JP3102743B2 - Motion adaptive Y / C separation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion adaptive Y / C separation circuit for separating a luminance signal and a carrier chrominance signal used in a television receiver or the like.

[0002]

2. Description of the Related Art A conventional motion adaptive Y / C separation circuit converts a composite video signal sampled and digitized at a cycle of a frequency obtained by multiplying the frequency of a color subcarrier into a digital signal.
The carrier chrominance signal and the luminance signal are separated by the operation between lines, the carrier chrominance signal and the luminance signal are separated by the operation between frames, and the correlation amount of the image is detected in pixel units by using the correlation between the frames, At a rate based on the detected correlation amount, a luminance signal separated by a calculation between lines and a luminance signal separated by a calculation between frames are mixed as a luminance signal,
The carrier color signal separated by the operation between lines and the carrier color signal separated by the operation between frames are mixed and output as a carrier color signal.

[0003]

According to the above-mentioned conventional motion adaptive Y / C separation circuit, separation using line correlation is performed in a moving image. If there is no correlation between lines, carrier color signal separation is performed by calculation between lines, so that leakage occurs between the luminance signal and the carrier chrominance signal, causing cross color and dot interference, deteriorating image quality. There was a problem.

Furthermore, the difference between the resolution of the carrier chrominance signal and the luminance signal separated by the operation between the lines and the resolution of the carrier chrominance signal and the luminance signal separated by the operation between the frames is large, and the resolution at the time of moving images is low. There was a problem that it was low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motion adaptive Y / C separation circuit which accurately separates a luminance signal and a carrier chrominance signal and has a high resolution even during a moving image.

[0006]

According to the present invention, the motion adaptive Y /
The C-separation circuit is a motion-adaptive Y / C separation circuit that separates a luminance signal and a carrier chrominance signal from a composite video signal sampled and digitized at a cycle of a frequency obtained by multiplying the frequency of the chrominance subcarrier by a pixel of interest. A first carrier color signal separation circuit that separates a carrier color signal from the composite video signal by calculating a pixel corresponding to the target pixel and a pixel corresponding to the target pixel on a line adjacent to the line including: The carrier color is calculated by calculating one or more pixels on the field immediately before the field including the pixel of interest and in which the phase of the color subcarrier is inverted with respect to the pixel of interest in the vicinity of the pixel corresponding to the pixel of interest and the pixel of interest A second carrier chrominance signal separation circuit for separating a signal from the composite video signal; and A third carrier color signal separation circuit for separating a carrier color signal from the composite video signal by calculating a pixel corresponding to an eye pixel and the target pixel, and a carrier color separated by the second carrier color signal separation circuit A first correlation detection circuit for detecting a correlation amount between pixels on which a signal operation is based, and a correlation between pixels on which a carrier chrominance signal separated by a third carrier chrominance signal separation circuit is based; A second correlation detection circuit for detecting the amount, and a second carrier color signal separation performed by calculating a carrier color signal obtained by an operation between pixels having the largest correlation amount among the correlation amounts detected by the first correlation detection circuit. First selecting means for selecting from among the circuits, and one of the carrier color signal selected by the first selecting means and the carrier color signal separated by the third carrier color signal separation circuit,
Second selecting means for selecting based on the correlation amount detected by the second correlation detection circuit and the maximum correlation amount among the correlation amounts detected by the first correlation detection circuit, and a first carrier color signal The carrier chrominance signal separated by the separation circuit and the carrier chrominance signal selected by the second selection means are used to calculate the correlation amount between the correlation amount detected by the second correlation detection circuit and the correlation amount detected by the first correlation detection circuit. A color signal mixing circuit that mixes and outputs the separated carrier color signals as a separated carrier color signal based on the maximum correlation amount, and subtracts the separated carrier color signal output from the color signal mixing circuit from the composite video signal as a separated luminance signal. And a subtraction means for outputting.

[0007]

According to the motion adaptive Y / C separation circuit of the present invention, the carrier chrominance signal is calculated by calculating the pixel on the line adjacent to the line including the pixel of interest and corresponding to the pixel of interest. It is separated from the video signal by a first carrier chrominance signal separation circuit. The carrier chrominance signal is calculated by calculating one or more pixels on the field immediately before the field including the line and having the phase of the color subcarrier inverted near the pixel corresponding to the target pixel and the target pixel. It is separated from the composite video signal by the second carrier color signal separation circuit. A carrier color signal is separated from the composite video signal by a third carrier color signal separation circuit by an operation of the pixel on the field immediately before the immediately preceding field and corresponding to the pixel of interest and the pixel of interest.

