JPH0638541Y2 - Digital processing circuit for television signals - Google Patents

Description

TECHNICAL FIELD The present invention relates to a digital processing circuit for a television signal, which is installed in a television receiver and is used for improving image quality.

2. Description of the Related Art In recent television receivers, it has been considered to provide a digital signal processing circuit for improving the picture quality by installing a remarkable digital signal processing circuit of a high technology level and at a low cost.

In such a typical digital processing circuit, an analog television signal is once converted into a digital signal, and motion adaptive Y / C separation, noise removal, contour enhancement, and motion adaptive scan line interpolation processing are performed. Various digital processes such as (non-interlacing process) are performed, and the processed digital signal is returned to the analog signal and supplied to the display unit in the subsequent stage.

In the motion adaptive Y / C separation circuit, the output of the Y / C separation unit that uses the inter-frame correlation and the output of the Y / C separation unit of the comb filter that uses the inter-line correlation are combined at a variable combination ratio. , This variable composition ratio is dynamically changed according to the magnitude of the motion within the screen.

Further, in the motion adaptive scanning line interpolation circuit, the output of the scanning line interpolation unit by inter-field interpolation and the output of the scanning line interpolation unit using inter-line correlation are combined at a variable combination ratio, and this variable combination ratio is It is dynamically changed according to the size of movement on the screen.

Problems to be Solved by the Invention In the above conventional digital processing circuit, since Y / C separation and scanning line interpolation processing are both realized by motion adaptation, the image quality deteriorates as the movement in the screen increases. There is a problem.

That is, in a still image with no motion, the inter-frame correlation is
Since it is 100%, Y / C separation based on the correlation between frames and scanning line interpolation processing between fields are completely completed, and the best image quality is obtained. Then, as the movement in the screen increases, the weight shifts to the Y / C separation using the correlation between lines and the scanning line interpolation. However, the correlation between lines is
Since a 100% non-patterned screen is practically impossible, both Y / C separation and scanning line interpolation based on this line-to-line correlation are always incomplete. Therefore, as the movement increases, Y / C
There is a problem that the image quality deteriorates both in terms of separation and scanning line interpolation.

Means for Solving Problems A digital signal processing circuit for a television signal according to the present invention includes a motion adaptive digital Y / C separation circuit and a motion adaptive digital scanning line interpolation circuit, as well as a Y / C separation circuit. And a motion adaptive digital contour enhancement circuit for performing contour enhancement processing while increasing the gain on the low frequency side with an increase in the motion of the generated luminance signal.

Action Generally, when motion increases, Y / C separation and scan line interpolation become incomplete, and the resolution in the display screen deteriorates.

According to the present invention, the adaptive digital contour enhancement circuit enhances the contour of the low frequency component as the motion increases, compensating for the deterioration of the resolution due to the motion that occurs in Y / C separation and scanning line interpolation, and the deterioration of the image quality. Is prevented.

Hereinafter, details of the present invention will be described together with embodiments.

Embodiment FIG. 1 is a block diagram showing the configuration of a digital processing circuit for a television signal according to an embodiment of the present invention.

In FIG. 1, IN is an input terminal, 1 is an A / D conversion unit, 2 is a motion detection unit, 3 is a motion adaptive Y / C separation unit, 4 is a motion adaptive contour enhancement unit, 5 is a delay unit, and 6a. , 6b are motion adaptive scanning line interpolation units, 7 is a matrix unit, 8a, 8b, 8c are D / A conversion units, OUT
Is an output terminal.

The analog video signal of the television supplied to the input terminal IN is converted into a digital video signal in the A / D conversion circuit 1 and supplied to the motion detection unit 2 and the motion adaptive Y / C separation unit 3. The motion detection unit 2 supplies the motion detection signal created by detecting the magnitude of motion in the screen based on the change in the video signal between adjacent frames to various processing units that perform motion adaptive processing.

The motion adaptive Y / C separator 3 includes a Y / C separator that uses inter-frame correlation, a comb filter Y / C separator that uses inter-line correlation, and a Y / C separator for each of these Y / C separators. It is composed of a synthesizer that synthesizes the output at a ratio according to the motion signal received from the motion detector 2. This motion adaptive Y / C separation unit 3
While the motion in the screen is small, the luminance signal Y and the color signal C mainly including the components separated by using the inter-frame correlation are output, and the components using the inter-line correlation are increased as the motion increases. .

The motion adaptive contour emphasizing unit 4 is composed of a digital filter having a delay group, a coefficient group and an adder group.
The motion adaptive contour emphasizing unit 4 performs the contour emphasizing process on the separated luminance signal Y output from the motion adaptive Y / C separating unit 3 while increasing the motion and increasing the gain on the low frequency side.

The color signal C output from the motion adaptive Y / C separation unit 3
The contour enhancement processing is omitted for cost performance. For this color signal C, the luminance signal Y
A delay time equal to the contour enhancement processing time for is given by the delay device 5.

The motion-adaptive scanning line interpolator 6a receives a scanning line interpolator using inter-frame correlation, a scanning line interpolator using inter-line correlation, and outputs of these scanning line interpolators from the motion detector 2. And a time axis compressor for interlacing the interpolated signal and the original signal in an interlaced manner on the time axis, and a motion adaptive scanning line for the luminance signal Y. Perform interpolation processing. That is, the motion-adaptive scanning line interpolator 6a outputs the interpolated luminance signal Y mainly composed of the interpolated component created by utilizing the inter-frame correlation while the motion in the screen is small, and increases with the motion. The interpolated luminance signal Y including the interpolated component in which the component using the correlation between lines is increased is output.

