JPH04352595A - Horizontal/vertical change detection circuit - Google Patents

Abstract

PURPOSE:To exactly detect the horizontal change component and vertical change component of an image even at a pattern part, where only the luminance signal having a high frequency component exists, concerning the horizontal/vertical change detection circuit suitable as a direction change detection circuit in an adaptive Y/C separator provided at a television receiver or the like. CONSTITUTION:A judgement circuit 34 judges the presence/absence of an output from a luminance signal vertical direction high-pass filter circuit 24. Based on the judged result, a selection circuit 33 selects whether the sum of outputs from high-pass filter circuits 23 and 25 are outputted as a horizontal change detection signal or the sum of outputs from high-pass filter circuits 23, 25 and 26 is outputted as the horizontal change detection signal. Based on the judged reuslt of a judgement circuit 48, a selection circuit 47 similarly selects and outputs a vertical change detection signal.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an adaptive Y/R signal that separates a luminance signal (Y signal) and a carrier color signal (C signal) from a composite color television signal, which is provided in a television receiver or the like. The present invention relates to a horizontal/vertical change detection circuit suitable as a direction change detection circuit in a C separator. Further, the present invention provides a horizontal/vertical change detection circuit that can accurately detect horizontal change components and vertical change components of an image even in a picture area where only a luminance signal having a high frequency component exists. The purpose is to

0002

2. Description of the Related Art Composite color television signals such as the NTSC system currently used in television broadcasting etc. have luminance signal components and color signal components frequency multiplexed. Therefore, unless the luminance signal and chrominance signal are accurately separated on the receiving side, crosstalk between the luminance signal and chrominance signal and a decrease in resolution will occur. Therefore, the horizontal direction change component and the vertical direction change component of the composite color television signal are detected (detecting the two-dimensional change state of the image), and according to the detection results,
Y/C so as to pass high frequency components in the direction of rapid changes.
Adaptive Y/C separation devices that attempt to accurately separate luminance signals and color signals by changing the characteristics of separation filters are being researched and developed. FIG. 3 shows an example of a conventional adaptive Y/C separation device.

Generally, there is a correlation between changes in the brightness signal and changes in the color signal, such that when the brightness signal changes in the horizontal direction, the color signal also changes in the horizontal direction. Therefore, in order to detect a state of two-dimensional change in an image, it is sufficient to use high frequency components in the horizontal and vertical directions. NTSC
In the case of a composite color television signal, such as a color subcarrier, it is necessary to detect the high frequency component while avoiding the color subcarrier in order to avoid the influence of the color subcarrier included in the high frequency component. Therefore, for example, by extracting the horizontal high-frequency component and the vertical high-frequency component as shown in FIG.
), and the spectrum of the color signal is spread around the color subcarrier (SC), so that changing components in both the horizontal and vertical directions can be detected. The horizontal high frequency component portion shown in FIG. 4A is the horizontal change detection area, and the vertical high frequency component portion is the vertical change detection area. Specific configuration examples of the horizontal direction change component detection circuit 12 and the vertical direction change component detection circuit 13 for realizing detection of horizontal and vertical direction change components are shown in FIGS. 5 and 6, respectively.

As shown in FIG. 3, in the conventional adaptive Y/C separation device, a composite color television signal inputted from an input terminal 11 is passed through a horizontal direction change component detection circuit 12 and a vertical direction change component detection circuit 13. , horizontal color signal separation filter circuit 14, vertical color signal separation filter circuit 15,
The signals are respectively supplied to the subtraction circuit 16. The comparison circuit 17 is
The magnitude relationship between the output of the horizontal direction change component detection circuit 12 and the output of the vertical direction change component detection circuit 13 is compared. and,
When the vertical change component is larger (
(when there is a large change in the vertical direction), the selection circuit 18 selectively outputs the output (color signal) of the horizontal color signal separation filter circuit 14 that sufficiently passes the vertical high frequency components of the color signal. A control signal is output to the selection circuit 18. On the other hand, when the horizontal change component is larger (when the horizontal change is severe), the comparison circuit 17 detects the output of the vertical color signal separation filter circuit 15 (color A control signal is output to the selection circuit 18 so that the selection circuit 18 selectively outputs the signal). The color signal selectively output from the selection circuit 18 is output from the output terminal 19.