The carrier color selected by the first selecting means based on the largest correlation amount among the correlation amounts detected by the first correlation detection circuit and the correlation amount detected by the second correlation detection circuit. One of the signal and the carrier color signal separated by the third carrier color signal separation circuit is selected by the second selection means, and the carrier color signal separated by the first carrier color signal separation circuit and the second selection. The carrier color signal selected by the means is mixed based on the correlation amount detected by the second correlation detection circuit and the maximum correlation amount among the correlation amounts detected by the first correlation detection circuit, and separated and transported. It is output as a color signal.

However, the phase of the color subcarrier with respect to the pixel of interest is located on the field immediately before the field including the line having the pixel of interest and near the pixel corresponding to the pixel of interest. And the maximum correlation amount among the correlation amounts between the one or more pixels and the correlation amount between the pixel on the field immediately before the immediately preceding field and corresponding to the pixel of interest and the pixel of interest. , The correlation centering on the target pixel is locally detected between the field and the frame, and the carrier color signal separated by the second carrier color signal separation circuit and the third One of the carrier color signals separated by the carrier color signal separation circuit is selected, and the selected carrier color signal and the carrier color signal separated by the first carrier color signal separation circuit are selected. Since being mixed is output as separated carrier chrominance signal, accurate carrier chrominance signal and luminance signal are separated. As a result, the resolution of a moving image is high, and the image quality difference between a still image and a moving image is reduced.

[0010]

The present invention will be described below with reference to examples. FIG.
FIG. 1 is a block diagram showing a configuration of an embodiment of a motion adaptive Y / C separation circuit according to the present invention.

The motion-adaptive Y / C separation circuit according to the present embodiment has a frequency 4f obtained by multiplying the frequency fsc of the chrominance subcarrier by four.
From a composite video signal sampled and digitized at a cycle of sc (hereinafter, referred to as a composite video signal), a pixel corresponding to the pixel of interest on a line adjacent to a line including the pixel of interest and A line-correlation type color signal separation circuit 1 which is a first carrier color signal separation circuit for separating a carrier color signal by operation with the pixel of interest
And one or more pixels that are on the field immediately before the field including the line and that have a phase of the color subcarrier inverted with respect to the pixel of interest with respect to the pixel of interest in the vicinity of a pixel corresponding to the pixel of interest. And an inter-field color signal separation circuit 4 which is a second carrier color signal separation circuit for separating a carrier color signal from the composite video signal by an operation of the target pixel and the target pixel. And an inter-frame color signal separation circuit 2 which is a third carrier color signal separation circuit that separates a carrier color signal from the composite video signal by calculating a pixel corresponding to the pixel of interest and the pixel of interest. .

The motion adaptive Y / C separation circuit of the present embodiment
Further, it detects a correlation amount between pixels which cooperates with the inter-field color signal separation circuit 4 and is the basis of the calculation of the carrier chrominance signal separated by the inter-field color signal separation circuit 4, and detects the correlation amount in the correlation amount. A first correlation detecting circuit and an inter-field correlation detecting circuit as first selecting means for selecting and outputting a carrier color signal obtained by an operation between pixels having the maximum correlation amount from the inter-field color signal separating circuit 4 5
And an inter-frame correlation detection circuit 3 which is a second correlation detection circuit for detecting a correlation amount between pixels on which the calculation of the carrier color signal separated by the inter-frame color signal separation circuit 2 is based.
And

The motion adaptive Y / C separation circuit of the present embodiment
A correlation amount comparison circuit 7 for comparing the correlation amount detected by the inter-frame correlation detection circuit 3 with the correlation amount output from the inter-field correlation detection circuit 5, and a carrier color signal separated by the inter-frame color signal separation circuit 2 And a carrier color signal output from the inter-field color signal separation circuit 4, a selection circuit 6 serving as second selection means for selecting based on the output of the correlation amount comparison circuit 7, and an output from the selection circuit 6. The mixing ratio of the carrier color signal and the carrier color signal output from the line correlation type color signal separation circuit 1 is controlled based on the output from the correlation amount comparison circuit 7, and the input carrier color signal is controlled at the controlled mixing ratio. A color signal mixing circuit 8 for mixing the color signals and outputting the separated color signals as separated carrier color signals, and a color signal mixing circuit 8
And a subtracter 9 which is a subtraction means for subtracting the carrier color signal output from the printer.

