JPH0748867B2 - Vertical and horizontal change detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a luminance signal color signal separation for extracting a luminance signal and a color signal separately from a composite color television signal in a device for handling an image such as a television receiver. The present invention relates to a device, and more particularly to a vertical and horizontal change detection circuit used in such a separating device.

[Prior Art] Currently, a color television standard system generally used in television broadcasting is a composite signal in which a luminance signal component and a color signal component are frequency-multiplexed. Therefore, in a color television receiver or the like, it is necessary to separate and extract a luminance signal and a color signal from the composite signal. Currently, a fixed type two-dimensional filter using a comb filter is used as the direction. On the other hand, recently, as shown in JP-A-60-165889, by using the digital signal processing technology,
Adaptive filters have been developed that switch the characteristics of a two-dimensional filter depending on the shape of each pixel in the image. This method prepares two types of filters, a vertical filter and a horizontal filter, as a separation filter, and in each pixel, when the surrounding vertical change is small, the vertical separation filter output is output, and conversely, the horizontal change is generated. When the number is small, the horizontal separation filter output is used as the separated output. In this case, high-frequency components remain in the direction in which the high-frequency components change drastically, that is, in the direction in which there are many high-frequency components in the two-dimensional spatial frequency range, while
Crosstalk components are removed. As a result, dot interference and cross color can be reduced without significantly reducing the resolution.

[Problems to be Solved by the Invention] In the conventional adaptive luminance signal / chrominance signal separation device using the above digital signal processing technique, there are only two types of filter characteristics, and since the characteristics are extreme, they are switched for each pixel. In that case, the waveform at the switching point becomes discontinuous, and noise is apparently generated. Since such noise is switched independently for each pixel, if there is not much difference in the degree of change between the vertical direction and the horizontal direction, the filter will switch instably, which is a particular problem.

Further, in the conventional method, the separation filter is a filter only in the vertical direction or only in the horizontal direction. Therefore, in the case of the vertical direction filter, the band of the luminance signal is limited independently of the horizontal direction in the vertical direction, and conversely in the horizontal direction filter. The horizontal direction is restricted regardless of the vertical direction. for that reason,
The luminance signal is reduced to the area where there is no color signal, and the resolution is likely to decrease.

On the other hand, in the conventional method, the vertical and horizontal cannot be controlled separately in the characteristics of the two-dimensional filter.
Even if there are many change components in both the vertical and horizontal directions, the band of the color signal in either direction is widened, and there is a problem that the cross color cannot be sufficiently suppressed.

In order to solve the above problems, prior to the present invention, the applicant company developed an improved adaptive luminance signal color signal device and applied for a patent (Japanese Patent Application No. 62-320965), and at the same time the Institute of Electronics, Information and Communication Engineers and Television. Announced at the conference (March 28, 1988)
Proceedings of the Annual Meeting of the Japan Electronics and Information Communication Society, pages 2-174 and 6
May 25, 2013, Technical Report of the Television Society of Japan, pages 25 to 30).
In this adaptive luminance signal / chrominance signal separation device, as a basic configuration, a filter close to a comb filter which is generally used at present is used, and the bands of the vertical direction filter and the horizontal direction filter are set there. They are changed separately according to the degree of change of.

That is, according to this adaptive luminance signal / chrominance signal separating device, there is provided an adaptive luminance signal / chrominance signal separating device for separating a luminance signal and a chrominance signal from a composite color signal by using a vertical direction filter and a horizontal direction filter. The filter is a variable vertical bandpass filter that responds to the composite color signal, the horizontal filter is a variable horizontal bandpass filter that is cascaded to the variable vertical bandpass filter, and the horizontal vertical filter is responsive to the composite color signal, respectively. Vertical change detecting means for detecting a difference between sample points in the horizontal direction and horizontal change detecting means for detecting a difference in sample points in the horizontal direction of the image, and outputs from the vertical change detecting means and the horizontal change detecting means. The band of the variable vertical band filter and the variable water depending on the signal. By providing control signal generating means for generating a control signal for controlling the band of the bandpass filter, a color signal output is obtained from the variable horizontal bandpass filter, and means for outputting a luminance signal using the composite color signal and the color signal is provided. It is provided.

