JPH04309088A - Yc separation circuit - Google Patents

Abstract

PURPOSE:To solve unnaturality of a picture and to realize the YC separator circuit with an excellent characteristic by selecting an output of an in-field color separation circuit or an output of an in-frame color separation circuit stepwise. CONSTITUTION:A mixer circuit 6 is provided with acyclic filters 10, 11 and a coefficient circuit 12 as its internal constitution and receives a 1-bit movement detection signal being an output of a movement detection circuit 3 and obtains an output of the acyclic filters 10, 11 and the coefficient circuit 12. A coefficient generator 13 generates a mixed coefficient changing stepwise. The output of the coefficient generator 13 is used to mix the outputs of the in-field color separation circuit 4 and the in-frame color separation circuit 5 and the result is outputted from a terminal 8 as a color signal. Moreover, the color signal is subtracted from an original video signal at a subtractor 7 and a luminance signal is obtained and outputted from a terminal 9. Through the constitution above, natural YC separation is implemented even with respect to a picture having a slow movement.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a YC separation circuit that can be used in a device that separates a composite video signal into a luminance signal and a color signal and then displays or records a color video signal. It is related to.

0002

[Background Art] In recent years, with the development of digital technology, it has become possible for YC separation circuits to utilize a large amount of semiconductor memory, and motion-adaptive YC separation circuits that perform interframe processing depending on the presence or absence of movement are being used. be.

A conventional YC separation circuit is disclosed in, for example, Japanese Patent Laid-Open No. 37191/1983.

A conventional YC separation circuit will be explained below. FIG. 3 is a block diagram showing the configuration of this conventional YC separation circuit. The operation will be explained below with reference to FIG.

A digital video signal input from terminal 101 is input to frame memory 102 and is delayed by one frame time. The input signal from the terminal 101 and the output from the frame memory 102 are input to a motion detection circuit 103, which detects "motion" based on the difference between one frame and outputs it as a motion detection signal.

On the other hand, the input signal from the terminal 101 is input to the intra-field color separation circuit 104. In the intra-field color separation circuit 104, color signals are separated by intra-field processing and output to the switch 106.

[0007] Furthermore, the input signal from the terminal 101 is transmitted to a frame memory 102, a subtracter 110, and a coefficient circuit 111.
The color signals are separated by an interframe color separation circuit 105 consisting of the following, and inputted to a switch 106. This interframe color separation circuit 105 is generally referred to as a frame comb filter.

The output of the intra-field color separation circuit 104 input to the switch 106 and the inter-frame color separation circuit 105
The output is selected by the motion detection signal that is the output of the motion detection circuit 103, and is output from the terminal 108 as a color signal. The selection of the output signal at this switch 106 is as follows:
If the motion detection circuit 103 determines that the image is "moving," the output of the intra-field color separation circuit 104 is selected, and if the image is determined to be "still," the output of the inter-frame color separation circuit 105 is selected.

The output of the switch 106 is input to a subtracter 107, subtracted from the composite video signal which is the input signal from the terminal 101, and outputted from the terminal 109 as a luminance signal.

0010

However, in the above-mentioned conventional configuration, the output of the intra-field color separation circuit 104 and the output of the inter-frame color separation circuit 105 are switched by the switch 106, so that it is difficult to detect images with slow movement. has the problem that unnaturalness occurs at the switching point.

[0011] The present invention solves the above-mentioned conventional problems, and although a 1-bit control signal is used to control the output of the intra-field color separation circuit and the output of the inter-frame color separation circuit, It is an object of the present invention to provide a YC separation circuit that can perform stepwise mixing.

0012

[Means for Solving the Problems] In order to achieve this object, the YC separation circuit of the present invention uses a frame memory that delays an input digital signal by one frame time, and detects movement from the input and output signals of the frame memory. an intra-field color separation circuit that separates color signals through intra-field processing, and an inter-frame color separation circuit that separates color signals using a frame comb filter; A mixing circuit that outputs a color signal by stepwise mixing the output of the intra-field color separation circuit and the output of the inter-frame color separation circuit using a 1-bit motion detection signal, and a video signal based on the color signal of the mixing circuit. Subtract from
The configuration includes a subtracter that outputs a luminance signal.

