JPH09261684A - Color signal separator circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color signal separator circuit in which cross color due to crosstalk of a luminance signal is reduced effectively. SOLUTION: A composite color television signal is given to a time vertical BPF 21 and its output is given to a horizontal BPF 22, Tap coefficients of the time-vertical BPF 21 are selected to be -1/16 for 0-th line delay signal, -1/8 for 262nd line delay signal, 1/8 for 263rd line delay signal, -1/16 for 524th line delay signal, 1/4 for 525th line delay signal, -1/16 for 526th line delay signal, 1/8 for 787th line delay signal, -1/8 for 788th line delay signal, and -1/16 for 1050th line delay signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal separating circuit for separating a carrier color signal (C signal) from a composite color television signal used in a television receiver or the like, and more particularly to a C signal separating circuit. The present invention relates to a color signal separation circuit that can effectively reduce cross color due to crosstalk of luminance signals (Y signals) without sacrificing resolution.

[0002]

2. Description of the Related Art At present, in a composite color television signal such as an NTSC system used in television broadcasting, a C signal is frequency-multiplexed with a Y signal. Therefore,
On the receiving side, it is necessary to separate the Y signal and the C signal again. However, if the C signal separation is not performed accurately, C
The Y signal remains in the signal, resulting in cross color, which deteriorates the reproduced image.

As a color signal separation circuit which has been widely used in the past, there is a two-dimensional comb filter. FIG. 9 is a block diagram showing an example of a conventional two-dimensional comb filter. In FIG. 9, the composite color television signal is input to the vertical bandpass filter (BPF) 1. Vertical B
The PF 1 is composed of a 1-line delay device 11 and a subtractor 12. The 1-line delay unit 11 delays the input composite color television signal by 1 line (1H) and inputs it to the subtractor 12. The subtractor 12 subtracts the output of the 1-line delay device 11 from the input composite color television signal to limit and output the vertical band. The output of the vertical BPF 1 is input to the horizontal bandpass filter (BPF) 2, and the horizontal BPF 2 limits the horizontal band and outputs the C signal.

In this way, the C signal is separated from the composite color television signal by the two-dimensional comb filter.

[0005]

In the conventional color signal separation circuit (two-dimensional comb filter) described above, in order to reduce the cross color, the pass band of the horizontal BPF 2 is set so that the Y signal does not pass as much as possible. It should be narrow. However, if the pass band of the horizontal BPF 2 is narrowed, the horizontal high frequency component of the C signal is lost and the transient C response becomes a blurred C signal. Therefore, in the past, the horizontal BP was considered by considering the balance between the cross color and the resolution of the C signal.
The pass band of F2 was determined. That is, conventionally, there has been a problem that the cross color due to the crosstalk of the Y signal cannot be reduced without sacrificing the resolution of the C signal.

The present invention has been made in view of the above problems, and the Y signal can be obtained without sacrificing the resolution of the C signal.
An object of the present invention is to provide a color signal separation circuit that can effectively reduce cross color due to signal crosstalk.

[0007]

In order to solve the above-mentioned problems of the prior art, the present invention provides: (1) In a color signal separation circuit for separating a carrier color signal from a composite color television signal, the time frequency is ft. [H
z], the vertical frequency is fv [cph], and the time-vertical frequency is represented by (ft, fv), the subcarrier of the color signal at (ft, fv) with respect to the input composite color television signal. The frequencies (15, -525/4) and (-15, 525/4) are set to the pass center frequencies, and (a)
0 line delay signal to -1/16, (b) 262 line delay signal to -1/8, (c) 263 line delay signal to 1 /
8, (d) -1 to 524 line delay signal, (e)
1/4 for 525 line delay signal, -1/16 for (f) 526 line delay signal, 1 for (g) 787 line delay signal
/ 8, (h) -1/8, (i) for 788 line delay signal
A time-vertical bandpass filter that multiplies a 1050 line delay signal by a tap coefficient of -1/16, adds all of them, and outputs the result, and a carrier color that limits the horizontal band of the output signal of the time-vertical bandpass filter. Provided is a color signal separation circuit characterized by comprising a horizontal bandpass filter for outputting a signal.

