JPH06245225A - Motion adaptive luminance signal chrominance signal separator circuit - Google Patents

Abstract

PURPOSE:To improve the performance of Y/C separation by allowing the circuit to execute still picture processing even in the case of inching or panning. CONSTITUTION:A motion picture Y/C separator circuit 3, a BPF 6 and a subtractor 7 obtains a 2nd chrominance signal and a 2nd luminance signal, and they are given respectively to MIX circuits 8, 9. A delay circuit group 21 and subtractors 22A-22M obtain a correlation among a predetermined picture element of a current picture, a picture element of a preceding frame and its surrounding picture elements for each picture element. A minimum value detection circuit 26 allows selection circuits 23, 27 to select an output of a subtractor giving a minimum motion. Thus, Y/C separation is executed between picture elements having highest correlation and still picture processing is applied even to a very small motion to obtain excellent Y/C separation performance.

Description

Detailed Description of the Invention

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion adaptive luminance signal / color signal separation circuit adopted in a color television receiver or the like.

[0002]

2. Description of the Related Art Conventionally, in a television receiver, a video tape recorder and the like, in order to improve the performance of separating a luminance signal and a color signal (hereinafter referred to as Y / C separation),
There is also one that employs a three-dimensional Y / C separation circuit adapted to the movement of the picture. In this conventional motion adaptive Y / C separation circuit, motion detection and motion adaptive operation are major factors that determine the Y / C separation performance. The motion of the pattern is detected by the size of the frame difference value (frame non-correlation) of the input composite video signal, and the motion and the detected pattern (moving image) are Y / C separated by using the line correlation and then stopped. The pattern (still image) determined to be Y / C is separated using frame correlation.

FIG. 4 is a block diagram showing such a conventional motion adaptive luminance signal / color signal separation circuit. The circuit shown in FIG. 4 shows an example in which the circuit is implemented as an LSI. The National Conference of the Television Society of 1989 (Miyazaki et al .: “3D YC Processing LS”).
I Development ”, P215-P216).

The input composite video signal (NTSC signal) input through the input terminal 1 is given to the A / D converter 2 to be converted into a digital signal, and the Y / C separation LSI 15 for moving picture Y.
Input to the / C separation circuit 3. The moving image Y / C separation circuit 3 takes in signals of three consecutive lines by using two 1H delay circuits (H is a horizontal period) 4 and 5 to obtain Y / C for moving images.
C separation is performed. That is, the Y / C separation circuit 3 for moving images is
First, the vertical correlation of the image is detected from the horizontal low frequency components of three adjacent lines. The outputs of the two comb filters for obtaining vertical high-frequency components (line non-correlation components) for the center line and the upper and lower lines are mixed based on the vertical correlation result. The vertical high-frequency components extracted by the moving picture Y / C separation circuit 3 are separated into color carrier band components in a bandpass filter (hereinafter referred to as BPF) 6 and are converted into a color signal at the time of moving picture (hereinafter referred to as moving picture C). It is given to the subtractor 7 and the MIX circuit 8. The subtractor 7 also inputs the output of the 1H delay circuit 4, subtracts the moving image C from the 1H-delayed NTSC signal, separates the luminance signal at the time of moving image (hereinafter, referred to as moving image Y), and outputs it to the MIX circuit 9. Output.

N delayed by 1H by the 1H delay circuit 4
The TSC signal is supplied to the still image Y / C separation circuit 12 and also to the 1-frame delay circuit 10 operating with a delay time of 525H (1 frame period). 1-frame delay circuit
Reference numeral 10 delays the input signal for one frame period and supplies it to the still image Y / C separation circuit 12 and one frame delay circuit 11.
The Y / C separation circuit 12 for still image is given an NTSC signal of about 1 frame from the 1H delay circuit 4 and the 1-frame delay circuit 10, and by adding these two input signals, the luminance signal at the time of still image ( (Hereinafter referred to as still image Y)
The color signal component (frame non-correlation component) at the time of still image is separated by subtracting two input signals. The still image Y separated in the still image Y / C separation circuit 12 is given to the MIX circuit 9,
The color signal component (frame non-correlation component) is band-limited by the BPF 13 and then given to the MIX circuit 8 as a color signal for a still image (hereinafter, still image C).