As shown in FIG. 2, the line-correlation-type color signal separation circuit 1 is supplied with a composite video signal and stores a composite video signal for one line. That is, there are provided a subtractor 12 for subtracting the composite video signal of the previous line from the composite video signal, and a １３ circuit 13 for reducing the output level of the subtractor 12 to レ ベ ル. The corresponding carrier color signal is obtained and 1 /
By being halved by the two circuits 13, a carrier chrominance signal is output from the 回路 circuit 13.

As shown in FIG. 3, the inter-frame color signal separation circuit 2 is supplied with a composite video signal and stores a composite video signal for one frame. A subtractor 22 for subtracting the composite video signal one frame before from the composite video signal and a １ ／ circuit 23 for reducing the output level of the subtracter 22 to 1/2 are provided. Is obtained by the half color circuit 23,
A carrier color signal is output from the 1/2 circuit 23.

As shown in FIG. 4, the inter-frame correlation detection circuit 3 receives a composite video signal, delays it by one frame period, and outputs the delayed one-frame period. The one-frame delay circuit 31 delays one frame. A one-frame delay circuit 32 for further delaying the composite video signal by one frame period and outputting the same, a subtractor 33 for subtracting the composite video signal output from the one-frame delay circuit 31 from the input composite video signal,
A digital low-pass filter 34 to which the output of the subtracter 33 is input; a difference between the input composite video signal and the composite video signal of one frame before is output from the subtractor 33;
As a result, the low-frequency component correlation amount for one frame is detected.

The inter-frame correlation detection circuit 3 further receives the composite video signal delayed by the one-frame delay circuit 32, that is, the composite video signal delayed by two frames and the input composite video signal, and outputs two frames. The two-frame correlation amount detection circuit 35 for detecting the correlation amount and the output of the digital low-pass filter 34, that is, the smaller of the one-frame low-frequency component correlation amount and the two-frame correlation amount detected by the two-frame correlation amount detection circuit 35, are selected. And a correlation amount decoder 36 which outputs the correlation amount as a correlation amount. The correlation amount decoder 36 outputs an inter-frame correlation amount.

The inter-field color signal separation circuit 4 and the inter-field correlation detection circuit 5 are configured as shown in FIG. The inter-field color signal separation circuit 4 delays the composite video signal for a period of one sampling clock cycle, for example, delay circuits 411, 412, 441 to 443, and 4.
71 and 472, composite video signal of 262H
(H is one horizontal scanning period) Delay circuit 4 for delaying
2, a delay circuit 46 for delaying 1H, a subtractor 43,
45 and 48, a selection circuit 49, and a 1/2 circuit 50.

An input composite video signal (hereinafter, referred to as a composite video signal)
The composite video signal A) is delayed through delay circuits 411 and 412 for a period of two sampling clock cycles. At the same time, the composite video signal A is delayed through the delay circuit 42 for a period of 262H, and further delayed through the delay circuit 46 for a period of 1H. Delay circuit 41
2 is subtracted by a subtractor 43 from a composite video signal (hereinafter, referred to as a composite video signal C) output from the delay circuit 42 from a composite video signal (hereinafter, referred to as a composite video signal B) output from a carrier color signal c.
Output as

Here, since the composite video signal B is delayed from the composite video signal A by the period of two sampling clocks, the composite video signal B is shifted with respect to the phase of the color subcarrier of the pixel A by the composite video signal A. The phase of the color subcarrier of the pixel A due to the composite video signal A is shifted by 180 degrees with respect to the composite video signal A because the phase of the color subcarrier of the pixel B due to B is shifted by 180 degrees. And the phase of the color subcarrier of the pixel C by the composite video signal C is the same. Therefore, the phase of the color subcarrier of the pixel C by the composite video signal C is shifted by 180 degrees with respect to the phase of the color subcarrier of the pixel B by the composite video signal B, and the phase of the color subcarrier of the pixel B of interest is shifted. Pixel C
Are shifted by 180 degrees, and the carrier chrominance signal c whose level is doubled by the subtraction by the subtracter 43 is separated and output.

The composite video signal C is supplied to a delay circuit 441
Through 443, a period of four sampling clock cycles is delayed. The composite video signal output from the delay circuit 443 is referred to as a composite video signal E. Subtracter 4 subtracts composite video signal E from composite video signal B
5 and output as a carrier color signal b. Here, the composite video signal E is delayed from the composite video signal C by a period of 4 sampling clock periods, and the phase of the color subcarrier of the pixel E by the composite video signal E is the color of the pixel C by the composite video signal C. It is in phase with the phase of the subcarrier. Therefore, the phase of the color subcarrier of the pixel E by the composite video signal E is 1 with respect to the phase of the color subcarrier of the pixel B by the composite video signal B.
The phase of the color subcarrier of the pixel E is shifted by 180 degrees with respect to the phase of the color subcarrier of the target pixel B, and the carrier chrominance signal b whose level is doubled by the subtractor 45 is separated. Will be output.

