JPH06350877A - Contour compensating device and gain control signal generation circuit to be used in the same - Google Patents

Abstract

PURPOSE:To continuously control the gain of a contour compensation signal two- dimensionally in a horizontal direction and a vertical direction by generating waveform approximating to the inverse characteristic of a modulation degree in order to compensate the deterioration of visibility due to the decline of the modulation degree of the optical system of a lens, etc., at the circumference of a screen in a single plate type or a multi-plate type video camera using a solid state image pickup element. CONSTITUTION:In order to compensate a modulation degree characteristic to deteriorate in the form of a concentric circle, a central processing circuit 12 designates the shape of the inverse function of the modulation degree characteristic by either a saw tooth wave or a parabola. In response to the designation by the central processing circuit 12, a two-dimensional contour gain control circuit 11 sets the amplitude and the inclination of the saw tooth wave or the parabola in the horizontal and the vertical deractions. Then, a contour compensation signal addition circuit 8 amplifies continuously the output signal of a contour compensation circuit 7 by the gain corresponding to the peak value of the saw tooth wave or the parabola changing two-dimensionally in the horizontal and the vertical directions, and adds it to the signal of a process main line processing circuit 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-plate type or multi-plate type video camera using a solid-state image pickup device, and image clarity due to a decrease in modulation factor (MTF) on the screen peripheral surface of an optical system due to a lens or the like. The present invention relates to a contour compensation device and a gain control signal generation circuit used in the device for compensating for the deterioration of the image quality and obtaining a high-quality image over the entire screen.

[0002]

2. Description of the Related Art Conventionally, in this type of contour compensation device,
In particular, paying attention to the decrease in the degree of modulation of the lens in the periphery of the screen, a method is used in which the gain of the contour compensation signal is made larger than the center of the screen only at the four corners of the screen. Gain in the center of the screen is 1
The gain at the four corners of the screen is about twice as large as that at the center of the screen. FIG. 7 is a block diagram showing a schematic configuration of a conventional contour compensation device.

In FIG. 7, 1 is an optical system composed of a lens and the like, 2 is an image pickup device such as a solid-state image pickup device, 3 is an analog process circuit for performing noise reduction, black level, white level, pregamma and the like, 4 Is an A / D converter. Reference numeral 5 denotes a digital process circuit group, the internal structure of which is as follows. 6 is a process main line processing circuit for performing gamma processing, matrix processing, etc., 7 is a contour compensation circuit for performing horizontal and vertical contour enhancement,
Reference numeral 8 denotes a contour compensation signal addition circuit for amplifying the output signal of the contour compensation circuit 7 and adding it to the process main line processing circuit 6.

Further, 26 is a selector for switching the gain of the contour compensation signal to 1 time at the center of the screen and more than it at the 4 corners of the screen, and 28 and 29 are vertical gate generating circuit and horizontal gate generating respectively. The circuit 27 is a gate that takes the logical product of vertical and horizontal gate signals.

The operation of the conventional horizontal and vertical two-dimensional gain control type contour compensator will be described below with reference to FIG.

In FIG. 7, an optical system 1 including a lens and the like.
The input optical image is formed on the image pickup device 2 such as a solid-state image pickup device, and is output as an electric signal by a predetermined vertical and horizontal read pulse drive (not shown). This image pickup signal is used in the analog process circuit 3 for noise reduction of random noise reduction by correlated double sampling, black level adjustment by black balance, white level adjustment by white balance, and expansion of the dynamic range of digital signal processing. The pre-gamma and the prinny treatment are performed.

After this, this analog signal is
In order to perform signal processing excellent in characteristics, it is converted into a digital signal by the A / D converter 4 in the subsequent stage. This A / D
The output signal of the converter 4 is subjected to process main line processing and contour enhancement processing in the digital process circuit group 5. The main line signal is subjected to gamma correction processing by the process main line processing circuit 6,
Various digital processes such as blanking process and matrix process are performed, and in parallel with the main line process, the contour compensating circuit 7 generates a contour compensating signal for enhancing the contours in the horizontal and vertical directions. The contour compensation signal is amplified by the adder circuit 8 and added to the process main line signal.

