JPS61203791A - Contour signal extraction filter - Google Patents

Abstract

PURPOSE:To extract accurately a counter signal by sampling a composite video signal by a prescribed multiple of a color subcarrier frequency and using the neighboring sampling point at which the color subcarrier wave phase is in phase relative to the sampling point being noticed. CONSTITUTION:The composite video signal of the PAL system is inputted to an A/D converter 2 and sampled by a signal from a pulse generator 12 which is a prescribed multiple of the color subcarrier frequency. The neighboring sampling point in phase with the color subcarrier wave phase is extracted relative to the sampling point in consideration by delay circuits delaying by one preriod of the color subcarrier frequency 5-7, 5-8, a delay circuit 5-9, 5-10 delaying a time equal to the time of two horizontal scanning of the sample value system signal of the output of the converter 2 less the 1/2 period of the color subcarrier wave, and a coefficient circuit 6-2 multiplying the output signal of the circuit 5-9, by -4 in a filter 100. These extracted values are added at a summing circuit 7-4 and subjected to second order differentiation while the output signal of circuit 7-4 is multiplied by N by a multiplier circuit 11 to output counter signals at the terminal 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a contour signal extraction filter, and particularly to a contour signal extraction filter for digitally extracting a contour signal from a composite video signal in which a luminance signal and a color signal are frequency multiplexed. Related to signal extraction filters.

[Prior Art] Various methods for extracting contour components from image information have been proposed from various fields for a long time.For example, in television receivers, a contour signal is extracted from a luminance signal and added to the original luminance signal. By combining these two images, the sharpness of the image is improved.

Generally, a PAL composite video signal 5(t) includes a luminance signal Y(t) and two color difference signals IJ(t) and V(
t) Signal as color subcarrier fgc (=4.43361875
It is a composite signal with the color signal C(t) which is quadrature two-phase modulated at MHz). That is, S(t)−Y(t)
+C(t > =Y (t) +U (t) sin 2πr, ct
±v(t) cos2πr, ct However, the sign of V(t) is switched between + and - for each scanning line.

Conventionally proposed contour extraction filters of this kind, whether of analog or digital format, separate the luminance signal Y(t) from the composite video signal 5(t), and extract the separated luminance signal from the composite video signal 5(t). Generally, a horizontal contour signal is obtained for Y (t) by a horizontal contour extraction filter, and a vertical contour signal is obtained by a vertical contour extraction filter.

Next, a conventional horizontal contour extraction filter will be explained with reference to FIG. 4, and a conventional vertical contour filter will be explained with reference to FIG. Furthermore, with reference to FIG. 6, a conventional example of a horizontal/vertical contour extraction filter that simultaneously extracts a horizontal contour signal and a vertical contour signal will be described.

FIG. 4 is a block diagram showing an example of a conventional digital horizontal contour extraction filter. In the figure, this horizontal contour extraction filter includes an input terminal 1 into which an analog composite video signal is input, an A/D conversion circuit 2 that converts the analog signal into a digital signal, and a circuit that separates the composite video signal into a luminance signal and a color signal. It includes a luminance signal/chrominance signal separation circuit 3, a horizontal contour extraction filter 8, and an output terminal 4 for deriving the output of the horizontal contour filter 8. The horizontal contour extraction filter 8 includes a first delay circuit 5-1, a second delay circuit 5-2, a coefficient circuit 6-1, and an addition circuit 7-1.

