JPH01195793A - Television receiver - Google Patents

Abstract

PURPOSE:To obtain an excellent display picture even at changeover of a still picture and a moving picture by detecting the movement based on an inter-frame difference signal in a noise reduction circuit and controlling the scanning line interpolation system in response to its detection signal. CONSTITUTION:A movement detection circuit 3 inputs at least one inter-frame difference signal as to a luminance signal or a demodulation color signal in a noise reduction circuit 1 to detect the movement and gives its detection signal to a scanning line interpolation circuit 2. The scanning line interpolation circuit 2, based on the detection signal, controls the scanning line interpolation of the luminance signal or the demodulation color signal corresponding to the detection signal adaptively. Thus, the scanning line interpolation is applied adaptive to the movement in response to the movement detection signal nearly coincident with the time base of the signal processed by the scanning line interpolation circuit thereby improving the display quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a television receiver, and is particularly suitable for application to a television receiver equipped with a noise reduction circuit and a scanning line interpolation circuit.

BACKGROUND ART Recently, a so-called IDTV has been proposed that uses digital processing technology to improve the image quality of a television receiver.

In such IDTV, S/N is determined by utilizing the frame correlation of television signals, that is, by utilizing the fact that when television signals that differ by one frame are added together, the signal component becomes larger than the noise component. A noise reduction circuit is provided to improve the ratio.

In addition, in order to increase the vertical resolution of a displayed image by converting an input television signal into a non-interlaced television signal with double the number of scanning lines, we also provide a scanning line interpolation circuit that doubles the number of scanning lines, and a post-interpolation circuit that doubles the number of scanning lines. A time base compression circuit is provided that compresses the time base of the television signal to 1/2.

Here, regarding scanning line interpolation, when the television signal is a still image, an interfield interpolation method in which the television signal one field before is used as the interpolation signal is good for improving vertical resolution; When interpolating a video using the interpolation method, scanning line interpolation will actually reduce the image quality, so when a video is input,
An inter-line interpolation method is applied in which interpolation is performed using the average value of the lines above and below the line of interest in the same field.

The motion detection signal for switching the scanning line interpolation method is Y/C, which separates the luminance signal and chroma signal from the composite video signal using a separation method adapted to the motion.
A detection signal from a motion detection circuit was used which provided a motion detection signal to a separation circuit.

[Problems to be solved by the invention] By the way, such a motion detection circuit is
The signal is for motion adaptive control of the Y/C separation circuit, and the time axis of the motion detection signal from the motion detection circuit and the time axis of the signal processed by the Y/C separation circuit coincide.

However, after being separated in the Y/C separation circuit, the luminance signal undergoes processing such as contrast adjustment in the Y/C processing circuit, and is further reduced in noise by the above-mentioned noise reduction circuit and then sent to the scanning line interpolation circuit. The color signal is subjected to processing such as ACC processing and color demodulation in the Y/C processing circuit, and then the noise is reduced in the above-mentioned noise reduction circuit and provided to the scanning line interpolation circuit. Therefore, the time axis of the signal subjected to scanning line interpolation by the scanning line interpolation circuit and the time axis of the motion detection signal given from the motion detection circuit to the scanning line interpolation circuit are significantly different. When switching from an image to a still image, scanning line interpolation was not performed properly, and the vertical resolution of the image quality was disturbed for a short time.

The present invention has been made in consideration of the above points, and is a television receiver capable of executing scanning line interpolation in accordance with movement without reducing vertical resolution even when switching between still images and moving images. The aim is to provide an opportunity.

[Means for Solving the Problem] In order to solve the problem, in the present invention, a luminance signal and a demodulated color signal are input to obtain respective inter-frame difference signals, and input is performed based on these inter-frame difference signals. In a television receiver equipped with a noise reduction circuit that reduces the noise component of the incoming luminance signal and demodulated color signal, and a scanning line interpolation circuit that doubles the number of scanning lines of the incoming luminance signal and demodulated color signal, a motion detection circuit that performs motion detection by inputting an interframe difference signal of at least one of the luminance signal and the demodulated color signal in the reduction circuit;
In response to the detection signal of the motion detection circuit, the scanning line interpolation circuit performs scanning line interpolation of the luminance signal or the demodulated color signal corresponding to the detection signal in accordance with the motion.

[Operation] The motion detection circuit receives an interframe difference signal of at least one of the luminance signal or the demodulated color signal in the noise reduction circuit, detects motion, and provides the detection signal to the scanning line interpolation circuit. Based on this detection signal, the scanning line interpolation circuit controls scanning line interpolation of a luminance signal or a demodulated color signal corresponding to the detection signal in accordance with the movement.