Explaining how the contour compensation signal is amplified, the vertical synchronizing signal and the horizontal synchronizing signal are input, and the vertical gate generating circuit 28 and the horizontal gate generating circuit 29 are vertically and horizontally respectively. A gate signal is generated, a logical product of vertical and horizontal gate signals is obtained by the gate 27, and the amplification factor of the contour compensation signal gain is multiplied by 1 at the center of the screen by the selector 26, and the screen is centered at the four corners of the screen. Switch so that it is about twice as large as the
The amplification factor of the contour compensation signal in the two-dimensional area in the vertical direction is controlled. The vertical gate generation circuit 28 and the horizontal gate generation circuit 29 use a circuit such as a monostable multivibrator as a concrete method of realizing.

An actual control waveform by the conventional horizontal and vertical two-dimensional gain control type contour compensator will be described with reference to FIG. Generally, the degree of modulation (M
Since TF) is reduced in the periphery of the screen, it is necessary to make the contour compensation signal gain larger than usual in order to compensate for the deterioration of the sharpness of the image. FIG. 8 shows the relationship between the horizontal and vertical two-dimensional coordinates of the screen and the contour compensation signal gain, where the center of the screen is a normal contour compensation signal gain and the gain sharply increases at the four corners of the screen. Show the situation.

[0010]

However, in the horizontal and vertical two-dimensional gain control type contour compensating apparatus having the above-mentioned conventional structure, the distance from the center of the screen is increased like the modulation characteristic of the optical system by an actual lens or the like. However, the gain control is not a gain control that is consistent with the tendency that the modulation degree is continuously decreased, but is a very simplified control that is performed by simply two-step discrete switching of 1 or 2 times. There is a problem that a discontinuous feeling and an unnatural feeling remain in the changing part.

Further, in the case of the conventional broadcasting system, the aspect ratio is 4: 3, and it is not so fatal even if the modulation degree of the optical system due to the lens or the like is lowered concentrically from the center of the screen. Even the simple type two-dimensional gain control type contour compensating device described above could be expected to some extent. However, HDTV and second-generation EDTV represented by high-definition
When the aspect ratio becomes 16: 9 due to the widening of the screen, as in broadcasting systems such as, the screen becomes horizontally long and the imaging surface expands in the horizontal direction, so that the degree of modulation in the horizontal direction of the screen decreases more than ever. It has become conspicuous, and the conventional two-dimensional gain control type contour compensator having a simple structure has a problem that satisfactory performance cannot be secured for a wide screen.

The first and first inventions solve the above-mentioned conventional problems, and a signal for completely correcting the modulation characteristic of the optical system by a lens or the like is generated to horizontally adjust the gain of the contour compensation signal. By continuously controlling in two dimensions in the vertical direction, it is natural rather than discrete and can be satisfied even in a wide screen, and even if the lens is exchanged and the modulation degree characteristic changes, it can be easily changed. It is an object of the present invention to provide an excellent contour compensator capable of obtaining a high quality image over the entire screen.

A second object of the present invention is to provide a two-dimensional contour compensation gain control signal generating circuit for realizing the above-mentioned contour compensating apparatus.

[0014]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object 1, a contour compensating apparatus according to a first aspect of the present invention comprises an optical system and an imaging device including a lens for imaging a copy, and an imaging device. An A / D converter that shapes the output and then converts it into a digital signal, a process main processing circuit that digitally processes the output of the A / D converter, and contour enhancement in horizontal and vertical directions with respect to the signal of the process main processing circuit. A contour compensation circuit that generates a compensation signal for performing the image processing, and a central processing that sets the shape of the inverse function of the modulation degree characteristic to compensate for the deterioration of the image sharpness due to the reduction of the modulation degree around the screen of the optical system. Circuit and a two-dimensional contour gain control circuit for continuously controlling the amplification gain of the contour compensation signal in two dimensions in the horizontal and vertical directions according to the setting signal from the central processing circuit, and the output of the two-dimensional contour gain control circuit. Servant It is obtained by a contour compensation signal adding circuit for adding the signal processing main processing circuit amplifies the output signal of the contour compensation circuit Te.

