JP2557513B2 - Motion detection circuit for television display screen - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motion detection circuit for a television display screen installed in a television receiver.

(Prior art) In a television receiver of a standard system such as NTSC or IDTV or EDTV which is similar to this, Y / C separation, line interpolation, or line interpolation is performed by using the correlation between adjacent lines or the correlation between adjacent frames.
Various types of image quality improvement processing such as noise removal, contour correction, and flare correction are performed. That is, in many parts of the display screen, the video signals of adjacent lines tend to be similar to each other since the video signals of adjacent lines tend to be spatially changing in the vertical direction (line direction), and correlation between lines is established. Further, since a slow temporal conversion (movement) tends to occur in many parts of the display screen, the video signals of adjacent frames become similar, and inter-frame correlation is established.

A typical image quality improvement processing circuit that uses the correlation between adjacent lines and adjacent frames includes a processing unit that uses the correlation between adjacent lines and a processing unit that uses the correlation between adjacent frames. A synthesis unit that synthesizes the output of the processing unit based on a synthesis ratio that is dynamically changed for each unit in the display screen, and a spatial change and a temporal change movement in the vertical direction for each unit in the display screen. It is composed of a vertical change detection unit and a motion detection unit which detect and output a control signal for dynamically controlling the composition ratio of the composition circuit.

Conventionally, as shown in FIG. 3, the above-described motion detection circuit includes an A / D conversion circuit 51, a luminance signal motion detection unit 52, and
It is composed of a motion detector for color signals. The color signal motion detection unit includes a color signal extraction unit 53 for extracting a color signal from the reference line of the current frame, a color signal extraction unit 54 for extracting a color signal from the reference line of the previous frame, and 524 lines of the video signal. 524 line delay circuit 55, which gives delay time, subtraction circuit 5
6. It is composed of a low pass filter circuit 57 and an absolute value circuit 58. The color filter C in the video signal supplied from the A / D conversion circuit 51 is separated by the comb filter composed of the one-line delay circuit 53a and the subtraction circuit 53b, and the center frequency becomes the color subcarrier frequency (f sc). Set bandpass filtering circuit
It is supplied to one input terminal of the subtraction circuit 56 via 53c and the absolute value circuit 53d. On the other hand, the color filter C is separated from the video signal on the same line one frame before, which has passed through the 524 line delay circuit 55, by the comb filter including the one line delay circuit 54a and the subtraction circuit 54b, and the band pass filtering circuit 54c.
And the absolute value circuit 54d, and is supplied to the other input terminal of the subtraction circuit 56. The inter-frame difference signal ΔC of the color signal output from the subtraction circuit 56 is supplied to one input terminal of the maximum value selection circuit 59 as a motion detection signal of the color signal via the low-pass filtering circuit 57 and the absolute value circuit 58. To be done.

Further, the inter-frame difference signal ΔY (including the color signal component) of the luminance signal output from the subtraction circuit 52a passes through the low-pass filtering circuit 52b for removing the color signal and the absolute value circuit 52c to detect the movement of the luminance signal. It is supplied as a signal to the other input terminal of the maximum value selection circuit 59. The maximum value selection circuit 59 compares the motion detection signal of the luminance signal and the motion detection signal of the color signal supplied to each input terminal, selects the larger one, and outputs it to the output terminal OUT as the final motion detection signal. To do.

(Problems to be Solved by the Invention) In the conventional motion detection circuit shown in FIG. 3, a high-frequency component of a color signal leaks into a motion detection signal of a luminance signal, so that a motion that does not actually exist is detected. Is detected.

That is, since the phases of the color signals included in the same pixel signal on the same line are inverted between adjacent frames, the subtraction circuit 52a outputs the inter-frame difference signal ΔY of the luminance signal and the color signal whose amplitude is doubled. 2C and are output. In order to remove this color signal component 2C, a low pass filter circuit 52b is provided in the subsequent stage.
However, since the filtering characteristic is insufficient or the high and low frequency components of the color signal spread to the band of the luminance signal, this color signal component cannot be sufficiently removed. In particular, there is a problem that color signals easily leak at the boundary between magenta and green of the color bar signal, resulting in deterioration of image quality such as dot interference.