The composite video signal output from the delay circuit 46 (hereinafter, referred to as composite video signal F) is delayed by a period of two sampling clocks through delay circuits 471 to 472. The composite video signal output from the delay circuit 472 is referred to as a composite video signal G. The composite video signal G is subtracted from the composite video signal B by the subtractor 48 and output as the carrier color signal a. Here, since the composite video signal F is delayed by a period of 263H with respect to the composite video signal A,
The phase of the color subcarrier of the pixel F by the composite video signal F is shifted by 180 degrees with respect to the phase of the color subcarrier of the pixel A by the composite video signal A.

Since the composite video signal G is delayed by two sampling clock cycles with respect to the composite video signal F, the composite video signal G is shifted with respect to the phase of the color subcarrier of the pixel F by the composite video signal F. , The phase of the color subcarrier of the pixel G due to the composite video signal G is the same as the phase of the color subcarrier of the pixel A due to the composite video signal A. For this reason, the phase of the color subcarrier of the pixel G by the composite video signal G is shifted by 180 degrees with respect to the phase of the color subcarrier of the pixel B by the composite video signal B, and the phase of the color subcarrier of the pixel B of interest is shifted. Thus, the phase of the color subcarrier of the pixel G is shifted by 180 degrees, and the carrier chrominance signal a whose level is doubled by the subtraction by the subtractor 48 is separated and output.

The separated carrier chrominance signals a, b, and c are supplied to a selection circuit 49 to select one of them based on an output of a correlation comparison circuit 54 described later, and the level is reduced to 1/2 by a half circuit 50. 2 and send it out as a carrier color signal. Therefore,
The carrier chrominance signal whose level has been returned to the original level is output via the selection circuit 49 and the 回路 circuit 50.

On the other hand, the inter-field correlation detection circuit 5 includes digital low-pass filters 51 to 53 and a correlation amount comparison circuit 54, and the carrier chrominance signals a, b, c are respectively applied to the digital low-pass filters 51, 52, 53. The low-pass correlation is supplied to the digital low-pass filters 51 and 5,
The output of each correlation amount detected by 2 and 53 is supplied to a correlation comparison circuit 54 to output the maximum correlation amount as a field correlation amount, and to output a carrier color signal which outputs the maximum correlation amount to a selection circuit 49. Is sent out. Here, digital low-pass filters 51, 5
The large output level of 2, 53 indicates that the motion is large and the correlation amount is small.

Therefore, the digital low-pass filter 5
The output levels of 1, 52 and 53 are minimum, that is, the inter-field correlation detection circuit 5 sends out the maximum correlation amount among the correlation amounts of the carrier chrominance signals a, b and c as the field correlation amount. On the other hand, the carrier color signal having the maximum correlation amount is selected from the carrier color signals a, b, and c from the inter-field color signal separation circuit 4, and the level is returned to the original and transmitted.

Here, the current field α is indicated by a solid line, the immediately preceding field β is indicated by a broken line, and the scanning lines are indicated by γ, δ, ε, and the composite video signal A input to the delay circuit 411 at one point in time. Pixel is pixel A, delay circuit 4
Pixels according to the composite video signal B having 12 outputs are represented by pixels B as shown in FIG. A pixel based on the composite video signal C output from the delay circuit 42 is denoted by a pixel C, a pixel based on the composite video signal E output from the delay circuit 444 is denoted by a pixel E, and a pixel based on the composite video signal G output from the delay circuit 472 is denoted by a pixel G. , Pixels C, E and G
Is on the immediately preceding field β, and assuming that the pixel of interest is pixel B, the difference between pixel B and pixel C, the difference between pixel B and pixel E, and the difference between pixel B and pixel G are subtractors 43, 45, 48, and output as carrier color signals b, c, a.

The correlation amount comparison circuit 7 (see FIG. 1) compares the correlation amount output from the inter-field correlation detection circuit 5 with a predetermined threshold value, the correlation amount output from the inter-frame correlation detection circuit 3, and other information. As shown in FIG. 7, one of the correlation amounts is selected as the output correlation amount based on the comparison result with the predetermined threshold value, and the carrier output from the inter-frame color signal separation circuit 2 selected by the selection circuit 6 is selected. A switching signal for determining which of the color signal and the carrier color signal output from the inter-field color signal separation circuit 4 is selected and output is transmitted.