As a result, motion-adaptive scanning line interpolation can be performed in accordance with the motion detection signal that substantially coincides with the time axis of the signal processed by the scanning line interpolation circuit, and display quality can be improved.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In the figure, the noise reduction circuit 1 includes a Y/C processing circuit (
Luminance signal Y1 that has been subjected to contrast adjustment etc. (not shown) and color difference signal C obtained after processing such as color demodulation
1 is given. The noise reduction circuit 1 receives these signals Y1
and C1, and provide the reduced luminance signal Y2 and color difference signal C2 to the scanning line interpolation circuit 2. The scanning line interpolation circuit 2 also receives a motion detection signal S1 from the motion detection circuit 3.
and S2 are given, and these motion detection signals S1 and S2
The scanning line interpolation signals Y3 and C3 of the input luminance signal ¥2 and color difference signal C2 are formed in accordance with the input signals Y2 and C2, and outputted to a time axis compression circuit (not shown) together with the input signals Y2 and C2 described above.

Next, the detailed configuration of each circuit 1 to 3 will be explained.

The noise reduction circuit 1 is constructed of a so-called frame cyclic type. In this noise reduction circuit 1, the input luminance signal Y1 is given to a subtraction circuit 11.

The subtraction circuit 11 subtracts a noise component ΔY1 of the luminance signal, which will be described later, from the luminance signal Y1 to reduce the noise component, and obtains a luminance signal Y2 with an improved S/N ratio. The signal is applied to a one-frame delay circuit 12 having a frame memory configuration.

The luminance signal Y4 delayed through this delay circuit 12 is given to a subtraction circuit 13 as a subtraction input.

The above-mentioned input luminance signal Y1 is given to the subtraction circuit 13 as an input to be subtracted, and the subtraction circuit 13 obtains a difference signal ΔY between these luminance signals Y2 and Y4 and outputs it to the variable coefficient circuit 1.
Give to 4. The variable coefficient circuit 14 is formed of, for example, a conversion table configured in a ROM, and according to the input difference signal ΔY, obtains a noise component ΔY1 obtained by multiplying the signal ΔY by a predetermined value and supplies the obtained noise component ΔY1 to the above-mentioned subtraction circuit 11.

In this way, the subtraction circuit obtains an inter-frame difference signal ΔY between the input luminance signal Y1 and the luminance signal ¥4 obtained by weighting and combining the luminance signals of the past several frames, and this signal Δ
The noise component ΔY1 is obtained based on Y, and the input luminance signal Y1 is
The noise component is reduced by subtracting it from .

The noise reduction circuit 1 has the same noise reduction configuration for the color difference signal C1 as for the luminance signal Y1. That is, it has a configuration consisting of a subtraction circuit 15, a frame delay circuit 16, a subtraction circuit 17, and a variable coefficient circuit 18. In addition,
A description of the configurations of these circuits 15 to 18 will be omitted.

The luminance signal Y2 and color difference signal C2 whose noise has been reduced in this way are provided to the scanning line interpolation circuit 2. The scanning line interpolation circuit 2 receives the input luminance signal Y2 and color difference signal C.
2 is output as is as the original signal.

In this scanning line interpolation circuit 2, the input luminance signal Y2 is
1 field delay circuit 21 with field memory configuration, average value circuit 22 with addition circuit configuration, and 1 field delay circuit 21 with line memory configuration
The signal is applied to the line delay circuit 23. The one-field delay circuit 21 delays the input luminance signal Y2 by one field, forms an interpolated signal Y5 just before the original signal Y2 according to the interfield interpolation method, and outputs it to the synthesis circuit 24. Further, the one-line delay circuit 23 obtains a luminance signal Y6 delayed by one line from the luminance signal Y2, and supplies it to the average value circuit 22. The average value circuit 22 receives the incoming luminance signals Y2 and Y6.
The synthesis circuit 24 obtains the average value signal Y7 and uses that signal as an interpolated signal immediately before the original signal Y2 according to the interline interpolation method.
Output to. The synthesis circuit 24 generates the above-mentioned interpolated luminance signal Y.
5 and Y7 at a ratio specified by the motion detection signals S1 and S2 to finally obtain an interpolation signal Y3 and output it to the next stage time axis compression circuit.

On the other hand, in this scanning line interpolation circuit 2, the input color difference signal C
2 is applied to an average value circuit 25 having an adder circuit configuration and a 1-line delay circuit 26 having a line memory configuration. The one-line delay circuit 26 obtains a color difference signal C5 delayed by one line from the color difference signal C2, and supplies it to the average value circuit 25. The average value circuit 25 obtains an average value signal C3 of the incoming color difference signals C2 and C5, and outputs this signal to the time base compression circuit as an interpolated signal immediately before the original signal C2 according to the interline interpolation method.

Therefore, in this embodiment, scanning line interpolation adapted to the movement of the television signal is performed only on the luminance signal.