Next, the operation of the circuit shown in FIG. 4 will be explained. The analog composite video signal input to the input terminal 1 is given to the A/D conversion circuit 2. The A/D conversion circuit 2 converts the analog composite video signal into a digital composite video signal at a certain sampling frequency f. The digital composite video signal output from the A/D conversion circuit 2 is separated into a luminance signal and a chrominance signal by a luminance signal/chrominance signal separation circuit 3. The luminance signal separated by the luminance signal color signal separation circuit 3 is sent to the horizontal contour filter 8.
is applied to the first delay circuit 5-1, and also applied to the adder circuit 7-1. The output of the first delay circuit 5-1 is given to the second delay circuit 5-2, and the coefficient circuit 6
−1 is given. The coefficient circuit 6-1 is the first delay circuit 5
It is configured to multiply the output signal of -1 by "-2". The adder circuit 7-1 is configured to add the output of the luminance signal/color signal separation circuit 3, the output of the coefficient circuit 6-1, and the output of the second delay circuit 5-2. Also, 1st. The delay time of the second delay circuit 5-1, 5-2 is determined by the reciprocal of the sampling frequency fs, and is configured to be one sample interval T of the digital signal sequence that is the output of the A/D conversion circuit 2. has been done. Therefore, if the luminance signal r(t), which is the output signal of the luminance signal/chrominance signal separation circuit 3, is f (nT) at a certain time t-nT, as understood from the above explanation, the addition circuit 7 The output is f (nT)-2f ((n-1)T)+f (
(n −2) T) is obtained. This corresponds to two or more components of the luminance signal f(t) in the horizontal direction on the screen, and therefore, the horizontal high frequency component of the luminance signal, that is, the horizontal contour signal is extracted.

FIG. 5 is a block diagram showing an example of a conventional digital vertical contour extraction filter. In the figure, the configuration is the same as that in FIG. 4, except that a vertical contour extraction filter 9 is used instead of the horizontal contour extraction filter 8 in FIG. 4, and corresponding parts are given the same reference numbers. . The vertical contour extraction filter 9 includes a third delay circuit 5-3, a fourth delay circuit 5-4, a coefficient circuit 6-1, and an adder circuit 7-2. Third. The delay time of the fourth delay circuit 5-3, 5-4 is configured to be one horizontal scanning time.

Coefficient circuit 6-1. The adder circuit 7-2 is configured in the same way as in the case of FIG. The output of the signal separation circuit 3, the output of the coefficient circuit 6, and the output of the fourth delay circuit 5-4 are added. Therefore, as is clear from the explanation in FIG. 4, in the configuration of FIG.
Since the luminance signal, which is the output signal of the luminance signal/color signal separation circuit 3, is processed by several components in the vertical direction on the screen, the vertical high frequency component of the luminance signal, that is, the vertical contour signal is extracted. be done. FIG. 6 is a block diagram showing a conventional contour extraction filter constructed by overlapping FIGS. 4 and 5. In the figure, the configuration is the same as that in FIGS. 4 and 5 except that the contour extraction filter 10 is used, and corresponding parts are given the same reference numerals. The contour extraction filter 10 is a filter that extracts horizontal and vertical contour signals. a second delay circuit 5-1.5-2; Sixth delay circuit 5-5, 5-6 and coefficient circuit 6-2
and an adder circuit 7-3. 1st. The second delay circuit 5-1.5-2 includes the first delay circuit 5-1.5-2 described in FIG. Second
It has the same delay time as the delay circuits 5-1 and 5-2. Also, 5th. Sixth delay circuit 5-5.5-6
is configured such that its delay time is equal to the delay time obtained by subtracting the delay R11Jl of the 1.degree. second delay circuit 5-1.5-2 from one horizontal scanning period. Therefore, the delay time of the first delay circuit 5-1 and the fifth delay circuit 5
-5 delay time is one horizontal scanning time, and the delay time of second delay circuit 5-2 and sixth delay circuit 5-6 is one horizontal scanning time. It becomes. The coefficient circuit 6-2 is the first delay circuit 5
It is configured to boost the output signal of -1 by -4 times. The adder circuit 7-3 receives the output of the luminance signal/color signal separation circuit 3, the output of the fifth delay circuit 5-5, the output of the coefficient circuit 6-2, and the output of the second delay circuit 5-2. , and the output of the sixth delay circuit 5-6. That is, the contour extraction filter 10 has the fifth delay circuit 5-
5. First delay circuit 5-1. Second delay circuit 5-2. Sixth delay circuit 5-6. Coefficient circuit 6-2. Addition circuit 7-3
a vertical contour extraction filter consisting of a first delay circuit 5;
-1. Second delay circuit 5-2. Coefficient circuit 6-2. Since the horizontal contour extraction filters constituted by the adder circuit 7-3 are superimposed, it is possible to extract a vertical contour signal and a horizontal contour signal. Furthermore, although the configuration shown in FIG. 6 will be described in detail later, it can be considered that calculations for two or more aircraft in the diagonal direction are also performed, and contour signals in the diagonal direction can also be extracted.