Second, in order to achieve the above-mentioned second object, the second
The gain control signal generating circuit according to the invention of claim 1, the central processing circuit for setting the waveform of the control signal, the decoder for decoding the setting information of the central processing circuit, and the horizontal synchronizing signal at a frequency division ratio according to the output of the decoder. The vertical clock frequency divider circuit, the vertical up / down counter whose initial value and vertical increase / decrease amount are specified by the output of the decoder using the output of the vertical clock frequency divider circuit as a clock, and digital processing with the frequency division ratio according to the output of the decoder. A horizontal clock frequency dividing circuit for dividing the main clock, and a horizontal increase / decrease circuit that uses the output of the horizontal clock frequency dividing circuit as a clock to specify the horizontal increment / decrement amount and the vertical up / down counter output to specify the initial value. The down counter and vertical up / down counter are switched up / down at the center point of one vertical scanning period, and the counter is stopped. A vertical up / down counter control circuit for controlling the start of the horizontal up / down counter and a horizontal up / down counter control circuit for controlling the stop / start of the counter by performing the up / down switching of the horizontal up / down counter at the center point of one horizontal scanning period. Is.

[0016]

According to the first and second aspects of the present invention, the amplification gain of the contour compensation signal can be continuously controlled two-dimensionally in the horizontal and vertical directions with respect to the modulation degree characteristic of the optical system such as a lens. As a result, it is possible to improve the blurring feeling around the screen, and not only the broadcasting system with an aspect ratio of 4: 3 but also the aspect ratio of 1
Even with the 6: 9 broadcasting system, high-quality images can be obtained over the entire screen. Also, by changing the setting signal from the central processing circuit, it is possible to easily respond to changes in the modulation factor characteristics of the optical system due to the lens, etc., and the versatility of the target lens can be increased and even low-cost lenses can be used. can do.

According to the second aspect of the present invention, with the configuration of the second aspect, it is possible to generate a waveform similar to the inverse characteristic of the modulation degree of the optical system by a lens or the like, for example, a sawtooth wave, by up-down counter control. By independently varying the inclination of the sawtooth wave in the horizontal and vertical directions, a control signal that continuously increases the gain as it moves away from the screen center is created, and a fine two-dimensional contour compensation gain control signal can be generated. Can be

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of the contour compensating apparatus of the present invention. The same components as those in FIG. 7 are designated by the same reference numerals and the description thereof will be omitted. Regarding the lens of the optical system 1 in FIG. 1, first, general modulation factor characteristics (MTF) will be described. FIG. 2 shows the modulation degree characteristics of typical broadcast and professional lenses, and shows that the modulation degree characteristics deteriorate concentrically as the lens moves away from the center of the screen. Figure 2
(A) is the case where the screen aspect ratio is 4: 3, and the deterioration in the periphery of the screen is larger in the horizontal direction than in the vertical direction. Further, FIG. 2B shows the case where the screen aspect ratio is 16: 9. The widening is promoted, the screen becomes horizontally long, and the image pickup surface relatively expands in the horizontal direction. The degree of horizontal modulation deteriorates more than ever before and becomes noticeable. Therefore, the aspect ratio is 4:
In any of the cases of 3 and 16: 9, a method for improving the blur feeling around the screen is required.

