KR100251536B1 - Method for separating composite video signal into luminance and chroma signal to compensate vertical resolusion and separating circuit for performing the same - Google Patents

Abstract

PURPOSE: A method and circuit for separating a luminescence and a chrominance signal in which a vertical resolution is corrected is provided to improve the image quality by separating a luminescence and a chrominance signal from a composite video signal without a cross-talk. CONSTITUTION: The first signal separation unit(200) enables the first luminescence signal and the second luminescence and chrominance signal to respectively detect a video signal interleaved. A luminescence signal generation unit(300) removes a low frequency component from the first luminescence signal. A switching unit(500) controls an output of the first luminescence signal from a high frequency component(321) of the first luminescence signal delayed. An energy detection unit(410) detects an energy of the first signal separation unit(321) and controls the switching unit(500). A calculation unit(600) calculates and outputs the first luminescence signal passed through a switch of the switching unit(500) and the second luminescence signal from the first signal separation unit(200).

Description

Luminance and color signal separation method with vertical resolution corrected and luminance and color signal separation circuit for performing the same

The present invention relates to a luminance and color signal separation method of a television receiver and a luminance and color signal separation circuit for performing the same. More specifically, the present invention relates to a color and luminance signal separation method in which the vertical resolution is corrected in order to reduce attenuation by the high frequency region of the vertical frequency of the luminance signal, and a luminance and color signal separation circuit particularly suitable for performing the same.

In general, the human eye is known that color information such as hue and saturation does not need to be as detailed as the information necessary for luminance in the image quality and image of the same sharpness. Therefore, the largest frequency band is allocated to the luminance signal in the frequency band of the television. On the other hand, for hue and saturation that do not correspond to the amount of change in luminance, the human eye should have 1/10 to 1/3 of the resolution required for brightness.

Color signals modulated as color subcarriers by the above properties are put in a band much narrower than the luminance signal band. For example, in the NTSC system, an I signal component of a color signal modulated as a color subcarrier uses a 1.3 MHz band, and a Q signal component uses a 0.5 MHz band. Providing a wider band for the I signal component compared to the Q signal component of the color signal is because the I signal is better for color resolution.

Since the frequency of the color subcarrier is 3.58 MHz, the modulated color signal is interleaved on the high frequency sideband of the luminance signal to generate a composite image signal. The comb filter method is used to minimize the attenuation of the luminance signal and the interference by the luminance signal of the color signal when the luminance signal and the color signal interleaved with the luminance signal are separated from the composite image signal.

1 is a block diagram illustrating an example of a conventional luminance and color signal separation circuit. In FIG. 1, the luminance and color separation circuit 100 includes a retarder 110, a low pass filter 120, a subtractor 130, a comb filter 140, and an adder 150. The delayer 110 delays the input composite video signal 111 by a predetermined time and then provides the delayed composite video signal 112 to the subtractor 130. The low pass filter 120 passes only the composite image signals 122 in the frequency range of 3 MHz or less from the input composite image signal 111 and passes only the low pass composite image signals 122 to pass the low pass. The complex image signal 122 is provided to the subtractor 130 and the adder 150. The composite video signal passing through the low pass filter 120 is a frequency signal of only a luminance component.

The subtractor 130 subtracts a frequency signal of only a luminance component within a frequency range of 3 MHz or less input from the low pass filter 120 from the composite image signal 111 input from the delay unit 110 to display luminance and luminance. The 3MHz or more composite video signal of which color signals are interleaved is generated, and the generated 3MHz or more composite video signal is provided to the comb filter 140. The comb filter 140 comb-filters the input interleaved composite video signal of 3 MHz or more to generate a color signal C and a luminance signal 411 of 3 MHz or more to output the generated color signal C. A luminance signal 411 of 3 MHz or higher is provided to the adder 150. Then, the adder 150 adds the luminance signal 122 from the low pass filter 120 and the luminance signal 411 from the comb filter 140 to generate an original luminance signal having a high luminance component. It generates (Y) and outputs it.