FIG. 4B shows the pass frequency bands of the horizontal color signal separation filter circuit 14 and the vertical color signal separation filter circuit 15. The pass frequency band of the horizontal color signal separation filter circuit 14 is a wide band in the vertical direction of the figure, which is the vertical change direction of the image, and allows the high frequency components in the vertical direction of the color signal to be sufficiently passed through without being removed. . The pass frequency band of the vertical color signal separation filter circuit 15 is a wide band in the horizontal direction of the figure, which is the horizontal direction of change of the image.
To sufficiently pass horizontal high frequency components of a color signal without removing them. Therefore, by detecting the two-dimensional change state of the image and selecting and outputting the color signal from the color signal separation filter circuit that is suitable for the change state, composite color Color signals can be separated from television signals. On the other hand, the luminance signal is obtained by subtracting the separated color signal from the composite color television signal input from the input terminal 11 by the subtraction circuit 16, and this luminance signal is output from the output terminal 20. In this way, by using the correlation between changes in the luminance signal and changes in the color signal, change components in the horizontal and vertical directions are detected and By selecting a color signal separation filter circuit that does not remove high-frequency components in the direction (direction), the adaptive Y/C separation device shown in Fig. 3 can separate luminance and color signals without mutual crosstalk or deterioration of resolution. and can be obtained.

[0006]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional adaptive Y/C separator, for example, as shown in FIG. In the horizontal direction change component detection circuit 12
and the vertical direction change component detection circuit 13 cannot accurately detect the direction of change in the image, resulting in the following problem. The horizontal high frequency component 21 is only partially included in the horizontal high frequency component (horizontal change detection area) shown in FIG. 4(A), but is included in the vertical high frequency component (vertical change detection area). All parts included. Therefore, the detected value is larger for the vertical change component than for the horizontal change component, and as a result,
The output of the horizontal color signal separation filter circuit 14 is selected by the selection circuit 18. A part of the horizontal high frequency component 21 of the luminance signal is included in the pass frequency band of the horizontal color signal separation filter circuit 14 shown in FIG. 4(B). Therefore,
Since a part of the horizontal high-frequency component 21 of the luminance signal is separated as a color signal, problems such as a decrease in resolution and the occurrence of cross colors occur in the picture area. The problem to be solved by this invention is to accurately detect the horizontal and vertical change components of an image even in a picture part that contains many diagonal components of the luminance signal or a picture part that only has a luminance signal with high frequency components. The problem is what measures should be taken to create a horizontal/vertical change detection circuit that can detect changes in the horizontal and vertical directions.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides that, in a composite color television signal in which a carrier color signal is superimposed on a luminance signal, fh is a horizontal frequency (unit: MHz), The composite color television signal is supplied, and the two-dimensional center frequency (fh, fv) of the passband is (0,525/8)
A first filter in the vicinity and the composite color television signal are supplied, and the two-dimensional center frequency (f
The composite color television signal is supplied with a second filter in which h, fv) is near (fsc, 525/8), and the two-dimensional center frequency (fh, f
The composite color television signal is supplied with a third filter in which v) is near (fsc/2, 0), and the two-dimensional center frequency (fh, fv) of the passband is (fsc/2, 0).
fsc/2, 525/4), a first determination circuit that determines whether the output of the first filter is zero and outputs a first determination signal; If the first determination circuit determines that the output of the first filter is zero based on the first determination signal, the outputs of the second, third, and fourth filters are combined and output. a first combining circuit that combines and outputs the outputs of the third and fourth filters when the first determination circuit determines that the output of the first filter is other than zero; a second determination circuit that determines whether the output of the filter is zero and outputs a second determination signal; and based on the supplied second determination signal, the second determination circuit If the output of the filter is determined to be zero, the outputs of the first, second, and fourth filters are combined and output, and
It is characterized by comprising a second synthesis circuit that combines and outputs the outputs of the first and second filters when the second judgment circuit judges that the output of the third filter is other than zero. The present invention provides a horizontal/vertical change detection circuit.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a means to solve the problems of the conventional adaptive Y/C separation device, the present invention provides components corresponding to horizontal and vertical variation components of a luminance signal and color components from a composite color television signal. Components corresponding to horizontal and vertical change components of the signal are detected independently. As mentioned above, generally the direction in which the luminance signal changes and the direction in which the color signal changes tend to be the same, so even though the horizontal direction change component of the luminance signal was not detected, the color signal When a horizontal change component of is detected (for example,
This component is determined to be a vertical variation component of the luminance signal (see the intersection of the horizontal high-frequency component of the color signal and the vertical high-frequency component of the luminance signal shown in Figure 2). . Similarly, when the vertical change component of the color signal is detected even though the vertical change component of the luminance signal is not detected (for example, as in the part 21 shown in Figure 4, fine black and white This component is determined to be a horizontally changing component of the luminance signal (see the intersection of the vertical high-frequency component of the color signal and the horizontal high-frequency component of the luminance signal shown in FIG. 2). As a result, the horizontal change component and the vertical change component of the image can be accurately detected even in a picture part containing many diagonal components of the luminance signal or a picture part in which only a luminance signal having a high frequency component exists. Therefore, the horizontal/vertical change detection circuit of the present invention can be combined with the conventional horizontal change component detection circuit 12 and the vertical change component detection circuit 1.
3, the adaptive Y/C separation device used in place of the vertical color signal separation filter circuit can be used in the vertical color signal separation filter circuit even in a picture area where only a luminance signal having a horizontal high frequency component, such as the horizontal high frequency component 21, exists. It is possible to select from 15 outputs (color signals), and it is possible to obtain luminance signals and color signals without mutual crosstalk or deterioration of resolution in all picture parts.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1(A) is a block diagram showing an embodiment of a horizontal change detection circuit portion in a horizontal/vertical change detection circuit according to the present invention. FIG. 1(B) is a block diagram showing an embodiment of the vertical change detection circuit portion of the horizontal/vertical change detection circuit according to the present invention. Moreover, FIG. 2 shows the pass frequency band of each high-pass filter circuit.

