JP2001197518A - Color signal separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce cross color disturbance in separating colors of a composite color television signal. SOLUTION: A time-vertical band pass filter 2 uses '15 [Hz], -525/4 [cph]', '-15 [Hz], 525/4 [cph]' that are chrominance subcarrier frequencies of a composite color television signal for pass center frequencies, applies band limit to the '15 [Hz], 525/4 [cph]', the '-15 [Hz], -525/4 [cph]', the time 0 [Hz] and the vertical 0 [cph] and provides an output to a horizontal band pass filter 3. The horizontal band pass filter 3 uses a horizontal subcarrier frequency of a chrominance signal for its pass center frequency, applies horizontal direction filtering processing to the signal to extract the chrominance signal. Since the chrominance signal can be separated in three-dimensions of time-vertical direction-horizontal direction, the luminance signal can effectively be clocked and cross-color disturbance cab be reduced without one-sidedly deteriorating the horizontal resolution.

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 apparatus suitable for use in a television receiver or the like, and more particularly to a color signal separating apparatus for reducing cross-color interference.

[0002]

2. Description of the Related Art At present, in a composite color television signal of the NTSC system used in television broadcasting or the like, a chrominance signal is frequency-multiplexed with a luminance signal. Therefore, the television receiver, after receiving the composite color television signal, separates again into a luminance signal and a chrominance signal. However, if the luminance signal and the chrominance signal are not accurately separated, the color When the luminance signal remains in the signal, a so-called cross-color disturbance occurs, which deteriorates the image quality of the reproduced image.

A conventional television receiver is provided with, for example, a two-dimensional comb filter as shown in FIG. 6 as a color signal separating device. In the case of a composite color television signal of the NTSC system, as shown in FIG. 7, the spectral distribution at time frequency [Hz] -vertical frequency [cph] is "-15 [Hz], 525/4 [cph]", , And "15 [Hz], -525/4 [cph]" as the center frequencies.

For this reason, this two-dimensional comb filter is
First, a vertical band-pass filter 102 is applied to a composite color television signal supplied through an input terminal 101.
Is -525/4 [cph] and 525/4 [cph
] In the vertical direction with the respective pass center frequencies. Then, the horizontal bandpass filter 103 performs a horizontal filtering process using the horizontal subcarrier frequency of the chrominance signal as a pass center frequency on the filtered output subjected to the vertical filtering process by the vertical bandpass filter 102. By performing this, a color signal is extracted from the composite color television signal (separating a luminance signal and a color signal), and this is output to an output terminal 1.
04 to be output.

[0005]

Conventionally, however, color signals have been extracted by two-dimensional filtering in the vertical and horizontal directions using the two-dimensional comb filter. The filtering characteristics of the two-dimensional comb filter are adjusted so that the horizontal pass band of the color signal is narrowed and the luminance signal is not transmitted as much as possible. However, if the horizontal pass band is too narrow, the horizontal height of the color signal is reduced. The area signal component is also lost, and there is a problem that color blur occurs in the displayed image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a color signal separating apparatus capable of effectively reducing cross-color interference caused by crosstalk of a luminance signal to obtain a good reproduced image. The purpose is to provide.

[0007]

According to a first aspect of the present invention, there is provided a color signal separating apparatus comprising: a plurality of tap coefficients each having a power of 2 as a denominator; By filtering the color television signal and adding each filtering output formed by this filtering process for a predetermined time,
A time-vertical filter means for performing a filtering process in a time direction and a vertical direction for extracting a color signal from the composite color television signal; Horizontal filtering means for extracting a color signal by performing a horizontal filtering process using the carrier frequency as a pass center frequency.