However, in the operation of the comb filter, the vertical phase relationship between the luminance signal and the color signal has a high degree of vertical correlation, for example, in the image having no change between lines, without high crosstalk on the luminance signal of the color signal. The luminance signal of the frequency band can be saved, but if the image is a moving picture, the vertical correlation of the picture deviates. Therefore, in this case, the luminance signal output from the comb filter results in a high frequency component of the luminance signal flowing into the color signal component to generate a crosstalk phenomenon. And, if there is a high-frequency portion at a certain vertical frequency or more it can not be compensated.

Accordingly, a first object of the present invention is to provide a luminance and color signal that can be separated from a composite video signal without crosstalk, and to compensate for the presence of a high frequency portion of a predetermined vertical frequency. It is to provide a color signal separation method.

It is a second object of the present invention to provide a luminance and color separation circuit which is particularly suitable for performing the above-described luminance and color signal separation method.

1 is a block diagram illustrating an example of a conventional luminance and color signal separation circuit.

2 is a block diagram illustrating a luminance and color signal separation circuit according to an exemplary embodiment of the present invention.

3 is a flowchart illustrating a method of separating luminance and color signals according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

201: input terminal 202: composite video signal

210: low pass filter 220,310: first and second subtractors

230: comb filter 240,300: first, second 1H delay

410: energy detector 510: α amplifier

520: switching unit 610: an adder

In order to realize the first object of the present invention, the present invention comprises the steps of: (a) separating each of the video signal interleaved with the first luminance signal and the second luminance and color signals from the composite image signal; (b) dividing the video signal in which the second luminance and color signals separated by step (a) are interleaved into a second luminance and a second color signal, respectively; (c) delaying the first luminance signal of step (a) based on the image signal; (d) calculating the 1H delayed first luminance signal delayed by step (c) and the first luminance signal according to step (a); (e) subtracting the first luminance signal delayed by the predetermined time by the step (c) and the current first luminance signal and outputting a subtracted signal; (f) amplifying the subtracted signal calculated by step (e); (g) detecting energy using the subtracted signal calculated by step (e); (h) comparing the energy detected by step (g) with a predetermined reference value; And (i) controlling the switch according to the result compared by step (h).

In order to realize the second object of the present invention described above, the present invention provides a first signal separation means for detecting a video signal interleaved with a first luminance signal and a second luminance and color signal from an input composite image signal ( 200); 1H delayed luminance signal generating means (300) for removing low frequency components from said first luminance signal; Switching means (500) for controlling an output of a first luminance signal from a high frequency component (321) of said 1H delayed first luminance signal based on an image signal; Energy detecting means (410) for detecting the energy of the 1H delayed first luminance signal (321) from the 1H delayed first luminance signal generating means (300) to interrupt the switching means (500); And calculating a first luminance signal from the first signal separating means 200, a first luminance signal passing through a switch of the switching means 500, and a second luminance signal from the first signal separating means 200. Comprising a calculation means 600 for outputting, it provides a luminance and color signal separation circuit characterized in that for detecting the energy of the input composite video signal, and performing signal separation according to the detected energy degree.

In the composite image video signal input through the input terminal, the second luminance signal and the second color signal are separated from the composite image signal in which the first luminance signal and the second luminance and color signals are interleaved. The first luminance signal separated from the composite image signal outputs a luminance signal delayed by 1H, and then energy of the first luminance signal delayed by 1H is detected. The vertical frequency of the 1H delayed first luminance signal input to the energy detector is detected. The 1H delayed first luminance signal is a signal in which the horizontal frequency is 0 to 3 MHz and the vertical frequency is high. That is, the energy detector checks whether the horizontal frequency of the 1H delayed first luminance signal is greater than or equal to a reference value. The energy detector operates a switch from the detected energy when the vertical frequency of the first luminance signal input to the energy detector is high, that is, the detected energy is above the reference value. If the energy of the 1H delayed first luminance signal is greater than or equal to the reference value, the energy detector detects this energy and operates a switch to multiply the 1H delayed first luminance signal by multiplying the gain [alpha] and provide it to the adder. Next, the second luminance signal, the first luminance signal and the first luminance signal are calculated to generate a final luminance signal. In the case where the vertical frequency of the luminance signal is high, the image quality may be improved by correcting this.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a block diagram illustrating a luminance and color signal separation circuit according to an exemplary embodiment of the present invention. The luminance and color signal separation circuit 800 includes a first signal separation unit 200, a 1H delayed luminance signal generation unit 300, and a luminance signal output unit 700.

