Abstract:
A system and method for improving decisions for 2D combing of a video. A 2D-comb is applied to a baseband video signal, thus producing a chroma component of the signal, and an associated combing error. A narrowband filter is applied to the chroma component to produce a filtered chroma component. The chroma component and the filtered chroma component are blended in proportions based on the amount of combing error to produce a new chroma component. A larger combing error induces selection or blending a larger portion of the filtered chroma component, which as a result of narrowband filtering contains less cross-chroma error. Subtracting the new chroma component from the baseband video signal produces a new luma component. The chroma component can also be filtered using a wider band filter to produce a non-complementary chroma component to be subtracted from the baseband video signal to produce the new luma component.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE 
       [0001]    [Not Applicable] 
       FIELD OF THE INVENTION 
       [0002]    Certain embodiments of the invention relate to processing of video signals. More specifically, certain embodiments of the invention relate to a method and system for improving video combing decisions. 
       BACKGROUND OF THE INVENTION 
       [0003]    A composite video signal is the sum of a luminance (brightness) signal and a chrominance (color) signal. These signals may be referred to as luma and chroma signals, respectively. The frequency ranges of the luma and chroma signals are designed to overlap. In video processing, the luma and chroma signal components are added together in order to generate a composite video signal. The luma and chroma video elements are integrated and broadcasted as a single composite video stream. Once the broadcasted composite signal is received, the luma and chroma signal components must be separated in order for the video signal to be processed and displayed. A comb filter may be utilized for separating the chroma and luma video signal components. For example, a television may be adapted to receive a composite video input and utilize an integrated comb filter to separate the chroma and luma video signal components. However, before the television can display the received video signal, the chroma and luma video components have to be separated. 
         [0004]    Several combing techniques exist, including spatial or 2D techniques and temporal or 3D techniques. In conventional video processing, there are three ways to separate the luma and chroma video components and these include combing horizontally, combing vertically, and combing temporally. During separation of the luma and chroma components, there are three bandwidth directions that may incur losses in the separation process and in the separated signal. Depending on the combing method that is utilized, the separated signal may have reduced vertical bandwidth, horizontal bandwidth, and/or temporal bandwidth 
         [0005]    The first way to separate the luma and chroma video components is by horizontal combing. Horizontal combing may be accomplished by utilizing a notch filter, for example. Since the chroma signal component in a composite video signal may be modulated at 3.58 MHz, a notch filter set at 3.58 MHz may be utilized. Combing vertically may also be utilized to separate the luma and chroma video components. Combing vertically may be achieved in three different ways—the current line may be combed with the previous and the next line, the current line may be combed with the line just before it, or the current line may be combed with the line just after it. The vertical combing is performed spatially, which involves combing only within one field at a time and without any temporal combing. 
         [0006]    During combing in a current frame, for example, if the current line is added to the previous line, the chroma content may cancel out and two times the luma content may be obtained. On the other hand, if the previous line is subtracted from the current line, the luma content may cancel out and two times the chroma content may be obtained. In this way, luma and chroma content may be separated from the composite video signal for further processing. However, vertical combing may result in a reduced vertical bandwidth. 
         [0007]    Another way to comb a composite signal is to comb temporally. Combing temporally comprises combing between two adjacent frames, for example, the current frame and the previous frame. Further, temporal combing may be characterized by a reduced temporal bandwidth. Luma and chroma content may be separated by utilizing the same addition and subtraction method between a current line and a previous line as it was utilized with vertical combing. 
         [0008]    The problem with using one combing technique over another is that while one technique may work well in certain portions of a video sequence or a video image, it may not work as well with other portions. As a result, using “the best” combing technique may result in high error rates. 
         [0009]    Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    A system and/or method is provided for improving video combing decisions, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims. 
         [0011]    These and other advantages, aspects and novel features of the present invention, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings. 
     
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
         [0012]      FIG. 1  is a diagram illustrating generation of a conventional composite video signal, in accordance with an embodiment of the present invention. 