1. Next, a contour compensator according to a first embodiment of the present invention will be described. In FIG. 1, among the components of the contour compensation signal addition circuit 8, 10 is a multiplier and 9 is an adder. 12 is a central processing circuit (C
PU) and 11 are two-dimensional contour gain control circuits that continuously control the amplification gain of the contour compensation signal in two dimensions in the horizontal and vertical directions according to the setting signal from the central processing circuit 12.

The operation of the contour compensating apparatus according to the first embodiment will be described below. In FIG. 1, an optical image input from an optical system 1 including a lens or the like is formed on an image pickup device 2 such as a solid-state image pickup element and output as an electric signal. This image pickup signal is subjected to random noise reduction, black level adjustment, pre-gamma, prini processing, etc. in the analog process circuit 3. After that, it is converted into a digital signal by the A / D converter 4, and the digital process circuit group 5
At process main line processing and contour enhancement processing are performed. The digital main line signal is subjected to various types of digital processing such as gamma correction processing, blanking processing, and matrix processing by the process main line processing circuit 6, and further, in parallel with the main line processing, the contour compensation circuit 7 performs horizontal and vertical contour enhancement. A contour compensation signal for performing is generated, and the contour compensation signal adding circuit 8 including the multiplier 10 and the adder 9 amplifies the contour compensation signal and adds it to the process main line signal.

Here, the central processing circuit 12 sets the shape of the inverse function of the modulation degree characteristic in order to compensate for the deterioration of the sharpness of the image due to the reduction of the modulation degree in the periphery of the screen of the optical system.
The dimensional contour gain control circuit 11 continuously controls the amplification gain of the contour compensation signal in two dimensions in the horizontal and vertical directions according to the output signal of the central processing circuit 12. As shown in FIG. 2, since the reduction amount of the lens modulation degree around the screen is about 50%, the maximum value of the amplification gain of the contour compensation signal around the screen is about twice, and the amplification of the contour compensation signal at the center of the screen is increased. The gain is set to 1. Further, control is performed so that the change in the amplification gain from the center of the screen to the periphery of the screen is continuous, and the amplification gain increases in a shape that is as concentric as possible. Further, the amplification gain can be changed two-dimensionally in the horizontal and vertical directions independently, so that fine control is possible even when the aspect ratio is 16: 9.

Next, another embodiment of the contour compensation signal adding circuit 8 including the multiplier 10 and the adder 9 will be described. FIG. 3 shows a circuit corresponding to the contour compensation signal adding circuit 8 in which the multiplier is eliminated and the circuit scale is simplified. In FIG. 3, 2
0 is a bit shift that makes the contour compensation signal 1/4, 21 is a bit shift that makes it 1/2, 22, 24 and 25 are adders, and 23 is a selector.

Explaining the operation of FIG. 3, the output of the contour compensating circuit 7 is input, and the bit shifts 20 and 21 generate signals of 1/4 and 1/2 of the input. Further, the adder 22 produces a 3/4 signal, and the selector 23
A signal from 0 to 1 is given to the input terminal of the unit at intervals of 1/4. The output of the two-dimensional contour gain control circuit 11 is used as a 3-bit representation for the switching control signal of the selector 23.
The output of the selector 23 and the output of the contour compensation circuit 7 are the adder 2
4 and the output of the contour compensation circuit 7 is increased from 1 to 1
A signal amplified in 5 steps up to 2 times in / 4 steps is created. Further, it is added to the process main line signal by the adder 25. In this way, it is possible to realize a circuit that amplifies the contour compensation signal and adds it to the process main line signal when the accuracy is lowered to the limit of the practical level and the circuit scale reduction is prioritized.

As described above, according to the first embodiment,
The shape of the inverse function of the modulation degree characteristic can be set in the central processing circuit 12 in order to compensate for the deterioration of the sharpness of the image due to the reduction of the modulation degree around the screen of the optical system. Reference numeral 11 indicates the amplification gain of the contour compensation signal in the horizontal and vertical directions according to the setting output signal of the central processing circuit 12.
Since it can be controlled independently and continuously in dimension,
Blurring feeling around the screen can be improved by amplifying the contour compensation signal, and the entire screen can be displayed not only for a broadcasting system with an aspect ratio of 4: 3 but also for a broadcasting system with an aspect ratio of 16: 9. It has an advantage that a natural and high-quality image can be obtained.