On the other hand, the output of the 1H delay circuit 4 (1H delay signal) and the outputs of the 1 frame delay circuits 10 and 11 (1 frame delay signal, 2 frame delay signal) are also given to the motion detection circuit 14. The motion detection circuit 14 outputs the larger one of the motion signal detected based on the difference value between 1 frames and the motion signal detected based on the difference value between 2 frames to the MIX circuits 8 and 9 as a motion signal. . The MIX circuit 9 receives the moving image Y and the still image Y, mixes both at a ratio according to the motion signal, and outputs the luminance signal Y to the output terminal 16. MIX
The circuit 8 receives the moving image C and the still image C, mixes them at a ratio according to the motion signal, and outputs the color signal C to the color processing LSI 17.

As described above, the moving picture Y / C separation circuit 3 obtains the moving picture C and the moving picture Y by the Y / C separation using the line correlation, and the still picture Y / C separation circuit 12 uses the frame correlation Y. A still image C and a still image Y are obtained by separating / C.

By the way, the still image Y / C separation circuit 12 subtracts the frame non-correlation component of the entire band from the input signal to obtain the still image Y.
While the video Y is calculated from the input signal, BPF6
It is obtained by subtracting the frame-uncorrelated component whose band is limited by. Therefore, in the Y / C separation process for moving images,
The resolution is lower than the Y / C separation process for still images. The still image processing and the moving image processing are performed at a rate based on the motion detection result. Therefore, even fine movement of a fine pattern visually observed as a change of a still image, a pattern at the time of panning of a camera, and the like are processed as a moving image, and the image quality is deteriorated. FIG. 5 is an explanatory diagram for explaining this problem. FIG. 5A shows an image of the (n-1) th frame, and FIG. 5B shows an image of the nth frame.
The image of the frame is shown, and black circles A and A'in the figure show pixels at the same position on the screen.

It is assumed that the object B in the (n-1) th frame indicated by the diagonal lines in FIG. 5A moves to the position indicated by the diagonal lines in FIG. 5B in the nth frame. In this case,
Even if the movement of the object B is slight, the pixels A ′ and A are processed as a moving image portion.

However, when the movement of the object B is due to the panning of the camera, the deterioration of the image quality becomes remarkable due to the reduction of the resolution due to the moving image processing. Further, when the movement of the object B is caused by a fine movement of a fine pattern such as the movement of leaves in the wind, cross color and dot interference occur due to the moving image processing. Further, when the movement of the fine pattern repeats the progress and the stop, the resolution changes correspondingly, the cross color and the state of dot interference also change, and the screen quality is extremely deteriorated.

[0011]

As described above, in the conventional motion adaptive luminance signal / color signal separation circuit described above,
Even if there is no problem even if visual still image processing is performed, such as when a fine pattern moves slightly or when the camera is panned, moving image processing is performed, resulting in reduced resolution, cross color and dot interference. However, there is a problem in that

According to the present invention, a portion which can be visually judged to be a still image movement is subjected to still image processing,
An object of the present invention is to provide a motion adaptive luminance signal / color signal separation circuit capable of improving resolution and suppressing occurrence of cross color and dot interference.

[Constitution of Invention]

A motion adaptive luminance signal / color signal separation circuit according to the present invention separates a second luminance signal and a second color signal by utilizing intra-screen correlation of an input composite video signal. And a predetermined separating pixel of the input composite video signal, and an operation of the target pixel n frames (n is an integer of 1 or more) before in the same position as the predetermined pixel of the input composite video signal, and a plurality of peripheral pixels around the target pixel and the predetermined pixel. And a motion detecting unit that detects a motion between the predetermined pixel and a peripheral pixel including the target pixel for each pixel, and a motion that outputs a motion detection signal based on the minimum motion detected by the motion detecting unit. The detection signal output unit and the pixel determined to have the highest correlation with the predetermined pixel based on the detection result of the motion detection unit among the peripheral pixels including the target pixel and the predetermined pixel are calculated by the inter-screen operation. Luminance signal and First separating means for separating one color signal, first mixing means for mixing and outputting the first color signal and the second color signal based on the motion detection signal, and the motion Second mixing means for mixing and outputting the first luminance signal and the second luminance signal based on a detection signal is provided.