           [0013]      FIG. 2  is a diagram illustrating modulated chroma signals in contiguous composite video frames, in accordance with an embodiment of the present invention. 
           [0014]      FIG. 3  is a diagram illustrating combing of a correlated current line and a previous line in a current frame, in accordance with an embodiment of the present invention. 
           [0015]      FIG. 4  is a diagram illustrating combing of a non-correlated current line and a previous line in a current frame, in accordance with an embodiment of the present invention. 
           [0016]      FIG. 5  is a diagram illustrating an exemplary video processing system implementing complimentary 2D combing, in accordance with an embodiment of the present invention. 
           [0017]      FIG. 6  is a flow diagram illustrating an exemplary method of implementing complimentary 2D combing, in accordance with an embodiment of the present invention. 
           [0018]      FIG. 7  is a diagram illustrating an exemplary video processing system implementing non-complimentary 2D combing, in accordance with an embodiment of the present invention. 
           [0019]      FIG. 8  is a flow diagram illustrating an exemplary method of implementing non-complimentary 2D combing, in accordance with an embodiment of the present invention. 
           [0020]      FIG. 9  is a diagram illustrating an exemplary video processing system implementing optimized non-complimentary 2D combing, in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    Certain embodiments of the invention may be found in a method and system for improving video combing decisions. 
         [0022]      FIG. 1  is a diagram illustrating generation of a conventional composite video signal, in accordance with an embodiment of the present invention. Referring to  FIG. 1 , a conventional composite video signal  105  is generated from a luma component  103  and a chroma component  101 . The composite video signal  105  is generated by adding the chroma video signal component  101  and the luma video signal component  103 . The chroma signal component  101  may be modulated at 3.58 megahertz and it may or may not comprise a constant chroma across the entire line. The luma signal component  103  may increase in amplitude in a stair step fashion or it may not. 
         [0023]      FIG. 2  is a diagram illustrating modulated chroma signals in contiguous composite video frames, in accordance with an embodiment of the present invention. The chroma component may be modulated so that a frequency of each successive line of video may be phase-shifted by  180  degrees with respect to the previous line. Referring to  FIG. 2 , the previous frame  201  may comprise a previous line  203 , a current line  205 , and a next line  207 . Similarly, the current frame  209  may comprise a previous line  211 , a current line  213 , and a next line  215 . The current line  213  in the current frame  209  may be phase-shifted by  180  degrees from the previous line  211  in the current frame  209 , as well as from the next line  215  in the current frame  209 . Similarly, the current line  205  in the previous frame  201  may be phase-shifted by  180  degrees from the previous line  203  in the previous frame  201 , as well as from the next line  207  in the previous frame  201 . In addition, since frames in the contiguous composite video signal are at a frequency rate of 59.94 Hz, there may be a 180-degree phase shift between two adjacent frames, for example, the current frame  209  and the previous frame  201 . Correspondingly, the current line  213  in the current frame may be  180  degrees phase-shifted from the current line  205  in the previous frame  201 . 
         [0024]      FIG. 3  is a diagram illustrating combing of a correlated current line and a previous line in a current frame, in accordance with an embodiment of the present invention. In this case, there is no vertical bandwidth and the previous line  222  and the current line  224  are perfectly correlated. The current line  224  may be added with the previous line  222  and two times luma may be obtained. Similarly, the previous line  222  may be subtracted from the current line  224  so that two times chroma may be obtained. 
         [0025]      FIG. 4  is a diagram illustrating combing of a non-correlated current line and a previous line in a current frame, in accordance with an embodiment of the present invention. In this case, there may be significant vertical bandwidth. The vertical bandwidth may be high enough so that there may be no correlation between the current line  234  and the previous line  232 . When the current line  234  and the previous line  232  are combed together, there may be significant error in both the luma and chroma. This may produce combing artifacts in the obtained combed video signal. A substantially the same result may be obtained when combing temporally when there is temporal bandwidth, which indicates motion. Higher bandwidth in a given direction may cause combing in that direction to result in more incorrectly separated luma and chroma. 