Further, according to the above embodiment, when it is desired to reduce the improvement accuracy to the limit of the practical level and give priority to the reduction of the circuit scale, the adder and the selector are used instead of the multiplier, so that the small scale is realized. It also has the advantage that the contour compensation signal can be amplified in the circuit.

2. Next, a gain control signal generating circuit according to a second embodiment of the present invention will be described. FIG. 4 is a block diagram showing a schematic configuration of the gain control signal generating circuit of the present invention. The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 4, 13 is a decoder for decoding the shape setting command from the central processing circuit, 14 is a vertical clock frequency dividing circuit for dividing the horizontal synchronizing signal, 15 is a vertical up / down counter control circuit, 16 is a vertical up / down counter,
Reference numeral 17 is a horizontal clock frequency dividing circuit for dividing the main clock for digital processing, 18 is a horizontal up / down counter control circuit, and 19 is a horizontal up / down counter.

Next, the operation of the gain control signal generating circuit of the second embodiment will be described with reference to the vertical time axis. In FIG. 4, when the central processing circuit 12 sets a waveform for performing the two-dimensional contour compensation gain control and the setting output signal is given to the decoder 13, the decoder 13 decodes the setting information of the central processing circuit 12. . Then, the vertical clock frequency dividing circuit 14 frequency-divides the horizontal synchronizing signal at a frequency dividing ratio according to the output of the decoder 13 and uses it as a clock for the vertical up / down counter 16. Further, the operating condition of the vertical up / down counter 16 depends on the initial value in the vertical direction designated by the output of the decoder 13, the vertical increase / decrease amount which is the up / down resolution, and the counting clock generated by the vertical clock frequency dividing circuit 14. The output of the vertical up / down counter 16 becomes the contour compensation gain control output in the vertical direction.

At this time, the vertical up / down counter control circuit 15 controls the vertical up / down counter 16 as follows. First, up-down switching is performed at the vertical center point, and down-counting is performed in the first half portion before reaching the vertical center point, and up-counting is performed in the second half portion after passing through the vertical center point. When the output of the vertical up / down counter 16 becomes zero (that is, at the zero cross point) in the first half before reaching the center point in the vertical direction, the down count is stopped.

Further, in the latter half after passing through the center point in the vertical direction, vertical up / down is performed at a time point (restart point) which becomes a control point of the latter half with the center point as a boundary with respect to the zero cross point of the first half. The counting operation of the counter 16 is restarted, and this time up counting is performed. Further, during the blanking period, it is preset to the vertical initial value designated by the output of the decoder 13.

In this way, when the vertical increase / decrease amount by the decoder 13 is set to a constant value, left and right symmetrical sawtooth waves with the vertical center point as a boundary are produced, and the output of the vertical up / down counter 16 is generated. Is equal to the specified vertical initial value at both vertical edges of the screen, and is maximum at both vertical edges and minimum at the vertical center point. The amplitude of the sawtooth wave is an initial value in the vertical direction by the decoder 13, the inclination of the sawtooth wave is the frequency division ratio of the vertical clock frequency dividing circuit 14, and the increase / decrease step accuracy of the sawtooth wave is determined by the vertical increase / decrease amount by the decoder 13.