The motion detection circuit 3 is provided with the inter-frame difference signal ΔY output from the subtraction circuit 13 of the noise reduction circuit 1 described above. The motion detection circuit 3 includes a low-pass filter 30, an absolute value circuit 31, and a coefficient setting circuit 32.
The high-frequency noise component is removed through the low-pass filter 30 to prevent motion detection errors due to this noise component, and the absolute value of the difference signal from which the high-frequency noise component has been removed is Absolute value circuit 31
Further, the coefficient setting circuit 32 obtains the cumulative value of these absolute value signals AB over a predetermined period, and outputs motion detection signals S1 and S2 according to the cumulative value.

Here, the coefficient setting circuit 32 provides the synthesis circuit 24 with motion detection signals S1 and S2 that output the interpolation signal Y5 as is when the cumulative value is very small and can be reliably determined to be a still image. When the motion detection signals S1 and S2 are very large and can be reliably determined to be a moving image, the motion detection signals S1 and S2 are supplied to the synthesis circuit 24 so as to output the interpolated signal Y7 as is, and when the cumulative value is in the middle, the interpolated signals Y7 and Y5 are output.
The motion detection signals S1 and S2 are supplied to the synthesis circuit 24 so that the motion detection signals S1 and S2 are synthesized at a ratio determined depending on whether the images are closer to a still image or a moving image.

Note that in order to detect motion, a three-dimensional difference between television signals is required, and in this embodiment, the difference signal is obtained by the subtraction circuit 13, so in this sense it is a 1-frame delay circuit. 12 and the subtraction circuit 13 constitute a part of the motion detection circuit 3.

In the above configuration, input luminance signal ¥1 and color difference signal C
1 has its noise reduced by a frame cyclic noise reduction circuit 1 and is supplied to a scanning line interpolation circuit 2 . The difference signal ΔY between the input luminance signal Y1 obtained in the processing system of the noise reduction circuit 1 and the past luminance signal information Y4 is given to the motion detection circuit 3, and the motion detection circuit 3 converts the motion detection signals S1 and S2. can get.

The scanning line interpolation circuit 2 forms a scanning line interpolation signal C3 from the color difference signal C2 applied to the scanning line interpolation circuit 2, and outputs it to the time axis compression circuit regardless of the motion detection signals S1 and S2. On the other hand, from the luminance signal Y2, an interpolation signal Y7 according to the interfield interpolation method and an interpolation signal Y5 according to the interline interpolation method are formed in the scanning line interpolation circuit 2, and these interpolation signals Y7 and Y5 are generated by the synthesis circuit 24 into the motion detection signal S1 and The signals are synthesized at a synthesis ratio determined according to S2 and output to the time axis compression circuit as an interpolation signal Y3.

Therefore, according to the embodiment described above, the motion detection signal for switching the scanning line interpolation method in accordance with the motion is formed by a signal whose time axis is not significantly different from the time axis of the signal given to the scanning line interpolation circuit. Therefore, it is possible to prevent the image quality from deteriorating when switching the scanning line interpolation method due to the difference in the time axis. In this case, since a part of the noise reduction circuit 1 is used as a part of the motion detection circuit for obtaining such a motion detection signal, the configuration is not particularly complicated.

In the above-described embodiment, the scanning line interpolation method is switched in accordance with motion only for the luminance signal, but motion detection is also performed for the chrominance signal using a part of the configuration of the noise reduction circuit 1. The scanning line interpolation method may be controlled in accordance with the motion.

In addition, in the above-mentioned embodiment, an application is shown to a television receiver in which the signal obtained by color demodulation is a color difference signal, but the signal obtained by color demodulation is a color signal according to the ■ axis and the Q axis. It can also be applied to television receivers.

[Effects of the Invention] As described above, according to the present invention, motion is detected based on the interframe difference signal in the noise reduction circuit, and the scanning line interpolation method is controlled according to the detection signal. With this configuration, the scanning line interpolation method can be controlled using a motion detection signal that has a small difference in time axis from the original signal for scanning line interpolation, and a good display image can be achieved even when switching between still images and moving images. Obtainable.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of a television receiver according to the present invention. 1... Noise reduction circuit, 2... Scanning line interpolation circuit, 3
...Motion detection circuit, 11.13...Subtraction circuit, 12
...1 frame delay circuit, 21...1 field delay circuit, 22...average value circuit, 23...1 line delay circuit, 24...combining circuit, 31...absolute value circuit,
32...Coefficient setting circuit.

Claims (1)

[Claims] A luminance signal and a demodulated color signal are input to obtain respective inter-frame difference signals, and noise components of the input luminance signal and demodulated color signal are reduced based on these inter-frame difference signals. In a television receiver equipped with a noise reduction circuit and a scanning line interpolation circuit that doubles the number of scanning lines of an incoming luminance signal and a demodulated color signal, at least one of the luminance signal or the demodulated color signal in the noise reduction circuit is A motion detection circuit is provided that performs motion detection by inputting the inter-frame difference signal, and in response to the detection signal of the motion detection circuit, the scanning line interpolation circuit detects the scanning line of the luminance signal or demodulated color signal corresponding to the detection signal. A television receiver characterized in that interpolation is performed adaptively to movement.