JPH054669U - Image quality improvement device - Google Patents

Abstract

(57) [Summary] [Object] An image quality improving apparatus for adding a two-dimensional middle-high frequency component signal to a luminance signal to create a contour-enhanced luminance signal forms a two-dimensional middle-high frequency component signal directly from a composite television signal. [Structure] A first low-pass filter 1 for extracting a low-pass vertical component signal from a composite television signal, and a second low-pass filter 5 for extracting a low-pass horizontal component signal to form a two-dimensional low-pass component signal YL. Subordinately connect and. The subtractor 9 subtracts the two-dimensional low-frequency component signal YL delayed by the delay device 11 from the luminance signal separated from the composite television signal by the Y / C separator 3 and input through the delay device 11 to emphasize the high frequency region. The signal ΔY is formed and output to the adder 13 via the gain adjuster 15. Adder 13
Outputs the emphasized luminance signal by adding the high frequency emphasizing signal ΔY to the luminance signal from the delay device 11.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to an image quality improving device, and particularly to a large color television receiver, for example, a projection type. The present invention relates to an image quality improving device suitable for being mounted on a color television receiver.

[0002]

[Prior art]

  Conventionally, this type of image quality improvement device has been designed to produce a Y / C separated bright signal from a composite TV signal. Two-dimensional low-frequency component is extracted from the degree signal (Y signal), and the low-frequency component signal is extracted from the luminance signal. The two-dimensional middle-high range component signal is extracted by taking the difference of Signal that has been edge-enhanced by adding the signal to the luminance signal after gain adjustment. Has been proposed to improve image quality in the horizontal and vertical directions (two-dimensional). It

[0003]

[Problems to be solved by the device]

  However, the above-described image quality improving device does not provide the brightness separated from the composite TV signal. The signal is used to extract a two-dimensional low-frequency component to obtain an edge-enhanced luminance signal. However, due to various reasons, the secondary signal is separated without using the luminance signal separated from the composite TV signal. In some cases, it may be desirable to extract the original low frequency component.   For example, as a means for extracting a two-dimensional low-frequency component signal, a digital device having a delay device In many cases, filters are used, but the Y / C component that separates the luminance signal and the color signal (C signal) is used. Generally, a delay circuit is also used for the separation circuit, and the digital filter is Y / C separated. It was necessary to form a delay device separately from the circuit.   The present invention has been made under such circumstances, and has a configuration different from the conventional one. An object of the present invention is to provide an image quality improving device that improves image quality in the horizontal and vertical directions.

[0004]

[Means for Solving the Problems]

  In order to solve such a problem, the present invention has a delay time of one horizontal scanning period. Having a plurality of delay units for extracting a low frequency vertical component signal from a composite television signal, Of the low pass filter and the output signal of the first low pass filter A second low-pass filter to be extracted and a luminance signal and a color signal are separated from the composite television signal. The Y / C separator to be separated and the luminance signal of this Y / C separator are used to generate the second low-pass filter. The subtracter that subtracts the output signal and outputs the high-frequency emphasis signal, and the Y / C separator An adder for adding the high-frequency emphasis signal to the luminance signal is provided.

[0005]   In the present invention, the Y / C separator has a delay time of one horizontal scanning period. And a delay device for the first low-pass filter. It is also possible to share with.   Further, according to the present invention, the high frequency emphasizing signal from the subtractor is below a predetermined reference level. In this case, a coring circuit that does not output the high frequency emphasis signal to the adder When the signal exceeds the reference level, the high-frequency emphasized signal level is attenuated by the reference level and added. It is preferable to configure the coring circuit to output to the calculator.

[0006]

[Action]

  In the present invention having such means, the first low-pass filter is provided before the separation of the luminance signal. The low-pass vertical component signal is extracted from the composite television signal of and output to the second low-pass filter. , The second low-pass filter extracts the low-pass horizontal component signal and subtracts the two-dimensional low-pass component signal Output to a two-dimensional low-frequency component from the luminance signal from the Y / C separator. The minute signal is subtracted to form the high-frequency emphasis signal, and the Y / C separator is added in the adder. The high-frequency emphasis signal is added to the brightness signal from the No. is output.   Then, the delay device of the Y / C separator is shared by the delay device of the first low-pass filter. In the configuration, the luminance signal is based on the signal passing through the delay device of the first low pass filter. To be separated.