(2) In the color signal separation circuit for separating the carrier color signal from the composite color television signal, the still picture band pass filter for separating the carrier color signal of the still picture part from the inputted composite color television signal. From the input composite color television signal, a moving image bandpass filter for separating the carrier color signal of the moving image portion, and a motion detection signal by detecting the motion of the image of the input composite color television signal, A motion detection circuit for outputting, a mixing circuit for adaptively mixing the output signal of the still image part bandpass filter and the output signal of the moving image part bandpass filter according to the motion detection signal, and a time period. When the frequency is ft [Hz], the vertical frequency is fv [cph], and the time-vertical frequency is represented by (ft, fv), the still image band Filter, to the input composite color television signal, (ft, fv) of the color signals in the sub-carrier frequency (15, -525 /
4) and (-15,525 / 4) as pass center frequencies, and also has a characteristic of limiting the 0 Hz band in ft. (A) 0 line delay signal has -1/8, (b) 262
-1/8 for line delay signal, (c) 1/8 for 263 line delay signal, (d) 1/4 for 525 line delay signal,
(E) 787 line delay signal is multiplied by 1/8, (f) 788 line delay signal is multiplied by -1/8, and (g) 1050 line delay signal is multiplied by tap coefficient -1/8, and all are added and output. A time-vertical bandpass filter and a horizontal bandpass filter for limiting the horizontal band of the output signal of the time-vertical bandpass filter to output the carrier color signal of the still image portion, and the moving image portion bandpass filter Is
With respect to the input composite color television signal,
The subcarrier frequencies (15, -525/4) and (-15, 525/4) of the chrominance signal at (ft, fv) are used as the passage center frequencies, and (a) 0-line delay signal has a 1/1.
6, (b) -1 to the 262 line delay signal, (c) 2
63 line delay signal is 1/8, (d) 524 line delay signal is -1/16, and (e) 525 line delay signal is 1/8.
4, (f) -1 to the 526 line delay signal, (g)
1/8 to 787 line delay signal, (h) -1/8 to 788 line delay signal, (i) -to 1050 line delay signal
1/16 times the tap coefficient and adds all of them, and outputs the result-vertical bandpass filter, and the time-
Provided is a color signal separation circuit comprising a horizontal bandpass filter for limiting a horizontal band of an output signal of a vertical bandpass filter and outputting a carrier color signal of a moving image portion.

[0009]

DETAILED DESCRIPTION OF THE INVENTION A color signal separation circuit of the present invention will be described below with reference to the accompanying drawings. 1 is a block diagram showing a first embodiment of a color signal separation circuit of the present invention, FIG. 2 is a diagram for explaining tap coefficients of a time-vertical bandpass filter 21 in FIG. 1, and FIG. 4 is a block diagram showing a specific configuration of the time-vertical bandpass filter 21, FIG. 4 is a diagram showing frequency characteristics of the time-vertical bandpass filter 21 in FIG. 1, and FIG. 5 is a diagram showing a color signal separation circuit of the present invention. Two
FIG. 6 is a block diagram showing an embodiment, FIG. 6 is a diagram for explaining tap coefficients of the time-vertical bandpass filter 31 in FIG. 5, and FIG. 7 is a time-vertical bandpass filter 31 in FIG.
FIG. 8 is a block diagram showing the specific configuration of FIG.
5 is a diagram showing frequency characteristics of output 1 in the vertical bandpass filter 31. FIG.

First, the principle of the present invention will be described. FIG. 10 shows the spectrum distribution of the NTSC signal, where the horizontal axis represents time frequency ft [Hz] and the vertical axis represents vertical frequency fv [cph].
(Cycle Per Height). This N
Looking at the spectrum distribution of the TSC signal, the C signal is distributed around the subcarrier (SC) frequency. In the present invention, the band of the C signal is expanded from two-dimensional to three-dimensional,
The time-vertical pass band of the signal separated as the C signal is C
The minimum required band that matches the spectral distribution of the signal. As a result, the Y signal in the time high frequency band of the C signal can be blocked, so that the cross color can be significantly reduced.

