Systems and methods for processing signal and television

TECHNICAL FIELD The present invention relates to a method and system for signal processing, and in particular, to a method and system for processing composite television signals.

2. Description of the Related Art Color information (color information) carried by a composite TV signal is modulated in a quadrature manner on a subcarrier. The frequency of the sub-carrier corresponds to the scan line frequency (1 ine scan frequency), so that the sub-carrier can insert color information between the energy spectra of the luminance baseband signal. In a color TV system (such as NTSC or PAL), color information includes luminance (Y) and chrominance (C) information, and the two share a certain part of the entire bandwidth of the signal Copies. Therefore, a brightness and chroma separation program is needed in the receiving end to separate the brightness and chroma information. For the brightness and chroma information of certain image areas, especially for an image area with a high-frequency brightness motion edge (motion edge), the coding technology is not perfect, which often causes difficulties in recognition. For example, the demodulator of a TV will demodulate it by mistake due to the influence of high-frequency brightness on the vertical edge. It becomes the information of chroma. The above problems cause color ringing, smearing, and rainbow-like display results instead of the original high-frequency grayscale information.

Recently, control methods and systems for suppressing cross-color artifacts derived from orthogonally modulated composite television signals have received increasing attention from the industry, such as US Patent Nos. 5, 305, 120 and Patent No. 6,504, 579 discloses a method for suppressing cross-color. in

200610002781.3 No. 5, 305, 120 in US Patent No. 5, 305, 120, is based on the motion information (motion inf or mat ion) and uses the time averaging method to suppress the cross-color; or, if it is detectable in the TV signal For mobile scenes, you can use the spatial averaging method. Comb filtering is also a well-known brightness and chroma separation method commonly used for cross-color suppression. In U.S. Patent No. 6,504,579, Remy Scherrer disclosed a method that uses horizontal image gradients, vertical image gradients, and diagonal image gradients to determine which direction has a greater weight in the comb filtering method. Enhance certain effectiveness. Unfortunately, not all unwanted cross-colors can be removed by comb filter processing. Therefore, cross-color suppression is required to reduce image defects caused by cross-color effects.

SUMMARY OF THE INVENTION The object of the present invention is to provide a signal processing method and system to suppress the cross-color effect of composite television signals.

In order to achieve the above objective, the present invention provides a signal processing method for a composite television signal. The method includes the following steps: calculating an image similarity of the composite television signal; separating a luminance signal from the composite television signal (Y ) And a chroma signal (O; demodulate the chroma signal (0 to output a base frequency chroma signal OH, VI); and adjust the fundamental frequency chroma signal (Ul, VI) to generate an adjusted base frequency chroma Signal (U2, V2). According to the image similarity, a final chroma signal (U, V) is calculated from the base frequency chroma signal (Ul, VI) and the adjusted base frequency chroma signal (U2, V2).

The present invention provides a signal processing system for a composite television signal. The system includes an image similarity calculator, a Y/C separator, a chroma demodulator, a chroma adjuster, and a chroma mixer . The image similarity calculator is used to calculate an image similarity of the composite television signal. The Υ/C separator is used to distinguish the color information in the composite TV signal to separate a luminance signal (Y) and a chrominance signal (0. The chrominance demodulator is used to demodulate the chrominance signal (C). ) To output a fundamental frequency chroma signal (U1, VI)₀The chroma adjuster is used to adjust the base frequency chroma. Signals (U1, VI) to output an adjusted base frequency chroma signal (U2, V2)_oThe chroma mixer is based on the image similarity and uses the fundamental frequency chroma signal (Ul, VI)

200610002781.3 and adjust the base frequency chroma signal (U2, V2) to calculate a final chroma signal (U, V)_oIn some embodiments, the signal processing system further includes a similarity mapping table, which outputs a variation coefficient K to the chroma mixer based on the image similarity obtained by the image similarity calculator; the chroma mixer is based on The variation coefficient K determines the final chroma signal (U, V).