The first signal separator 200 includes a low pass filter 210, a first 1H retarder 240, a first subtractor 220, and a comb filter 230.

The low pass filter 210 low-pass filters the composite video signal 202 input from the input terminal 201 and outputs a first luminance signal 211 composed of luminance components. The filtering frequency of the low pass filter 210 is preferably set to 3MHz.

The 1H delayer 240 delays the input composite video signal 202 by a predetermined time and provides the delayed composite video signal 241 to the first subtractor 220.

The first subtractor 220 is a composite video signal 241 delayed by the first 1H delayer 240 by a first 1H delayer 240 to the composite video signal 202 composed of the second luminance and color signals input from the input terminal 201 Detects an image signal 221 in a range of 3 MHz to 4.5 MHz by subtracting a first luminance signal 211 that is a low-band luminance signal composed of a frequency signal of 3 MHz or less output from the low pass filter 210 at. The detected image signal 221 is provided to the comb filter 230. The video signal 221 is a video signal in which a high-frequency luminance signal and a color signal of 3 MHz or more are interleaved, hereinafter referred to as a second luminance and color signal 221.

The comb filter 230 uses the high correlation between the scan lines or the frames, and the second luminance signal from the second luminance and color signals 221 from the first subtractor 220 of the first signal separation unit 200. 231 and the second color signal 232 are separated.

The 1H delayed luminance signal generator 300 includes a second 1H delayer 310 and a second subtractor 320.

The second 1H delayer 310 delays the first luminance signal 211 received from the low pass filter 210 of the first signal separator 200 by 1H, and the 1H delayed low frequency first 3MHz or less. The luminance signal 311 is provided to the second subtractor 320.

The second subtractor 320 subtracts the first luminance signal 211 input from the low pass filter 210 from the 1H delayed first luminance signal 311 input from the second 1H delayer 310. The subtracted signal 321 is provided to the luminance signal output unit 700.

The luminance signal output unit 700 includes an energy detector 410, a switching unit 500, and an operation unit 600.

The energy detector 410 is a part for detecting the energy of the 1H delayed first luminance signal 321 output to the second subtractor 320. The 1H delayed first luminance signal 321 is output from the low pass filter 210 in the 1H delayed first luminance signal 311 with a low frequency first luminance signal 211 output from the low pass filter 210. This signal is obtained by subtracting the lower first luminance signal 211 of 3 MHz or less. That is, a signal obtained by subtracting a 3 MHz low pass luminance signal from a 3 MHz low pass 1H luminance signal, and a high frequency component in which a low frequency component of 3 MHz or less is excluded from the luminance signal of the current frame among the signal components before 1H. 410 and the switching unit 500 is provided. The first luminance signals Y _LH 321 output from the second subtractor 320 are signals having a horizontal frequency of 0 to 3 MHz and a vertical frequency of high frequency. Accordingly, the energy detector 410 detects whether the energy of the subtracted signal 321 is equal to or greater than the reference value. When the energy detected by the energy detector 410 is greater than or equal to the reference value, the switch 520 of the switching unit 500 is turned on.

The switching unit 500 includes an amplifier 510 for amplifying the first luminance signal 321 provided by the second subtractor 320 by α and a switch 520 for switching the α amplified first luminance signal. It is composed of

The switch 520 operates according to the energy detected by the energy detector. When the detected energy is equal to or greater than the reference value, the switch 520 amplifies the first luminance signal 321 provided by the second subtractor by α, and then amplifies the first luminance by α. The signal 511 is provided to the calculator 600.

