JP3228091B2 - Video signal contour correction device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a television receiver,
The present invention relates to a video signal contour correction device such as a video tape recorder, a video camera, a video disk, and a video signal transmission device that corrects the contour of a video luminance signal and improves image quality.

[0002]

2. Description of the Related Art In recent years, video signal contour correction apparatuses have been regarded as important in order to improve the image quality by adjusting the contours of video luminance signals that tend to be unclear due to the widening and large screen of color television receivers. Have been.

Hereinafter, an example of the above-described conventional image signal contour correction apparatus will be described with reference to the drawings.

FIG. 6 is a block diagram showing a conventional video signal contour correcting apparatus. In FIG. 6, 1 is the first
And a first-order differentiating circuit for performing a first-order differentiation on the input video luminance signal a. Reference numeral 3 denotes a second primary differentiating circuit, which further performs the primary differential of the primary differential signal b to output a secondary differential signal d. 9
Is a gain control circuit that adjusts the amplitude of the secondary differential signal d according to the correction amount l. Reference numeral 10 denotes a delay circuit that delays the input video luminance signal a and outputs a delayed video luminance signal i. Reference numeral 11 denotes a subtraction circuit, which is a secondary differential signal h whose gain is controlled from the delayed video luminance signal i.
Is subtracted.

The operation of the video signal contour correcting apparatus having the above configuration will be described below with reference to the operation waveform diagram of FIG.

First, an input video luminance signal a is first-order differentiated by a first primary differentiating circuit 1 to obtain a first-order differentiated signal b.
Next, the primary differential signal b is further primary differentiated by the second primary differential circuit 3 to become a secondary differential signal d. The amplitude of the secondary differential signal d is adjusted by the gain control circuit 9 so as to have a desired correction amount l, and a correction signal h is obtained.
Further, the input video luminance signal a is adjusted by the delay circuit 10 so as to match the timing with the correction signal h, and then input to the subtraction circuit 11. The subtraction circuit 11 subtracts the correction signal h from the delayed video luminance signal i to obtain an output video luminance signal j.

[0007]

However, in the above arrangement, the amplitudes of the contours added to the white side and the black side of the video signal are the same, and when the correction amount is increased, blooming occurs on the CRT. However, there has been a problem that the correction effect cannot be sufficiently improved.

In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 6-14694 has been proposed. However, even in this configuration, if the correction on the black side is performed, a black border may be excessively attached to the outline portion, and the image may be difficult to return.

The present invention has been made in view of the above problems, and provides a contour correction circuit characterized in that the black side correction is sufficiently performed while suppressing the amplitude of the white side contour, and the black border can be reduced in the black side correction. Is what you do.

[0010]

In order to solve the above-mentioned problems, a contour correcting apparatus for a video signal according to the present invention includes a full-wave rectifier circuit, an adding circuit, and a first contour correcting apparatus in addition to the conventional contour correcting apparatus shown in FIG. , A second amplifier circuit, a minimum value selection circuit, and a coring circuit.

[0011]

According to the present invention, the full-wave rectified signal of the primary differential signal of the input image luminance signal is added to the secondary differential signal to enhance the black outline, and then the full-wave rectified signal and the minimum value are added. And restrict the black outline. As a result, it is possible to limit the amount of the black-side contour that is pushed into black while emphasizing the black-side contour, and to obtain a sufficient contour-correcting effect while reducing the black border.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an outline of a video signal contour correcting apparatus according to an embodiment of the present invention.

FIG. 1 is a block diagram of a video signal contour correcting apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a first primary differentiator circuit, 2 denotes a coring circuit, 3 denotes a second primary differentiator circuit, 4 denotes a full-wave rectifier circuit, 5 denotes an adder circuit, and 6 denotes a first amplifier circuit. , 7 is the second
, An amplification circuit 8, a minimum value selection circuit 9, a gain control circuit 9, a delay circuit 10, and a subtraction circuit 11.

The operation of the video signal contour correcting apparatus configured as described above will be described below with reference to FIGS.

