JPS63224494A - Reduction system for picture-quality disturbance of television signal - Google Patents

Abstract

PURPOSE:To reduce picture-quality disturbance by detecting a stationary and a dynamic area at a front stage where a luminance signal and a color signal are multiplexed, multiplexing a luminance signal Y and a color signal C through prefilters for Y and C in the dynamic area of multiplexing a luminance signal and a color signal which are not passed through both prefilters in the stationary area, and thus outputting composite signals respectively. CONSTITUTION:A comparator 15 compares the absolute value of a frame difference signal with a fixed value nearby zero to output a high-level signal when the absolute value of the frame difference signal is larger than the fixed value or a low-level signal to S terminals of switches 18 and 19 when the absolute value is smaller. Then when the high-level signal is outputted, namely, in a moving area, the luminance signal Y is passed through the prefilter 16 for Y and the color signal C is passed through the filter 7 for C; and they are multiplexed. When the low-level signal is outputted, namely, in the stationary area, both signals are not passed through the prefilters 16 and 17 for Y and C and interframe separation is employed as the Y/C separation of a rear-stage image receiver to prevent the resolution in the stationary area from the deteriorating. Then the Y and C signals are added by an adder 20 and inputted as a composite signal to a D/A converter 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reducing image quality interference of a television signal, which reduces image quality interference caused by multiplexing a color signal of a television signal onto a luminance signal.

[Conventional technology]

FIG. 5 is a block diagram showing a conventional television signal image quality interference reduction method. In the same figure, 1 is R, G, H
2 is a standard television camera that outputs three types of signals, 2 is a luminance signal Y2 which is a matrix conversion of these R, G, and B signals.
a matrix conversion circuit that outputs color signals I and Q;
3 is this color difference signal! and a modulator that inputs a color difference signal Q and performs orthogonal phase modulation with a subcarrier and outputs a color signal C, 4 is a prefilter for Y, 5 is a prefilter for C, 6 is an adder circuit that outputs a composite signal P, and γ is various types. 8 is a transmitter, and 9 is a receiver in each home.

Next, the operation of the television signal image quality interference reduction method with the above configuration will be explained. First, on the imaging side, a color television signal represented by three types of information, R2O and B signals output from a standard television camera 1, is subjected to matrix conversion by a matrix conversion circuit 2 in order to effectively utilize the transmission path band. The luminance signal Y and the color difference signals (2) and (Q) are separated and output. Therefore, the modulator 4 directly phase-modulates the subcarrier using this color difference signal generator and Q, and outputs a color signal C. The luminance signal Y passes through a Y prefilter 4 which is a band elimination filter, removes frequency components leaking to the color circuit on the receiver side, and inputs the signal to an adder circuit 6. On the other hand, the color signal C passes through a C prefilter 5 which is a bandpass filter, removes frequency components leaking to the luminance circuit on the receiver side, and inputs it to an adder circuit 6. Therefore, the luminance signal and color signal input to this adder circuit 6 are made so that there are no overlapping frequency components. Therefore, the adder circuit 6 combines the luminance signal and the color signal and outputs a composite signal P to various systems 7. Then, it is transmitted from the various systems 7 via the transmitter 8 to the receiver 9 of each home. and,
The receiver 9 can separate this and return it to the original R, G, and B signals.

[Problem that the invention seeks to solve]

The above-mentioned conventional image quality interference reduction method for television signals, although it is possible to perform complete KY/C separation without overlapping frequency components by using Y/C separation between frames in the still area of the image, Even in the still area of the image, there is a drawback that the image passes through a Y prefilter and a C prefilter, which causes deterioration in resolution.

[Rounding method to solve problems]

The image quality interference reduction method for television signals of this invention detects static areas and moving areas before multiplexing the luminance signal and color signal, and in the moving area, the luminance signal is passed through a Y prefilter and the C prefilter is detected. A composite signal is output by combining a color signal with a luminance signal that does not pass through a Y prefilter and a color signal that does not pass through a C prefilter in a static area.

