JP2537933B2 - Video signal separation device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for separating a luminance signal and a color signal (hereinafter abbreviated as Y / C separation) used in a video tape recorder or the like.

2. Description of the Related Art In recent years, consumer video tape recorders have been required to have high image quality, and S-VHS and ED beta, which have high Y resolution and have Y / C separated input / output, have been created, and composite signals The importance of Y / C separation equipment for Y / C separation is increasing. Comb shapes and filters are used for Y / C separation,
In some cases, dot interference or cross color may be conspicuous, and it is necessary to determine whether to use a comb filter or a simple bandpass filter by checking the correlation between lines.

Hereinafter, an example of the conventional Y / C separation device described above will be described with reference to the drawings.

FIG. 2 shows a conventional Y / C separation device. In FIG. 2, reference numeral 12 is a bandpass filter that passes the color signal band. 13 is a delay circuit. The length of the delay circuit is 1H for an NTSC signal and 2H for a PAL signal. Reference numeral 14 is an arithmetic circuit, which is an addition circuit. Reference numeral 15 is a selection circuit. 16 is a subtraction circuit. 17 is a circuit that multiplies by 1/2. Reference numeral 18 is a switching circuit. 19 is a subtraction circuit.

The operation of the Y / C separation device configured as described above will be described below with reference to FIG.

The color signal band component of the video signal is separated by the BPF 12, and the first color signal is output. The first color signal is delayed by the delay circuit 13. The first color signal;
The first color signal that has passed through the delay circuit 13 is added by the addition circuit 14, and the subtraction circuit 16 subtracts the first color signal that has passed through the delay circuit 13 from the first color signal, and The value is halved in the multiplication circuit 17. The output of the multiplication circuit 17 becomes the comb filter output of the color signal. The output of the adder circuit 14 is
When the value input to the selection circuit 15 is smaller than a certain value, it is determined that the first color signal and the color signal output from the delay circuit 13 are related to each other, and the output of the switching circuit 18 is output from the multiplication circuit 17. It becomes an output, and this becomes a color signal output. If the value input to the selection circuit 15 is larger than a certain value, it is determined that there is no correlation between the two color signals, and the output of the switching circuit 18 is the first
Is output, and this is the color signal output. The subtraction circuit 19 subtracts the color signal from the video signal, and outputs a luminance signal.

Problems to be Solved by the Invention However, in the above-mentioned configuration, there is a problem in that the component of the vertical line of the high frequency band of Y becomes a color signal, resulting in cross color. Further, if the length of the delay circuit is doubled, various correlation information can be obtained, but there is a problem that the cost is increased accordingly. Even when the Y / C separation was digitally processed, the same problem was encountered.

In view of the above problems, the present invention provides a Y / C separation device that can perform more accurate Y / C separation without increasing the memory.

Means for Solving the Problems In order to solve the above problems, the present invention is a Y / C separation device, an A / D converter for converting a video signal into a digital signal,
The BPF that passes the color signal band from the video signal converted to a digital signal by this A / D converter, and the first delay circuit that delays the first white signal output from the BPF (1H for NTSC signal, A length of 2H in the case of a PAL signal), the first color signal, and the first color signal output from the first delay circuit, and the correlation between the two color signals is calculated. A first arithmetic circuit, and a conversion circuit that converts the result output from the first arithmetic circuit into a correlation value of a certain fixed type,
A second delay circuit (length of 1H for NTSC signal, length of 2H for PAL signal) for delaying the correlation value output from the conversion circuit, and output from the first color signal and the first delay circuit A second arithmetic circuit for halving the difference from the first color signal, and outputs either the second color signal output from the second arithmetic circuit or the first color signal. A switching circuit; a selection circuit for determining which of the switching circuits should be output from the correlation value output from the conversion circuit and the correlation value output from the second delay circuit; The output signal is the third color signal, the video signal minus the third color signal is the luminance signal output, and the third color signal is the color signal output.

Action According to the present invention, the video signal is converted into a digital signal by the A / D converter with the above-described configuration. The video signal converted into the digital signal passes through the BPF that passes the color signal band, and the first color signal is output. The first color signal is input to a first delay circuit, and the first color signal and the first color signal output from the first delay circuit are input to a first arithmetic circuit, The sum is calculated and then the first
The output of the arithmetic circuit is input to a conversion circuit that converts a certain type of correlation value. The output from the conversion circuit is delayed by the second delay circuit. Based on the output of the conversion circuit and the output of the conversion circuit output from the second delay circuit, it is determined whether to output a comb filter or simply use BPF as a color signal output. The luminance signal is obtained by subtracting the output color signal from the original video signal.

Examples Regarding the Y / C separation device which is one example of the present invention,
This will be described with reference to the drawings. FIG. 1 shows a Y / C separation device in an embodiment of the present invention.

In FIG. 1, 1 is an A / D converter, 2 is BPF, 3 is a first delay circuit, 4 is an adder, 5 is a conversion circuit, and 6 is
Second delay circuit, 7 is a subtractor, 8 is a multiplier, 9 is
The selection circuit, 10 is a switching circuit, and 11 is a subtractor.