First, in the horizontal direction change detection circuit shown in FIG. Band pass filter circuit 2
4. The color signal is supplied to a horizontal high-pass filter circuit 25 and the color signal is supplied to a vertical high-pass filter circuit 26, respectively. The outputs of the filter circuits 23 to 26 are then supplied to absolute value conversion circuits 27 to 30, respectively, and the absolute values thereof are taken. The outputs of the absolute value converting circuits 27 and 29 are sent to the adding circuit 31.
The outputs thereof are supplied to one input terminal of the addition circuit 32 and one input terminal of the selection circuit 33, respectively. On the other hand, the output of the absolute value conversion circuit 30 is
2, and is added to the output of the adder circuit 31 here. The output of the adder circuit 32 is supplied to the other input terminal of the selection circuit 33. Further, the output of the absolute value conversion circuit 28 is supplied to the determination circuit 34. In the determination circuit 34, when the output of the absolute value conversion circuit 28 is zero, the selection circuit 33 selects and outputs the output of the addition circuit 32, and when the output is other than zero, the selection circuit 33 selects and outputs the output of the addition circuit 32.
outputs a control signal to the selection circuit 33 so that the output of the addition circuit 31 is selectively output. The selection circuit 33 outputs either the output of the addition circuit 31 or the output of the addition circuit 32 based on the control signal of the determination circuit 33, and outputs either the output of the addition circuit 31 or the output of the addition circuit 32,
A horizontal change detection signal is obtained.

When the output of the absolute value conversion circuit 28 is other than zero,
This is a case in which the direction of change can be detected correctly even with a conventional horizontal direction change component detection circuit. Therefore, the horizontal direction change detection circuit portion of the embodiment includes a luminance signal horizontal direction high-pass filter circuit 23 and a color signal horizontal direction high-pass filter circuit so as to operate in the same manner as the conventional horizontal direction change component detection circuit. The output of the adder circuit 31, which is the sum of the absolute values of the outputs of the circuit 25, is output as a horizontal change detection signal.