According to a second aspect of the present invention, there is provided a color signal separating apparatus, wherein the composite color television signal is a composite color television signal conforming to the NTSC system. The time-vertical band-pass filter multiplies a 0-line delay signal of the composite color television signal by a 1/64 tap coefficient,
Multiply a 1-line delay signal by a tap coefficient of-1/64, multiply a 262 line delay signal by a 1/32 tap coefficient, multiply a 263 line delay signal by a-1/16 tap coefficient, 1/3 to 264 line delay signal
2, a 524-line delay signal is multiplied by a 1/64 tap coefficient, and a 525-line delay signal is multiplied by a 3/32 tap coefficient.
The line delay signal is multiplied by a 3/32 tap coefficient, the 527 line delay signal is multiplied by a -1/64 tap coefficient, and the 787 line delay signal is multiplied by a-1/16 tap coefficient. 1/8 for line delay signal
789 line delay signal is multiplied by −1/16 tap coefficient, and 1049 line delay signal is multiplied by −1/64 tap coefficient.
The 50-line delay signal is multiplied by a 3/32 tap coefficient, the 1051 line delay signal is multiplied by a −3/32 tap coefficient, and the 1052 line delay signal is 1/64.
, A 1312 line delay signal is multiplied by a 1/32 tap coefficient, and a 1313 line delay signal is multiplied by a -1/16 tap coefficient.
The 14-line delay signal is multiplied by 1/32 tap coefficient, the 1575-line delay signal is multiplied by -1/64 tap coefficient, and the 1576-line delay signal is 1/64
Are multiplied, and all the multiplied outputs obtained by multiplying the tap coefficients are added and supplied to the horizontal filter means.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a color signal separation device according to the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a color signal separation device according to an embodiment of the present invention is a composite color television signal (hereinafter simply referred to as a “video signal”) according to the NTSC system input via an input terminal 1. ), A time-vertical bandpass filter 2 for performing a predetermined band limitation on the time frequency-vertical frequency, and a horizontal frequency band limitation on the video signal from the time-vertical bandpass filter 2 to output terminal 4. And a horizontal band-pass filter 3 that outputs the signal through the filter.

As shown in FIG. 2, the time-vertical band-pass filter 2 includes one-line memories 11, 13,.
14, 16, 17, 18, 20, 21, 23, 24, 2
5, 27, 28, 30 and 260 line memories 15, 1
9, 22, 26, 261 line memories 12, 29,
It has multipliers 31 to 51 and an adder 52.

The one-line memory 11 delays the video signal from the input terminal 1 by one line and supplies the delayed signal to the 262-line memory 12 and the multiplier 32. The video signal from the input terminal 1 is supplied not only to the one-line memory 11 but also to the multiplier 31. 261 line memory 12
Delays the video signal from the one-line memory 11 by 261 lines (about one field period), and supplies this to the one-line memory 13 and the multiplier 33. 1-line memory 13
Delays the video signal from the 261 line memory 12 by one line, and supplies it to the one line memory 14 and the multiplier 34. The one-line memory 14 is a one-line memory 13
Is delayed by one line and supplied to the 260-line memory 15 and the multiplier 35. The 260-line memory 15 converts the video signal from the one-line memory 14 into two
The signal is delayed by 60 lines and supplied to the one-line memory 16 and the multiplier 36.

The one-line memory 16 delays the video signal from the 260-line memory 15 by one line and supplies it to the one-line memory 17 and the multiplier 37. The one-line memory 17 delays the video signal from the one-line memory 16 by one line, and delays the video signal by one line memory 18 and the multiplier 3.
8 The one-line memory 18 delays the video signal from the one-line memory 17 by one line, and
It is supplied to the line memory 19 and the multiplier 39. The 260-line memory 19 delays the video signal from the one-line memory 18 by 260 lines, and supplies this to the one-line memory 20 and the multiplier 40. The one-line memory 20 has 26
The video signal from the 0-line memory 19 is delayed by one line and supplied to the one-line memory 21 and the multiplier 41.

The one-line memory 21 is a one-line memory 2
The video signal from 0 is delayed by one line and supplied to the 260-line memory 22 and the multiplier 42. The 260-line memory 22 delays the video signal from the one-line memory 21 by 260 lines, and supplies this to the one-line memory 23 and the multiplier 43. The one-line memory 23 includes 260
The video signal from the line memory 22 is delayed by one line,
This is supplied to the one-line memory 24 and the multiplier 44.
The one-line memory 24 delays the video signal from the one-line memory 23 by one line, and supplies this to the one-line memory 25 and the multiplier 45. The one-line memory 25 delays the video signal from the one-line memory 24 by one line, and supplies this to the 260-line memory 26 and the multiplier 46.