The present invention also provides a signal processing method for a composite television signal. The method includes the following steps: calculating an image similarity based on the composite television signal; separating a luminance signal (Y) and a composite television signal from the composite television signal Saturation signal (0; demodulate and change the chroma signal (0 to output a base frequency chroma signal (Ul, VI); adjust the chroma signal (C) to output an adjusted chroma signal (C2); demodulate and adjust Chroma signal (C2) to output an adjusted base frequency chroma signal (U3, V3); and based on image similarity, calculated from the base frequency chroma signal (Ul, VI) and adjusted chroma signal (U3, V3) A final chroma signal (U, V)_o The present invention also provides a signal processing system for a composite television signal. The system includes an image similarity calculator, a Y/C separator, a first chrominance demodulator, and a second chrominance solution. Adjuster, a chroma adjuster, and a chroma mixer. The image similarity calculator is used to calculate an image similarity of the composite television signal, and the Y/c separator is used to separate a luminance signal (Y) and a chrominance signal (C) from the composite television signal. The first chrominance demodulator is used to demodulate the variable chrominance signal (C) to output a baseband chrominance signal (U1, VI). The chroma adjuster is used to adjust the chroma signal (C) to output an adjusted chroma signal (C2), and the second chroma demodulator is used to demodulate and change the chroma signal (C2) to output an adjustment base Frequency chroma signal (U3, V3). The chroma mixer is used to calculate a final chroma signal (U, V) based on the image similarity and the fundamental frequency chroma signal (U1, VI) and adjust the fundamental frequency chroma signal (U3, V3). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an embodiment of a signal processing system for cross-color suppression.

Fig. 2 is another embodiment of a signal processing system for cross-color suppression, Fig. 2 to Fig. 3d are schematic diagrams of the spatial and temporal correlation of the sampled values of the composite television signal.

200610002781.3 Figure 4 is a functional block diagram of a television embodiment

<td>10、20</td><td>Signal processing system</td>

<td>11、21</td><td>Υ/C separator</td>

<td>12、22</td><td>Delay unit</td>

<td>13, 23a,</td><td>23b chroma demodulator</td>

<td>14、24</td><td>Chroma adjuster</td>

<td>15、25</td><td>Chroma mixer</td>

<td>16、26</td><td>Image similarity calculator</td>

<td>17、27</td><td>Similarity mapping table</td>

<td>18、28</td><td>Control device</td>

<td colspan="2">29 Average unit</td>

<td colspan="2">40 TV</td>

<td colspan="2">402 receiver·</td>

<td colspan="2">404 signal processor</td>

DETAILED DESCRIPTION The present invention provides a signal processing method and system for processing cross-color suppression (cross-color suppression) ₀The suppression of the cross-color effect is through the detection of the image area. When the similarity measurement value of some image areas is small (that is, the two-dimensional and three-dimensional Y/C separation fails), the cross-color may be formed. Need to be suppressed. For a specific image area, the similarity measurement includes the similarity in the horizontal and vertical dimensions, and the similarity in the temporal dimension. The image area where cross-color may occur is detected, and the chrominance is changed. To achieve the purpose of suppressing cross-color.

FIG. 1 shows a schematic diagram of an embodiment of a signal processing system 10 for suppressing cross-color. Y/C separator (Y/C separator) 11 separates the input composite TV signal (composite TV signal)

200610002781.3 The first luminance signal (Y) and chrominance signal (C). The chroma demodulator (chroma demodulator) 13 demodulates the transformed chroma signal (C) to obtain the fundamental frequency chroma signal (U1, VI), which is then provided to the chroma regulator (chroma regulator) 14 and the chroma mixer (chroma). mixer)

15. The chrominance adjuster 14 adjusts the baseband chrominance signal (Ul, VI) and outputs a regulated baseband chrominance signal (U2, V2). In some embodiments, the chrominance adjuster 14 reduces the signal strength of the fundamental frequency chrominance signal (U1, VI), for example, the amplitude of the fundamental frequency chrominance signal (U1, VI) is reduced to one half or one quarter. One, or use filtering to change the fundamental frequency chroma signal (Ul, VI)₀The chroma adjuster 14 averages multiple sampling points separated by a predetermined number of lines or frames in the fundamental frequency chroma signal (Ul, VI)) to obtain the adjusted fundamental frequency chroma signal (U2, V2), and Averaging in time or space can effectively suppress the signal strength of the fundamental frequency chroma signal (U1, VI).