[Problems to be Solved by the Invention] As mentioned above, the conventional contour extraction filter extracts the contour signal using the luminance signal, so it is necessary to separate the composite video signal into the luminance signal and the color signal.暉The delay circuit that delays the 1N signal color signal branching circuit for one horizontal scanning time signal and the delay circuit that delays the one horizontal scanning time signal required for the contour extraction filter cannot be shared, resulting in increased costs. There was a problem that could not be avoided. Further, there was a problem in that the extraction accuracy of the contour No. 1S depended on the characteristics of the *+1 signal color signal separation circuit.

This invention was made to solve the above-mentioned problems, and it is possible to directly extract a contour signal from a composite video signal, thereby eliminating the need for a delay circuit and a contour signal in the Ti variable magnification signal color signal separation circuit. It is an object of the present invention to provide a contour signal extraction filter that can share a delay circuit necessary for the extraction filter.

[Means for Solving the Problems] The present invention provides a method for sampling a PAL system composite video signal at a predetermined multiple of the color subcarrier frequency and extracting a contour signal from the sampled digital composite video signal. A method for simultaneously extracting the sample value of a sample point and sample values of neighboring sample points whose color subcarrier phase is in phase with the sample point, and obtaining a contour signal based on each of these extracted sample values. It is designed to perform calculations for several machines.

[Operation] In the present invention, a contour signal is directly extracted from the sampled composite video signal without separating the composite video signal into a luminance signal and a color signal.

Embodiment] FIG. 1 is a schematic block diagram showing an embodiment of the present invention. In the figure, this contour signal extraction filter has an input terminal 1 to which a composite video signal, which is an analog signal, is input;
An A/D converter 2 that converts an input analog composite video signal into a digital composite video signal, and this A/D I
A sampling pulse generation circuit 12 that provides a sampling pulse to the binary converter 2, a contour signal extraction filter 100 that extracts a contour signal from the output of the A/D converter 2, and an output that derives the output of the contour signal extraction filter 100. terminal 4. The contour signal extraction filter 100 includes a seventh delay circuit 5-7 and an eighth delay circuit 5-7.
delay circuit 5-8, ninth delay circuit 5-9, and tenth delay circuit 5-8.
delay circuit 5-10, coefficient circuits 6-2, and addition circuit 7
-4 and a multiplication circuit 11. 7th. The eighth delay circuit 5-7, 5-8 is configured to delay the sample value series that is the output of the A/D conversion circuit 2 by one period of the color subcarrier. 9th. Tenth delay circuit 5-
9.5-10 is configured to delay the sample value series that is the output of the A/D conversion circuit 2 by subtracting 1/2 period of the color subcarrier from the 2 horizontal scanning times.

Next, the operation of the circuit shown in FIG. 1 will be explained. The sampling pulse generation circuit 12 has a color subcarrier frequency rsc that is three times or four times the color subcarrier frequency rsc of the composite video signal input from the input terminal 1.
This is an oscillation circuit that synchronously oscillates at twice the frequency.The sampling pulse that is the output of this sampling pulse generation circuit 12 is
The signal is applied to the A/D conversion circuit 2, and the A/D conversion circuit 2 converts the analog composite video signal input from the input terminal 1 into a digital signal. If we pay attention to the phase of the color signal on the screen, the sampled signal sequence of the PAL system composite video signal, which has been converted into a standard using the above-mentioned sampling pulse, will be arranged as shown in FIG. 2.