In FIG. 7, when H exceeds the threshold,
That is, it means that there is a correlation, L means the case where it is equal to or less than a threshold value, that is, there is no correlation, and the description with the field correlation amount means the correlation amount output from the inter-field correlation detection circuit 5; The description of the amount means the correlation amount output from the inter-frame correlation detection circuit 3, the description of the frame color signal means the carrier color signal output from the inter-frame color signal separation circuit 2, and the description of the field color signal Means the carrier color signal output from the inter-field color signal separation circuit 4.

In the correlation amount comparison circuit 7, when the correlation amount output from the inter-field correlation detection circuit 5 is equal to or smaller than the threshold value and the correlation amount output from the inter-frame correlation detection circuit 3 is equal to or smaller than the threshold value, the inter-frame color The reason for selecting the carrier chrominance signal output from the signal separation circuit 2 is to match with the conventional case. The carrier color signal output from the inter-frame color signal separation circuit 2 when the correlation amount output from the inter-frame correlation detection circuit 3 exceeds the threshold value regardless of the correlation amount output from the inter-field correlation detection circuit 5 The selection is made in this case because a still image is often used. When the correlation amount output from the inter-frame correlation detection circuit 3 is equal to or less than the threshold value and the correlation amount output from the inter-field correlation detection circuit 5 exceeds the threshold value, the correlation value is output from the inter-field color signal separation circuit 4. To select the carrier color signal
This is because in this case, there are many cases of moving images.

As shown in FIG. 8, the color signal mixing circuit 8 includes multipliers 81 and 82, lookup tables 83 and 84, switching circuits 851 and 852, and an adder 86. The look-up table 83 stores the mixing coefficient pair (a10, b1
, (A11, b11),..., (A1n, b1n) are stored, and the output correlation amount output from the correlation amount comparison circuit 7 is referred to to search for a mixed coefficient pair. n is an integer of 1 or more. The look-up table 84 stores the mixing coefficient pairs (a20, b20), (a21, b21),.
2n, b2n) are stored, and the output correlation amount output from the correlation amount comparison circuit 7 is referred to to search for a mixture coefficient pair. Mixing coefficient a10>a11>...> A1n, b1
0 <b11 <... <b1n, a20>a21>...> a
2n, b20 <b21 <... <B2n, and the sum (a10i + b10i) of the mixing coefficient pair is set to {1}. As the output correlation amount output from the correlation amount comparison circuit 7 increases, the larger coefficients b1i and b2i are retrieved and output.

One of the lookup tables 83 and 84 is selected by the switching circuits 851 and 852 based on the switching signal output from the correlation amount comparison circuit 7, and the selected lookup table (83 or 84) is selected. Is multiplied in the multiplier 82 by the carrier chrominance signal output from the selection circuit 6 and the mixing coefficient (a1i or a2i) retrieved from the lookup table (83 or 84) is selected. b1i or b2
i) is obtained by multiplying the carrier chrominance signal output from the line correlation type color signal separation circuit 1 by the multiplier 81, adding the output of the multiplier 81 and the output of the multiplier 82 by the adder 86, and Are output as separated carrier color signals.

Therefore, in the present embodiment, the correlation amount centering on the target pixel B is locally detected between the field and the frame, and is separated by the inter-field color signal separation circuit 4 based on the correlation amount. One of the carrier color signal and the carrier color signal separated by the inter-frame color signal separation circuit 2 is selected, and the selected carrier color signal and the carrier color signal separated by the line correlation type color signal separation circuit 1 are selected. They are mixed and output as a separated carrier color signal. Since the separated carrier chrominance signal is subtracted from the composite video signal in the subtractor 9, the carrier chrominance signal and the luminance signal are accurately separated, and leakage during this time is reduced. As a result, the resolution of a moving image is high, and the image quality difference between a still image and a moving image is reduced.

Next, another embodiment of the present invention will be described. In another embodiment of the present invention, the correlation amount is detected over the field immediately after the field including the target pixel and the two frames immediately before the field including the target pixel in the above-described embodiment.