The composite TV signal will also be sent to an image similarity calculator (image, similarity calculator) 16, which calculates the image similarity S based on the temporal and spatial correlation of the sampling points of the composite TV signal. Spatial correlation refers to the correlation between sampling points separated by a predetermined number of horizontal or vertical lines, while temporal correlation refers to the correlation between sampling points separated by a predetermined number of frames. Only when the result of the spatial and temporal correlation is lower than a certain threshold (representing a high probability of cross-color occurrence), the signal S output by the image similarity calculator 16 will indicate that the degree of image similarity is not high value. The image similarity S calculated by the image similarity calculator 16 will cause the similarity mapping table 17 to output a corresponding variation coefficient. The similarity mapping table 16 is used to store a set of variation coefficients, and each variation coefficient corresponds to an image. Similarity or similarity of a certain range of images. A small image similarity corresponds to a large variation coefficient, and a large image similarity corresponds to a small variation coefficient. The similarity mapping table 17 is programmable, and the control device 18 is used to manage and plan the content of the similarity mapping table 17.

The chroma mixer 15 receives the fundamental frequency chroma signal (Ul, VI) (from the chroma demodulator gate), adjusts

200610002781.3 After the fundamental frequency chroma signal (U2, V2) (from the chroma adjuster 14), and the coefficient of change K (from the visual image table 17), a final chroma signal (U, V2) is determined according to all the inputs. V), and the chroma mixer 15 can be actually operated by a multiplexer. If the variation coefficient K is less than a default value, it means that the similarity in at least one dimension exceeds the threshold. At this time, the multiplexer can select the fundamental frequency chroma signal (Ul, VI) as the output, otherwise the multiplexer selects Adjust the base frequency chroma signal (U2, V2) as output. In some embodiments, the chrominance mixer 15 can use a weighting factor equivalent to the variation coefficient K to mix the fundamental frequency chrominance signals (Ul, VI) and adjust the fundamental frequency chrominance signals (U2, V2). ) And get the final chroma signal (U, V), as shown in the following formula:

U = KxU2+ (1-K) X U1;

V = KxV2+ (1-K) x VL When the variation coefficient K is large, the final chroma signal (U, V) mainly depends on adjusting the fundamental frequency chroma signal (U2, V2), which means the similarity in all dimensions All are less than the threshold. Conversely, when the coefficient of variation K is very small, the final chroma signal (U, V) mainly depends on the fundamental frequency chroma signal (U1, VI), and this means that the similarity in at least one dimension exceeds the threshold.

The luminance signal output by the Y/C separator 11 passes through a delay unit 12 to match and compensate the calculation time required for the final chrominance signal (U, V).

FIG. 2 shows a schematic diagram of another embodiment of a signal processing system 20 for suppressing cross-color. The signal processing system 20 is similar to the signal processing system 10 of FIG. 1 except that the chrominance adjuster 24 is used to adjust the chrominance signal before demodulation. The Υ/C separator 21 also separates the synthesized vision signal into a luminance signal (Y) and a chrominance signal (C), and the chrominance adjuster 24 reduces the signal intensity of the chrominance signal (C) and outputs the adjusted chrominance signal (C2). Then, the adjusted chroma signal (C2) is provided to the chroma demodulator 23a to generate the adjusted base frequency chroma signal (U3, V3). In addition, the chroma signal (C) is also provided to another chroma demodulator 23b to generate the base frequency chroma signal (Ul, VI). The image similarity calculator 26 calculates the image similarity S of the composite TV signal, and the similarity mapping table 27 outputs a corresponding image.

200610002781.3 The variation coefficient K of the first image similarity S to the chromaticity mixer 25. The control device 28 can manage and plan the content of the similarity mapping table 27. The averaging unit 29 is arranged between the chrominance demodulator 23a and the chrominance mixer 25, and is used to adjust the fundamental frequency chrominance signal (U3, V3) separated by a predetermined number of lines or frames. Take the average of the sampling points.

The chroma mixer 25 receives the fundamental frequency chroma signal (Ul, VI), and the average fundamental frequency chroma signal (U3,,

V3^!), and generate the final chroma signal (U, V) according to the variation coefficient K, as shown in the following formula:

U = KX U3⁵ + (1-Κ) X U1;

V = Kx ν3^;+ (1 -K) x Vl_o The output of the signal processing system 20 is the final chrominance signal (U, V) and the luminance signal (Y), where the luminance signal (Y) will be buffered by the delay unit 22 to match the final chrominance signal (U, V). Generation time.