The color signal separation circuit of the present invention based on this principle will be described in more detail below with reference to the first embodiment. In FIG. 1, a composite color television signal, which is an NTSC signal as an example, is input to a time-vertical bandpass filter (BPF) 21. When the time-vertical frequency is represented by (ft, fv), the time-vertical BPF 21 is
The time-vertical high frequency of the C signal is limited with the subcarrier frequencies (15, -525/4) and (-15, 525/4) of the C signal at (ft, fv) as the pass center frequencies. The output of the time-vertical BPF 21 is input to the horizontal bandpass filter (BPF) 22 and the horizontal BPF 22
Outputs a C signal by limiting the horizontal band. In addition, horizontal B
The PF 22 has a horizontal frequency (fh) of 3.58 [MHz], which is a subcarrier frequency of the C signal, as its center frequency and limits 0 [Hz], but its characteristics may be set appropriately.

The time-vertical BPF 21 will now be described in detail. The sampling frequency in the time direction of the NTSC signal is 60 [Hz]. Therefore, the Nyquist frequency is 30 [Hz]. Similarly, the sampling frequency in the vertical direction of the NTSC signal is 525 [cph].
Therefore, the Nyquist frequency is 525/2 [cph]. When these are applied to the C signal, the subcarrier frequency (15, -525 / of the C signal at (ft, fv) is obtained.
4) and (-15,525 / 4) time-vertical maximum frequencies are (-15, -525 / 4) and (15,525 /).
4) That is, the characteristics of the time-vertical BPF 21 are as follows: (15, -525/4) and (-15, 525/4) in (ft, fv) are pass center frequencies, and (-1
5, -525 / 4) and (15,525 / 4) are moderately limited, and it can be said that the diamond-shaped pass band characteristic which is the same as the interlaced pixel structure of the NTSC signal is optimum.

FIG. 2 shows the pixel arrangement in the vertical-time direction of the NTSC signal and the tap coefficient of the time-vertical BPF 21. Time multiplied by tap coefficient shown in FIG. 2—vertical BPF 21
This is realized by the configuration shown in FIG. As shown in FIG. 2, (a) -1/16 to 0 line delay signal, (b) 2
62 line delay signal is -1/8, (c) 263 line delay signal is ⅛, (d) 524 line delay signal is -1 /
16, (e) 1/4 to 525 line delay signal, (f) 5
26 line delay signal -1/16, (g) 787 line delay signal ⅛, (h) 788 line delay signal -1
/ 8, (i) the 1050 line delay signal is multiplied by a tap coefficient of -1/16.

As shown in FIG. 3, the time-vertical BPF 21
Is 262H, 1H, 261H, 1 in order from the left side in the figure.
H, 1H, 261H, 1H, 262H delay device group 211, and from the left side of the figure, input signal (0 line delay signal), 262 line delay signal, 263 line delay signal,
524 line delay signal, 525 line delay signal, 526
-1/1 for line delay signal, 787 line delay signal, 788 line delay signal, and 1050 line delay signal respectively
6, -1/8, 1/8, -1/16, 1/4, -1/1
It is composed of a multiplier group 212 that multiplies tap coefficients of 6, 1/8, -1/8, and -1/16, and an adder 213 that adds all the outputs of the multiplier group 212.

The time-vertical BPF 2 thus constructed
The frequency characteristic of No. 1 is shown in FIG. In FIG. 4, (A) is a perspective view and (B) is a plan view. Time-Vertical BPF21
As shown in FIG. 4, the frequency characteristics of the subcarrier frequency of the C signal at (ft, fv) are (15, −525 /
4) and (-15,525 / 4) are set as pass center frequencies,
C signal time-vertical highest frequency (-15, -525 /
4) and (15,525 / 4) are the diamond-type passband characteristics that gently limit. With this characteristic, it is possible to narrow the band of the C signal without an afterimage and prevent the Y signal in the time-vertical maximum frequency band of the C signal, so that it is possible to significantly reduce the cross color.