The operation of the gain control signal generating circuit has been described above with respect to the vertical time axis, but the same applies to the horizontal time axis. A case where the horizontal increase / decrease amount by the decoder 13 is set to a constant value will be described. The horizontal up / down counter control circuit 18 controls the operation of the horizontal up / down counter 19. In order to create a symmetrical sawtooth wave with the horizontal center point as the boundary, the inclination of the sawtooth wave is a horizontal clock frequency divider circuit that divides the digital processing main clock at a frequency division ratio according to the output of the decoder 13. 17, the accuracy of the sawtooth wave increase / decrease is determined by the horizontal increase / decrease amount by the decoder 13, and the horizontal up / down counter 1
The output of 9 becomes the contour compensation gain control output in the horizontal direction. However, the initial value of the horizontal up / down counter 19 is set to the output of the vertical up / down counter 16, and the amplitude of the horizontal sawtooth wave is modulated by the amplitude of the vertical sawtooth wave so that the output of the horizontal up / down counter 19 becomes horizontal or vertical. As a result of the change in the sawtooth wave in both directions, the waveform for performing the two-dimensional contour compensation gain control is obtained on the screen.

Next, the operation timing of the gain control signal generating circuit of the second embodiment will be described with reference to FIG. 5, which is a typical operation example. FIG. 5A is a vertical view of FIG.
(B) shows the operation timing in the horizontal direction. Figure 5 (A)
In, the vertical sawtooth wave amplitude is the output of the vertical up / down counter 16, and the vertical synchronizing signal and the vertical center point pulse are given from the outside. The vertical sawtooth wave amplitude is preset to the initial value during the blanking period of the vertical sync signal,
The down-counting is performed in the first half before reaching the center point, and when it reaches zero, the vertical up / down counter control circuit 15 measures the time T1 to the center point as a zero cross point.

Further, the time point after the lapse of time T2 after passing through the vertical center point is set as the restart point, and the vertical up / down counter control circuit 15 causes the vertical up / down counter 16 to operate.
The counting operation of is restarted to count up. T1 and T2 become substantially equal to each other, and the operation of the vertical up / down counter 16 is stopped during the T1 + T2 period. When there is no zero-cross point, that is, when the vertical sawtooth wave amplitude is larger than zero at the center point, only up / down switching is performed. Thus, in FIG. 5A, the value of E, which is the final value in one vertical scanning period, becomes substantially equal to the initial value.

FIG. 5B shows the operation timing in the horizontal direction, which is almost the same as that in the vertical direction.
At the time in the vertical direction corresponding to F, the horizontal sawtooth wave amplitude at that time is also F. Therefore, the horizontal sawtooth wave amplitude changes depending on the amplitude of the vertical sawtooth wave, and a gain control waveform having a large gain in the periphery of the screen and a small gain in the center of the screen is obtained.

Next, a typical example of the two-dimensional contour compensation gain control waveform obtained by the gain control signal generating circuit of the second embodiment will be described with reference to FIG. FIG. 6A shows the relationship between the horizontal and vertical two-dimensional coordinates of the screen and the contour compensation signal gain, and the center of the screen is the normal contour compensation signal gain.
The gain is continuously increased as the distance from the center of the screen increases, and the gain doubles at the corners of the screen 4 as shown in the figure. The shape is cut diagonally from the corners of the screen 4 toward the center of the screen, and the slope to be cut can be freely selected. The region where the gain is multiplied by 1 in the horizontal and vertical planes has a basic shape of a rhombus. In an extreme example, if the tilt is zero, the gain can be maximized over the entire screen.

Further, FIG. 6B shows a region where the gain in the horizontal and vertical planes becomes 1 when the vertical inclination is changed while the horizontal inclination is constant, and the vertical zero-cross point moves. The rhombus can be expanded and contracted horizontally. Further, FIG. 6C shows a region where the gain in the horizontal and vertical planes becomes 1 when the horizontal inclination is changed while the vertical inclination is constant. In this case, the rhombus should be expanded and contracted in the vertical direction. You can

As described above, according to the second embodiment,
The decoder 13 decodes the output of the central processing circuit 12 that sets the waveform for performing the two-dimensional contour compensation gain control, and specifies the frequency division ratio of the up / down counter, the initial value, and the up / down increase / decrease amount, and the vertical up The output of the down counter 16 becomes a control output vertical component which is a symmetrical sawtooth wave with the center point in the vertical direction as a boundary.