[0013]

[Operation] According to the above-described configuration, the motion detection signal of the motion detection circuit has a stepwise change at the switching point by passing it through two acyclic filters and a coefficient circuit that are internal components of the mixing circuit. Since the motion detection signal is a 1-bit motion detection signal, the output of the intra-field color separation circuit and the output of the inter-frame color separation circuit can be switched in stages.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a YC separation circuit in one embodiment of the present invention. The operation will be explained below with reference to FIG.

A digital video signal is input from terminal 1. A digital video signal input from terminal 1 is input to frame memory 2 and is delayed by one frame time. The input signal from the terminal 1 and the output from the frame memory 2 are input to a motion detection circuit 3, which detects motion based on the difference between one frame and outputs it to the mixer 6 as a 1-bit motion detection signal.

On the other hand, the input signal from the terminal 1 is input to the intra-field color separation circuit 4. In this intra-field color separation circuit 4, color signals are separated by intra-field processing and output to a mixing circuit 6.

The input signal from the terminal 1 is separated into color signals by an interframe color separation circuit 5 comprising a frame memory 2, a subtracter 14, and a coefficient circuit 15, and is input to a mixing circuit 6. This inter-frame color separation circuit 5 is generally referred to as a frame comb filter.

The output of the intra-field color separation circuit 4 and the output of the inter-frame color separation circuit 5, which are input to the mixing circuit 6, are mixed by the motion detection signal output from the motion detection circuit 3 and output as a color signal. The operation of this mixing circuit 6 will be explained below.

The output of the motion detection circuit 3 is input to an acyclic filter 10 which is an internal component of the mixing circuit 6. This acyclic filter 10 includes delay elements 16, 17, 18
, coefficient circuits 22 and 23, and an adder 26. The output of this acyclic filter 10 is input to a coefficient generator 13 as a signal having levels of 0 to 8.

Furthermore, the output of the delay element 18 is transmitted to the coefficient circuit 12.
is input to the coefficient generator 13 as a signal having a level of 0 or 8.

Furthermore, the output of the delay element 18 is input to the acyclic filter 11. This acyclic filter 11 consists of delay elements 19, 20, 21, coefficient circuits 24, 25, and an adder 27, and like the acyclic filter 10, its output generates coefficients as a signal having levels of 0 to 8. The signal is input to the device 13.

In the coefficient generator 13, the maximum value of the outputs of the coefficient circuit 12 and the acyclic filters 10, 11 is selected, 1/8 of the maximum value is set as k, and the mixing coefficients k and 1-k are respectively applied to the multiplier 30, Output to 31.

The operation of the mixing circuit 6 will be supplementarily explained below using the signal waveform diagram shown in FIG. The output of the motion detection circuit 3 is n3, and the delay elements 16, 17, 18, 19, 20, 21
The outputs of n2, n1, n0, n-1, n-2,
Let it be n-3. If the output of the acyclic filter 10 is N1, then N1=n3+3・n2+3・n1+n0,
The output N2 of the acyclic filter 11 is N2=n0+3・
It becomes n-1+3, n-2+n-3. Also, coefficient circuit 1
The output N3 of 2 becomes N3=8·n0.

Here, FIG. 2(a) shows the output of the motion detection circuit 3, and "1" represents the output determined to be motion. Now, if time is t0, n3=1, and the rest is "0", so the outputs N1, N2, N3 of the acyclic filters 10, 11 and the coefficient circuit 12 are N1=1 N2=0 N3=0, respectively. and is input to the coefficient generator 13. Coefficient generator 13
First, take the maximum value of N1 to N3. The maximum value is N
1 of 1, and 1/8 of this is the mixing coefficient k. Therefore, the coefficient generator 13 outputs k=1/8 and 1-k=7/8. Similarly, considering t1, t2,..., the coefficient k becomes an output as shown in Figure 2(b), and Figure 2
In (a), the area determined to be "movement" (the area where "1" is output) is saved, and the mixing ratio changes stepwise at the switching point.

