enhancement ON signal is outputted to a low luminance region. On the other hand, the short-time contour enhancement ON signal is output to the high brightness area. And
The contour-enhanced Y signal output from the contour enhancement circuit 3 and the C signal obtained from the Y / C separation circuit 2 are synthesized in the Y / C synthesis circuit 4 and sent to the monitor as a video output.

Next, the operation of the seventh embodiment will be described. As described above, in the seventh embodiment, the same image as that of the first embodiment is obtained, and in addition, the contour enhancement is performed in a region having a lower luminance for a long time and in a region having a slightly higher luminance for a short time. At the same time, the effect that the contour is flushed can be given to the image, and at the same time, a larger change in the contour can be given to the image as compared with each of the above-described embodiments, and the image with improved visibility can be obtained.

Next, FIG. 19 shows an eighth embodiment of the present invention. In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, the color signal level discrimination circuit 5b is composed of a comparison circuit for discriminating and binarizing the C signal extracted from the Y / C separation circuit 2 based on a predetermined threshold voltage Vref. Is sent to the contour emphasis circuit 3 as a contour emphasis on / off signal.

Next, the operation of the eighth embodiment will be described. Since the NTSC composite signal does not add false color to the image, corrections such as high brightness coloring prevention and low saturation compression are added. These corrections are performed by eliminating the high-luminance color signal in the high-luminance coloration prevention and eliminating the low-luminance color signal in the low-chroma compression. Therefore, if it is detected that these corrections are made, it can be seen that the brightness is high or low. Therefore, in the eighth embodiment, when the above-described correction is performed, the contour is emphasized to improve the visibility of the images captured at high brightness and low brightness.

First, the video camera 1 converts image information into a composite video signal. The Y / C conversion circuit 2 extracts only the Y signal and the C signal from the composite video signal output from the camera. The color signal level determination circuit 5b compares the color signal extracted by the Y / C separation circuit 2 with a certain set threshold voltage Vref, and when the color signal is lower than the set threshold voltage, "L" is set. ", And a comparison result that is" H "when high is output.

The contour emphasizing circuit 3 controls the frequency characteristic of the luminance signal amplifying section and enhances the gain in the high frequency band to enhance the contour of the image. The same effect can be obtained by differentiating the luminance signal and adding the differentiated signal to the original luminance signal. Further, this circuit can control the degree of contour enhancement, that is, the gain of the high frequency band and the addition weight of the differential signal by an external signal. For example, the contour enhancement level is increased in inverse proportion to the voltage level of the control signal. To do.

The color signal level determination circuit 5b determines whether the level of the color signal is higher or lower than the set value. In other words, it is determined whether the color is dark or light. The contour emphasis level by the contour emphasis circuit 3 is controlled by the output of the color signal level discrimination circuit 5b. Since the contour emphasis level is inversely proportional to the control signal, the contour is emphasized when the color density falls below a certain set value. The contour emphasis circuit 3 emphasizes the contour, the luminance signal and the color signal separated by the Y / C separation circuit 2 are added by the Y / C synthesis circuit 4, and the composite signal is output to the monitor as a video output. Therefore, according to the eighth embodiment, when there are areas of high brightness or low brightness in the captured screen, the contours of these areas are emphasized and the visibility of obstacles is significantly improved. Becomes

In each of the above embodiments, the threshold voltage and the edge enhancement level are fixed values, but they can be of a variable type or a selection type as in the first embodiment. In this case, for example, contour enhancement suitable for the monitor device used can be performed.

Next, a ninth embodiment of the present invention is shown in FIG. In the figure, the same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the figure, a timing generator 15 generates an area recognition signal indicating a shooting area from a horizontal synchronizing signal and a vertical synchronizing signal superimposed in a composite video signal, and is composed of a counter and a multivibrator. The output of the timing generator 15 is sent to the contour emphasis circuit 3 as a contour emphasis ON / OFF signal.