[0014]

In the present invention, the second separating means separates the luminance signal and the chrominance signal by utilizing the intra-screen correlation during the moving image.
The motion detecting means obtains a motion for each pixel by calculating a pixel of interest at the same position as the predetermined pixel and n pixels before and a peripheral pixel. The motion detection signal output means converts the detection result of the motion that gives the minimum motion into a motion detection signal. The first separating means separates the luminance signal and the chrominance signal in the still image by using the correlation of about n frames. That is, the first separating unit separates the luminance signal and the color signal by calculating the pixels having the highest correlation according to the detection result of the motion detecting unit. As a result, in the first and second mixing circuits, the ratio of the output of the first separating means is increased, and the Y / C separation performance is improved.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a motion adaptive luminance signal / color signal separation circuit according to the present invention. Figure 1
4, the same components as those in FIG. 4 are designated by the same reference numerals.

The input composite video signal input through the input terminal 1 is given to the A / D converter 2. The A / D converter 2 converts the composite video signal into a digital signal and supplies it to the Y / C separation circuit 3 for motion picture and the 1H delay circuit 4. 1H delay circuit 4
Delays the input signal by 1H, outputs the delayed signal to the moving image Y / C separation circuit 3, and outputs it to the moving image Y / C separation circuit 3 via the 1H delay circuit 5. Video Y / C separation circuit 3
Has a line comb filter, and the current signal from the A / D converter 2 and 1H and 2H from the 1H delay circuits 4 and 5
A delayed signal is input and a vertical high frequency component (line non-correlation component) is extracted by utilizing the vertical correlation of the signals of these three lines.

The extracted vertical high frequency component is given to the BPF 6. The BPF 6 separates only the component of the color carrier band from the vertical high frequency component and outputs it to the MIX circuit 8 and the subtractor 7 as a second color signal which is a color signal at the time of moving image. The output of the 1H delay circuit 4 (composite video signal delayed by 1H) is also input to the subtractor 7, and the subtractor 7 subtracts the second color signal from the composite video signal delayed by 1H, thereby The second luminance signal which is a luminance signal is obtained and output to the MIX circuit 9.

On the other hand, the output of the 1H delay circuit 4 is Y /
It is also given to the delay circuit group 21 which delays the video signal for about one frame period for C separation. The delay circuit group 21 has delay circuits 21A to 21M connected in cascade, and the delay amounts of the delay circuits 21A to 21M are (523H-2d), 2d, 2 respectively.
d, (1H-3d), 2d, (1H-3d), 2d, 2
d, (1H-3d), 2d, (1H-3d), 2d, 2
d. Note that 2d is a color subcarrier period. The output of the 1H delay circuit 4 and the outputs of the delay circuits 21A to 21M are given to the subtractors 22A to 22M of the subtractor group 22, respectively. Subtractor
The video signals of about 1 frame are input to 22A to 22M. Moreover, since the delay amount 2d is set to the color subcarrier period, the output of each delay circuit 21A to 21M has the opposite phase of the color signal component with respect to the output of the 1H delay circuit 4, and the subtractor 22A to 22M separates the frame uncorrelated components by subtracting the outputs of the delay circuits 21A to 21M from the output of the 1H delay circuit 4, respectively. Subtractors 22A to 22
The output of M is supplied to the selection circuit 23 and also to the low-pass filter (hereinafter referred to as LPF) group 24.

The LPF group 24, the absolute value circuit group 25, the minimum value detecting circuit 26, the selecting circuit 27 and the non-linear circuit 28 constitute a motion detecting circuit. The LPF group 24 is composed of 13 LPFs having a cutoff frequency of 1.0 to 1.5 MHz. The motion detection circuit is adapted to obtain a motion detection signal from the motion component in the low range of the luminance signal. That is, the subtractors 22A to 22M provide the difference value between the frames of the video signal to the LPF group 24, and each LPF of the LPF group 24 band-limits the output of the subtractors 22A to 22M.
The difference value of one frame of the horizontal low frequency component is obtained. LPF
The output of the group 24 is given to the absolute value circuit group 25, and the absolute value circuit group 25 obtains the absolute value of each LPF output and outputs it to the minimum value detection circuit 26 and the selection circuit 27.