In the above-mentioned adaptive luminance signal / color signal separation apparatus by the applicant, the vertical direction change detecting means for converting the difference at the sample point in the vertical direction of the image into an absolute value and performing non-linear conversion, and the difference at the sample point in the horizontal direction of the image are absolute. It has a horizontal direction change detection means for digitizing and performing non-linear conversion, and according to the vertical direction change detection output signal and the horizontal direction change detection output signal, the vertical direction variable band pass filter and the horizontal direction variable band pass filter It controls the bandwidth. In this case, it is possible to set a filter characteristic that is more suitable for the spectral distribution of the signal, and it is possible to reduce dot interference without reducing S / N and resolution. Further, when there are a large number of change components in both the vertical and horizontal directions, it is possible to suppress the occurrence of cross color by narrowing the pass bands of the filters in both the vertical and horizontal directions.

However, in the vertical and horizontal direction change detection means, the difference between the two sample points is converted into an absolute value and nonlinearly converted into the vertical and horizontal direction change detection signals.
Only a simple one-dimensional or two-dimensional band can be detected.
That is, if a filter having a complicated detection band is to be configured, the number of taps increases, and particularly the number of line memories increases in the vertical direction, which is not practical.

Further, no matter which frequency in the pass band the signal is output as the same change detection signal, it cannot be said that the vertical and horizontal direction change detection signals are created after grasping the two-dimensional spectral distribution.

Further, in the case of a one-dimensional detection filter alone, the S / N of the change detection signal is poor, which causes erroneous detection.

Therefore, the present invention is practical as a vertical direction change detection circuit and a horizontal direction change detection circuit in an adaptive luminance signal color signal separation device, and can grasp a two-dimensional spectrum distribution,
It is an object of the present invention to provide a device capable of obtaining a detection signal with a good S / N.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a plurality of two-dimensional filters having different passbands, and makes the respective outputs absolute values, performs non-linear conversion, and performs comparison and synthesis. By doing so, vertical and horizontal change detection signals are obtained. In this non-linear conversion, a dead zone, a slope, and a saturation zone can be set for each two-dimensional filter.

That is, according to the present invention, the vertical and horizontal directions used in the adaptive luminance signal color signal separation device that performs signal processing according to changes in the vertical and horizontal directions of an image and separates a luminance signal and a color signal from an input composite signal. In the direction change detection circuit, a plurality of vertical direction detection circuit parts and a plurality of horizontal direction detection circuit parts each responding to the input composite signal.
-Dimensional filter, a plurality of absolute value conversion circuits that respond to the outputs of the plurality of two-dimensional filters, a plurality of nonlinear circuits that respond to the plurality of absolute value conversion circuits, and a plurality of outputs of the plurality of nonlinear circuits There is provided a vertical and horizontal direction change detection circuit comprising:

[Operation] By providing a plurality of two-dimensional filters having different separation bands, each frequency component of the input signal can be extracted in real time. Next, the output of each two-dimensional filter is converted into an absolute value and nonlinearly converted. The non-linear circuit used here can set a dead zone, a slope in a linear zone, and a saturation zone for each filter, thereby optimizing the balance of each detection level when synthesizing each filter output. After that, the respective filter outputs are combined by a combining circuit. This combining circuit compares and combines the respective filter outputs representing the two-dimensional frequency distribution of the input signal so as to match the target control, and vertically and horizontally. It is converted into a change detection signal.

Embodiments 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 vertical direction change detection circuit portion in a vertical direction and horizontal direction change detection circuit according to the present invention. A video signal in which a luminance signal (Y) and a color signal (C) are superimposed is input to the input terminal, that is, a composite color television signal (hereinafter referred to as a composite color signal) is input, and the first luminance signal vertical high frequency component is passed. Filter 10, second luminance signal vertical high-pass filter 1
2, luminance signal color signal diagonal high-pass filter 14,
The color signals are provided to the high-pass filter 16 in the vertical direction. The composite color signal is assumed to be a digital signal by an A / D conversion circuit (not shown). The outputs of the band pass filters 10, 12, 14, 16 are converted into absolute values by the absolute value conversion circuits 18a-18d, respectively, and then supplied to the non-linear circuits 20a-20d. The four nonlinearly converted outputs A, B, C and D are combined by the next combining circuit 22, and a vertical direction change detection signal is obtained at the output terminal thereof.