Further, by setting the initial value of the horizontal up / down counter 19 as the output of the vertical up / down counter 16, the amplitude of the horizontal sawtooth wave is modulated by the amplitude of the vertical sawtooth wave, and the output of the horizontal up / down counter 19 is obtained. Has a symmetrical sawtooth wave with the center point as a boundary in both horizontal and vertical directions, and has the advantage that a two-dimensional contour compensation gain control waveform can be output. The gain of the contour compensation signal may be controlled in correspondence with the peak value of the sawtooth wave that changes in two dimensions.

Further, according to the above-described embodiment, since the inclinations of the sawtooth wave in the horizontal and vertical directions can be independently changed, the distance from the screen center approximates to the inverse characteristic of the modulation degree of the optical system by the lens or the like. With this, it is possible to generate a control signal in which the gain continuously increases in a rhombus shape, and it is possible to generate a fine two-dimensional contour compensation gain control signal.

In the above-described embodiment, the sawtooth wave as the two-dimensional contour compensation gain control signal is taken as an example, but the vertical and horizontal increments / decrements of the up / down counter are changed not every fixed value but every lock. By changing the clock interval given to the up / down counter with a constant vertical / horizontal increase / decrease value, or by changing both the vertical / horizontal increase / decrease amount and the clock interval given to the up / down counter. Although the amount is increased, it has an advantage that it is possible to obtain a control signal that approximates parabolic shapes of various shapes.

[0042]

The present invention has the following effects, as is apparent from the above-mentioned embodiments.

1. In order to compensate the deterioration of the image sharpness due to the reduction of the modulation degree around the screen of the optical system by the lens or the like, a signal for inversely correcting the modulation degree characteristic is generated to horizontally adjust the gain of the contour compensation signal. , By controlling independently in two dimensions in the vertical direction continuously, it is possible to improve the blurring feeling in the periphery of the screen by a method of amplifying the contour compensation signal, which is natural rather than discrete and has an aspect ratio of 4: 3. It is possible to obtain a high-quality image over the entire screen not only in the broadcasting system described above but also in the wide broadcasting system having an aspect ratio of 16: 9. Furthermore, by changing the setting signal from the central processing circuit, it is possible to easily respond to changes in the modulation characteristics of the optical system due to the lens, etc., increasing the versatility of the target lens and even using low-cost lenses. Can be

2. The vertical up / down counter outputs a control output vertical component which is a symmetrical sawtooth wave with the center point in the vertical direction as a boundary, and further outputs the initial value of the horizontal up / down counter to the vertical up / down counter. By the output, the amplitude of the horizontal sawtooth wave is modulated by the amplitude of the vertical sawtooth wave, and the horizontal up-down counter output is a symmetrical sawtooth wave with the center point as a boundary for both horizontal and vertical directions. Therefore, a two-dimensional contour compensation gain control waveform can be output. The gain of the contour compensation signal may be controlled in correspondence with the peak value of the sawtooth wave that changes in two dimensions. In addition, since the inclination of the sawtooth wave in the horizontal and vertical directions can be independently varied, the gain is continuously and rhombus-shaped as the distance from the screen center approximates to the inverse characteristic of the modulation degree of the optical system by the lens etc. It is possible to generate a control signal that increases, and it is possible to generate a fine two-dimensional contour compensation gain control signal.

As the two-dimensional contour compensation gain control signal, not only the sawtooth wave but also the vertical / horizontal increase / decrease amount of the up / down counter is changed not every constant value but every 1 clock, or the vertical / horizontal increase / decrease amount is changed. By changing the clock interval given to the up / down counter to a constant value, or by changing both the vertical / horizontal increment / decrement amount and the clock interval given to the up / down counter, the parabola of various shapes increases while the circuit amount increases. It is also possible to obtain a control signal that approximates the shape.