Further, in the conventional motion detection circuit shown in FIG. 3, when the level of the luminance signal leaking into the color signal increases due to the collapse of the correlation between the adjacent lines, this is erroneously detected as the motion of the non-existent color signal. There is a problem that it ends up.

(Means for Solving the Problem) A motion detection circuit for a television display screen according to the present invention performs Y / C separation based on correlation between adjacent lines for each of video signals of adjacent frames. Comb filters, and the difference between adjacent frames for each of the luminance signal separated by these first and second comb filters and the video signal before separation is generated as the first and second motion detection signals related to the luminance signal. A first and a second difference generator for outputting,
A synthesizing unit for synthesizing the first and second motion detection signals relating to the luminance signal output from the first and second difference generation units while giving a large synthesis ratio to the former, and outputting as a motion detection signal of the luminance signal; And a third difference generation unit that generates a difference between the color signals separated by the first and second comb filters and outputs the difference as a motion detection signal of the color signal. That is, according to this motion detection circuit, By using the first motion detection signal based on the difference between adjacent frames of the brightness signal after the color signal removal by the comb filter as the main motion detection signal of the brightness signal, the motion which does not exist due to the leakage of the color signal False positives are effectively avoided.

Also, according to this motion detection circuit, the second motion detection signal based on the difference between adjacent frames of the video signal before Y / C separation by the comb filter is used as the auxiliary motion detection signal. The drawbacks of using only motion detection signals are complemented. That is, the removal of the color signal by the comb filter is performed by adding the video signals between the adjacent lines by utilizing the fact that the phase of the color signal is inverted between the adjacent lines. Therefore, the processing for removing the color signal is nothing but the averaging processing of the luminance signal between the adjacent lines, and a special luminance signal such that the magnitude relationship of the luminance signals on the adjacent lines is inverted between the adjacent frames. The motion cannot be detected by the first motion detection signal accompanied by the averaging process. Such a special motion can be detected by the second motion detection signal without averaging processing between adjacent lines.

Further, the motion detection circuit of the present invention detects the high frequency component of the luminance signal included in the video signal, and as it increases, it reduces the combination ratio of the color signal to the motion detection signal and combines it with the motion detection signal of the luminance signal. Since it is the final motion detection signal, erroneous detection of non-existent motion due to the luminance signal component leaking into the color signal due to the collapse of the correlation can be effectively avoided.

 Hereinafter, the operation of the present invention will be described in detail with reference to Examples.

(Embodiment) FIG. 1 is a block diagram showing the configuration of a motion detection circuit for a television display screen according to an embodiment of the present invention. This motion detection circuit is composed of a motion detection unit with reference numerals 1 to 16 and a detection unit for a luminance signal high frequency component with reference numerals 21 to 50.

That is, the motion detection unit is an A / D conversion circuit 1, a 524 line delay circuit 2, a comb filter for performing Y / C separation on the video signal of the current frame, and a Y signal for the video signal one frame before.
Comb filter 4 for performing / C separation, subtraction circuits 5,6,12, filtering units 5a5b, subtraction circuits 6,7, low pass filtering circuits 7a, 7b, band pass filtering circuits 8a, 8b, absolute value circuit 9a, 9b, 10a, 10b, 13, maximum value selection circuits 11, 15, a coefficient circuit 14, and a coring circuit 16.