Next, a second embodiment will be described. Second
The embodiment is a color signal separation circuit using the principle of the present invention in a motion adaptive type three-dimensional Y / C separation circuit. In FIG. 5, a composite color television signal, which is an NTSC signal as an example, is input to a time-vertical bandpass filter (BPF) 31 and a motion detection circuit 34. Time-vertical BPF3
1 has the characteristic of limiting the band of 0 [Hz] in ft, and the subcarrier frequencies (15, -525/4) and (-15, 525) of the C signal in (ft, fv).
/ 4) as a pass center frequency, and has a characteristic of gently limiting the time-vertical high frequency of the C signal.

Time-zero at ft of vertical BPF 31
Signal output by band limitation of [Hz] (output 1)
Is input to the horizontal bandpass filter (BPF) 32,
The horizontal BPF 32 limits the horizontal band and outputs the C signal of the still image portion. In addition, in time-vertical BPF 31, (ft,
fv) C signal subcarrier frequency (15,-
The signal (output 2) output by band limitation with the pass center frequencies of (525/4) and (-15,525 / 4) is input to the horizontal band pass filter (BPF) 33, and the horizontal BPF 33 limits the horizontal band. Then, the C signal of the moving image portion is output. As the horizontal BPFs 32 and 33, the horizontal frequency (fh) 3.
The center frequency is 58 [MHz] and 0 [Hz] is limited, but the characteristics may be set appropriately.

On the other hand, the motion detection circuit 34 detects the amount of motion of the image and outputs motion data (motion detection signal). The C signal of the still image part output from the horizontal BPF 32 and the horizontal B
The C signal of the moving image portion output from the PF 33 and the motion data output from the motion detection circuit 34 are input to the mixing circuit 35. The mixing circuit 35 adaptively mixes so that the still image portion outputs the C signal of the still image portion and the moving image portion outputs the C signal of the moving image portion according to the size of the motion data. In this way, the mixing circuit 35 outputs the C signal separated from the composite color television signal.

It should be noted that the portion for generating the output 1 of the time-vertical BPF 31 and the horizontal BPF 32 constitute a still image part bandpass filter, and the portion for generating the output 2 of the time-vertical BPF 31 and the horizontal BPF 33. And form a moving image bandpass filter.

Now, the time-vertical BPF 31 will be described in detail. FIG. 6 shows the vertical-time pixel array of the NTSC signal and the tap coefficient of the time-vertical BPF 31.
The configuration shown in FIG. 7 realizes the time-vertical BPF 31 that multiplies the tap coefficient shown in FIG. 6 to generate the output 1 and the output 2. As shown in FIG. 6, in order to obtain the output 1, (a) 0 line delay signal is -1/8, (b) 262
-1/8 for line delay signal, (c) 1/8 for 263 line delay signal, (d) 1/4 for 525 line delay signal,
(E) 787 line delay signal is multiplied by 1/8, (f) 788 line delay signal is multiplied by -1/8, and (g) 1050 line delay signal is multiplied by -1/8.

On the other hand, in order to obtain the output 2, as in the case of FIG. 2 described in the first embodiment, (a) -1 is added to the 0 line delay signal.
/ 16, (b) -1 to the 262 line delay signal,
(C) 1/8 for 263 line delay signal, (d) -1/16 for 524 line delay signal, (e) 1/4 for 525 line delay signal, (f) -1/1 for 526 line delay signal
6, (g) 1/8 to the 787 line delay signal, (h) 78
The 8-line delay signal is multiplied by -1/8, and (i) the 1050 line delay signal is multiplied by -1/16.