Next, the operation of the ninth embodiment will be described. A composite signal corresponding to the condition of the subject is output from the video camera 1, and this signal is separated into a Y signal and a C signal by the Y / C separation circuit 2. The timing generator 15 generates a signal indicating a certain predetermined area in the screen, and this signal is supplied to the contour emphasis circuit 3 for contour emphasis ON / OFF.
It is output as an off signal. As a result, the contour emphasis circuit 3
In the captured image, contour enhancement is performed only on a predetermined contour, and thereafter, the Y / C synthesizing circuit 4 obtains a video output subjected to the contour enhancement operation as in the first embodiment.

For example, in a rear confirmation monitor device in which a camera is installed at the rear end of the vehicle as shown in FIG. 21 and the environment behind the vehicle is photographed, the photographed image is as shown in FIG.
As shown in, the upper part of the screen is brightened by sunlight.
Since the lower part is a low-saturation road surface, it is often a darker image than the upper part.Furthermore, because there is an object with brightness and saturation similar to that of a road surface such as a curb, it is possible to confirm obstacles. Have difficulty. Therefore, the contour emphasis ON / OFF signal output from the timing generator 15 is turned off at the upper portion of the screen and is turned on at the lower portion, so that the contour enhancement can be performed only at the lower portion, as shown in FIG. It is possible to obtain an image that makes it easy to recognize obstacles.

[0088]

As is apparent from the above description of each embodiment, according to the invention of each claim, the visibility of the monitor screen obtained by this type of surrounding monitor device is remarkably improved as compared with the conventional one. Can be made.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a block diagram showing two examples of a Y / C separation circuit.

FIG. 3 is a block diagram showing two examples of a contour emphasis circuit.

FIG. 4 is a diagram showing an example of a Y / C synthesis circuit.

FIG. 5 is a diagram illustrating the operation of the first embodiment.

FIG. 6 is a timing chart illustrating the operation of the first embodiment.

FIG. 7 is a diagram illustrating the operation of the first embodiment.

FIG. 8 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 9 is a diagram illustrating the operation of the second embodiment.

FIG. 10 is a timing chart illustrating the operation of the second embodiment.

FIG. 11 is a diagram illustrating the operation of the second embodiment.

FIG. 12 is a block diagram showing a configuration of a third exemplary embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration of a fourth exemplary embodiment of the present invention.

FIG. 14 is a block diagram showing an example of a contour extraction circuit used in the fourth embodiment.

FIG. 15 is a block diagram showing the configuration of a fifth embodiment of the present invention.

FIG. 16 is a circuit diagram showing an example of a color signal phase shift circuit in a fifth embodiment.

FIG. 17 is a block diagram showing a configuration of a sixth exemplary embodiment of the present invention.

FIG. 18 is a block diagram showing a configuration of a seventh embodiment of the present invention.

FIG. 19 is a block diagram showing the structure of an eighth embodiment of the present invention.

FIG. 20 is a block diagram showing the structure of a ninth embodiment of the present invention.

FIG. 21 is an explanatory diagram of the ninth embodiment of the present invention.

FIG. 22 is a diagram for explaining the effect of the eighth embodiment of the present invention.

FIG. 23 is a block diagram showing a conventional example of a contour correction device for improving image quality.

FIG. 24 is a diagram for explaining a problem of the conventional example.

[Explanation of symbols]

 1 Video Camera 2 Y / C Separation Circuit 3 Edge Enhancement Circuit 4 Y / C Synthesis Circuit 5 Luminance Signal Level Discrimination Circuit 6 Enhancement Level Operation Circuit 7 Division Circuit 8 Addition Circuit 9 Color Signal Phase Shift Circuit 10 Counter Circuit 11 Switch Circuit 12 Counter circuit 13 D / A conversion circuit

Claims (16)