Ignoring the influence of noise, the difference value between one frames is 0 in a complete still image and a finite value in a moving image. That is, the amount of movement is proportional to the difference value between frames. The minimum value detection circuit 26 detects the minimum value among the outputs of the absolute value circuit group 25 and gives the minimum value.
The output of 25 is selected by the selection circuit 27. The selection circuit 27 selects the output showing the smallest movement among the outputs of the absolute value circuit group 25 and supplies it to the non-linear circuit 28.

The non-linear circuit 28 uses the fact that the larger the motion is, the larger the difference value between one frame is.
27 output, that is, the minimum absolute value of the difference signal of the luminance signal horizontal low-frequency component between one frame is converted into the motion detection signal K and M
Output to the IX circuits 8 and 9. The motion detection signal K is K = 0 in the case of a completely still image and K = 1 in the case of a completely moving image (0 ≦ K ≦ 1).

On the other hand, the subtractors 22A to 22M also output color signals of all frequency band components including the luminance signal low frequency component by subtracting the video signals of about one frame. The selection circuit 23 selects the output of the subtractor corresponding to the absolute value output determined to have the smallest movement by the minimum value detection circuit 26, and the MIX circuit 8 is used as the first color signal which is the color signal in the still image. And to the subtractor 29. That is, the selection circuit 23 outputs the color signal by performing the correlation calculation of the parts having the highest correlation, and the degree of the still image processing is large. The subtractor 29 subtracts the first color signal from the selection circuit 23 from the output of the 1H delay circuit 4 to separate the first luminance signal, which is the luminance signal at the time of still image, and outputs it to the MIX circuit 9. .

The MIX circuit 8 inputs the second color signal at the time of moving image and the first color signal at the time of still image from the BPF 6 and the selection circuit 23, respectively, and mix ratio based on the motion detection signal K from the non-linear circuit 28. Then, the both are mixed and output as a color signal which is subjected to motion adaptive Y / C separation. Further, the MIX circuit 9 inputs the second luminance signal at the time of moving image and the first luminance signal at the time of still image from the subtractor 7 and the subtractor 29, respectively, and mixes both at a mixing ratio based on the motion detection signal K. Then motion adaptive Y / C
It is designed to be output as a separated luminance signal.

Next, the operation of the embodiment thus constructed will be described with reference to FIGS. 2 is an explanatory diagram for explaining the operation of the delay circuit group 21, and FIG. 3 is an explanatory diagram for explaining the operation of the embodiment.

The operation of Y / C separation for moving images is the same as the conventional one. That is, the input composite video signal input through the input terminal 1 is given to the A / D converter 2. The A / D converter 2 converts the composite video signal into a digital signal and supplies it to the Y / C separation circuit 3 for motion picture and the 1H delay circuit 4. The 1H delay circuit 4 delays the input signal by 1H and outputs the delayed signal to the Y / C separation circuit 3 for moving images and the Y for moving images via the 1H delay circuit 5.
It outputs to the / C separation circuit 3. The moving picture Y / C separation circuit 3 has a line comb filter and receives the current signal from the A / D converter 2 and the 1H and 2H delay signals from the 1H delay circuits 4 and 5 and outputs these 3 lines. The vertical high frequency component (line decorrelation component) is extracted by utilizing the vertical correlation of the signal of.

The extracted vertical high frequency component is given to the BPF 6. The BPF 6 separates only the component of the color carrier band from the vertical high frequency component and outputs it to the MIX circuit 8 and the subtractor 7 as a second color signal which is a color signal at the time of moving image. The output of the 1H delay circuit 4 (composite video signal delayed by 1H) is also input to the subtractor 7, and the subtractor 7 subtracts the second color signal from the composite video signal delayed by 1H, thereby The second luminance signal which is a luminance signal is obtained and output to the MIX circuit 9.