         [0026]      FIG. 5  is a diagram illustrating an exemplary video processing system implementing complimentary 2D combing, in accordance with an embodiment of the present invention. Referring to  FIG. 5 , a video processing system  500  may comprise a 2D comb  503 , a narrowband filter  509 , and a multiplexer  515 . A baseband composite input video signal  501  may be communicated to the 2D comb  503 . The 2D comb  503  may generate output signals  507  and  505 . The signal  507  may be the 2D chroma component of the baseband composite video signal  501 . The signal  505  may be the combing error. As a result of filtering, the 2D comb  503  may remove some of the energy of the chroma signal that may be caused by cross-chroma errors and luma. The narrowband filter  509  may filter the 2D chroma component  507 , which may result in removing more energy, and removing large cross-chroma errors from the 2D chroma component. 
         [0027]    The multiplexer  515  may multiplex the output of the narrowband filter  509  and the 2D chroma component  507 . The control signal for the multiplexer  515  may be the combing error signal  505 , which was generated by the 2D comb  503 . Based on the amount of combing error, the multiplexer  515  may select one of the two signals, either the 2D chroma component  507  or the filtered 2D chroma component. The selected chroma is output as the new chroma signal  511  for display. The new chroma signal  511  may be also subtracted from the baseband composite video signal  501 , which may result in the new luma signal  513 . The new chroma signal  511  and the new luma signal  513  may be displayed together. 
         [0028]    The 2D comb  503  may be a conventional 2D comb, which may make a decision regarding the appropriate combing based on the content of the baseband composite input video signal  501 . The decision may be based on a calculation of an error value, which may indicate how appropriate vertical combing may be for a current image. This variable may evaluate combing of a plurality of combinations of the top, current, and bottom lines to find the output with the smallest amplitude. If there is a lot of luma energy in the chroma frequency band, the error value may exceed a certain threshold and as a result, it may be determined that vertical combing may not be selected, and instead perform horizontal combing. 
         [0029]    Another variable associated with the image and used in the determination of whether to perform horizontal or vertical combing may indicate a measure of parasitic luma generated due to improper vertical combing applied in images with gradual vertical chroma amplitude variation. When the value of this variable exceeds a certain threshold, and the parasitic amplitude modulation becomes visible, vertical combing may not be selected. 
         [0030]    The video processing system  500 , therefore, may allow choosing between vertical combing and horizontal combing within the 2D comb  503 , and additionally, the choice of further narrowband horizontal filtering by the narrowband filter  509 . The two signals produced by the system  500 , the new chroma signal  511  and the new luma signal  513  may be complimentary, since the new chroma signal  511  is subtracted from the input baseband composite video signal  501  to produce the complimentary new luma signal  513 . Placing the narrowband filter  509  after the 2D comb  503  may allow both filters to remove more energy from the chroma signal  507 . Removing more energy from the chroma signal may result in leaving more energy in the luma signal. 
         [0031]      FIG. 6  is a flow diagram illustrating an exemplary method of implementing complimentary 2D combing, in accordance with an embodiment of the present invention. Referring to  FIG. 5  and  FIG. 6 , at  601  a baseband composite video signal  501  may be input into a video processing system  500 . The baseband composite video signal  501  may comprise video data, which may include chroma and luma components. The baseband composite video signal  501  may then be processed by applying a 2D comb  503  at  603 . The output of the 2D comb  503  may comprise the chroma of the input signal and a combing error value associated with the processed video image. The chroma signal output by the 2D comb  503  may have some of the cross-chroma energy and luma energy removed as a result of filtering, hence enhancing the chroma. At  605 , a narrowband filter  509  may filter the chroma value output by the 2D comb  503 , and as a result output a twice-filtered chroma signal, where the twice-filtered chroma signal may have less cross-chroma energy and luma energy than the chroma output by the 2D comb  503 . The chroma signal output by the 2D comb  503  and the twice-filtered chroma signal output by the narrowband filter  509  may then be multiplexed to select one of the two chroma signals at  607 . The combing error value output by the 2D comb  503  may be used as a control signal in multiplexing the two chroma signals. If the error value is not too large, indicating that the chroma signal output by the 2D comb  503  had most of the cross-chroma and luma energy removed, then there may be no need to utilize the twice-filtered chroma signal. If the error value is too large, then the twice-filtered chroma signal may be selected instead. At  609 , the selected chroma signal may be used to determine the new luma value by subtracting the selected chroma signal from the input broadband composite video signal  501 . 