[0007]   Furthermore, if the high-frequency emphasis signal level is low in the configuration with the coring circuit, For example, the luminance signal in which the noise component is emphasized with respect to the noise signal is not output.   Furthermore, the reference level is attenuated from the high frequency emphasized signal level and output to the adder. In the configuration that forms the coring circuit so that the high frequency emphasis is excessively emphasized, The luminance signal is output in a suppressed state.

[0008]

【Example】

  Embodiments of the present invention will be described below with reference to the drawings.   FIG. 1 is a block diagram of essential parts showing an embodiment of an image quality improving device according to the present invention.   In FIG. 1, the input terminal P1 to which the composite television signal is applied is the composite television signal. First low-pass filter 1 for extracting the low-frequency vertical component signal from the signal and its composite television signal. Signal is connected to a Y / C separator 3 for separating a luminance signal and a chrominance signal.   The first low-pass filter 1 is connected to the second low-pass filter 5, The low pass filter 5 extracts a low pass horizontal component signal from the output signal of the first low pass filter 1. To form a two-dimensional low-frequency component signal YL, which has a predetermined delay time. It is connected to the subtractor 9 via the delay unit 7. A first and a second low pass filter 1, Details of 5 will be described later.

[0009]   The Y / C separator 3 has a conventionally known circuit configuration, and the subtractor 9 and the subtractor 9 are connected via a delay device 11. And adder 13.   The delay device 11 includes a signal passing time from the first low-pass filter 1 to the subtractor 9 and Y The signal passing time from the / C separator 3 to the subtractor 9 is matched. Therefore, one of the delay devices 7 and 11 may be omitted, or both of the delay devices 7 and 11 may be omitted. It is possible.   The subtractor 9 converts the luminance signal from the delay device 11 into the two-dimensional low-frequency component signal from the delay device 7. YL is subtracted to form a high frequency emphasizing signal .DELTA.Y. Connected to the adder 13.

[0010]   The adder 13 adds the high-frequency emphasis signal ΔY to the luminance signal from the delay device 11 and emphasizes it. The luminance signal is output to the output terminal P2.   FIG. 2 shows the first and second low-pass filters 1 and 5 more specifically. It is a block diagram of an improvement device.   In FIG. 2, a plurality of delay devices having a delay time of one horizontal scanning period (H Connected to the input terminal P1 with a series circuit of 17a, 17b, 17c and 17d, The input side of the delay device 17a, the connection points of the delay devices 17a, 17b, 17c and 17d, and Coefficient multipliers (abbreviated as K in the figure) 19a, 19b, 19c are provided on the output side of the delay device 17d. , 19d, 19e, 19f, and 19g are connected in a ladder shape, and these coefficient units 1 9a to 19g are connected to the adder 21, and a transversal type first low-pass filter 1 is formed.

[0011]   In the first low pass filter 1, the coefficient signals applied to the coefficient multipliers 19a to 19g are appropriately By selecting, the desired low-frequency vertical component signal can be extracted from the composite TV signal. And the adder 21 is connected in series with the second low-pass filter 5.   The second low-pass filter 5 has substantially the same circuit configuration as the first low-pass filter 1, For example, a plurality of delay devices (abbreviated as D) 23a having a delay time of several tens of nanoseconds, The series circuit of 23b, 23c, and 23d is connected to the adder 21, and the input of the delay device 23a Side, each connection point of the delay devices 23a, 23b, 23c and 23d and the output of the delay device 23d. Coefficient multipliers (abbreviated as k in the figure) 25a, 25b, 25c, 25d, and 25e on the force side, respectively. , 25f and 25g are connected in a ladder shape, and these coefficient units 25a to 25g are added. The transversal second low-pass filter 5 is formed by connecting to the calculator 21. It

[0012]   In the second low-pass filter 5, the coefficient signal added to the coefficient multipliers 25a to 25g is suitable. By making the appropriate selection, the desired low-frequency horizontal component signal from the composite TV signal, It is possible to extract a low-frequency component signal on the frequency axis, and the adder 27 is a subtractor. 9 is connected. It should be noted that the delay device 7 is omitted in the drawings after FIG.   In the image quality improving apparatus having such a configuration, the composite television signal applied to the input terminal P1 The low-pass vertical component signal is extracted by the first low-pass filter 1, and the second low-pass filter In step 5, the low-frequency horizontal component signal is extracted to form the two-dimensional low-frequency component signal YL, and Y / C The enhancement signal ΔY is formed by subtracting the two-dimensional low-frequency component signal YL from the luminance signal of the separator 3. And the enhanced signal ΔY is added to the luminance signal by the adder 13 to form an enhanced luminance signal. To be done.