On the other hand, the output of the 1H delay circuit 4 is Y /
It is also given to the delay circuit group 21 for C separation. Each of the delay circuits 21A to 21M of the delay circuit group 21 sequentially delays the input signal. Now, it is assumed that the output of the 1H delay circuit 4 is a signal one frame after the signal of the central pixel G ′ in FIG. 2 (the signal of the pixel G). That is, the pixel G'is a pixel at the same position as the input composite video signal, and the pixels A ', B',
C ', D', E ', F', H ', I', J ', K',
L ′ and M ′ are peripheral pixels in which the phase of the color subcarrier is the same as that of the pixel G ′.

The delay circuit 21A delays the input signal of the pixel G by (523H-2d). Then, the signal output from the delay circuit 21A corresponds to the position of the pixel A'in FIG. The delay circuit 21B delays the output of the delay circuit 21A by 2d, and the output of the delay circuit 21B corresponds to the position of the pixel B'in FIG. Similarly, the delay circuits 21B to 21L
Of the delay circuits 21C to 21M, and the outputs of the delay circuits 21C to 21M correspond to the positions of the pixels C'to M'in FIG. 2, respectively.

The subtractors 22A to 22M are respectively 1H delay circuits 4
From the output of each of the delay circuits 21A to 21M.
That is, the subtracters 22A to 22M obtain the difference between the signal of the pixel G and the signals of the peripheral pixels including the pixel G '(about one frame difference). That is, since the color subcarrier phases of the pixel G and the pixel G ′ are opposite to each other and the color subcarrier phases of the pixel G ′ and the peripheral pixels A ′ to M ′ are the same phase, the subtracter 22
A to 22M determine the motion and color signal components between the pixel G and each peripheral pixel including the pixel G'of the previous frame at the same position as the pixel G.

Now, the hatched object in the (n-1) th frame shown in FIG. 3A corresponds to the object shown in FIG.
It shall move to the position shown in (b). The subtractors 22A to 22M respectively include the pixel G of the nth frame and the (n−) th pixel.
1) Frame pixel A ', pixel G and pixel B', pixel G and pixel C ', pixel G and pixel D', pixel G and pixel E ', pixel G and pixel F', pixel C and pixel H ', Pixel G and pixel I ',
Motion is detected between pixel G and pixel J ', pixel G and pixel K', pixel G and pixel L ', and pixel G and pixel M'. In this case, since the object on the pixel D ′ in the (n−1) th frame moves to the pixel G in the next frame,
The magnitude of motion between pixel G and pixel D'is minimal.
Therefore, in this embodiment, Y / C separation processing is performed between the pixel G and the pixel D '. That is, the difference between the pixel G and the pixel D ′ having the highest correlation is calculated for about one frame, so that the image is processed as a still image although it actually moves.

This movement is detected by the LPF 24 and the absolute value circuit 25.
And the minimum value detection circuit 26. The LPF group 24 passes the low-frequency component of each output of the subtracters 22A to 22M, extracts the low-frequency component in which the luminance signal and the color signal are not frequency-multiplexed, and outputs the low-frequency component to the absolute value circuit group 25. Each absolute value circuit of the absolute value circuit group 25 obtains the absolute value of the 13 LPF outputs of the LPF group 24 and outputs it to the selection circuit 26 and the minimum value detection circuit 26.

The minimum value detection circuit 26 detects the smallest movement between the pixel G and each of the pixels A'to M'in FIG. 3A from each absolute value output. The minimum value detection circuit 26 determines the pixel having the strongest frame correlation with the pixel G, and the minimum value circuit 26
Outputs to the selection circuits 23 and 27 a signal for selecting the signal of the pixel having the strongest correlation with the pixel G among the pixels A ′ to M ′. As a result, the selection circuits 27 and 23 select the output of the subtractor 22D corresponding to the pixel D '.