In another embodiment of the present invention, the same components as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted to avoid duplication. A delay circuit 10 for delaying the input composite video signal by 1H
1 and delayed for 1H period,
Is passed through a delay circuit 102 for delaying 261H, and the composite video signal output from the delay circuit 102 is delayed for 1H.
The signal is supplied to the inter-field color signal separation circuit 4 through the circuit 03. Therefore, the composite video signal output from the delay circuit 103 is the composite video signal A. The output of the delay circuit 102 is supplied to a line correlation type color signal separation circuit 1 to separate a carrier color signal. Therefore, the composite video signal A of the composite video signal A is
The carrier chrominance signal is separated from the composite video signal before the scanning line. The operation of the inter-field color signal separation circuit 4 is the same as that of the above-described embodiment except for the selection signal of the selection circuit 49.

A composite video signal E is subtracted from a composite video signal (hereinafter, referred to as a composite video signal H) output from the delay circuit 101 by a subtractor 109, and a subtraction output from the subtracter 109 is supplied to an absolute value circuit 110. Then, the output of the absolute value circuit 110 and the output of the digital low-pass filter 52 are supplied to the low correlation amount selection circuit 111 to select the one with the smaller correlation amount, that is, the one with the larger motion amount. Here, the composite video signal H
Is a composite video signal in a field two fields after the field including the composite video signal E, which is a composite video signal 262H after the composite video signal B, and the phase of the color subcarrier of the pixel H by the composite video signal H is The phase of the color subcarrier of the pixel E by the composite video signal E is the same. Therefore, the in-phase is subtracted by the subtractor 109, and the correlation amount between the high-frequency component and the low-frequency component is detected.

The composite video signal H is delayed by a period of 4 sampling clocks through delay circuits 104 to 107 for delaying the composite video signal by a period of one sampling clock, and a composite video signal (hereinafter, referred to as a composite video signal) output from the delay circuit 107 is output. The composite video signal C is subtracted from the composite video signal I).
8 and the subtraction output from the subtractor 108 is supplied to an absolute value circuit 112 to take an absolute value.
2 and the output of the digital low-pass filter 53 are supplied to the low correlation amount selection circuit 113 to select the one with the smaller correlation amount, that is, the one with the larger motion amount. Here, the composite video signal I is a composite video signal before the period of four sampling clock cycles from the composite video signal H, and the phase of the color subcarrier of the pixel I by the composite video signal I and the pixel C by the composite video signal C The phase of the chrominance subcarrier is the same. Therefore, subtracter 1
In 08, the in-phase is subtracted, and the correlation amount between the high-frequency component and the low-frequency component is detected.

A composite video signal (hereinafter, referred to as a composite video signal J) input to the delay circuit 101 is passed through delay circuits 114 to 115 for delaying the composite video signal by one sampling clock period, and is output for two sampling clock periods. Delay the delay circuit 11
5 to a composite video signal G (hereinafter, referred to as a composite video signal K).
Is subtracted by a subtractor 116, and a subtraction output from the subtractor 116 is supplied to an absolute value circuit 117 to take an absolute value, and an output of the absolute value circuit 117 and the digital low-pass filter 51 are output.
Is supplied to the low correlation amount selection circuit 118 to select the smaller correlation amount, that is, the larger motion amount.

The composite video signal J is located in a field immediately after the field containing the composite video signal A,
The composite video signal K is a composite video signal before the period of two sampling clock cycles from the composite video signal J, and the pixel K by the composite video signal K
And the phase of the color subcarrier of the pixel G by the composite video signal G are the same. Therefore,
The in-phase is subtracted by the subtractor 116, and the correlation amount between the high-frequency component and the low-frequency component is detected.

Low correlation amount selection circuits 111, 113 and 1
Each of the correlation amount signals output from 18 is a high correlation amount selection circuit 1
The carrier color signal which selects the largest correlation amount signal among the correlation amount signals supplied to and is input to 19 and outputs the selected correlation amount signal as the field correlation amount, and outputs the largest correlation amount among the carrier color signals a, b and c. Is sent to the selection circuit 49 to select the data. Therefore, a carrier color signal based on the maximum correlation amount is output from the selection circuit 49,
The level is halved by the 回路 circuit 50 and output.

On the other hand, the composite video signal F is delayed by a delay circuit 122 through the delay circuit 122 for a period of 262H, and the composite video signal L delayed through the delay circuit 122 is delayed by a period of one sampling clock cycle. Delay circuit 123
And a composite video signal (hereinafter, referred to as a composite video signal M) output from the delay circuit 124 is subtracted from the composite video signal B by the subtractor 125. Here, the composite video signal L is in the frame immediately before the field including the composite video signal B, and the phase of the color subcarrier of the pixel M by the composite video signal M is the same as the phase of the color subcarrier of the pixel B by the composite video signal B. The difference is 180 degrees, and the subtraction output from the subtractor 125 is output as a carrier color signal, and is also supplied to a digital low-pass filter 126 to extract a low-frequency component correlation amount.