[Effect]

The present invention can reduce image quality disturbances caused by multiplexing luminance signals and color signals without degrading the resolution of still areas.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a television signal image quality interference reduction method according to the present invention. In the figure, 101 to 10e are luminance signals Y2 color signals!
11 is a frame memory, 12 is a digital color difference signal processor, and a modulator that inputs Q and outputs a color signal C by orthogonal phase modulation with a subcarrier; 13 is the frame memory. A subtracter that subtracts the digital luminance signal output from the Φ converter 10m from the output signal of 11 and outputs a frame difference signal, 14 is an absolute value circuit that takes the absolute value of this frame difference signal, and 15 is this frame difference. The absolute value of the signal is compared with a fixed value near zero, and if the absolute value of the frame difference signal is larger than the fixed value, a high level signal is output, and if the absolute value of the frame difference signal is smaller than the fixed value, a low level signal is output. The output comparator 16 uses a comb filter to remove components near the subcarrier frequency of the luminance signal Y, as shown in FIG.
IT is a C printer that removes components other than subcarrier frequency components, as shown in the detailed block diagram of FIG. It has an L terminal to which the digital luminance signal Y output from 10m is input, an H terminal to which the output signal of the Y pre-printer 16 is input, and an O terminal which is the output terminal.
A switch 19 is such that when a high level signal is input to the terminal, the signal input to the H terminal is output to the 0 terminal, and when a low level signal is input to the S terminal, the signal input to the L terminal is output to the 0 terminal. an S terminal to which the output signal of the comparator 15 is input; an L terminal to which the color signal C output from the modulator 12 is input; an H terminal to which the output signal of the C prefilter 17 is input;
It has a 0 terminal which is an output terminal, and when a high level signal is input to the S terminal, the signal input to the H terminal is output to the 0 terminal, and when a low level signal is input to the S terminal, the signal input to the L terminal is output. 20 is an adder that adds the luminance signal output from the switch 1B and the color signal C output from the switch 19 to output a composite signal; 21 is an adder that outputs a composite signal; The D/A converter 22 for converting into an analog signal is a receiver equipped with a motion adaptive Y/C separation circuit, a detailed block diagram of which is shown in FIG.

Note that in the Y prefilter 16 shown in FIG.
3 and 23b are IH delay circuits, 24 is an example, t l'
i' 3.58 MHz bandpass filter, 25&
˜25c is an adder. Further, in the C filter 17 shown in FIG. 3, 26a and 26b are IH delay circuits, 2T is a band pass filter of, for example, 3.58 MHz, and 281 and 28b are adders. In the motion adaptive Y/C separation circuit shown in FIG. 4, 29m and 29b are IH delay circuits, 30m and 30b are 1-frame delay circuits, 31a to 31g are adders, 32 is an absolute value circuit, and 33 is a comparison circuit. 34 is, for example, a 3.58 h bandpass filter, and 35a and 35b are switchers.

Next, the operation of the television signal image quality interference reduction method with the above configuration will be explained. First, on the imaging side, R output from the standard television camera 1.