         [0032]      FIG. 7  is a diagram illustrating an exemplary video processing system implementing non-complimentary 2D combing, in accordance with an embodiment of the present invention. Referring to  FIG. 7 , an exemplary video processing system  700  may comprise a 2D comb  703 , filters  709  and  719 , and blenders  715  and  725 . A baseband composite input video signal  701  may be communicated to the 2D comb  703 . The 2D comb  703  may generate output signals, a first signal  707  and a second signal  705 . The first signal  707  may be the 2D chroma component of the baseband composite video signal  701 . The second signal  705  may be the combing error. As a result of filtering, the 2D comb  703  may remove some of the energy of the chroma signal that may be caused by cross-chroma errors and luma. 
         [0033]    The first filter  709  may be a narrowband filter and may filter the 2D chroma component  707 , which may result in removal of more energy, and removal of large cross-chroma errors from the 2D chroma component  707 . The blender  715  may then blend the outputs of the first filter  709  and the 2D chroma component  707 . The control signal for the blender  715  may be the combing error signal  705 , which was generated by the 2D comb  703 . Based on the amount of combing error, the blender  715  may then select one of the two signals, either the 2D chroma component  707  or the filtered 2D chroma component  707 , or blend portions of the two signals, where the amount contributed by each signal may depend on the amount of combing error. The resulting chroma may then be a first new chroma output signal  711 . 
         [0034]    The second filter  719  may be a filter with a wider band than the first filter  709 , and may filter the 2D chroma component  707 , which may result in removal of some energy, and some cross-chroma errors from the 2D chroma component  707 . The multiplexer  725  may then multiplex the output of the second filter  719  and the 2D chroma component  707 . The control signal for the multiplexer  715  may be the combing error signal  705 , which was output by the 2D comb  703 . Based on the amount of combing error, the blender  725  may then select one of the two signals, either the 2D chroma component  707  or the filtered 2D chroma component  707 , or blend portions of the two signals, where the amount contributed by each signal may depend on the amount of combing error. The resulting chroma may be a second new chroma output signal  721 . 
         [0035]    The second new chroma output signal  721  may be subtracted from the baseband composite video signal  701 , which may result in a new luma signal  713 . The first new chroma output signal  711  and the new luma signal  713  may then be displayed together. Since the new luma signal  713  is the result of subtracting the second new chroma output signal  721 , but is combined with the first new chroma output signal  711 , the new luma signal  713  and the first new chroma output signal  711  do not compliment each other, but combining them may yield less error in the image displayed than if the complimentary signals are combined. 
         [0036]    In an embodiment of the present invention, in regions of large combing error, i.e., where the error signal  705  is large, the filtered signal may be selected by the blenders  715  and  725 , where the output signals have more energy removed from them. The first filter  709  may remove a large amount of energy from the chroma signal, and the second filter  719 , may take less energy out of the chroma channel, and as a result, when subtracted from the baseband composite video signal  701 , remove a large amount of energy from the luma signal. The two resulting signals, the new chroma signal  711  and the new luma signal  713  may be non-complimentary as a result. However, in regions with small combing error, i.e., where the error signal  705  is small, the signals from the first filter  709  and the second filter  719  may not be selected by the blenders  715  and  725  and as a result, the two resulting signals, the new chroma signal  711  and the new luma signal  713  may be complimentary signals. 