As shown in FIG. 7, time-vertical BPF 31
Is 262H, 1H, 261H, 1 in order from the left side in the figure.
H, 1H, 261H, 1H, 262H delay device group 311 and the input signal (0 line delay signal), 262 line delay signal, 263 line delay signal from the left side in the figure,
525 line delay signal, 787 line delay signal, 788
For line delay signal and 1050 line delay signal respectively-
1/8, -1/8, 1/8, 1/4, 1/8, -1 /
A multiplier group 312 that multiplies a tap coefficient of 8, -1 / 8,
And an adder 313 that adds all the outputs of the multiplier group 312. With these, the output 1 is obtained.

Further, from the left side of the figure, the input signal (0 line delay signal), 262 line delay signal, 263 line delay signal, 524 line delay signal, 525 line delay signal, 526 line delay signal, 787 line delay signal, 7
88 line delay signal and 1050 line delay signal are -1/16, -1/8, 1/8, -1/16, 1 /
A multiplier group 314 that multiplies the tap coefficients of 4, −1/16, 1/8, −1/8, and −1/16, and an adder 315 that adds all the outputs of the multiplier group 314 are provided. With these, the output 2 is obtained.

The time-vertical BPF 3 thus configured
8 shows the frequency characteristic of the output 1 of the output No. 1 of FIG. In FIG. 8, (A) is a perspective view and (B) is a plan view. Output 1
As shown in FIG. 8, the frequency characteristic of the subcarrier frequency of the C signal at (ft, fv) is (15, −525 /
4) and (-15,525 / 4) are set as pass center frequencies,
C signal time-vertical highest frequency (-15, -525 /
4) and (15,525 / 4) are gently limited, and 0 [H in ft where the Y signal exists in the still image part
It can be seen that this is a pass band characteristic that limits z]. The frequency characteristic at the output 2 of the time-vertical BPF 31 is shown in FIG.
Is the same as With this characteristic, it is possible to significantly reduce the cross color of the moving image portion, reduce the image quality difference between the still image portion and the moving image portion, and obtain a more natural reproduced image.

[0025]

As described in detail above, the color signal separation circuit of the present invention is configured by connecting the time-vertical bandpass filter and the horizontal bandpass filter in cascade, and the time-vertical bandpass filter taps are provided. Coefficients are -1/16 for the 0 line delay signal and -1/8, 2 for the 262 line delay signal.
63 line delay signal 1/8, 524 line delay signal -1/16, 525 line delay signal 1/4, 526 line delay signal -1/16, 787 line delay signal 1
Since / 8 and 788 line delay signals are set to -1/8 and 1050 line delay signals are set to -1/16, cross color due to crosstalk of luminance signals is effectively reduced without sacrificing resolution of color signals. can do.

As a three-dimensional Y / C separation circuit, tap coefficients of the still image part band pass filter are set to -1/8 for a 0 line delay signal and -1/8 for a 262 line delay signal.
63 line delay signal 1/8, 525 line delay signal 1/4, 787 line delay signal 1/8, 788 line delay signal -1/8, 1050 line delay signal -1 /
8 and the tap coefficient of the moving image band pass filter is 0
Line delay signal -1/16, 262 line delay signal -1/8, 263 line delay signal 1/8, 524 line delay signal -1/16, 525 line delay signal 1 /
4, 526 line delay signal -1/16, 787 line delay signal 1/8, 788 line delay signal -1/8,
Since the 1050 line delay signal is set to -1/16, the cross color of the moving image part can be significantly reduced, and the image quality difference between the moving image and the still image can be reduced, and thus a more visually natural image can be reproduced. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a tap coefficient of a time-vertical bandpass filter 21 in FIG.

3 is a block diagram showing a specific configuration of a time-vertical bandpass filter 21 in FIG.

FIG. 4 is a diagram showing frequency characteristics of a time-vertical bandpass filter 21 in FIG.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

FIG. 6 is a diagram for explaining tap coefficients of the time-vertical bandpass filter 31 in FIG.