FIG. 2 shows an operation waveform diagram of the present embodiment. First, an input video luminance signal a is input to a first primary differentiating circuit 1 to obtain a primary differential signal b. The primary differential signal b is input to the coring circuit 2 having input / output characteristics as shown in FIG. 3 and cored according to a preset coring amount k to obtain a coring primary differential signal c. By providing this coring circuit, it is possible to prevent an increase in noise in the output signal by limiting the operation of the present device to a small-amplitude signal containing noise.
The coring primary differential signal c is input to the second primary differential circuit 3 to obtain a secondary differential signal d. At the same time, the coring primary differential signal c is input to the full-wave rectifier circuit 4 and
The next differential signal e is obtained. Next, the full-wave rectified primary differential signal e is passed through a first amplifier to adjust the signal amplitude, and then the addition circuit 5
Is added to the secondary differential signal d. As a result, an asymmetric second derivative signal f having a wide width on the black side (+ side of the signal) and a narrow width on the white side (− side of the signal) is obtained. If correction is performed using this signal, the outline on the black side will be too bordered and the image will be difficult to see. Therefore, in the present outline correction device, the full-wave rectifier whose amplitude is adjusted by the second amplifier circuit 7 is further provided. The primary differential signal and the asymmetric secondary differential signal f are input to the minimum value selection circuit 8 to obtain a corrected asymmetric secondary differential signal g in which the size of the black side contour is limited as shown in FIG. 2g.

Next, the signal g is supplied to the gain control circuit 9.
To adjust the amplitude in accordance with the correction amount l to obtain a signal h.
Further, the input video luminance signal a is delayed by the delay circuit 10 to obtain a delayed input video luminance signal i. Finally, the signal h is subtracted from the signal i by the subtraction circuit 11 to obtain an output video luminance signal j. As shown in FIG. 2, the signal j has a thick outline on the black side and a thin outline on the white side, and the initial target is achieved.

As described above, according to this embodiment, in addition to the conventional contour correction device, a full-wave rectifier circuit, an adder circuit, a first amplifier circuit, a second amplifier circuit, a minimum value selection circuit, and a coring circuit. After adding the full-wave rectified signal of the primary differential signal of the input video luminance signal to the secondary differential signal to emphasize the black outline, the full-wave rectified signal of the primary differential signal and the minimum value are further determined. By limiting the outline on the black side, it is possible to limit the amount of the black side outline that penetrates into black while emphasizing the outline on the black side. It is possible to obtain.

A second embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a block diagram showing a video signal contour correcting apparatus according to a second embodiment of the present invention. 4, the difference between the first embodiment and FIG. 1 is that the coring circuit 2 is arranged between the first primary differentiating circuit 1 and the second primary differentiating circuit 3 in the configuration of FIG. In the present embodiment, what has been described is arranged between the minimum value selection circuit 8 and the gain control circuit 9.

The operation of the video signal contour correcting apparatus configured as described above is the same as the operation of FIG. By moving the arrangement of the coring circuit 2,
In the first embodiment, the coring circuit performs the noise removal in the state of the primary differential signal b, but in the present embodiment, the coring is performed in the state of the corrected asymmetric second differential signal g. The effect of the coring circuit is similar to that of the first embodiment.

As described above, also in this embodiment, in addition to the conventional contour correction device, a full-wave rectifier circuit, an adder circuit, a first amplifier circuit, a second amplifier circuit, a minimum value selection circuit, and a coring circuit are used. After the full-wave rectified signal of the primary differential signal of the input video luminance signal is added to the secondary differential signal to emphasize the contour on the black side, the full-wave rectified signal of the primary differential signal and the minimum value are obtained. By limiting the black-side contour, it is possible to limit the amount of the black-side contour protruding into black while enhancing the black-side contour, and obtain a sufficient contour correction effect while reducing the black border. It becomes possible.

FIG. 5 is a block diagram showing a video signal contour correcting apparatus according to a third embodiment of the present invention. FIG. 5 is different from FIG. 4 of the second embodiment in that:
The second differentiating circuit 12 is used.

The operation of the video signal contour correcting apparatus configured as described above is the same as the operation of FIG. By using the secondary differentiating circuit 12, the secondary differential signal d can be directly obtained. Since the primary differential signal is required for the input of the full-wave rectifier circuit 4,
The second derivative signal c is obtained. For other operations,
This is the same as the embodiment.

As described above, also in this embodiment, in addition to the conventional contour correction device, a full-wave rectifier circuit, an adder circuit, a first amplifier circuit, a second amplifier circuit, a minimum value selection circuit, and a coring circuit are used. After the full-wave rectified signal of the primary differential signal of the input video luminance signal is added to the secondary differential signal to emphasize the contour on the black side, the full-wave rectified signal of the primary differential signal and the minimum value are obtained. By limiting the black-side contour, it is possible to limit the amount of the black-side contour protruding into black while enhancing the black-side contour, and obtain a sufficient contour correction effect while reducing the black border. It becomes possible.

In the first to third embodiments, a coring circuit is provided to prevent noise of an output signal. However, if the noise of the output signal may increase,
The coring circuit can be eliminated.