         [0037]    The 2D comb  703  may be a conventional 2D comb, which may make a decision regarding the appropriate combing based on the content of the baseband composite input video signal  701 . The decision may be based on a calculation of an error value, which may indicate how appropriate vertical combing may be for a current image. This error value may be used to evaluate combing of a plurality of combinations between the top, current, and bottom lines to find the output with the smallest amplitude. If there is a lot of luma energy or the amount of luma energy is greater than a specified value in the chroma frequency band, the error value may exceed a certain threshold. As a result, it may be determined that vertical combing may not be selected, and instead perform horizontal combing. 
         [0038]      FIG. 8  is a flow diagram illustrating an exemplary method of implementing non-complimentary 2D combing, in accordance with an embodiment of the present invention. Referring to  FIG. 7  and  FIG. 8 , at  801  a baseband composite video signal  701  may be input into a video processing system  700 . The baseband composite video signal  701  may comprise video data, which may include chroma and luma components. The baseband composite video signal  701  may then be processed by applying a 2D comb  703  at  803 . The output generated from the 2D comb  703  may comprise the chroma of the input signal and a combing error value associated with the processed video image. The chroma signal output by the 2D comb  703  may have some of the cross-chroma energy and luma energy removed as a result of filtering, therefore enhancing the chroma. 
         [0039]    At  805 , a narrowband filter  709  may filter the chroma value output by the 2D comb  703 . As a result, a twice-filtered chroma signal may be generated, where the twice-filtered chroma signal may have less cross-chroma energy and luma energy than the chroma signal generated by the 2D comb  703 . The chroma signal generated by the 2D comb  703  and the twice-filtered chroma signal generated by the narrowband filter  709  may then be blended to generate a new chroma signal at  807 . The combing error value output by the 2D comb  703  may be used as a control signal in blending the two chroma signals. If the error value is not too large or not greater than a specified value, this may indicate that the chroma signal output by the 2D comb  703  had most of the cross-chroma and luma energy removed. As a result, there may be no need to utilize the twice-filtered chroma signal or a smaller portion thereof may be blended. If the error value is too large or greater than a specified value, then the twice-filtered chroma signal may be selected instead, or a larger portion thereof may be used in the blending. 
         [0040]    At  809 , a second filter  719  with a wider band than the first filter  709  may filter the chroma value output by the 2D comb  703 . As a result, a twice-filtered chroma signal may be generated, where the twice-filtered chroma signal may have less cross-chroma energy and luma energy than the chroma output by the 2D comb  703 . However, the amount of energy removed by the second filter  719  may be less than the amount of energy removed by the first filter  709 . The chroma signal output by the 2D comb  703  and the twice-filtered chroma signal output by the second filter  719  may then be blended to generate a new chroma signal at  811 . The combing error value output by the 2D comb  703  may be used as a control signal in blending the two chroma signals. If the error value is not too large or less than a specified value, this may indicate that the chroma signal output by the 2D comb  703  had most of the cross-chroma and luma energy removed. As a result, there may be no need to utilize the twice-filtered chroma signal or a smaller portion thereof may be blended. If the error value is too large or greater than a specified value, then the twice-filtered chroma signal may be selected instead, or a larger portion thereof may be used in the blending. At  813 , the chroma signal selected at  811  may be used to determine the new luma value by subtracting the selected chroma signal from the input broadband composite video signal  701 . The new luma value and the new chroma value may be combined for display. When the error value is large or greater than a specified value, the new chroma value and the new luma value may be non-complimentary. However, in regions with less combing error, the new luma value and the new chroma value may be complimentary. 
         [0041]      FIG. 9  is a diagram illustrating an exemplary video processing system implementing optimized non-complimentary 2D combing, in accordance with an embodiment of the present invention. Referring to  FIG. 9 , a video processing system  900  may comprise a 2D comb  903 , two filters  909  and  919 , blenders  915  and  925 , amplitude-measuring block  927 , and luma return block  917 . A baseband composite input video signal  901  may be provided as an input to the 2D comb  903 . The 2D comb  903  may then output two signals, a first signal  907  and a second signal  905 . The first signal  907  may be the 2D chroma component of the baseband composite video signal  901 . The second signal  905  may be the combing error. As a result of filtering, the 2D comb  903  may remove some of the energy of the chroma signal that may be caused by cross-chroma errors and luma. 