FIG. 2 is a block diagram showing an embodiment of the horizontal direction change detection circuit portion in the vertical direction and horizontal direction change detection circuit according to the present invention. The composite color signal is input to the luminance signal horizontal direction high band component pass filter 24, the luminance signal color signal diagonal direction high band component pass filter 26, and the color signal horizontal direction high band component pass filter 28. The outputs of the band-pass filters 24, 26, 28 are absolute-valued by the absolute-value conversion circuits 18e-18g, and then applied to the nonlinear circuits 20e-20g, respectively. The three nonlinearly converted outputs E, F, G are combined by the next combining circuit 30, and a horizontal change detection signal is obtained at the output terminal thereof. The luminance signal chrominance signal diagonal direction high-pass filter 26 has the same structure as the filter 14 of FIG. 1 and can be used in common.

Next, the specific configuration and operation of each unit will be described. 2 each
The center frequency of the dimensional filter is as shown below.

Note that fh is the horizontal frequency (MHz) and fv is the vertical frequency (Cycle
/ Height) and fsc are subcarrier frequencies (MHz) (for example, 3.58MHz).

First luminance signal vertical direction high-pass filter 10: (fh,
fv) = (0,525 / 4) Second luminance signal vertical high-pass filter 12: (fh,
fv) = (0,525 / 8) Luminance signal Color signal Diagonal high-pass filter 14, 26:
(Fh, fv) = (fsc / 2,525 / 8) Color signal vertical direction high-pass filter 16: (fh, fv) =
(Fsc, 525/8) Luminance signal horizontal high-pass filter 24: (fh, fv) ＝
(Fsc / 2, 0) Color signal horizontal high-pass filter 28: (fh, fv) =
(Fsc / 2,525 / 4) FIG. 3 shows the pass frequency band of each two-dimensional filter. As shown in FIG. 3, high frequency components in each direction of the luminance signal and the color signal are extracted.

Each filter output is converted into an absolute value and then nonlinearly converted. The non-linear conversion has a dead zone, a linear zone, and a saturation zone. To make it less susceptible to noise, or to optimize the balance of change detection signals after combining,
The dead zone, slope, and saturation zone are set for each filter output.
The input / output characteristics of the nonlinear conversion are shown in FIG.

FIG. 5 is a block diagram showing a specific configuration of the non-linear circuits 20a to 20g shown in FIGS. Each absolute value conversion circuit 18a-1
The output signal of 8g is a subtractor 82 as an 8-bit digital signal.
Is given to. A setting switch that can manually set any 8-bit data "a" to one input of this subtractor 82
80 outputs are given. This data "a" corresponds to the width of the dead zone in FIG. 4, and the width of the dead zone can be variably controlled by manually setting "a" arbitrarily. The output of the subtractor 82 is given to the bit selector 84, and the output of the setting switch 86 for manually setting the number of bits to be output is also given here. Of the 8-bit data from the subtractor 82, if only the upper 7 bits are output as shown in the figure, the data has been compressed in half, and if only the upper 6 bits are output, it becomes 1/4 or the upper 5 If only the bits are output, they are compressed to 1/8.
That is, for data (1/2) ^b (b is 1, 2, 3
...). Therefore, by selecting "b" according to the output of the setting switch 86, the inclination in the linear region can be arbitrarily set. Bit selector 84
Is output to a limiter 88, where it is compressed into 4-bit data. That is, 0 is output when the input value is 0 or less, 0 is output when the input value is 0 to 15, and 15 is output when the input value is 15 or more.
The dead zone and the saturation zone are provided before and after the linear zone. Since the above "a" and "b" can be set by manually setting the two setting switches 80 and 88, each of the non-linear circuits 20a to 20g selects the most suitable inclination in the dead region and the linear region. It becomes possible to do. To find the most suitable value, make a manual adjustment while visually checking the playback screen. In this way, the filter outputs subjected to the non-linear conversion are combined to obtain the optimum change detection signal for separating the luminance signal and the color signal.