On the other hand, the pattern of the part 21 shown in FIG. 4 (the pattern in which only the luminance signal having the horizontal high-frequency component 21 exists)
When a signal enters the input terminal 22, the output of the absolute value conversion circuit 28 becomes zero (the output of the luminance signal vertical high-pass filter circuit 24 is zero), and the vertical change component of the luminance signal is detected. Not done. Furthermore, the absolute values (horizontal change components) of the outputs of the luminance signal horizontal high-pass filter circuit 23 and the color signal horizontal high-pass filter circuit 25 also become extremely close to zero (see FIG. 2). . Therefore, if the output of the adder circuit 31 is directly output as a horizontal change detection signal, even though the image is changing in the horizontal direction, the signal as shown in FIG.
The above-mentioned problem occurs in that the detected value of the vertical change component detected by the vertical change detection circuit shown in FIG. Therefore, it is said that the detection value of the horizontal change component detected by this horizontal direction change detection circuit is larger than that of the vertical change component detected by the vertical direction change detection circuit by compensating for the shortage of the horizontal direction change component. It is necessary to restore the correct detection state. Therefore, the absolute value of the output of the color signal vertical high-pass filter circuit 26 is the sum of the absolute values of the outputs of the luminance signal horizontal high-pass filter circuit 23 and the color signal horizontal high-pass filter circuit 25. Add and output. Filter circuit 2
The reason for adding the outputs of 6 is, as mentioned before, when the output of the luminance signal vertical high-pass filter circuit 24 is zero, the chrominance signal vertical high-pass filter circuit 26 is added.
This is because the output can be regarded as the horizontal direction change component of the luminance signal. Therefore, even in a picture area where only a luminance signal having a horizontal high frequency component such as the horizontal high frequency component 21 exists, the direction of change in the image can be detected accurately.

Next, the vertical change detection circuit shown in FIG. 1(B) will be explained. The composite color television signal input to the input terminal 36 is processed through a luminance signal horizontal high-pass filter circuit 37, a luminance signal vertical high-pass filter circuit 38, and a color signal horizontal high-pass filter circuit 39.
, color signals are supplied to the vertical high-pass filter circuit 40, respectively. The characteristics of each filter circuit 37 to 40 are shown in FIG.
The characteristics are the same as those of the filter circuits 23 to 26 shown in (A). The outputs of the filter circuits 37 to 40 are supplied to absolute value converting circuits 41 to 44, respectively, and their absolute values are taken. The outputs of the absolute value converting circuits 42 and 44 are sent to the adding circuit 4.
5, and the output thereof is supplied to one input terminal of the addition circuit 46 and one input terminal of the selection circuit 47, respectively. On the other hand, the output of the absolute value converting circuit 43 is supplied to the other input terminal of the adding circuit 46, where it is added to the output of the adding circuit 45. The output of the adder circuit 46 is sent to the selection circuit 47.
is supplied to the other input end of the . In addition, the absolute value conversion circuit 41
The output of is supplied to the judgment circuit 48, and the selection circuit 47 selects the output of the addition circuit 46 when the output of the absolute value conversion circuit 41 is zero, and the output of the addition circuit 45 when it is other than zero. A control signal is output to the selection circuit 47 so as to output the signal. The selection circuit 47 selects and outputs either the output of the addition circuit 45 or the output of the addition circuit 46 based on the control signal of the determination circuit 48, and a vertical change detection signal is obtained at the output terminal 49.

When the output of the absolute value conversion circuit 41 is other than zero,
This is a case in which the direction of change can be detected correctly even with a conventional vertical direction change component detection circuit. Therefore, the vertical change detection circuit portion of the embodiment includes a luminance signal vertical high-pass filter circuit 38 and a chrominance signal vertical high-pass filter circuit so as to operate in the same manner as a conventional horizontal change component detection circuit. The output of the adder circuit 45, which is the sum of the absolute values of the outputs of the circuit 40, is output as a vertical change detection signal.