[Claims] 1. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. When the level of the luminance signal separated in step 1 is low, the edge enhancement circuit which increases the degree of edge enhancement for the luminance signal, the luminance signal whose contour is changed by the edge enhancement circuit and the Y / C separation circuit A Y / C synthesizing circuit for synthesizing a color signal to generate a new composite signal. 2. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. The edge enhancement circuit that increases the edge enhancement degree with respect to the luminance signal when the luminance signal level separated by is high, the luminance signal whose edge is changed by the edge enhancement circuit, and the Y / C separation circuit A Y / C synthesizing circuit for synthesizing a color signal to generate a new composite signal. 3. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. A contour extraction circuit for extracting a contour signal from the luminance signal separated by the contour extraction circuit; a contour enhancement circuit for increasing the degree of contour enhancement for the luminance signal when the contour signal level extracted by the contour extraction circuit is low; And a Y / C synthesizing circuit for synthesizing the luminance signal whose contour is changed by the chrominance signal and the chrominance signal separated by the Y / C separating circuit to generate a new composite signal. Surrounding monitor device. 4. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. A luminance signal level discriminating circuit for comparing the luminance signal separated by a predetermined threshold value, a contour emphasizing circuit whose contour emphasizing level is controlled by the output of the luminance signal level discriminating circuit, and the contour emphasizing circuit. A Y / C synthesizing circuit for synthesizing a luminance signal whose contour is changed and a color signal separated by the Y / C separating circuit to generate a new composite signal, Monitor device. 5. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. A luminance signal level discriminating circuit for comparing the luminance signal separated by the threshold value with a predetermined threshold value; a contour extracting circuit for controlling the presence / absence of contour extraction by the output of the luminance signal level discriminating circuit; A color signal phase shift circuit for changing the phase of the color signal by the contour signal extracted from the color signal, a luminance signal separated by the Y / C separation circuit, and a color signal whose phase is changed by the color signal phase circuit. A surrounding monitor device comprising: a Y / C synthesizing circuit that synthesizes and a new composite signal. 6. The edge enhancement circuit performs edge enhancement when the brightness signal level determination circuit determines that the brightness signal has fallen below a predetermined threshold level. The ambient monitoring device according to claim 4. 7. The edge enhancement circuit performs edge enhancement when the brightness signal level determination circuit determines that the brightness signal has exceeded a predetermined threshold level. The ambient monitoring device according to claim 4. 8. The color signal phase shift circuit changes the phase of the color signal when the brightness signal level determination circuit determines that the brightness signal has fallen below a predetermined threshold level. The ambient monitoring device according to claim 5, wherein 9. The color signal phase shift circuit changes the phase of the color signal when the brightness signal level determination circuit determines that the brightness signal has exceeded a predetermined threshold level. The ambient monitoring device according to claim 5, wherein 10. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. A luminance signal level discriminating circuit for comparing the luminance signal separated by 4 with a plurality of predetermined threshold values; a contour emphasizing circuit whose contour emphasizing level is controlled by the output of the luminance signal level discriminating circuit; A Y / C synthesizing circuit for synthesizing the luminance signal whose contour is changed by the circuit and the chrominance signal separated by the Y / C separating circuit to generate a new composite signal. Surround monitor device. 11. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the Y / C separation circuit. A luminance signal level discriminating circuit for comparing the luminance signal separated by a plurality of predetermined threshold values, a contour emphasizing circuit for controlling presence / absence of contour extraction by an output of the luminance signal level discriminating circuit, A color signal phase shift circuit for changing the phase of the color signal by the contour signal extracted from the extraction circuit, a luminance signal separated by the Y / C separation circuit, and a phase change by the color signal phase circuit. A Y / C synthesizing circuit for synthesizing a color signal to generate a new composite signal. 12. An image pickup means for photographing a surrounding image to generate a corresponding composite signal, a Y / C separation circuit for separating and outputting a luminance signal and a color signal from the composite signal, and the color signal level discriminating circuit. Output of the contour enhancement circuit, a contour enhancement circuit whose contour enhancement level is controlled, a luminance signal whose contour is changed by the contour enhancement circuit, and a color signal separated by the Y / C separation circuit are combined to generate a new signal. A surroundings monitor device comprising: a Y / C synthesizing circuit for generating a composite signal; 13. The contour enhancement circuit enhances the contour when the color signal level determination circuit determines that the level of the color signal is equal to or lower than a predetermined threshold value. The ambient monitoring device according to claim 12. 14. The contour enhancement level in the contour enhancement circuit is periodically changed.
A surrounding monitor device according to any one of 2, 3, 4, 6, 7, 10, 12, and 13. 15. A phase shift level of the color signal phase circuit is periodically changed.
11. The surroundings monitor device according to any one of 11. 16. The surrounding monitor device according to claim 1, wherein the image pickup unit photographs a situation around the vehicle and generates a corresponding composite signal.