Note that in FIG. 2, line n indicates the n-th horizontal scanning line.

FIG. 3 is a diagram for explaining the above embodiment in detail,
This is the sample value series shown in FIG. 2 above with symbols attached to it. A case will be described in which the circuit of FIG. 1 is used to extract the outline of the sample point P3 in FIG. 3.

Now, if the A/D conversion circuit 2 outputs the sample value of the sample point P5 at a certain time T, the output of the seventh delay circuit 5-7 will be the sample value of the sample point P4 of the eighth delay circuit. The output of 5-8 is the sample value of the sample point Pl. The output of the 9th delay circuit 5-9 is the sample value of the sample point P3. The output of the 10th delay circuit 5-1o is the sample value of the sample point P2. Each is output. The coefficient circuit 6-2 is configured to multiply the output signal of the ninth delay circuit 5-9 by a factor of -4, and the adder circuit 7-4 outputs the output signal of the A/D conversion circuit 2 and the seventh delay circuit 5-9. Output signal of delay circuit 5-7 and eighth delay circuit 5-
The output signal of the ninth delay circuit 5-9 is added to the output signal of the ninth delay circuit 5-9. Therefore, adder circuit 7
In this case, the output signal of −4 is: (sample value of the sample point P5) + (sample value of the sample point P4) + (sample value of the sample point P2) + (sample filI of the sample point Pi) -4X (sample value of sample point P3), which can be converted to l as follows.

(Sample 1ii of the sampling point P5) -2X (Sample value of the sampling point P3) + (Sample value of the sampling point P2) + (P
4) - 2X (sample value of sample point P3) + (sample value of sample point P1) It can also be rewritten as follows.

(Sample of the sampling point Pl [1) - 2X (Sample value of the sampling point P3) + (Sample value of the sampling point P2) + (Sample value of the sampling point P4) - 2x (Sample of the sampling point P3) value) + (sample value of sample point P5) It can also be rewritten as follows.

(Sample value of the sampling point Pl') - 2X (Sample value of the sampling point P3) + (Sample II of the sampling point P5) + (P2
) - 2X (sample value of sample point P3) + (sample value of sample point P4) In other words, neighboring sample points whose color subcarriers are in phase with the sample point of interest It can be seen that contour signals in all directions can be extracted since calculations for two or more aircraft are performed using .

Note that the multiplier circuit 11 is a circuit that multiplies the output of the adder circuit 7-4 by N, and although this multiplier N is not shown, it is controlled from the outside by, for example, a microcomputer. By providing this multiplication circuit 11, the amplitude of the contour signal can be changed.