Similarly, the motion-adaptive scanning line interpolating unit 6b also includes a scanning line interpolator that uses inter-frame correlation, a scanning line interpolator that uses inter-line correlation, and outputs of these scanning line interpolators to a motion detecting unit. 2 is composed of a synthesizer for synthesizing at a ratio according to the motion signal received from 2 and a time axis compressor for synthesizing the interpolated signal and the original signal in an interlaced manner on the time axis. Scanning line interpolation processing is performed. That is, the motion-adaptive scanning line interpolator 6b outputs the interpolated color signal C mainly composed of the interpolated component created by using the inter-frame correlation while the motion in the screen is small, and increases with the motion. The interpolated color signal C including the interpolated component in which the component using the correlation between lines is increased is output.

The luminance signal Y and the color signal C output from the motion-adaptive scanning line interpolation units 6a and 6b are converted into R, G, B video signals of the three primary colors in the matrix unit 7. The R, G, B digital video signals are converted into R, G, B analog video signals in each of the A / D converters 8a, 8b and 8c,
An analog video signal with improved image quality is supplied from an output terminal O to a display unit in the subsequent stage (not shown).

The timing creation unit 9 extracts the sync signal and the color burst signal included in the analog television signal appearing on the input terminal IN, and the A / D conversion unit 1 to the D / A conversion units 8a, 8b,
The timing signals necessary for the above-described various processes in each unit up to 8c are created and supplied.

FIG. 2 is a block diagram illustrating the configuration of the motion adaptive contour enhancement unit 4 of FIG.

The motion adaptive contour enhancement unit 4 includes a vertical component creation unit 10, a horizontal component creation unit 20, and a synthesis unit 30.

The vertical component generator 10 includes a 1-line delay device 11 connected in cascade.
a, 11b, 11c, 11d, adders 12a, 12b, 12c, and coefficient units 13a, 13
b, 13c and a digital signal supplied to the input terminal I1.
A contour enhancement component in the vertical direction is created from the luminance signal Y, and this is passed to the horizontal component creation unit 20 in the subsequent stage.

The horizontal component creating unit 20 has 1 dot (pixel) connected in cascade.
Delay devices 21a, 21b, 21c, 21d, 21e, 21f and adders 22a, 22b, 22
c, 22d and coefficient units 23a, 23b, 23c, 23d, and a vertical-direction contour enhancement component from a vertical-direction contour enhancement component of the digital / luminance signal Y supplied from the preceding-stage vertical-component creating unit 10 Is created and supplied to the input terminal of the coefficient unit 32 of the combining unit 30.

The combining unit 30 is composed of a delay unit 31, a coefficient unit 32, and an adder 33. The synthesizing unit 30 delays the video signal supplied to the input terminal I ₁ and delayed by two lines in the horizontal component creating unit 10 by the delay unit 31 for the processing time required by the vertical component creating unit 20, and then the adder 33. Supply to one of the input terminals. The other input terminal of the adder 33 is supplied with a contour emphasis signal in the vertical / horizontal direction to which a coefficient value is added via the coefficient multiplier 32. Therefore, the adder 33 outputs a digital / brightness signal with contour enhancement in the vertical / horizontal directions, and supplies the digital / brightness signal via the output terminal O to the subsequent motion adaptive scanning line interpolating unit 6a.

The motion detection signal from the motion detection unit 2 (FIG. 1) is supplied to the input terminal I ₂ of the motion adaptive contour enhancement unit shown in FIG.
This motion detection signal is a coefficient unit 13a in the vertical component creating unit 10.
To 13c and coefficient units 23a to 24d in the horizontal component creating unit 20, the coefficient values are dynamically changed so as to increase the gain on the low frequency side as the motion increases. Further, by changing the coefficient value of the coefficient unit 32 in the synthesizing unit 30 with the manual switch 32a, the degree of contour enhancement can be adjusted by the listener of the television.

Although the configuration in which the contour enhancement is performed in both the vertical and horizontal directions has been illustrated above, the configuration may be performed in which the contour enhancement is performed in the horizontal direction from the viewpoint of cost performance.

Effect of the Invention As described in detail above, the digital processing circuit of the television signal according to the present invention includes the Y / C separation circuit of the motion adaptive type and the digital scanning line interpolation circuit of the motion adaptive type, and By providing a motion adaptive digital contour enhancement circuit that performs contour enhancement processing on the C-separated luminance signal while increasing the gain on the low frequency side as the motion increases, the contour of the low frequency component is enhanced as the motion increases. Since it is a configuration, the deterioration of resolution that occurs in Y / C separation and scan line interpolation with the increase in motion is compensated for by the contour emphasis unit,
Image quality deterioration is effectively prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital processing circuit for a television signal according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a configuration of the motion adaptive contour emphasizing section 4 of FIG. 1 ... A / D conversion unit, 2 ... Motion detection unit, 3 ... Motion adaptive Y / C separation unit, 4 ... Motion adaptive contour enhancement unit, 6a, 6b ...
Motion adaptive scanning line interpolation unit, 7 ... Matrix unit, 8a, 8b,
8c ... D / A converter, 10 ... vertical component creation unit, 20 ... horizontal component creation unit, 30 ... composite unit.

Claims (1)

[Scope of utility model registration request] 1. A motion adaptive digital Y / C separation circuit, a motion adaptive digital scanning line interpolation circuit, and an increase in motion with respect to a luminance signal separated by the motion adaptive digital Y / C separation circuit. A digital processing circuit for a television signal, which further comprises a motion-adaptive digital edge enhancement circuit that performs edge enhancement processing while increasing the gain on the low frequency side.