The calculation unit 600 passes the first luminance signal Y _L and 211 from the low pass filter 210 and the first luminance signal αY _LH 511 amplified by α through the switch of the switching unit 500. And an adder 610 for calculating and outputting the second luminance signals 231 and Y _H from the comb filter 230.

The adder 610 passes the first luminance signal Y _L and 211 from the low pass filter 210 and the first luminance signal α amplified by α through the switch 520 of the switching unit 500. Y _LH 511 and the second luminance signals 231 and Y _H from the comb filter 230 are added to each other to output a luminance signal Y '.

The luminance signal Y 'whose horizontal frequency is output from the adder 610 is corrected as follows.

The adder 610 is the low pass filter as the luminance signal Y 'when the switching unit 500 is open and the first luminance signal 511 amplified by α is not output. The first luminance signal 211 from 210 and the second luminance signal 231 from the comb filter 230 are added and output.

Next, the luminance and color signal separation circuit having the above configuration will be described with reference to the flowchart shown in FIG.

The composite video signal 202 input through the input terminal 201 is input to the low pass filter 210 and the first 1H delay unit 240 of the first signal separation unit 200. The low pass filter 210 filters the input composite video signal, detects only an image signal of 3 MHz or less, that is, a first luminance signal 211 to detect the first subtractor 220, the second subtractor 320, and the second. It outputs to the 1H retarder 310 and the trailing device 610 (step S1).

Then, the first subtractor 220 converts the composite image signal 202 from the low pass filter 210 to the first luminance signal 211 in the composite image signal 241 delayed by 1H in the first 1H delay unit. The second luminance and color signals are detected by subtracting the interleaved composite video signal (step S2). The second luminance and color signals 221 detected by the first subtractor 220 exist in an interleaved state in a frequency band of 3 MHz or more.

When the second luminance and color signals 221 interleaved from the first subtractor 220 are input, the comb filter 230 receives second color signals 232 and C from the second luminance and color signals 221. Is detected first, and the second luminance signal 231 is detected to separate the second luminance and color signals 221 into the second luminance signal 231 and the color signals 232 and C (step S3). The comb filter 230 may use a line comb filter using a correlation between a line of a scan line and a line, or a comb filter using a correlation between frames.

The first luminance signal 211, which is an output signal of the low pass filter 210, is provided to the luminance signal generator 300 having a 1H delay. The 1H delayed third luminance signal generator 300 delays the input first luminance signal 211 by the second 1H delayer 310 by 1H, and the delayed luminance signal 311 is a luminance signal of a high frequency component. 321 is output to the second subtractor 320 to generate. Then, the second subtractor 320 subtracts the first luminance signal 211 from the first luminance signal 311 delayed by 1H by the 1H delay unit 310 to subtract the subtracted value 321 by the energy detector ( 410 and the α amplifier 510. The energy detector 410 detects energy for a high frequency component from the subtracted signal 321 input from the second subtractor 320 (step S4). The α amplifier 510 amplifies the subtracted value 321 output by the second subtractor 320 by α and outputs it to the switch 520.

The subtracted signal 321 input by the energy detector 410 from the second subtractor 320 is compared with a predetermined reference signal (step S5). When the input subtracted signal 321 is larger than a predetermined reference signal, the switching unit 520 supplies the subtracted signal 511 amplified by α in the amplifier 510 to the adder 610 so as to supply the adder. A subtraction signal 511 amplified by α is added to the first luminance signal 211 and the second luminance signal 231 by 610 so that the first luminance signal 211 and the second luminance signal 231 are added. And the subtracted signal 511 amplified by? Is output as the luminance signal Y '(steps S9, S10, S11).

On the contrary, in step S5, when the subtracted signal 321 input from the second subtractor 320 is smaller than a predetermined reference signal, the switching unit 520 adds the subtracted signal 511 amplified by the α to the adder ( 520, the first luminance signal 211 and the second luminance signal 231 are added by the adder 610 so that only the first luminance signal 211 and the second luminance signal 231 are added. ) Outputs the added signal as the luminance signal Y '(steps S6, S7, S8).