[0013]   Therefore, the two-dimensional low frequency component signal YL is directly formed from the composite TV signal. Therefore, the image quality can be improved by the configuration different from the conventional one.   FIG. 3A shows the pass band in the first low-pass filter 1 in units of TV lines. FIG. 3 is a diagram showing an example of a characteristic in the case where B is the horizontal pass band of the second low-pass filter 5. It is a figure which shows one example of a characteristic at the time of showing as a unit of MHz.   By the way, in the present invention, the composite television signal is directly fed to the first and second low-pass filters. Since a two-dimensional low-frequency component signal YL is formed by passing signals 1 and 5, it becomes a composite television signal. The first and second low-pass filters 1 and 5 are provided to block the contained carrier color signal. Circuit of the second low-pass filter 5 or lower by appropriately setting the cutoff frequency. The configuration can be a conventionally known circuit configuration.

[0014]   Next, another embodiment of the image quality improving device of the present invention will be described.   FIG. 4 partially shares the circuit for the first low-pass filter 1 and the Y / C separator 31. It shows the configuration.   That is, the Y / C separator 31 is the input of the delay device 17b of the first low pass filter 1. Side, the connection point of the delay devices 17b and 17c, and the composite television signal from the output side of the delay device 17c. Is input to separate the luminance signal.   Various configurations have been generally introduced as a Y / C separator. For example, as shown in FIG. As described above, a delay device (abbreviated as H in the figure) 33 having a delay time of one horizontal scanning period is provided. Delay the composite TV signal by the series circuit of a and 33b, and input composite to the delay device 33a. The adder 35 adds the television signal and the delayed composite television signal from the delay device 33b, and The level is attenuated to 1/2 by the number calculator 37 and added to the subtractor 39. It is subtracted from the composite television signal delayed by the horizontal scanning period, and a band pass filter (BP F) Attenuate the level to 1/2 by a coefficient unit 43 via 41 and output a color signal On the other hand, the subtractor 45 subtracts the color signal from the composite TV signal delayed by one horizontal scanning period. There is known a configuration in which a luminance signal is calculated and output.

[0015]   As described above, the delay devices 33a and 33b having a delay time of one horizontal scanning period are provided. As for the Y / C separator 31 that does, the points A, B and C in FIG. Input side of delay device 17b, connection point of delay devices 17b and 17c, output side of delay device 17c To correspond to the delay units 33a and 33b of the first low-pass filter 1. 17b and 17c can be shared, which simplifies the circuit configuration and It has the advantage of being miniaturized.   As described above, there are generally various configurations as the Y / C separator. A Y / C separator having at least one delay device having a delay time for a scanning period and a first low delay device. It can be partially shared with the pass filter 1.

[0016]   FIG. 6 is a block diagram of essential parts showing still another embodiment of the present invention.   6, the output of the subtractor 9 of FIG. 1 is the output of the comparator 47 including an OP amplifier. One input terminal and the subtractor 49 are connected to each other, and a predetermined reference signal (REF) is applied to the comparator. It is connected to the other input terminal of 47 and the subtractor 49.   The subtractor 49 is connected to one fixed contact of a switch (abbreviated as SW in FIG. 6) 51. The other fixed contact is connected to the “0” level, and the movable contact is shown in FIG. The coring circuit 53 is formed so as to be connected to the gain adjuster 15.   The comparator 47 switches when the high-frequency emphasis signal ΔY exceeds the reference signal (REF). The movable contact 51 is connected to the fixed contact on the subtractor 49 side, and the high frequency emphasis signal ΔY is the reference signal. No. (REF) or less, the movable contact is turned off to connect to the fixed contact on the “0” level side. The subtractor 49 outputs the replacement signal from the high frequency emphasis signal ΔY to the reference signal. (REF) is subtracted and output to the switch 51.