On the other hand, when the signal of the part 50 shown in FIG. The output of the conversion circuit 41 becomes zero (the output of the luminance signal horizontal direction high-pass filter circuit 37 is zero), and the horizontal direction variation component of the luminance signal is not detected. Also, the absolute value (horizontal change component) of the output of the luminance signal vertical high-pass filter circuit 38 and the color signal vertical high-pass filter circuit 40.
also has a value extremely close to zero (see FIG. 2). Therefore, if the output of the adder circuit 45 is directly output as a vertical change detection signal, even though the image changes in the vertical direction, the vertical change component detected by the vertical change detection circuit Instead, a problem arises in that the horizontal change component detected by the horizontal change detection circuit shown in FIG. 1A has a larger detected value. Therefore, the deficiency in the detected value of the vertical change component is compensated for, and the detected value of the vertical change component detected by the vertical change detection circuit is larger than the horizontal change component detected by the horizontal change detection circuit. It is necessary to return to the correct detection state. Therefore, the absolute value of the output of the chrominance signal horizontal high-pass filter circuit 39 is the sum of the absolute values of the outputs of the luminance signal vertical high-pass filter circuit 38 and the chrominance signal vertical high-pass filter circuit 40. Add and output. The reason for adding the outputs of the filter circuit 39 is that, as mentioned earlier, when the output of the luminance signal horizontal high-pass filter circuit 37 is zero,
This is because the output of the color signal horizontal high-pass filter circuit 39 can be regarded as a vertical variation component of the luminance signal. Therefore, even in a picture area where only a luminance signal having a vertical high frequency component, such as the vertical high frequency component 50, exists, the direction of change in the image can be detected accurately.

As described above, the present embodiment accurately detects the direction of change in a picture part where only a luminance signal having a horizontal high-frequency component exists and a picture part where only a luminance signal having a vertical high-frequency component exists. can. Therefore, in this embodiment, the direction of change can be accurately detected even in a picture area that includes many diagonal components of the luminance signal.

The horizontal/vertical change detection circuit of this embodiment is used in place of the conventional horizontal change component detection circuit 12 and vertical change component detection circuit 13 to create an adaptive Y/V change detection circuit.
Configure the C separation device. The horizontal change detection signal outputted by the horizontal change detection circuit section and the vertical change detection signal outputted by the vertical change detection circuit section are supplied to the comparator circuit 17, and the two detection signals are used as in the conventional case. The selection circuit 18 is controlled in comparison to the above. As mentioned above, since the horizontal change detection signal and the vertical change detection signal accurately represent the change direction of all images, this adaptive Y/C separator uses the comparison result of the comparator circuit 17 to Based on this, the color signal separation filter circuits 14 and 15 can be appropriately selected. For example, even in a picture area where there is only a luminance signal having a horizontal high-frequency component such as the horizontal high-frequency component 21, this adaptive Y/C separation device can detect the output of the vertical color signal separation filter circuit 15 ( It is possible to obtain luminance signals and color signals without mutual crosstalk or deterioration of resolution in all picture areas.

Here, the two-dimensional center frequencies (fh, fv) of each high-pass filter circuit are as shown below. Note that fh is the horizontal frequency (MHz), fv is the vertical frequency (Cycle/Height), and fsc is the color subcarrier frequency (MHz). Luminance signal horizontal high-pass filter circuits 23, 37:
(fh, fv) = (fsc/2, 0) Luminance signal vertical high-pass filter circuit 24, 38: (f
h, fv) = (0,525/8) Color signal horizontal high-pass filter circuit 25, 39: (fh,
fv) = (fsc/2,525/4) Color signal vertical high-pass filter circuit 26, 40: (fh, fv)
=(fsc, 525/8) The set value of the two-dimensional center frequency (fh, fv) of each of the above high-pass filter circuits may be set close to the above set value depending on the usage situation. FIG. 2 shows the pass frequency bands of each high-pass filter circuit.