The 260-line memory 26 delays the video signal from the one-line memory 25 by 260 lines and supplies it to the one-line memory 27 and the multiplier 47. The one-line memory 27 delays the video signal from the 260-line memory 26 by one line, and supplies this to the one-line memory 28 and the multiplier 48. The one-line memory 28 delays the video signal from the one-line memory 27 by one line, and supplies this to the 261-line memory 29 and the multiplier 49.
The 261-line memory 29 delays the video signal from the one-line memory 28 by 261 lines, and supplies this to the one-line memory 30 and the multiplier 50. 1-line memory 30
Delays the video signal from the 261 line memory 29 by one line, and supplies this to the multiplier 51.

The multipliers 31, 36, 46 and 51 multiply the supplied video signal by 1/64, and multiply this by 1/64.
Feed to 2. The multipliers 32, 39, 43, and 50 multiply the supplied video signal by (−1/64), and supply this to the adder 52. Multipliers 33, 35, 47, 49
Multiplies the supplied video signal by 1/32 and supplies this to the adder 52. Multipliers 34, 40, 42, 4
8 multiplies the supplied video signal by (−1/16) and supplies this to the adder 52. Multipliers 37, 45
Multiplies the supplied video signal by (−3/32), and supplies this to the adder 52. Multipliers 38, 44
Multiplies the supplied video signal by 3/32 and supplies this to the adder 52. The multiplier 41 multiplies the supplied video signal by ８, and supplies this to the adder 52. The adder 52 adds the respective video signals, and supplies the calculation result to the above-described horizontal bandpass filter 3 via the output terminal 60.

Here, the time-vertical band-pass filter 2 is characterized in that a tap coefficient whose denominator is a power of 2 is used. If the denominator uses a tap coefficient other than a power of 2, the circuit configuration becomes complicated and impractical. However, as in this embodiment, by using a tap coefficient whose denominator is a power of 2, the time-vertical The bandpass filter 2 can be easily constituted by a delay circuit, a bit shifter and an adder.

With such a configuration, the time-vertical band-pass filter 2 has (a) 0 line delay signal with 1
/ 64, (b) -1/64 for the one-line delay signal, (c) 262
1/32 for line delay signal, (d) for 263 line delay signal
-1/16, (e) 1/32 for 264 line delay signal, (f) 5
1/64 for 24 line delay signal, (g) -3/32 for 525 line delay signal, (h) 3/32 for 526 line delay signal, (i)
-1/64 for 527 line delay signal, (j) -1/16 for 787 line delay signal, (k) 1/8 for 788 line delay signal, (l)
-1/16 for 789 line delay signal, -1/64 for (m) 1049 line delay signal, 3/32 for (n) 1050 line delay signal,
(O) -1/32 for 1051 line delay signal, (p) 1/64 for 1052 line delay signal, (q) 1/32 for 1312 line delay signal
, (R) -1/16 for 1313 line delay signal, (s) 1/32 for 1314 line delay signal, -1 for (t) 1575 line delay signal
/ 64, (u) The 1576 line delay signal is multiplied by a coefficient of 1/64, and all the addition results are output.

That is, the time-vertical bandpass filter 2 multiplies the pixel array in the time-vertical direction as shown in FIG. 3A by a tap coefficient as shown in FIG. Become. When the frequency characteristics of the time-vertical band-pass filter 2 are represented in three dimensions, they are as shown in FIG.
FIG. 5 shows the dimensions.

More specifically, the time-vertical band-pass filter 2 outputs a color signal (time [Hz], vertical [Cycle / Height]).
Subcarrier frequency (15 [Hz], -525/4 [cp
h]) and a frequency (−15 [Hz], 525/4) at a position symmetrical with the subcarrier frequency with respect to the origin.
[Cph]) is the pass center frequency. Furthermore, (1
5 [Hz], 525/4 [cph]) and (-15 [Hz],-
525/4 [cph]), time 0 [Hz] and vertical 0 [cph]
Is restricted. As a result, the time-vertical bandpass filter 2 limits the band in relation to the time frequency and the vertical frequency, and effectively removes the luminance signal component from the video signal.