The operation of the Y / C separation device configured as described above will be described below with reference to FIG.

The video signal is converted into a digital signal by the A / D converter 1. The video signal converted into the digital signal passes through BPF2 and the color signal component is extracted. The output of BPF2 is input to the first delay circuit 3. From the output of BPF2, the output of the first delay circuit 3 is subtracted by the subtractor 7 and halved by the multiplier 8 to become a comb filter component. Also BPF
The output of 2 and the output of the first delay circuit 3 are added by the adder 4 to obtain a correlation output signal. The output of the adder 4 is converted by the conversion circuit 5 into two types of correlation information (with and without correlation). The output of the conversion circuit 5 is input to the second delay circuit 6 and delayed.

The output of the conversion circuit 5 and the output of the second delay circuit 6 are input to the selection circuit 9, and here it is determined whether the comb filter output or the simple BPF output is output as the color signal output. To do. If the output of the conversion circuit 5 has a correlation, it is determined that the output of the BPF2 and the output of the first delay circuit have a correlation, and the output of the multiplier 8, that is, the comb filter output is used as the color signal output. When the output of the conversion circuit 5 is uncorrelated and the output of the second delay circuit is uncorrelated, it is determined that there is a high frequency component of Y, and the comb filter output is used as the color signal output. When the output of the conversion circuit 5 is uncorrelated and the output of the second delay circuit is correlated, it is determined that the output of BPF2 and the output of the first delay circuit are not correlated, and the output of BPF2 is output. Is the color signal output. The luminance signal is obtained by subtracting the color signal from the video signal by the subtracter 11.

As described above, according to this embodiment, when Y / C separating the A / D converted and digitized video signal, the correlation information between the original signal and the delayed signal is stored. Then, by using the information later, it is possible to detect the presence or absence of correlation more accurately, and there is almost no increase in memory.

As described above, according to the present invention, since only the correlation information between the original signal and the delayed signal is extracted and delayed, the amount of memory for delay can be small, and It is possible to obtain excellent effects such as a more accurate Y / C separation accuracy and a Y / C separation device.

[Brief description of drawings]

FIG. 1 is a block diagram showing a Y / C separation device in an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional Y / C separation device. 1 ... A / D converter, 2 ... BPF, 3 ... first delay circuit,
4 ... Adder, 5 ... Conversion circuit, 6 ... Second delay circuit, 7 ... Subtractor, 8 ... Multiplier, 9 ... Selection circuit, 10
...... Switching circuit, 11 …… Subtraction circuit, 12 …… BPF, 13 …… Delay circuit, 14 …… Addition circuit, 15 …… Selection circuit, 16 …… Subtraction circuit, 17 …… Multiplication circuit, 18 ・ ・ ・… Switching circuit, 19… Subtraction circuit.

Claims (3)

(57) [Claims] 1. An analog / digital converter for converting a video signal into a digital signal, a band pass filter for passing a color signal region from the video signal converted into a digital signal by the analog / digital converter, and a band pass filter. A first delay circuit for delaying the first color signal output from the first color signal by n (n is an integer) horizontal period; and the first color signal and the first color signal output from the first delay circuit. A first arithmetic circuit that calculates the difference between the two color signals by taking the sum; a conversion circuit that converts the result output from the first arithmetic circuit into a correlation value of a certain type; and the conversion circuit From a second delay circuit that delays the correlation value output from the second delay circuit by m (m is an integer) horizontal period, and a difference between the first color signal and the first color signal output from the first delay circuit. 1 /
2) a second arithmetic circuit, a second color signal output from the second arithmetic circuit, and a switching circuit for outputting either the first color signal or the output of the switching circuit. A selection circuit that determines whether or not the correlation value output from the conversion circuit and the correlation value output from the second delay circuit, and the signal output from the switching circuit is the third color signal. A video signal separation device, wherein a signal obtained by subtracting the third color signal from the video signal is used as a luminance signal output and the third color signal is used as a color signal output. 2. The length of the first delay circuit is one horizontal period, the length of the second delay circuit is one horizontal period, and the correlation values output from the conversion circuit are correlated and non-correlated. When the output of the conversion circuit is correlated or the output of the conversion circuit is uncorrelated and the output of the second delay circuit is uncorrelated, the second color signal is selected and converted. The first color signal is selected when the output of the circuit is uncorrelated and the output of the second delay circuit is correlated.
The video signal separation device according to the item. 3. The length of the first delay circuit is 2 horizontal periods, the length of the second delay circuit is 2 horizontal periods, and the correlation value output from the conversion circuit has correlation and non-correlation. , And the output of the conversion circuit is uncorrelated and the output of the second delay circuit is uncorrelated, the second color signal 2. The image according to claim 1, wherein the first color signal is selected when the output of the conversion circuit is uncorrelated and the output of the second delay circuit is correlated. Signal separation device.