A color television signal represented by 38 types of information such as G and B signals is matrix-converted by a matrix conversion circuit 2 and output to Φ converters 10a to 10c in order to effectively utilize the band of the transmission line. Therefore, the tome converters 10a to 10c each have a luminance signal Y9 color signal! and Q into digital signals. And adder 13
The digital luminance signal is subtracted from the output signal of the frame memory 11, the absolute value of the output frame difference signal is determined by the absolute value circuit 14, and the absolute value of the frame difference signal is output to the comparator 15. On the other hand, the modulator 12 is a digital color difference signal! and Q are orthogonally phase modulated using subcarriers, and a color signal C is output. Then, the comparator 15 compares the absolute value of the frame difference signal with a fixed value near zero, and if the absolute value of the frame difference signal is larger than the fixed value, it outputs a high level signal, and the absolute value of the frame difference signal is fixed. If it is smaller than the value, a low level signal is output to the S terminals of the switches 18 and 19. On the other hand, the Y prefilter 16 removes components near the subcarrier frequency of the digital luminance signal Y and outputs the removed signal to the H terminal of the switch 18. Further, the C prefilter IT removes components other than the subcarrier frequency component of the color signal and outputs the result to the H terminal of the switch 19. Then, the S terminal of the switch 18 and the switch 19
Since the no-repel signal, that is, the frame difference signal, is not zero but in a dynamic region at the S terminal of The color signal which is the output of the C prefilter 17 is output as is. Furthermore, since the low level signal, that is, the frame difference signal, is in the static region close to zero at the S terminal of the switch 18 and the S terminal of the switch 19, there is no signal from the output terminal of the switch 18 to the 0 converter 1.
The luminance signal Y, which is the output at 0 m, is output as is, while the chrominance signal, which is the output of the modulator 12, is output from the output terminal O of the switch 19 until that time. In other words, in the static area, the Y prefilter 16 and the C prefilter 1T
By not allowing the signal to pass through and making the Y/C separation in the subsequent receiver the inter-frame separation, it is possible to prevent the resolution of the still area from deteriorating.

Then, the luminance signal Y and the color signal C are added by an adder 20 and inputted to a D/A converter 21 as a composite signal. Therefore, this D/A converter 21 converts this composite signal into an analog signal, which is then sent out from the transmitter 8 through each of the external systems 7. Then, the original R, G, B
It can be turned back into a signal.

〔Effect of the invention〕

As explained in detail above, according to the television signal image quality interference reduction method according to the present invention, static areas and moving areas are detected before multiplexing the luminance signal and color signal, and in the moving area, the luminance signal is By combining the luminance signal and color signal in the static area without passing through the prefilter, the luminance signal can be synthesized without deteriorating the resolution of the static area. This has the effect of reducing image quality disturbances caused by multiplexing color signals.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the television signal image interference reduction method according to the present invention, FIG. 2 is a detailed block diagram of the Y prefilter shown in FIG. 1, and FIG. A detailed block diagram of the C prefilter, Figure 4 is
FIG. 5 is a block diagram showing a motion adaptive Y/C separation circuit of the television receiver shown in FIG. 5, and FIG. 5 is a block diagram showing a conventional image interference reduction method for a television signal. 1...Standard TV camera, 2...Fist/matrix conversion circuit, T...Various systems, 8...Transmitter, 10&~10a...Φ converter, 11...・Frame memory, 12...Modulator, 13...Adder, 14...Absolute value circuit, 15...Comparator, 1
6...Y prefilter, 1Tφ--C prefilter, 18 and 19...switcher, 20...Φ
Adder, 21, fist...D/A converter, 22...receiver, 23a, 23b, 26m, 28b,
29a and 29b --- IH delay circuit, 24.
27 and 34...Bandpass filter, 25m
, 25b, 28m, 28b, 31a-31
g -@...Adder, 30a and 30b...Fist/1 frame delay circuit, 32...Absolute value circuit, 33...
- Comparator, 35a and 35bφ/φ/switcher.

Claims (1)

[Claims] After removing frequency components near the subcarrier of the color signal included in the luminance signal with a Y prefilter, and removing frequency components that overlap with the luminance signal included in the color signal with a C prefilter, the luminance signal and the color signal are separated. In the image quality interference reduction method for television signals that combines and outputs a composite signal, static areas and moving areas are detected before multiplexing the luminance signal and chrominance signal, and in the moving area, the luminance signal is passed through a Y prefilter to convert it into a chrominance signal. The television is characterized in that a luminance signal that does not pass through a Y prefilter and a chrominance signal that does not pass through a C prefilter are combined in a still area to output a composite signal. Signal image quality interference reduction method.