Further, the high-frequency component of the luminance signal is detected by the first detection system 20.
And a second detection system 30 and a third detection system 30. Each of these detection systems includes a first and a second that constitute a motion detection unit.
The Y / C separated luminance signal extracted from each part of the comb filters 3 and 4 and the video signals before Y / C separation are added together,
Alternatively, an adder / subtractor circuit for subtraction, a bandpass filter circuit for extracting the high frequency component of the luminance signal included in these add / subtract values, an absolute value circuit for creating a non-polar signal, an absolute high frequency component of the extracted luminance signal. It is composed of a comparison circuit for comparing the value with a reference level, an expansion circuit, and the like. In these high-frequency component detection systems, the degree of leakage of the high-frequency component of the luminance signal into the color signal from the absolute value of the high-frequency component of the luminance signal and the predetermined reference level set in the comparison circuit in each detection system. Has exceeded a predetermined limit. The decoder 50 generates four types of coefficients on the basis of the combinations relating to the leak limit detected in each of these three systems, and supplies them to the coefficient circuit 14 of the color signal motion detecting section.

First, the motion detection section will be described. The comb filter 3 that performs Y / C separation on the video signal of the current frame appearing at the input terminal IN has a delay time of one line for the video signal of the current frame. 1-line delay circuits 3a and 3b connected in series, adding circuits 3c and 3d, and subtracting circuit 3e. Similarly, the comb filter 4 that performs Y / C separation for the video signal of one frame before is also connected in cascade to provide a delay time of one line to the video signal of one frame before, which is connected in cascade. 4b, adder circuits 4c and 4d,
It is composed of a subtraction circuit 4e.

The NTSC television video signal supplied to the input terminal IN is four times the color subcarrier (4f sc) in the A / D conversion circuit 1.
Is converted into an 8-bit width digital video signal while being sampled at the sampling frequency of, and supplied to the comb filter 3. The adder circuit 3c is a video signal directly supplied from the A / D conversion circuit 1 to one input terminal and a video signal delayed by two lines (two lines before) by passing through the one-line delay circuits 3a and 3b. And are added. Adder circuit 3c
From, the half is output by shifting the added value by 1 bit to the lower bit side. The other half of the addition value, that is, the average value is output, is the same for the other addition circuits.

Video signal (Y + C) being output from the 1-line delay circuit 3a
If the line including the line is used as the reference line of the display position and the correlation between adjacent lines is 100%, the output of the adder circuit 3c is the average value (Y-C) of the video signals on the two lines adjacent before and after the reference line. ) Is applicable. Here, the polarity (-) of the color signal C indicates that its phase is inverted from the phase of the color signal of the video signal on the reference line. Therefore, from the adder circuit 3d, two adjacent
The average value Y of the luminance signals included in the video signal on the line is output, and this is supplied to one terminal of the subtraction circuit 5.
Further, the video signal on the reference line of the current frame before Y / C separation is supplied to one input terminal of the subtraction circuit 6.

Further, the subtraction circuit 3e outputs the average value C of the color signals included in the video signal on the current line and on two lines adjacent to the current line. The low-pass luminance signal component leaking into the average value C of the chrominance signal due to the collapse of the correlation between the adjacent lines has the center frequency set to the chrominance subcarrier frequency (f sc) in the bandpass filtering circuit 8a. Removed by. The color signal C output from the band pass filtering circuit 8a is an absolute value circuit.
At 10a, a non-polarized color signal having only amplitude information is supplied to one input terminal of the subtraction circuit 12.

The output of the 1-line delay circuit 3a in the comb filter 3 is delayed by 1 frame via the 524-line delay circuit 2 to be combed as a video signal one frame before the video signal being processed by the comb filter 3. It is supplied to the mold filter 4. The comb filter 4 and the band pass filtering circuit 8b and the absolute value circuit 10b arranged in the subsequent stages are respectively the comb filter 3 and the band pass filtering circuit described above.
8a and the absolute value circuit 10a each have the same configuration,
In each of these units, the same processing as that for the video signal of the current frame is performed on the video signal of the preceding frame.