The horizontal band-pass filter 3 limits the horizontal 0 [Hz] to the video signal from the time-vertical band-pass filter 2 using the horizontal sub-carrier frequency fsc [Hz] of the color signal as the pass center frequency. .

The color signal separation device separates a color signal from a video signal by such a three-dimensional filtering process of the time-vertical band-pass filter 2 and the horizontal band-pass filter 3.

As is apparent from the above description, the color signal separating apparatus according to the present embodiment performs a filtering process in the time-vertical direction by the time-vertical band-pass filter 2 having a frequency characteristic as shown in FIG. Further, by performing a filtering process also in the vertical direction by the horizontal band-pass filter 3, the time-vertical-horizontal direction is filtered.
Separates the color signal from the video signal by dimension.

That is, since the three-dimensional separation band of the color signal is set to the minimum necessary band corresponding to the spectral distribution of the color signal, a luminance signal which disturbs three-dimensional time-vertical-horizontal is effectively prevented. can do. This allows
Cross color interference can be greatly reduced without unilaterally lowering only the horizontal resolution of the color signal.

In other words, the chrominance signal separation device considers extending the signal separation band from two-dimensional (vertical-horizontal), which has been conventionally performed, to three-dimensional (time-vertical-horizontal). The vertical pass band is the minimum necessary band that matches the spectral distribution of the color signal. As a result, it is possible to prevent the luminance signal in the color signal time-vertical high frequency range, so that the cross color is greatly reduced, and as a result, a good reproduced image can be obtained.

In the above description of the embodiment, the case of using the NTSC system as the composite color television signal has been described as an example.
It can also be applied to the ECAM method.

In this case, the subcarrier frequency of the color signal of each system and a tap coefficient having a pass center frequency at a frequency symmetrical to the subcarrier frequency with respect to the origin (intersection) of the time frequency-vertical frequency are set as the center. It may be used.

[0027]

According to the first aspect of the present invention, the color signal separating apparatus according to the present invention filters a composite color television signal using a plurality of tap coefficients having a power of 2 as a denominator, and is formed by this filtering processing. Time-vertical filter means for performing time-direction and vertical-direction filtering for extracting a color signal from a composite color television signal by adding each filtering output for a predetermined time, The filtering output from the means is subjected to horizontal filtering processing using the horizontal subcarrier frequency of the chrominance signal as the pass center frequency, so that the horizontal filtering means for extracting the chrominance signal allows time-vertical-horizontal processing. To separate color signals from composite color television signals in three dimensions Therefore, it is possible to effectively prevent the luminance signal, the horizontal resolution of the color signal can be greatly reduced cross color interference without unilaterally drop it.

Since a plurality of tap coefficients having a power of 2 as a denominator are used to perform filtering processing in the time direction and the vertical direction, a time-vertical filter means is formed by, for example, a bit shifter and an adder. Therefore, the configuration of the time-vertical filter means can be simplified, and the color signal separation device can be realized at low cost.

According to a second aspect of the present invention, in the color signal separating apparatus according to the present invention, the time-vertical band-pass filter includes an NTSC
The 0-line delay signal of the composite color television signal according to the standard is multiplied by a 1/64 tap coefficient, and the 1-line delay signal is multiplied by a 1/64 tap coefficient.
The 62 line delay signal is multiplied by a 1/32 tap coefficient, the 263 line delay signal is multiplied by -1/16 tap coefficient, and the 264 line delay signal is multiplied by 1/32 tap coefficient. 1 /
Multiply 64 tap coefficients, multiply the 525-line delayed signal by −3/32 tap coefficient, multiply the 526-line delayed signal by 3/32 tap coefficient,
The 7-line delay signal is multiplied by a -1/64 tap coefficient, the 787-line delay signal is multiplied by a -1/16 tap coefficient, and the 788-line delay signal is multiplied by a 1/8 tap coefficient. -1/1 to 789 line delay signal
6, a 1049 line delay signal is multiplied by -1/64 tap coefficient, a 1050 line delay signal is multiplied by 3/32 tap coefficient, and 1
051 line delay signal is multiplied by −3/32 tap coefficient, 1052 line delay signal is multiplied by 1/64 tap coefficient, and 1312 line delay signal is ３
2 multiplies the tap coefficient, 1313 line delayed signal by −1/16 tap coefficient, 1314 line delayed signal by 1/32 tap coefficient,
All the multiplied outputs obtained by multiplying the 575 line delay signal by a 1/64 tap coefficient, multiplying the 1576 line delay signal by a 1/64 tap coefficient, and multiplying each of the tap coefficients Is added to the horizontal filter means, and color signals in the time direction and the vertical direction can be accurately extracted from the composite color television signal conforming to the NTSC system.