In addition, the adjusted chroma signal (U3, V3) can also be directly input to the chroma mixer 25. In this case, the chrominance mixer 25 receives the fundamental frequency chrominance signal (Ul, VI) and adjusts the fundamental frequency chrominance signal (U3, V3), and generates the final chrominance signal (U, V ), as shown in the following formula:

U = KX U3 + (lK) xUl;

V = KX V3+ (1 -K) x Vl_o Image similarity can be calculated through temporal and/or spatial correlation. Figures 3a to 3d are examples of the spatial and temporal correlation of the sampled values of the composite TV signal. Here, the sampled values of the composite TV signal are based on 4 times the subcarrier frequency (that is, the sampling frequency is equal to 4 times). Sub-carrier frequency) for sampling for digitization. Figure 3a shows the waveform of the composite television signal and the corresponding composite television signal sampling values V0, VI, V2..., where the sampling frequency is equal to 4 times the sub-carrier frequency. Figure 3b shows the sampling values of the horizontal composite TV signal on three different scan lines 31-33 (the current scan line 32, the previous scan line 31, and the next scan line 33). The phase of each scan line of the composite television signal and its adjacent upper and lower scan lines have a 180-degree phase difference (out of phase).

200610002781.3 Figure 3c is used to illustrate how to determine whether the sampled value V2 of the composite TV signal on the current scan line 32 is spatially correlated. The left level difference LYD is the result of the absolute value of the difference between the average values yl and y2, where yl is the average of the sampled values V0 and V2, and y2 is the average of the sampled values VI and V3, as shown in the following formula:

LYD = absolute(yl-y2);

yl = (V0 + V2) /2;

y2= (V1+V3) /2.

If the left level difference LYD is less than a certain threshold, it means that there is a left correlation of the sampled value V2.

The horizontal difference RYD on the right is the result of taking the absolute value of the difference between the average values y3 and y2, where y3 is the average of the sampled values V2 and V4, as shown in the following formula:

RYD = absolute (y3-y2);

y3= (V2 + V4) /2.

If the right level difference RYD is less than a certain threshold, it means that there is a right correlation of the sampled value V2.

The upper horizontal difference UYD is the absolute value of the difference between the average values yu2 and y2, where yu2 is the average of the sampled values Vul and Vu3 (on the previous scan line 31), as shown in the following formula:

UYD = absolute(yu2-y2) yu2 = (Vul + Vu3) /2.

If the upper level difference UYD is less than a certain threshold, it means that there is an upper correlation of the sampled value V2.

The horizontal difference DYD below is the result of taking the absolute value of the difference between the average values yd2 and y2, where yd2 is the average of the sampled value Vdl and (on the next scan line 33), as shown in the following formula:

DYD = absolute(yd2-y2)

200610002781.3 The first yd2 = (Vdl + Vd3) /2.

If the lower level difference DYD is less than a certain threshold, it means that there is a lower correlation of the sampled value V2. If there is no left, right, top, or bottom correlation, the sampled value V2 does not have spatial correlation or the spatial correlation is not high.

Figure 3d is used to illustrate how to determine whether the sampled value V2 of the composite TV signal on the current scan line 32 is time-dependent. The sampled values VtlO~Vtl4 and the sampled values Vt20~Vt24 are respectively taken from the first two frames. And the position is the same as the sampled value V0-V4 of the current picture frame.

The time difference TD is the absolute value of the difference between the average values tyl and ty2, where tyl is the average of the sampled values V2 and Vtl2, and ty2 is the average of the sampled values Vtl2 and Vt22. If the time difference TD is less than a specific threshold, it means that there is a time correlation of the sampled value V2. If there is no temporal or spatial correlation, the signal processing system will determine that the sample value V2 needs to be cross-color suppressed, because the correlation in all dimensions is very small. The image similarity in the dimensions of the left, right, top, bottom, and time can also be counted by the inverse of the difference LYD, RYD, UYD, DYD, and TD.

FIG. 4 is a functional block diagram of an embodiment of a television 40, where the television 40 includes a signal processor 404 for suppressing cross-color. The signal processor 404 receives a composite TV signal from the receiver 402, calculates the image similarity of the composite TV signal, and separates the luminance signal (Y) and the chroma signal (C) from the composite TV signal, and then according to The image similarity is used to calculate the final chroma signal (U, V). The degree of cross-color suppression of the final chroma signal (U, V) is inversely proportional to the image similarity of the composite TV signal. The signal processor 404 in the television 40 can be actually operated by the signal processing system 10 of FIG. 1 or the signal processing system 20 of FIG. 2.

The foregoing specific embodiments are only used to illustrate the present invention, but not to limit the present invention.

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