7 is a block diagram showing a specific configuration of a time-vertical bandpass filter 31 in FIG.

8 is a diagram showing frequency characteristics of an output 1 in the time-vertical bandpass filter 31 in FIG.

FIG. 9 is a block diagram showing a conventional example.

FIG. 10 is a diagram showing a spectral distribution of an NTSC signal.

[Explanation of symbols]

 21, 31 Time-vertical bandpass filter 22, 32, 33 Horizontal bandpass filter 34 Motion detection circuit 35 Mixing circuit

Claims (2)

[Claims] 1. A color signal separation circuit for separating a carrier color signal from a composite color television signal, wherein the time frequency is ft [Hz] and the vertical frequency is fv [cp.
h] and the time-vertical frequency is represented by (ft, fv), with respect to the input composite color television signal, (f
Subcarrier frequency (1) of the color signal at t, fv)
5, -525 / 4) and (-15,525 / 4) as the passing center frequencies, and (a) 0 line delay signal has -1/16,
(B) -1 to the 262 line delay signal, (c) 263
1/8 for the line delay signal, -1/16 for the (d) 524 line delay signal, 1/4 for the (e) 525 line delay signal,
(F) -1 to 526 line delay signal, (g) 78
1/8 for 7 line delayed signal, (h) -1/8 for 788 line delayed signal, and (1 /) for (i) 1050 line delayed signal
A time-vertical bandpass filter that multiplies all 16 tap coefficients and adds them, and outputs the result, and a horizontal bandpass filter that limits the horizontal band of the output signal of the time-vertical bandpass filter and outputs the carrier color signal. A color signal separation circuit comprising: 2. A color signal separation circuit for separating a carrier color signal from a composite color television signal, and a still picture band pass filter for separating a carrier color signal of a still picture part from an inputted composite color television signal. A moving image bandpass filter for separating a carrier color signal of a moving image portion from the input composite color television signal; and detecting a motion of an image of the input composite color television signal to output a motion detection signal. A motion detection circuit, and a mixing circuit for adaptively mixing the output signal of the still image part bandpass filter and the output signal of the moving image part bandpass filter according to the motion detection signal. Is ft [Hz] and the vertical frequency is fv [cp]
h] and the time-vertical frequency is represented by (ft, fv), the still image section band-pass filter compares the color signal at (ft, fv) with respect to the input composite color television signal. Subcarrier frequency (15, -525 /
4) and (-15,525 / 4) as pass center frequencies, and also has a characteristic of limiting the 0 Hz band in ft. (A) 0 line delay signal has -1/8, (b) 262
-1/8 for line delay signal, (c) 1/8 for 263 line delay signal, (d) 1/4 for 525 line delay signal,
(E) 787 line delay signal is multiplied by 1/8, (f) 788 line delay signal is multiplied by -1/8, and (g) 1050 line delay signal is multiplied by tap coefficient -1/8, and all are added and output. A time-vertical bandpass filter, and a horizontal bandpass filter for limiting the horizontal band of the output signal of the time-vertical bandpass filter to output the carrier color signal of the still image portion. Is the sub-carrier frequency (15, -525 / of the color signal at (ft, fv) with respect to the input composite color television signal.
4) and (-15,525 / 4) are set as pass center frequencies,
(A) 0 line delay signal to -1/16, (b) 262 line delay signal to -1/8, (c) 263 line delay signal to ⅛, (d) 524 line delay signal to -1/16 ,
(E) 1/4 to 525 line delay signal, (f) -1/16 to 526 line delay signal, (g) 1/8 to 787 line delay signal, (h) -1/8 to 788 line delay signal,
(I) A time-vertical bandpass filter that multiplies a 1050 line delay signal by a tap coefficient of -1/16, adds all of them, and outputs the result, and limits the horizontal band of the output signal of the time-vertical bandpass filter. A color signal separation circuit comprising a horizontal bandpass filter that outputs a carrier color signal of the moving image section.