The composite video signal L is supplied to the delay circuit 127
The composite video signal N delayed by the delay circuit 127 for a period of 525H, and the composite video signal N delayed through the delay circuit 127 delays the composite video signal for a period of one sampling clock cycle.
9, the composite video signal output from the delay circuit 129 (hereinafter, referred to as composite video signal P) is subtracted from the composite video signal B by the subtractor 130. Here, the composite video signal N is in the frame two frames before the field including the composite video signal A, and the phase of the color subcarrier of the pixel P by the composite video signal P and the color subcarrier of the pixel B by the composite video signal B Are in phase.

The output from the digital low-pass filter 126 and the subtraction output from the subtractor 130 are supplied to a frame correlation amount comparison circuit 131 to compare them and select a larger one, that is, a smaller correlation amount. The output from the digital low-pass filter 126 is the low-frequency component correlation amount,
The output subtracted from 0 is the correlation amount between the high-frequency component and the low-frequency component, and the larger one is output.

The carrier color signal output from the line correlation type color signal separation circuit 1, the carrier color signal output from the half circuit 50, and the carrier color signal output from the subtractor 125 are supplied to a color mixing circuit 120. You. The color signal mixing circuit 120 includes the selection circuit 6, the correlation amount comparison circuit 7, and the color signal mixing circuit 8 in the above-described embodiment, and the correlation amount output from the high correlation amount selection circuit 119 and the frame correlation amount comparison circuit. The carrier chrominance signal output from 131 corresponding to the larger correlation amount, ie, 1/2 circuit 5 when the former is larger.
The carrier chrominance signal output from 0 is selected. If the latter is large, the carrier chrominance signal output from the subtractor 125 is selected, and the correlation amount output from the high correlation amount selection circuit 119 and the frame correlation amount comparison circuit 131 are output. The carrier color signal selected from the carrier color signal output from the 1/2 circuit 50 and the carrier color signal output from the subtractor 125, and the line correlation type color signal on the basis of the larger correlation amount. Mixing with the carrier chrominance signal output from the separation circuit 1 to form a separated carrier chrominance signal is the same as in the above-described embodiment.

The separated carrier color signal is a composite video signal A
Is subtracted in the subtractor 9 to separate the luminance signal.

As described above, in the present embodiment, in the field immediately before the target pixel B, the target pixel B
The carrier chrominance signal is separated between the pixels C, E, and G in which the phase of the chrominance subcarrier and the phase of the chrominance subcarrier are inverted, and the low-band correlation amount of the separated carrier chrominance signal is detected. The correlation between the phase of the color subcarrier of the pixel G and the phase of the color subcarrier of the pixel G in the field immediately after the pixel of interest B,
The correlation between the phase of the color subcarrier of the pixel C and the phase of the color subcarrier of the pixel C in the field immediately before the pixel of interest B is the same as that of the pixel I. The phase and the phase of the color subcarrier are correlated with the pixel H having the same phase.

In general, when there is no correlation between the pixel of interest B and neighboring pixels in a still image, and there is a correlation between neighboring pixels, for example, pixels G and K, pixels C and I, and pixels E
And the pixel H have a strong correlation, and the pixel of interest B and the pixel G,
If there is no correlation between the target pixel B and the pixel E and between the target pixel B and the pixel C, an erroneous detection is made, and an erroneous Y / C separation is performed.
However, as in the above-described other embodiments, the motion amounts of the low-frequency components of the target pixels B and G, the target pixels B and E, and the target pixels B and C are determined by the digital low-pass filters 51 to 53.
The absolute value circuits 110, 112, and 117 take the absolute values of the amounts of motion including the high-frequency components of the pixels G and K, the pixels C and I, and the pixels E and H, and obtain the digital low-pass filters 51 to 51. 53 output and low correlation amount detection circuit 1
By performing the comparison using 11, 113, and 118, accurate motion detection, that is, the correlation amount can be detected.

In another embodiment of the present invention described above, the case where the correlation signal output from the high correlation selection circuit 119 is directly supplied to the color signal mixing circuit 120 has been described. May be sent to the color signal mixing circuit 120. Here, the pseudo-median filter 132 includes, for example, two pixels each including the target pixel B on the line including the target pixel B, and a total of five pixels, and further, the five pixels on a line adjacent to the line including the target pixel B. 5 pixels are set in correspondence with the pixel of the above, a total of 10 pixels are weighted and multiplied, and the sum when the whole is added is taken as the inter-field correlation amount for the target pixel B, Since the median value is not used, the pseudo-median filter 132 is called. By providing the pseudo-median filter 132, it is possible to smooth out a sudden change and output the result.