That is, the addition circuit 4d in the comb filter 4 outputs the average value Y'of the luminance signals included in the video signal on the reference line in the display screen one frame before and the two lines adjacent before and after the reference line. And is supplied to the other input terminal of the subtraction circuit 5. Also, on the reference line one frame before
The video signal before Y / C separation is supplied to the other input terminal of the subtraction circuit 6. Further, the color signal C'separated from the video signal on the reference line one frame before is a band pass filtering circuit.
Absolute value circuit 10 after low-frequency luminance signal component is removed at 8b
At b, a non-polar color signal having only amplitude information is supplied to the other input terminal of the subtraction circuit 12.

As a result, from the subtraction circuit 12, the color signal C separated from the video signal on the reference line of the current frame and the color signal C'separated from the video signal on the reference line of the previous frame.
And the difference ΔC is output. The difference ΔC between the adjacent frames of the color signal is passed through the absolute value circuit 13 and the coefficient circuit 14 as the maximum value detection circuit 14 as the motion detection signal of the color signal in the display screen.
Is supplied to one of the input terminals.

Further, from the subtraction circuit 5, the difference between the adjacent frames between the luminance signal Y separated from the video signal on the reference line of the current frame and the luminance signal Y'separated from the video signal on the reference line of the previous frame. ΔY is output. The difference ΔY between adjacent frames is a low-pass filtering circuit 7a and an absolute value circuit for removing high-frequency color signal components included in the difference ΔY.
9a to become the first motion detection signal relating to the luminance signal, which is supplied to one input terminal of the maximum value selection circuit 11.
Further, the subtraction circuit 6 outputs the difference δY between the video signal on the reference line of the current frame and the video signal on the reference line of the previous frame. This adjacent-frame difference signal δY is passed through a low-pass filter circuit 7b for removing a high-frequency color signal component contained therein, an absolute value circuit 9b and a coring circuit 16 to detect a second motion relating to a luminance signal. It becomes a signal and is supplied to the other input terminal of the maximum value selection circuit 11.

The maximum value circuit 11 has a first motion detection signal ΔY supplied to both input terminals and a second motion detection signal δY after coring.
And the larger motion detection signal is selected as the motion detection signal of the luminance signal, and this is selected as the maximum value detection circuit.
Supply to the other 15 input terminal.

As described above, the first motion detection signal ΔY is generated based on the difference between the adjacent frames of the luminance signal from which the color signal has been removed by each of the comb filters 3 and 4. On the other hand, since the second motion detection signal δY is generated based on the difference between adjacent frames of the video signal before Y / C separation, the color signal leaks more than the first motion detection signal. Interference easily occurs. For this reason, the inter-frame difference δY is subjected to coring processing which is considered to be zero level as long as it does not exceed a predetermined level.
It is supplied to the maximum value selection circuit 11. Therefore, normally, the first motion detection signal ΔY is larger than the second motion detection signal δY, and the first motion detection signal ΔY selected by the maximum value selection circuit 11 is the motion detection signal of the luminance signal. Become.

As described above, by generating the first motion detection signal ΔY from the inter-frame difference of the luminance signal generated by the averaging processing over three lines in the comb filters 3 and 4, it is possible to prevent the color signal from leaking. False detection due to the influence of noise can be avoided. However, the first motion detection signal has a drawback that special motion in the display screen cannot be detected at all due to the averaging process over the adjacent lines for removing the color signal.

That is, as illustrated in FIG. 2, in the display screen (A) one frame before, the luminance levels of the pixel signals appearing on the line Ln−1 immediately before the reference line, the reference line Ln, and the line Ln + 1 immediately after that. Is 0 (black), 1 (white), 0 (black), and the display screen (B) of the next frame (current frame) is changed to 1, 0, 1 respectively. As is apparent from the configuration of the comb filters 3 and 4 in FIG. 1, the averaging process of the luminance signal over the three lines described above, first, average values are created for the lines immediately before and immediately after the current line, Next, an average value of this average value and the luminance signal of the current line is created. Therefore, the average values of the levels of the luminance signals created for the display screens of the previous frame and the current frame are both 1/2, and the first motion detection signal, which is the difference between them, is 0. Therefore, the special motion occurring on the display screen cannot be detected by the first motion detection signal.