[Effects of the Invention] As described above, according to the present invention, a contour signal is extracted using neighboring sample points whose color subcarrier phase is in phase with the sample point of interest. , the contour signal can be extracted directly and accurately from the composite video signal without being affected by the characteristics of the luminance signal/color signal separation circuit, and the horizontal contour signal, vertical contour signal, and diagonal contour signal can also be extracted simultaneously. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention. 2 and 3 are diagrams showing the arrangement of sampled signal sequences of a PAL system composite video signal for explaining the operation of the circuit shown in FIG. 1g1. FIG. 4, FIG. 5, and FIG. 6 are schematic block diagrams showing the configurations of a conventional horizontal contour extraction filter, vertical contour extraction filter, and horizontal/vertical contour extraction filter, respectively. In the figure, 1 is an input terminal, 2 is an A/D conversion circuit, 4 is an output terminal, 5-1 to 5-10 are delay circuits, 6-1 and 6-2 are coefficient circuits, and 7-1 to 7-4 is an adder circuit, 100
11 represents a contour signal extraction filter, and 11 represents a multiplication circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa Figure 2 Line (n-
2)・・
Line (n-1)・4fsc thread f) Yasumoto point 03fsc Soft freezing point Figure 3・・−−○−1−Line (n+
2) Figure 4 Figure 6 Procedural Amendment (Voluntary) 0C39 Showa Year Month Date Mr. Commissioner of the Patent Office 2゛-1, Indication of the case Patent Application No. 60-45206 2,
Name of the invention Contour signal extraction fill 3, Person making the amendment 5, Claims column 6 of M-Sei's Burning Specification, Contents of the amendment Attachment J3. Above 2, Claim (1) A 71' router for extracting a contour signal from a PAL composite video signal, the A10 for sampling the PAL composite video signal at a predetermined multiple of the color subcarrier frequency. Converter and ttI AID
A sample for simultaneously obtaining a sample value of a certain sample point from which a contour signal is to be extracted and a sample value of a neighboring sample point whose color n1 carrier wave phase is in phase with the sample point from the output of the converter. A contour signal extraction filter comprising a value extraction means and a calculation means for performing two or more calculations to obtain a contour signal based on the output of the sample value extraction means. (2) The contour signal according to claim 1, wherein the A/D converter is configured to sample the PAL composite video signal at three times or four times the color subcarrier frequency. Extraction filter. (3) The sample value extraction means includes a direct output means that outputs the output of the A/D converter as it is, and a first output means that delays the output of the A/D converter by one cycle of the color subcarrier. a delay circuit; a second delay circuit for delaying the output of the first delay circuit by a time equal to 1/'2 period of 6 times 31 transmissions subtracted from the 2nd horizontal scanning time period; and the second delay circuit; a third delay circuit that delays the output of the third delay circuit by a time equal to two horizontal scanning times minus 1/2 cycle m of the color subcarrier; and a fourth delay circuit that delays the output of the third delay circuit by one cycle of the color subcarrier. a delay circuit, and the calculation means includes: a coefficient circuit that multiplies the output of the second delay circuit by 14; the output of the direct output means; the output of the first delay circuit; and the coefficient circuit. 3. The contour signal extraction filter according to claim 2, further comprising an adder circuit that adds the output of the third delay circuit, the output of the third delay circuit, and the output of the fourth delay circuit. (4) Claims 1 to 3 further include multiplication means for multiplying the output of the calculation means by a predetermined multiplier. The contour signal extraction filter according to any one of 1.

Claims (4)

[Claims] (1) A filter for extracting a contour signal from a PAL composite video signal, the filter comprising: an A/D converter for sampling the PAL composite video signal at a predetermined multiple of a color subcarrier frequency; From the output of the D converter, a sample value of a certain sample point from which a contour signal is to be extracted and a sample value of a neighboring sample point whose color subcarrier phase is in phase with the sample point are obtained simultaneously. A contour signal extraction filter comprising a sample value extraction means and a calculation means for performing a second-order differential operation to obtain a contour signal based on the output of the sample value extraction means. (2) The limbus according to claim 1, wherein the A/D converter is configured to sample the PAL composite video signal at three times or four times the color subcarrier frequency. Signal extraction filter. (3) The sample value extraction means includes direct output means that outputs the output of the A/D converter as it is, and a first delay circuit that delays the output of the A/D converter by one cycle of a color subcarrier. , a second delay circuit that delays the output of the first delay circuit by a time obtained by subtracting 1/2 period of the color subcarrier from 2 horizontal scanning times; a third delay circuit that delays the output of the third delay circuit by one period of the color subcarrier; and a fourth delay circuit that delays the output of the third delay circuit by one period of the color subcarrier; The means includes: a coefficient circuit that multiplies the output of the second delay circuit by -4; the output of the direct output means; the output of the first delay circuit; the output of the coefficient circuit; and the third delay. 3. The contour signal extraction filter according to claim 2, further comprising an addition circuit that adds the output of the circuit and the output of the fourth delay circuit. (4) The contour signal extraction filter according to any one of claims 1 to 3, further comprising a multiplication means for multiplying the output of the calculation means by a predetermined multiplier.