[0017]   In the configuration having such a coring circuit 53, the reference signal (REF) is appropriately set. When the high frequency emphasis signal ΔY from the subtractor 9 is equal to or lower than the reference signal (REF), In this case, since the movable contact selects the “0” level side, the output from the gain adjuster 15 The luminance signal from the delay device 11 is directly output from the adder 13 to the output terminal P2. Is output.   Generally, in the case of a composite TV signal with a noise component, high frequencies based on the noise signal Since the enhancement signal ΔY level is low, it is possible to use the coring circuit 53 described above. The luminance signal is no longer emphasized by the high frequency emphasis signal ΔY based on the noise component The effect on the screen of can be suppressed.   Further, when the high frequency emphasis signal ΔY exceeds the reference signal (REF), the subtractor 49 raises the high level. The reference signal (REF) component is subtracted from the range emphasis signal ΔY to obtain the gain adjuster 15 and the addition signal. Since it is added to the calculator 13, even if the high frequency emphasis signal ΔY level is high, the adder 13 is suitable. A high frequency emphasis signal ΔY is added to the luminance signal to suppress excessive emphasis.

[0018]

[Effect of device]

  As described above, the image quality improving apparatus of the present invention is used in the television before separating the luminance signal. It becomes possible to directly extract the two-dimensional low-frequency component from the signal, which is different from the conventional one. The result is a luminance signal that improves image quality in the horizontal and vertical directions.   Then, the delay device of the Y / C separator is shared by the delay device of the first low-pass filter. Then, the circuit configuration can be simplified and the size can be reduced.   Also, in the configuration with the coring circuit, the luminance signal is emphasized by the noise component. It is possible to suppress the occurrence of noise, and the image quality due to noise is not deteriorated.   Furthermore, the high-frequency emphasized signal level is attenuated by the reference level and output to the adder. In the configuration that forms a coring circuit, the high frequency emphasis is not overemphasized and The image quality can be maintained high by suppressing the occurrence of a stuttering screen.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of an image quality improving device according to the present invention.

FIG. 2 is a block diagram specifically showing the image quality improving device of FIG.

3 is a diagram showing a characteristic example of first and second low-pass filters in the image quality improving apparatus of FIG.

FIG. 4 is a block diagram showing another embodiment of the image quality improving device of the present invention.

FIG. 5 is a block diagram showing an example of a Y / C separator.

FIG. 6 is a block diagram of a main part showing still another embodiment of the present invention.

[Explanation of symbols]

1 1st low-pass filter 3, 31 Y / C separator 5 2nd low-pass filter 7, 11, 17a-17d, 23a-23d, 33a,
33b Delay device 9, 13, 45, 49 Subtractor 15 Gain adjuster 19a-19g, 25a-25g, 37, 43 Coefficient device 21, 27, 35, 39 Adder 41 Bandpass filter (BPF) 47 Comparator 51 Switch 53 Coring circuit P1 Input end P2 Output end

Claims (4)

[Scope of utility model registration request] 1. A first low-pass filter for extracting a low-pass vertical component signal from a composite television signal, the first low-pass filter comprising a plurality of delay devices each having a delay time of one horizontal scanning period, A second low-pass filter for extracting a low-pass horizontal component signal from the output signal; and Y for separating a luminance signal and a chrominance signal from the composite television signal
/ C separator, a subtractor for subtracting the output signal from the second low-pass filter from the luminance signal from the Y / C separator to output a high-frequency emphasis signal, and the Y / C separator And an adder for adding the high-frequency emphasis signal to the luminance signal, and an image quality improving apparatus. 2. The Y / C separator is formed with a delay device having a delay time of one horizontal scanning period, and
The image quality improving device according to claim 1, wherein the image quality improving device is also used as a delay device of the first low-pass filter. 3. The image quality improvement according to claim 1, further comprising a coring circuit that does not output the high-frequency emphasized signal to the adder when the high-frequency emphasized signal from the subtractor is below a predetermined reference level. apparatus. 4. The image quality according to claim 3, wherein the coring circuit attenuates the high-frequency emphasis signal level by the reference level and outputs the high-frequency emphasis signal level to the adder when the high-frequency emphasis signal exceeds the reference level. Improvement device.