Here, as can be seen from FIG. 2, the outputs k, 1-k of the coefficient generator 13 are delayed with respect to the output of the motion detection circuit 3. Therefore, delay circuits 28 and 29 are used to correct this delay. That is, the output of the intra-field color separation circuit 4 is sent to the delay circuit 2 in the mixing circuit 6.
After adjusting the timing, the signal is input to the multiplier 30. Then, after multiplying by k in a multiplier 30, an adder 3
Enter 2. Similarly, the output of the interframe color separation circuit 5 is input to the delay circuit 29, which is an internal component of the mixing circuit 6, and after adjusting the timing, is input to the multiplier 31. Then, the multiplier 31 multiplies it by 1-k, and the adder 32
is input. In the adder 32, multipliers 30, 31
The outputs of the two are added together and outputted from the terminal 8 as a separated color signal.

Further, the color signal output from the adder 32 is input to the subtracter 7, where the composite video signal, which is the input signal from the terminal 1, is subtracted from the signal after timing adjustment in the delay circuit 33, and separated. The luminance signal is output from terminal 9 as a luminance signal.

As described above, according to this embodiment, the two acyclic filters 10 and 10 are used as internal components of the mixing circuit 6.
11 and the coefficient circuit 12, it is possible to obtain a color signal while varying the mixing ratio stepwise even though it is a 1-bit motion detection signal.

In this embodiment, the number of taps of the acyclic filters 10 and 11 is 4, and the coefficient of the coefficient circuit 12 is 8. is stored, and the coefficient generator 13
If the output of
Other values may be used for the coefficients.

[0030]

As described above, the present invention detects motion using a frame memory that delays an input digital signal by one frame time, and the input signal and output signal of the frame memory, and outputs a 1-bit motion detection signal. a motion detection circuit;
An intra-field color separation circuit that separates color signals through intra-field processing, an inter-frame color separation circuit that separates color signals using a frame comb filter, and a 1-bit motion detection signal that separates the output of the intra-field color separation circuit and the frame. By providing a mixing circuit that mixes the output of the intercolor separation circuit in stages and outputs a color signal, and a subtracter that subtracts the color signal of the mixing circuit from the original video signal and outputs a luminance signal. , it is possible to obtain good separation characteristics even for slowly moving pictures.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a YC separation circuit in an embodiment of the present invention.

[Fig. 2] Signal waveform diagram used to explain the operation of the mixing circuit 6 in the same embodiment.

[Figure 3] Block diagram showing the configuration of a conventional YC separation circuit

[Explanation of symbols]

2 Frame memory 3 Motion detection circuit 4 In-field color separation circuit 5. Inter-frame color separation circuit 6 Mixed circuit 7, 14 Subtractor 10, 11 Acyclic filter 12, 15, 22-25 Coefficient circuit 13 Coefficient generator 16-21 Delay element 26, 27, 32 Adder 28, 29, 33 Delay circuit

Claims (2)

[Claims] 1. A frame memory that delays an input digital signal by one frame time, a motion detection circuit that detects motion based on the input signal and output signal of the frame memory, and outputs a 1-bit motion detection signal; an in-field color separation circuit that separates color signals by processing;
an inter-frame color separation circuit that separates color signals using a frame comb filter, and stepwise mixing of the output of the intra-field color separation circuit and the output of the inter-frame color separation circuit using the 1-bit motion detection signal. A YC comprising a mixing circuit that outputs a color signal, and a subtracter that subtracts the color signal of the mixing circuit from an original video signal and outputs a luminance signal.
Separation circuit. 2. The mixing circuit includes two acyclic filters that process a 1-bit motion detection signal, a coefficient circuit that multiplies the 1-bit motion detection signal by a coefficient, and outputs of the two acyclic filters. 2. The YC separation circuit according to claim 1, further comprising: a coefficient generator that outputs a mixing coefficient from the output of the coefficient circuit and the output of the coefficient circuit.