FIG. 6 shows a specific configuration of the synthesizing circuit 22 used for detecting the vertical change in FIG. The four output signals A, B, C and D in FIG. 1 are the maximum value selection circuit 32 and the intermediate value selection circuit 34.
Are input respectively. The maximum value and the intermediate value are selected from A, B, and C, the average of these two signals is obtained by the addition coefficient unit 36, and the maximum value of this average and D is obtained by another maximum value selection circuit 38. The vertical direction change detection signal is selected.
This is because the NTSC signal is not band-limited in the vertical direction and dot interference at the vertical edge is particularly prominent, so the high-frequency component of the color signal in the vertical direction is weighted. As another configuration, the average value of A, B, and C is taken, and
It is also possible to obtain the vertical direction change detection signal by taking the maximum value of B and C and taking the average of the maximum value of A, B and C and the intermediate value.

Next, FIG. 7 shows a synthesizing circuit 30 used for horizontal change detection in FIG. Three output signals E, F, G in FIG.
Are input to the maximum value selection circuit 40 and the intermediate value selection circuit 42, respectively. The maximum value and the intermediate value are respectively selected from E, F, and G, and the average of these two signals is obtained by the addition coefficient unit 44 and used as the horizontal change detection signal. Further, as another configuration, horizontal change detection is performed by taking an average value of E, F, G, taking a maximum value of E, F, G, taking an average of the maximum value of E, F, G and an intermediate value. You can also get a signal.

Note that fh is the horizontal frequency (MHz) and fv is the vertical frequency (Cycle
/ Height), fsc is the subcarrier frequency (MHz) (eg
3.58MHz).

FIG. 8 is a block diagram showing an adaptive luminance signal / chrominance signal separation device using the vertical and horizontal direction change detection circuits of the present invention. The input terminal 50 is given a composite color signal which is a digital signal by an A / D converter (not shown),
It is given to the subtractor 58 via the delay compensation circuit 52. On the other hand, the composite color signal is a variable vertical bandpass filter (BP
Subtractor 58 via a cascade connection circuit of F) 54 and variable horizontal BPF 56
Is applied to one input and is also applied to the color signal output terminal 72. The output of the subtractor 58 is connected to the luminance signal output terminal 70. The composite color signal is applied to the vertical change detection circuit 60 shown in FIG. 1 and the horizontal change detection circuit 62 shown in FIG. 2, respectively, and the change in the vertical direction and the horizontal direction is detected by the above-described operation, and the detection result is the control signal. Generation circuit 64
Given to. The control signal generation circuit 64 generates two control signals, and a vertical low pass filter (LPF) 66 and a horizontal LPF 68, respectively.
To the variable vertical BPF 54 and the variable horizontal BPF 56 as a band control signal.

The configuration and operation of the parts other than the vertical and horizontal direction change detection circuits are the same as those of the above-mentioned Japanese Patent Application No. 62-320965 and two academic conferences, and therefore the description thereof will be omitted.

The vertical and horizontal direction change detection circuit can be used not only in the adaptive luminance signal / color signal separation device but also in image processing, adaptive noise reducer, enhancer and the like.

[Effects of the Invention] As is clear from the above description, according to the vertical direction and horizontal direction change detection circuit of the present invention, the sensitivity in the two-dimensional spatial frequency domain with respect to the input signal can be freely set. The vertical high-frequency component of the color signal and the diagonal high-frequency component of the luminance signal can be more accurately discriminated in the vertical change detection, and the horizontal high-frequency component of the color signal and the diagonal direction of the luminance signal can be detected in the horizontal change detection. High-frequency components can be discriminated more accurately. Therefore, when used in the adaptive luminance signal / color signal separation device, dot interference and cross color can be suppressed, and more optimal signal separation can be performed.

Also, since the balance between vertical direction change detection and horizontal direction change detection can be set freely, it is possible to achieve detection sensitivity suitable for NTSC signals that are not band-limited in the vertical direction but band-limited in the horizontal direction. it can.