[0025]

As described above, the present invention includes a full-wave rectifier circuit, an adder circuit, a first amplifier circuit, a second amplifier circuit, a minimum value selection circuit, and a coring circuit in addition to the conventional contour correction device. By providing the configuration, it is possible to limit the amount of the black-side contour that is pushed into black while emphasizing the black-side contour, and to obtain a sufficient contour-correcting effect while reducing the black border. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video signal contour correcting apparatus according to a first embodiment of the present invention;

FIG. 2 is an operation waveform diagram of the image signal contour correction device.

FIG. 3 is an input / output characteristic diagram of a coring circuit of the video signal contour correction device.

FIG. 4 is a block diagram of a video signal contour correcting apparatus according to a second embodiment of the present invention;

FIG. 5 is a block diagram of a video signal contour correcting apparatus according to a third embodiment of the present invention;

FIG. 6 is a block diagram of a conventional image signal contour correction device.

FIG. 7 is an operation waveform diagram of the video signal contour correction device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first primary differentiator circuit 2 coring circuit 3 second primary differentiator circuit 4 full-wave rectifier circuit 5 adder circuit 6 first amplifier circuit 7 second amplifier circuit 8 minimum value selection circuit 9 gain control circuit 10 Delay circuit 11 Subtraction circuit 12 Secondary differentiation circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-14771 (JP, A) JP-A-4-120980 (JP, A) JP-A-2-222268 (JP, A) JP-A-2- 94873 (JP, A) JP-A-4-296171 (JP, A) JP-A-63-125472 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5 / 14-5 / 217

Claims (3)

(57) [Claims] 1. An image luminance signal is input, and this signal is
A first primary differentiating circuit for performing secondary differentiation, a coring circuit connected to an output of the first primary differentiating circuit, for removing a small amplitude component of the primary differential signal, and an output of the coring circuit , A second primary differentiator circuit and a full-wave rectifier circuit, a first amplifier circuit for amplifying the amplitude of the output of the full-wave rectifier circuit with a constant gain, and an output of the full-wave rectifier circuit. A second amplifier circuit for amplifying the amplitude of the signal with a constant gain;
An adding circuit for adding the output of the first amplifying circuit and the output of the second primary differentiating circuit; selecting a smaller value of the output signal of the adding circuit and the output signal of the second amplifying circuit; A gain control circuit for adjusting the amplitude of the output signal of the minimum value selection circuit according to the correction amount;
A video signal contour correction device comprising: a delay circuit for delaying an input video luminance signal; and a subtraction circuit for subtracting an output signal of a gain control circuit from an output signal of the delay circuit. 2. An image luminance signal is input, and this signal is
A first primary differentiating circuit for performing second order differentiation, a second primary differentiating circuit and a full-wave rectifying circuit arranged in parallel with an output of the first primary differentiating circuit, and an output of the full-wave rectifying circuit. A first amplifier circuit for amplifying the amplitude with a constant gain, a second amplifier circuit for amplifying the amplitude of the output of the full-wave rectifier circuit with a constant gain, an output of the first amplifier circuit, and a second amplifier. An addition circuit for adding the output of the next differentiating circuit, a minimum value selection circuit for selecting and outputting the smaller of the output signals of the addition circuit and the second amplifier circuit, and an output of the minimum value selection circuit A coring circuit that removes a component having a small amplitude from the output signal of the minimum value selection circuit, a gain control circuit that adjusts the gain of the output signal of the coring circuit according to the correction amount, and an input video luminance signal. The delay circuit to be delayed and the output of this delay circuit From the signal, the contour correction apparatus of the video signal, characterized in that it comprises a subtraction circuit for subtracting an output signal of the gain control circuit. 3. An image luminance signal is input, and this signal is
A second-order differentiating circuit for performing second-order differentiation, a first-order differentiating circuit for similarly receiving an image luminance signal as input, and performing a first-order differentiation of the signal.
A full-wave rectifier circuit connected to the output of the next differentiator, a first amplifier circuit for amplifying the amplitude of the output of the full-wave rectifier circuit with a constant gain, and a constant gain for the amplitude of the output of the full-wave rectifier circuit. A second amplifier circuit that amplifies the output of the second amplifier circuit, an adder circuit that adds the output of the first amplifier circuit and the output of the second differentiator circuit,
A minimum value selection circuit for selecting and outputting the smaller one of the output signals of the adder circuit and the second amplifier circuit, and a small amplitude signal connected to the output of the minimum value selection circuit, the output signal of the minimum value selection circuit , A gain control circuit that adjusts the gain of the output signal of the coring circuit according to the correction amount, a delay circuit that delays the input video luminance signal, and an output signal of the delay circuit And a subtraction circuit for subtracting an output signal of a gain control circuit from the video signal.