In FIG. 1, a single-panel video camera having a solid-state image pickup element is used for description, but the invention is not limited to this configuration, and a multi-plate video camera can be used. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a contour compensating apparatus according to a first embodiment of the present invention.

[Fig. 2] Modulation degree characteristics of typical broadcasting and professional lenses (M
Figure showing TF)

3 is a contour compensation signal addition circuit diagram in which the circuit scale is simplified, which is a part of the block diagram of FIG. 1;

FIG. 4 is a block diagram showing a schematic configuration of a gain control signal generating circuit according to a second embodiment of the present invention.

FIG. 5 is a timing chart diagram for explaining a second embodiment.

FIG. 6 is a diagram showing a two-dimensional contour compensation gain control waveform obtained by the second embodiment.

FIG. 7 is a block diagram showing a schematic configuration of a conventional contour compensation device.

FIG. 8 is a diagram showing a two-dimensional contour compensation gain control waveform obtained by a conventional example.

[Explanation of symbols]

 1 Optical System 2 Imaging Device 3 Analog Process Circuit 4 A / D Converter 5 Digital Process Circuit Group 6 Process Main Line Processing Circuit 7 Contour Compensation Circuit 8 Contour Compensation Signal Addition Circuit 9, 22, 24, 25 Adder 10 Multiplier 11 2 Dimensional contour gain control circuit 12 Central processing circuit (CPU) 13 Decoder 14 Vertical clock frequency dividing circuit 15 Vertical up / down counter control circuit 16 Vertical up / down counter 17 Horizontal clock frequency dividing circuit 18 Horizontal up / down counter control circuit 19 Horizontal up / down counter 20, 21 bit shift 23, 26 selector 27 gate 28 vertical gate generation circuit 29 horizontal gate generation circuit

Claims (2)

[Claims] 1. An optical system including a lens and the like for imaging a copy and an imaging device, an A / D converter for converting the output of the imaging device into a digital signal, and an output of the A / D converter. A process main line processing circuit for digitally processing a signal, a contour compensating circuit for generating a compensation signal for carrying out horizontal and vertical direction contour enhancement on the signal of the process main line processing circuit, and modulation in the periphery of the screen of the optical system. Central processing circuit that sets the shape of the inverse function of the modulation degree characteristic in order to compensate for the deterioration of the image sharpness due to the decrease in the degree of sharpness, and the amplification gain of the contour compensation signal is set horizontally according to the setting signal from the central processing circuit. A two-dimensional contour gain control circuit for continuously controlling two-dimensionally in a vertical direction, and an output signal of the contour compensation circuit according to an output of the two-dimensional contour gain control circuit to amplify the output signal of the contour compensation circuit. And a contour compensation signal adding circuit for adding to the signal of the main line processing circuit. 2. A central processing circuit that sets the waveform of a control signal, a decoder that decodes the setting information of the central processing circuit, and a vertical clock that divides the horizontal synchronizing signal at a division ratio according to the output of the decoder. A frequency divider circuit, a vertical up / down counter whose initial value and vertical increase / decrease amount are designated by the output of the decoder using the output of the vertical clock frequency divider circuit as a clock, and digital processing with a frequency division ratio according to the output of the decoder. A horizontal clock frequency dividing circuit for frequency-dividing a main clock; a horizontal increase / decrease amount is specified by an output of the decoder using an output of the horizontal clock frequency dividing circuit as a clock; and an initial value is specified by an output of the vertical up / down counter. The up / down switching of the horizontal up / down counter and the vertical up / down counter is performed at the center point of one vertical scanning period. A vertical up / down counter control circuit for controlling the stop / start of the counter, and a horizontal up / down counter control circuit for controlling the stop / start of the counter by performing the up / down switching of the horizontal up / down counter at the center point of one horizontal scanning period. And a gain control signal generating circuit for producing a signal for controlling contour compensation gain in two dimensions.