Therefore, when the luminance signal is separated from the composite video signal, the high-band luminance signal interleaved with the color signal is output according to the energy of the subtracted signal obtained by subtracting the signal extracted from the low-pass luminance signal with the delayed signal by 1H. Alternatively, by blocking, the high frequency component of the luminance signal is introduced into the color signal component in the moving image, thereby preventing the crosstalk phenomenon.

As described above, the present invention provides a luminance and color signal separation and a method for separating the luminance signal and the color signal from the composite video video signal without crosstalk.

Although the present invention has been described in detail by the above embodiments, the present invention is not limited thereto, and variations and improvements can be made without departing from the ordinary knowledge of those skilled in the art.

Claims (7)

(a) separating the interleaved video signal of the first luminance signal and the second luminance and color signal from the composite image signal, and (b) interleaving the second luminance and color signal separated by step (a). Separating the video signal into a second luminance and a second color signal, respectively, (c) delaying the first luminance signal according to step (a) based on the image signal, (d) said step (c) Computing the 1H delayed first luminance signal delayed by and the first luminance signal according to step (a), (e) The first luminance signal and the current first luminance signal delayed by a predetermined time by the step (c) Subtracting and outputting a subtracted signal, (f) amplifying the subtracted signal calculated by step (e), and (g) detecting energy using the subtracted signal calculated by step (e) (h) a predetermined reference value using the energy detected by step (g) Comparing with; And (i) controlling the switch according to the result compared by step (h). The method of claim 1, wherein the step (a) comprises: (a-1) detecting a low luminance first luminance signal from the input composite image signal; And (a-2) subtracting the first luminance signal detected by step (a-1) from the signal of 1H delayed input composite video signal to detect the interleaved second luminance and second color signals. The brightness and color signal separation method characterized in that it is configured. A first signal separation means 200 for detecting a video signal interleaved with a first luminance signal and a second luminance and color signal from an input composite image signal, and a 1H delay for removing low frequency components from the first luminance signal; Luminance signal generating means 300, switching means 500 for intermittently outputting the first luminance signal from the high frequency component 321 of the 1H delayed first luminance signal based on the image signal, and the 1H delayed first luminance Energy detecting means (410) for detecting the energy of the 1H delayed first luminance signal (321) from the signal generating means (300) to control the switching means (500); And calculating a first luminance signal from the first signal separating means 200, a first luminance signal passing through a switch of the switching means 500, and a second luminance signal from the first signal separating means 200. And a calculation means (600) for outputting, detecting energy of the input composite video signal, and performing signal separation according to the detected energy level. 10. The method of claim 9, wherein the first signal separating means 200 is a first delay 240 for delaying the input composite video signal for a predetermined time, and only signals of a predetermined frequency band from the input composite video signal. A low pass filter 210 for detecting a first pass subtractor 220 for subtracting a frequency signal of a predetermined band detected by the low pass 210 from the composite image signal delayed by the first delayer 240. ); And a comb filter 230 that separates the second luminance signal and the second color signal from the second luminance and color signals from the first subtractor 220 by using a high correlation between scan lines or frames. A luminance and color signal separation circuit. 10. The apparatus of claim 9, wherein the 1H delayed luminance signal generating means (300) comprises: a second 1H delayer (310) for delaying the first luminance signal for a predetermined time; And a second subtractor (320) for subtracting the current first luminance signal from the first luminance signal delayed by the 1H delayer by 1H. 10. The apparatus of claim 9, wherein the switching means (500) comprises: an amplifier (510) for amplifying the first luminance signal (321) provided by the second subtractor (320) by α; And a switch (520) for switching the α amplified first luminance signal. 10. The apparatus of claim 9, wherein the calculating means (600) comprises a first luminance signal (511) amplified by a delay of 1H with a first luminance signal (211) and a second luminance from the first signal separation means (200). Color and luminance signal separation circuit, characterized in that consisting of an adder (610) for adding the signal.

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