Even when the first motion detection signal is generated from the difference between the adjacent frames of the luminance signal separated by the averaging process of the pixel signals not over the adjacent 3 lines but over the adjacent 2 lines, the above-mentioned special motion is detected. It becomes impossible. That is, for both (A) and (B) of FIG.
The average value of the pixel signals on the current line Ln and the line Ln-1 immediately before it is 1/2, and the difference between the two is 0. Similarly,
In both (A) and (B), the average value of the pixel signals on the current line Ln and the line Ln + 1 immediately after that is 1/2, and the difference between the two is 0.

On the other hand, the second motion detection signal δY has a maximum value of 1 on the display screen as shown in FIG. 2 because the averaging process is not performed on the adjacent lines. As a result, the maximum value circuit 12 selects the second motion detection signal δY,
The movement of the display screen of FIG. 2 is detected.

The luminance signal output from the subtraction circuit 3d of the comb filter 3 is supplied to the first luminance signal high frequency component detection system 20 in the high frequency component detection section by the band pass filter circuit 21 having the color subcarrier frequency as the center frequency. To be extracted. The high frequency component of the luminance signal becomes a non-polar signal having only level information through the absolute value circuit 22, and is supplied to one input terminal of the comparison circuit 23. The comparator circuit 23 compares the level of the signal supplied to the one input terminal with the reference level supplied to the other input terminal, and raises the output to high for a period in which the former exceeds the latter. This high signal is horizontally expanded by the expansion circuit 24 by an amount corresponding to the appropriate number of pixels on the line and supplied to one input terminal of the decoder 5.0.

The video signal on the reference line extracted from each of the output terminals of the 1-line delay circuit 3a of the comb filter 3 and the 1-line delay circuit 4a of the comb filter 4 is the second luminance signal high frequency component detection system 30. Are added by the adder circuit 35. By this addition, the color signals whose phases are inverted between the adjacent frames are destructively removed, and the average value of the luminance signals over the adjacent frames is output. The high frequency component of the luminance signal is extracted by the band pass filtering circuit 31 having the color subcarrier frequency as the center frequency, supplied to one input terminal of the comparison circuit 33 via the absolute value circuit 32, and compared with the reference level. . The high signal output from the comparison circuit 33 for the period in which the line difference signal of the luminance signal exceeds the reference level is supplied to one input terminal of the decoder 50 via the expansion circuit 34.

The separated luminance signals output from the adder circuit 3d of the comb filter 3 and the adder circuit 4d of the comb filter 4 are added by the adder circuit 45 of the third luminance signal high frequency component detection system 40, and the luminance signals over the adjacent frames are added. Is output as the average value of. The high frequency component extracted from the average value of the luminance signal by the band pass filtering circuit 41 having the color subcarrier frequency as the center frequency is supplied to the comparison circuit 43 via the absolute value circuit 42 and compared with the reference level. The high signal output from the comparison circuit 43 during the period in which the line difference signal of the average value of the luminance signal over the adjacent frames exceeds the reference level is supplied to one input terminal of the decoder 50 via the expansion circuit 44.

The decoder 50 is a high frequency component detection system 20, 30, 40 for the above three systems.
Are all outputs low, or only one is high,
Depending on whether two are high or all are high, coefficients of 1,0.5,0.25,0 are respectively generated and supplied to the coefficient circuit 14 of the motion detecting unit of the color signal. Therefore, in the motion detection signal synthesis circuit including the coefficient circuit 14 and the maximum value selection circuit 15, the synthesis ratio of the motion detection signal of the color signal decreases as the high frequency component of the luminance signal increases.

The configuration in which the larger one of the first luminance signal regarding the luminance signal and the second motion detection signal after coring processing is simply selected as the final motion detection signal of the luminance signal has been described above. However, in general, the first and second motion detection signals may be combined at an appropriate combining ratio while giving the former a larger combining ratio.