For this reason, it is possible to greatly reduce cross-color interference without unilaterally lowering the horizontal resolution of the color signal.

Further, since the denominator of each tap coefficient is a power of 2, the time-vertical filter means can be formed of, for example, a bit shifter and an adder, thereby simplifying the structure of the time-vertical filter means. Accordingly, the color signal separation device can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a color signal separation device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a specific configuration of a time-vertical bandpass filter of the color signal separation device according to the embodiment.

FIG. 3 is a diagram illustrating a vertical-time direction pixel array of a color television signal of the NTSC system and tap coefficients of a time-vertical bandpass filter.

FIG. 4 is a diagram showing frequency characteristics (time [Hz], vertical [cph]) of the time-vertical band-pass filter.

FIG. 5 is a diagram showing a frequency characteristic of the time-vertical band-pass filter.

FIG. 6 is a block diagram showing a configuration of a conventional color signal separation device including a two-dimensional comb filter.

FIG. 7 is a diagram showing a distribution (time [Hz], vertical [cph]) of a frequency spectrum of an NTSC color television signal.

[Explanation of symbols]

1: input terminal, 2: time-vertical bandpass filter, 3
... horizontal bandpass filter, 4 ... output terminals, 11 to 30
... Line memories, 31-51 ... Multipliers, 52 ... Adders

Claims (2)

[Claims] 1. A composite color television signal is subjected to filtering processing using a plurality of tap coefficients having a power of 2 as a denominator, and each filtering output formed by the filtering processing is added for a predetermined time to obtain a composite color television signal. A time-vertical filter unit for performing a filtering process in a time direction and a vertical direction for extracting a color signal from a color television signal; and a horizontal subcarrier of a color signal with respect to a filtering output from the time-vertical filter unit. A color signal separation device having horizontal filter means for extracting a color signal by performing a horizontal filtering process using a frequency as a pass center frequency. 2. The method according to claim 1, wherein the composite color television signal is N
A time-vertical band-pass filter that multiplies a 0-line delay signal of the composite color television signal by a 1/64 tap coefficient to generate a 1-line delay signal; Multiplies the tap coefficient of -1/64, multiplies the 262 line delay signal by the tap coefficient of 1/32, multiplies the 263 line delay signal by the tap coefficient of -1/16, and converts the 264 line delay signal to the 264 line delay signal. Multiply by 1/32 tap coefficient, multiply by 524 line delay signal by 1/64 tap coefficient, multiply by 525 line delay signal by −3/32 tap coefficient, and 526 line delay signal by 3 Multiplying by a tap coefficient of / 32, multiplying a 527 line delay signal by a tap coefficient of -1/64, and multiplying a 787 line delay signal by -1/1 788 line delay signal is multiplied by 1/8 tap coefficient, 789 line delay signal is multiplied by -1/16 tap coefficient, and 1049 line delay signal is -1/64 Multiplies the 1050 line delay signal by a 3/32 tap coefficient, multiplies the 1051 line delay signal by a -3/32 tap coefficient, and 1052 the line delay signal by 1/64 Multiplies the tap coefficient, multiplies the 1312 line delay signal by 1/32 tap coefficient, multiplies the 1313 line delay signal by -1/16 tap coefficient, and 1314 line delay signal by 1/32 tap Multiplies the coefficients, multiplies the 1575 line delay signal by a 1/64 tap coefficient, and multiplies the 1576 line delay signal by a 1/64 tap coefficient 2. The color signal separating apparatus according to claim 1, wherein all the multiplied outputs obtained by multiplying the tap coefficients are added and supplied to the horizontal filter means.