         [0042]    The first filter  909  may be a narrowband filter and may filter the 2D chroma component  907 , which may result in removing more energy, and removing large cross-chroma errors from the 2D chroma component  907 . The blender  915  may then blend the output of the first filter  909  and the 2D chroma component  907 . The control signal for the blender  915  may be the combing error signal  905 , which was generated by the 2D comb  903 . Based on the amount of combing error, the blender  915  may then select one of the two signals, either the 2D chroma component  907  or the twice-filtered 2D chroma component, or blend portions of the two signals, where the amount contributed by each signal may depend on the amount of combing error. When the combing error  905  is large or greater than a specified value, the twice-filtered 2D chroma component may be selected or a larger portion thereof may be selected for blending. When the coming error  905  is small or less than a specified value, the 2D chroma component  907  may be selected or a larger portion thereof may be selected for blending. The resulting chroma is then generated as a first new chroma signal  911 . 
         [0043]    The first new chroma signal  911  may then be provided as an input into the amplitude-measuring block  927 . The amplitude of the first new chroma signal  911  may be output as the narrowband amplitude signal  931 . 
         [0044]    The second filter  919  may be a filter with a wider band than the first filter  909 , and may filter the 2D chroma component  907 , which may result in removal of some energy, and some cross-chroma errors from the 2D chroma component  907 . However, the wider band filter may remove less energy than the narrowband filter. The blender  925  may then multiplex the output of the second filter  919  and the 2D chroma component  907 . The control signal for the blender  925  may be the combing error signal  905 , which was output by the 2D comb  903 . Based on the amount of combing error, the blender  925  may then select one of the two signals, either the 2D chroma component  907  or the twice-filtered 2D chroma component, or blend portions of the two signals, where the amount contributed by each signal may depend on the amount of combing error. When the combing error  905  is large or greater than a specified value, the twice-filtered 2D chroma component may be selected or a larger portion thereof may be selected for blending. When the combing error  905  is small or less than a specified value, the 2D chroma component  907  may be selected or a larger portion thereof may be selected for blending. The resulting chroma may be generated as a second new chroma signal  921 . 
         [0045]    The narrowband amplitude signal  931 , the second new chroma signal  921 , and the 2D chroma component  907  may then be input to the luma return block  917 . One rationale for adding the luma return is that if the first new chroma signal  911  is very small or less than a specified value, this may indicate that the associated region in the video may contain little chroma, and therefore more energy that was removed by the filters may be returned to the luma channel. On the other hand, if the first new chroma signal  911  is very large or greater than a specified value, that may indicate that the associated region in the video may contain a lot of chroma, and therefore the energy removed by the filters may need not be returned to the luma channel. This may be done according to the following equations: 
         [0000]      Delta=second new chroma signal (921)−2D chroma component signal (907) 
         [0000]      If (Delta&gt;0) {Delta=MAX(0, Delta−narrowband amplitude signal (931))} 
         [0000]      If (Delta&lt;0) {Delta=MIN(0, Delta+narrowband amplitude signal (931))} 
         [0000]      New adjusted chroma signal (923)=2D chroma component (907)+Delta 
         [0000]      New luma signal (913)=baseband composite video signal (901)−New adjusted chroma signal (923) 
         [0046]    The first new chroma signal  911  and the new luma signal  913  may then be displayed together. 
         [0047]    The 2D comb  903  may be a conventional 2D comb, which may make a decision regarding the appropriate combing based on the content of the baseband composite input video signal  901 . The decision may be based on a calculation of an error value, which may indicate how appropriate vertical combing may be for a current image. The error value may be utilized to evaluate combing of a plurality of possible combinations between the top, current, and bottom lines to find the output with the smallest amplitude. If there is a lot of luma energy in the chroma frequency band or the luma energy is greater than a specified value, the error value may exceed a certain threshold and as a result it may be determined that vertical combing may not be selected, and instead perform horizontal combing. 