Further, regarding the motion detection signal of the luminance signal and the motion detection signal of the chrominance signal, instead of simply selecting the larger one, they may be combined at an appropriate combining ratio.

Further, the configuration in which three systems of detection units are installed in order to detect the high frequency component of the luminance signal with high accuracy has been illustrated, but any two systems or only one system may be installed from the viewpoint of cost reduction. .

According to the experimental results of the present invention, suitable results were obtained with the third high frequency component detection system. Therefore, when the detection system is limited to one system, it is preferable to install this third system.

(Effects of the Invention) As described in detail above, the motion detection circuit of the television display screen according to the present invention uses the inter-frame difference of the luminance signal after Y / C separation by the comb filter as the motion detection signal of the luminance signal. Since this is the main constituent of the above, the erroneous detection of the movement due to the leakage of the color signals, which is a drawback of the conventional circuit, can be effectively avoided.

In addition, the auxiliary difference between the frames of the luminance signal extracted from the color signal after Y / C separation by the comb filter is used as an auxiliary second.
By using it as the motion detection signal of, the drawbacks of using only the first motion detection are complemented.

Further, the motion detection circuit of the present invention detects the size of the high frequency component of the luminance signal included in the video signal, and with the increase, decreases the synthesis ratio of the color signal to the motion detection signal while reducing the motion detection signal of the luminance signal. The final motion detection signal is synthesized with the above, and thus false detection of non-existent motion due to the high frequency component of the luminance signal leaking into the color signal due to the collapse of the correlation is effectively avoided. .

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a motion detection circuit for a television display screen according to an embodiment of the present invention, FIG. 2 is a conceptual diagram for explaining the operation of FIG. 1, and FIG. 3 is a conventional example. FIG. 3 is a block diagram showing a configuration of a motion detection circuit of the television display screen according to FIG. IN …… NTSC TV video signal input terminal, 1 …… A /
D conversion circuit, 2 ... 524 line delay circuit, 3 ... Comb filter for Y / C separation of the video signal of the current frame, 4 ...
... comb filter for Y / C separation of the video signal of one frame before, 5,6,12 ... Subtraction circuit, 7a, 7b ... Low pass filter circuit for removing color signal components, 8a, 8b ... ... Bandpass filtering circuit for removing luminance signal components, 9a, 9b, 10a, 10b,
13 …… Absolute value circuit, 11,15 …… Maximum value selection circuit, 14 ……
Coefficient circuit, 16 ... Coring circuit, 20, 30, 40 ... Coefficient system of 3 systems composing the detection part of the luminance signal high frequency component, 50 ...
Decoder, OUT …… Motion detection signal output terminal.

Claims (1)

(57) [Claims] 1. A first comb filter for performing Y / C separation based on correlation between adjacent lines for a television video signal of an arbitrary frame, and a television video signal of a frame adjacent to the arbitrary frame. A second comb filter that performs Y / C separation based on correlation between adjacent lines, and a first comb-related filter that generates a difference between adjacent frames of the brightness signals separated by the first and second comb filters. A first difference generating section for outputting as a motion detection signal; and a second difference regarding a luminance signal for generating a difference between adjacent frames of video signals extracted from the first and second comb filters.
A second difference generation section for outputting as a motion detection signal, and the first and second motion detection signals related to the luminance signal output from the first and second difference generation sections while giving a large synthesis ratio to the former. A synthesizing unit that synthesizes and outputs as a motion detection signal of a luminance signal, and a third unit that generates a difference between the color signals separated by the first and second comb filters and outputs the difference as a motion detection signal of a color signal.
Difference generation section, a final synthesis section that synthesizes the motion detection signal of the luminance signal and the motion detection signal of the color signal at a changeable synthesis ratio, and outputs the final motion detection signal, and the luminance included in the video signal. A television provided with an inter-adjacent-line-correlation detecting unit that supplies a control signal that detects a high-frequency component of a signal and decreases the combination ratio of the color signal with respect to the motion detection signal to the final combining unit. John Display screen motion detection circuit.