The output of the selection circuit 27 is given to the nonlinear circuit 28,
The non-linear circuit 28 converts the motion between the pixel G and the pixel D ′ into a motion detection signal K and outputs it to the MIX circuits 8 and 9. As a result, the signal at the position of the pixel G is more likely to be subjected to still image processing. Further, the selection circuit 23 obtains the frame non-correlation component at the position of the pixel D ′ having the highest correlation with the pixel G. Since the frame correlation is high, the color signals are reliably separated by the still image processing. The subtractor 29 subtracts the first color signal from the selection circuit 23 and the output of the 1H delay circuit 4 and outputs the first luminance signal in the still image to the MIX circuit 9.

The MIX circuit 8 uses the ratio based on the motion detection signal K to output the first color signal from the selection circuit 23 during the still image and BP.
The second color signal at the time of the moving image from F6 is mixed and output as the color signal C separated by the motion adaptive Y / C. Also, M
The IX circuit 9 mixes the first luminance signal and the second luminance signal at a ratio based on the motion detection signal K to obtain a motion adaptive Y /
Output as a volatility signal Y separated by C.

As described above, in this embodiment, the pixel G'is not only arranged between the current pixel G and the pixel G'at the corresponding position one frame before but by the delay circuit group 21 and the subtractor group 22. Processing is also performed between the surrounding pixels A ′ to M ′ that include the pixel P, and the pixel G has the highest correlation (small motion).
By using pixels, Y / C separation processing is performed as a still image portion, and Y / C separation performance can be improved. That is, even when a fine pattern slightly moves or when the camera pans, the movement distance is within the detection range, that is, within the range of the peripheral pixels A ′ to M ′ with respect to the current pixel G. For example, Y / as the still image part
C separation processing can be performed, occurrence of cross color and dot interference can be suppressed, and deterioration of resolution can be prevented. Furthermore, the movement of the fine pattern progresses,
Stable image quality can be displayed even when the stop is repeated, and the screen quality is improved.

In this embodiment, the MIX circuits 8 and 9 are separately provided, but the MIX circuit 9 is deleted and the subtractor 29 is arranged at the subsequent stage of the MIX circuit 8 so that the color signal from the composite video signal is changed. The luminance signal Y may be separated by subtracting C. Further, in the present embodiment, only the information of the luminance signal low frequency component is used for detecting the motion, but it is obvious that the information of the color signal may be used.

[0037]

According to the present invention, the portion which can be visually determined to be a still image is subjected to the still image processing to improve the resolution and suppress the occurrence of cross color and dot interference. It has the effect of being able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a motion adaptive luminance signal / color signal separation circuit according to the present invention.

FIG. 2 is an explanatory diagram for explaining the operation of the embodiment.

FIG. 3 is an explanatory diagram for explaining the operation of the embodiment.

FIG. 4 is a block diagram showing a conventional motion adaptive luminance signal / color signal separation circuit.

FIG. 5 is an explanatory diagram for explaining an operation of a conventional example.

[Explanation of symbols]

3 ... Y / C separation circuit for moving images, 8, 9 ... Mixing circuit, 21A ...
21M ... Delay circuit, 22A-22M ... Subtractor, 23, 27 ... Selection circuit, 26 ... Minimum value detection circuit

Claims (1)

[Claims] 1. A second separating means for separating a second luminance signal and a second chrominance signal by utilizing the intra-screen correlation of the input composite video signal, and a second separation means at the same position as a predetermined pixel of the input composite video signal. Between the predetermined pixel and the peripheral pixel including the target pixel by calculation with the target pixel n frames before (n is an integer of 1 or more) and a plurality of peripheral pixels around the target pixel and the predetermined pixel. Motion detection means for detecting motion for each pixel, motion detection signal output means for outputting a motion detection signal based on the minimum motion detected by the motion detection means, and the motion detection means among the peripheral pixels including the target pixel. First separating means for separating a first luminance signal and a first color signal by an operation between screens of the pixel determined to have the highest correlation with the predetermined pixel and the predetermined pixel according to the detection result of In the motion detection signal A first mixing means for outputting by mixing said first color signal and a second chrominance signal Zui, said first luminance signal based on the motion detection signal and the second
And a second mixing means for mixing and outputting the luminance signal of 1.