Moreover, even if the same two-dimensional spatial frequency domain as when the difference between two sample points is obtained is detected as a result, each detection filter is composed of two-dimensional filters.
The change detection signal obtained by the combination has a good S / N and a signal with few false detections can be obtained.

The output signal of each two-dimensional filter can be set to noise and sensitivity suitable for the passing frequency thereof by non-linear conversion and optimal for the target control when combined.

Further, there is an effect that a more dense control signal can be obtained by synthesizing the output of each filter subjected to the non-linear conversion by a method suitable for the target control such as averaging or weighting.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a vertical direction change detection circuit portion in a vertical direction and horizontal direction change detection circuit of the present invention, and FIG. 2 is a block diagram showing an embodiment of a horizontal direction change detection circuit portion. FIG. 3 is a diagram showing the pass frequency band of the two-dimensional filter in FIGS. 1 and 2, and FIG. 4 is a diagram showing the input / output characteristics of the non-linear circuit in FIG. 1 and FIG. Is a block diagram of the non-linear circuit in FIGS. 1 and 2, and FIG. 6 is a block diagram showing an example of a specific configuration of the synthesizing circuit in the vertical direction change detection circuit portion of FIG.
FIG. 7 is a block diagram showing an example of a concrete configuration of the synthesizing circuit in the horizontal change detecting circuit portion of FIG. 2, and FIG. 8 is an adaptive luminance signal using the vertical and horizontal change detecting circuits of the present invention. It is a block diagram of a color signal separation device. 10, 12 …… Brightness signal vertical high-pass filter, 1
4, 26 ... Luminance signal Color signal Diagonal high-pass filter, 16 ... Color signal vertical high-pass filter, 18a
〜18g …… Absolute value conversion circuit, 20a〜20g …… Nonlinear circuit, 2
2, 30 ... synthesis circuit, 24 ... luminance signal horizontal high-pass filter, 28 ... color signal horizontal high-pass filter, 32, 38, 40 ... maximum value selection circuit 34, 42 ... ... Intermediate value selection circuit, 36, 44 ... Addition coefficient unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Suzuki 3-12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Japan Victor Company of Japan, Ltd. (72) Kenji Kubota 3--12 Moriya-cho, Kanagawa-ku, Yokohama, Kanagawa Address inside Victor Company of Japan, Ltd.

Claims (3)

[Claims] 1. A vertical and horizontal change used in an adaptive luminance signal color signal separation device which performs signal processing according to vertical and horizontal changes of an image and separates a luminance signal and a color signal from an input composite signal. In the detection circuit, each of the vertical direction detection circuit portion and the horizontal direction detection circuit portion responds to a plurality of two-dimensional filters having different separation bands that respond to the input composite signal, and outputs of the plurality of two-dimensional filters, respectively. A vertical direction characterized by comprising a plurality of absolute value conversion circuits, a plurality of nonlinear circuits that respectively respond to the plurality of absolute value conversion circuits, and a combining circuit that combines a plurality of outputs of the plurality of nonlinear circuits. Horizontal change detection circuit. 2. The plurality of two-dimensional filters are first, second, and
It has 6 filters of 3rd, 4th, 5th and 6th, and fh is horizontal frequency (unit is MHz) and fv is vertical frequency (unit is Cyc
le / Height), fsc is the subcarrier frequency (unit is MHz)
Then, the two-dimensional center frequencies (fh, fv) of the respective pass bands are approximately (0,525 / 4) for the first filter, approximately (0,525 / 8) for the second filter, and approximately three for the third filter. (Fsc / 2,525 / 8), the fourth filter is approximately (fsc, 525/8), the fifth filter is approximately (fsc / 2, 8), and the sixth filter is approximately (fsc / 2,525 / 4). In the vicinity,
The vertical direction change detection circuit portion is configured to combine the outputs of the first, second, third, and fourth filters, and the horizontal direction change detection circuit portion includes the third, fifth, and sixth filters. The vertical and horizontal change detection circuit according to claim 1, wherein the output of the filters is combined. 3. The vertical according to claim 1, wherein each of the non-linear circuits has means for independently setting at least one of a dead zone, a slope in a linear zone, and a saturation zone with respect to another non-linear circuit. Directional and horizontal change detection circuit.