In the embodiment described above, the luminance signal horizontal high-pass filter circuits 23 and 37, the luminance signal vertical high-pass filter circuits 24 and 38, the chrominance signal horizontal high-pass filter circuits 25 and 39, and the chrominance signal horizontal high-pass filter circuits 24 and 38. Vertical high-pass filter circuits 26 and 40 are provided separately for a horizontal change detection circuit portion and a vertical change detection circuit portion, respectively. As another example, one each of a luminance signal horizontal high-pass filter circuit, a luminance signal vertical high-pass filter circuit, a chrominance signal horizontal high-pass filter circuit, and a chrominance signal vertical high-pass filter circuit. These filter circuits may be provided in both the horizontal direction change detection circuit section and the vertical direction change detection circuit section.

[0020]

As described above, the horizontal/vertical change detection circuit of the present invention can detect changes even in picture areas that include many diagonal components of luminance signals or in picture areas where only luminance signals with high-frequency components exist. As with other picture parts, horizontal and vertical variation components of the image can be detected accurately. Therefore, the horizontal/vertical change detection circuit of the present invention is used in place of the conventional horizontal change component detection circuit 12 and vertical change component detection circuit 13, and the horizontal/vertical change detection circuit is The adaptive Y/C separation device is configured to change the characteristics of the color signal separation filter based on the obtained horizontal and vertical change detection signals. For example, the adaptive Y/C separation device can select the output (color signal) of the vertical color signal separation filter circuit 15 even in a picture area where only a luminance signal with horizontal high-frequency components exists. In the picture area, luminance signals and color signals without mutual crosstalk or deterioration in resolution can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram showing pass frequency bands of each high-pass filter circuit.

FIG. 3 is a diagram showing a conventional adaptive Y/C separation device.

4A is a diagram showing a horizontal change detection area and a vertical change detection area, and FIG. 4B is a diagram showing the pass frequency bands of the horizontal color signal separation filter circuit 14 and the vertical color signal separation filter circuit 15. FIG.

FIG. 5 is a diagram showing a specific configuration example of the horizontal direction change component detection circuit 12.

FIG. 6 is a diagram showing a specific configuration example of the vertical direction change component detection circuit 13.

[Explanation of symbols]

22, 36 Input terminals 23, 37 Luminance signal horizontal high-pass filter circuit 24, 38 Luminance signal vertical high-pass filter circuit 25, 39 Color signal horizontal high-pass filter circuit 26, 40 Color signal vertical high-pass filter circuit Pass filter circuits 27 to 30, 41 to 44 Absolute value conversion circuit 31,
32, 45, 46 Addition circuit 33, 47
Selection circuit 34, 48 Judgment circuit 35, 49 Output terminal

Claims (1)

[Claims] Claim 1: In a composite color television signal in which a carrier color signal is superimposed on a luminance signal, fh is a horizontal frequency (unit: MHz), fv is a vertical frequency (unit: Cyc).
le/Height), fsc is the color subcarrier frequency (
When the unit is MHz), the composite color television signal is supplied and the two-dimensional center frequency of the passband (f
The composite color television signal is supplied with a first filter in which h, fv) is near (0, 525/8), and the two-dimensional center frequency (fh, f
The composite color television signal is supplied with a second filter in which v) is in the vicinity of (fsc, 525/8), and the two-dimensional center frequency (fh, fv) of the passband is in the vicinity of (fsc, 525/8).
A third filter near fsc/2, 0) and the composite color television signal are supplied, and the two-dimensional center frequency (fh, fv) of the passband is near (fsc/2, 0).
2,525/4) Determine whether the outputs of the fourth filter, which is a neighbor, and the first filter are zero;
a first determination circuit that outputs a determination signal; and when the first determination circuit determines that the output of the first filter is zero based on the supplied first determination signal;
The outputs of the third and fourth filters are combined and output, and when the first determination circuit determines that the output of the first filter is other than zero, the outputs of the third and fourth filters are combined and output. a first synthesis circuit that synthesizes and outputs the signal; a second judgment circuit that judges whether the output of the third filter is zero and outputs a second judgment signal; When the second determination circuit determines that the output of the third filter is zero based on the determination signal, the first, second, and fourth filters
The outputs of the filters are synthesized and output, and the outputs of the second filter are combined and output.
and a second combining circuit that combines and outputs the outputs of the first and second filters when the determination circuit determines that the output of the third filter is other than zero. Directional/vertical change detection circuit.