[0049]

As described above, according to the present invention, the pixel of interest is located on the field immediately before the field including the line having the pixel of interest and near the pixel corresponding to the pixel of interest. On the other hand, the phase of the chrominance subcarrier is the largest correlation amount among the correlation amounts between one or more pixels that are inverted with respect to the pixel of interest and is on the field immediately before the immediately preceding field and Like the correlation between the corresponding pixel and the target pixel, a correlation centering on the target pixel is locally detected between the field and the frame, and based on the correlation, a second carrier color signal separation circuit is used. One of the carrier color signal separated by the first carrier color signal separation circuit and the carrier color signal separated by the third carrier color signal separation circuit. Since the carrier chrominance signal separated is output as a separated carrier chrominance signal are mixed Te has an effect of accurately carrier chrominance signal and luminance signal are separated. As a result, it is possible to obtain an effect that the resolution of a moving image is high and the image quality difference between a still image and a moving image is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of one embodiment according to a motion adaptive Y / C separation circuit of the present invention.

FIG. 2 is a block diagram showing a configuration of a line correlation type color signal separation circuit in one embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an inter-frame color signal separation circuit according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an inter-frame correlation detection circuit in one embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of an inter-field color signal separation circuit and an inter-field correlation detection circuit in one embodiment of the present invention.

FIG. 6 is a schematic diagram for explaining the operation of an inter-field color signal separation circuit and an inter-field correlation detection circuit according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram for explaining an operation of a correlation amount comparison circuit in one embodiment of the present invention.

FIG. 8 is a schematic block diagram illustrating a configuration of a color signal mixing circuit according to an embodiment of the present invention.

FIG. 9 is a block diagram showing the configuration of another embodiment according to the motion adaptive Y / C separation circuit of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line correlation type color signal separation circuit 2 Inter-frame color signal separation circuit 3 Inter-frame correlation detection circuit 4 Inter-field color signal separation circuit 5 Inter-field correlation detection circuit 6 Selection circuit 7 Correlation amount comparison circuit 8 Color signal mixing circuit 9 Subtractor 111, 123 and 118 Low correlation amount selection circuit 119 High correlation amount selection circuit 131 Frame correlation amount comparison circuit

Claims (1)

(57) [Claims] 1. A motion adaptive Y / C separation circuit for separating a luminance signal and a carrier chrominance signal from a composite video signal sampled and digitized at a cycle of a frequency obtained by multiplying the frequency of a color subcarrier, A first carrier color signal separation circuit that separates a carrier color signal from the composite video signal by calculating a pixel corresponding to the pixel of interest on a line adjacent to the line including the pixel of interest and the pixel of interest; The carrier color is calculated by calculating one or more pixels on the field immediately before the field including the pixel of interest and in which the phase of the color subcarrier is inverted with respect to the pixel of interest in the vicinity of the pixel corresponding to the pixel of interest and the pixel of interest A second carrier chrominance signal separation circuit for separating a signal from the composite video signal; and A third carrier color signal separation circuit for separating a carrier color signal from the composite video signal by calculating a pixel corresponding to an eye pixel and the pixel of interest, and a carrier color separated by the second carrier color signal separation circuit A first method for detecting a correlation amount between pixels on which a signal operation is based
And a second detector for detecting the amount of correlation between pixels on which the calculation of the carrier color signal separated by the third carrier color signal separation circuit is based.
And a carrier color signal obtained by calculating between pixels having the largest correlation amount among the correlation amounts detected by the first correlation detection circuit from the second carrier color signal separation circuit. One of the carrier color signal selected by the first selection unit and the carrier color signal separated by the third carrier color signal separation circuit, the correlation detected by the second correlation detection circuit. Second selecting means for selecting based on the amount and the maximum correlation amount among the correlation amounts detected by the first correlation detection circuit; and a carrier color signal separated by the first carrier color signal separation circuit and a second The carrier color signal selected by the second selection means is mixed based on the correlation amount detected by the second correlation detection circuit and the maximum correlation amount among the correlation amounts detected by the first correlation detection circuit. Separated transport color signal A color signal mixing circuit for outputting the separated carrier color signal output from the color signal mixing circuit from the composite video signal and outputting the result as a separated luminance signal. Adaptive Y / C separation circuit.