         [0048]      FIG. 10  is a flow diagram illustrating an exemplary method of implementing optimized non-complimentary 2D combing, in accordance with an embodiment of the present invention. Referring to  FIG. 9  and  FIG. 10 , at  1001  a baseband composite video signal  901  may be input into a video processing system  900 . The baseband composite video signal  901  may comprise video data, which may include chroma and luma components. The baseband composite video signal  901  may then be processed by applying a 2D comb  903  at  1003 . The output of the 2D comb  903  may comprise the chroma of the input signal and a combing error value associated with the processed video image. The chroma signal output by the 2D comb  903  may have some of the cross-chroma energy and luma energy removed as a result of filtering, hence enhancing the chroma. At  1005 , a narrowband filter  909  may filter the chroma value output by the 2D comb  903 , and as a result generate a twice-filtered chroma signal, where the twice-filtered chroma signal may have less cross-chroma energy and luma energy than the chroma output by the 2D comb  903 . The chroma signal output by the 2D comb  903  and the twice-filtered chroma signal output by the narrowband filter  909  may then be blended to generate a new chroma signal at  1007 . The combing error value output by the 2D comb  903  may be used as a control signal in blending the two chroma signals. If the error value is not too large or less than a specified value, that may indicate that the chroma signal output by the 2D comb  903  had most of the cross-chroma and luma energy removed, then there may be no need to utilize the twice-filtered chroma signal or a smaller portion thereof may be blended. If the error value is too large or greater than a specified value, then the twice-filtered chroma signal may be selected instead or a larger portion thereof may be blended. 
         [0049]    At  1009 , a second filter  919  with a wider band than the first filter  909  may filter the chroma value output by the 2D comb  903 , and as a result output a twice-filtered chroma signal, where the twice-filtered chroma signal may have less cross-chroma energy and luma energy than the chroma output by the 2D comb  903 , but the amount of energy removed by the second filter  919  may be less than the amount of energy removed by the first filter  909 . The chroma signal output by the 2D comb  903  and the twice-filtered chroma signal output by the second filter  919  may then be blended to generate a new chroma signal at  1011 . The combing error value output by the 2D comb  903  may be used as a control signal in blending the two chroma signals. If the error value is not too large or less than a specified value, this may indicate that the chroma signal output by the 2D comb  903  had most of the cross-chroma and luma energy removed, then there may be no need to utilize the twice-filtered chroma signal or a smaller portion thereof may be blended. If the error value is too large or greater than a specified value, then the twice-filtered chroma signal may be selected instead or a larger portion thereof may be blended. 
         [0050]    At  1013 , the amplitude of the new chroma signal  911  may be determined. Then, at  1015 , the amplitude of the new chroma signal, the second new chroma signal, and the chroma signal output by the 2D comb may be utilized to determine a luma return value. The luma return value may be used to adjust the second new chroma signal, as shown by the equations above, and at  1017 . The resulting adjust new chroma signal may be used to determine the new luma value by subtracting the adjust new chroma signal from the input broadband composite video signal  901 . The new luma value and the new chroma value may be combined for display. 
         [0051]    Accordingly, aspects of the invention may be realized in hardware, software, firmware or a combination thereof. The invention may be realized in a centralized fashion in at least one computer system or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware, software and firmware may be a general-purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. 
         [0052]    One embodiment of the present invention may be implemented as a board level product, as a single chip, application specific integrated circuit (ASIC), or with varying levels integrated on a single chip with other portions of the system as separate components. The degree of integration of the system will primarily be determined by speed and cost considerations. Because of the sophisticated nature of modern processors, it is possible to utilize a commercially available processor, which may be implemented external to an ASIC implementation of the present system. Alternatively, if the processor is available as an ASIC core or logic block, then the commercially available processor may be implemented as part of an ASIC device with various functions implemented as firmware. 
         [0053]    The present invention may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which when loaded in a computer system is able to carry out these methods. Computer program in the present context may mean, for example, any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form. However, other meanings of computer program within the understanding of those skilled in the art are also contemplated by the present invention. 
         [0054]    While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiments disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.