Abstract:
The present invention relates to systems and methods for inverse telecine or video de-interlacing for picture quality improvement on set-top-box and TV products. The system comprises a film mode detector at the picture or sequence level, a global mixed video and film content detector at the region, picture, or sequence level on top of the detected film content, and a local video content detector at pixel level on top of the detected mixed video and film content. Inverse telecine processing is applied on detected film content fading in with a locally de-interlaced local video content. The invention further provides an apparatus and method for globally detecting mixed video and film content at region, picture, or sequence level. Such apparatus and method comprise a plurality of detectors for robustness and increased detection accuracy.

Description:
RELATED APPLICATIONS 
     The present application relates to co-pending U.S. patent application Ser. No. 12/978,154, filed on Dec. 23, 2010, and U.S. patent application Ser. No. 13/174,194, filed concurrently. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to an apparatus and method for inverse telecine and video de-interlacing, and, more particularly, to a cadence detection system and method that is programmable to improve picture quality of broadcasted videos with mixed video and film mode sources in TV and set-top-box (STB) products. 
     2. Relevant Background 
     Interlaced video was used for cathode ray tube (CRT) displays and is found throughout a number of broadcasting formats. Modern video displays, e.g., liquid crystal displays (LCD) and plasma displays, do not operate in interlaced mode. Therefore, de-interlacing circuitry is needed in set-top-box (STB)/TV to de-interlace video into progressive video that can be played on modern video displays. 
     Currently, there are a number of different source formats. Video formats usually display at 50 or 60 frames per second; film formats are commonly captured at 24 or 25 frames per second. Because of the difference in frame rate, telecine is applied to a film source video in order to properly display the film source video on a video display. Reverse telecine may be applied to the telecined film source video to recover a higher quality non-interlaced video to display on a compatible device, such as a modern video display. 
     Cadence detection involves finding the source format of a sequence of video fields or detects the absence of motion between frames (still pictures) and determines whether a video is originally from a video or film source that had interlacing or telecine applied. De-interlacing or inverse telecine can be appropriately applied to the video after cadence detection in order to remove the selected filtering. 
     Mixed video and film sources are commonly seen in broadcasted videos, e.g., graphics overlap over video or scrolling text on a film-source video. A global film mode detection and global switching between inverse telecine and video de-interlacing mode is suboptimal in this case as it would leave either compromised vertical resolution or unhandled feathering/comb artifacts on the part of the unremoved interlace or telecine filtering. 
     U.S. Patent Publication No. 2007/0291169, “Region-Based Cadence Detector,” discusses blocked based film/video decision and switching. A frame is segmented into a pre-set number of regions (or clusters of blocks) for cadence and phase tracking. A block level inverse telecine or video de-interlacing is applied to the mixed source video. However, region-based cadence detection suffers in picture quality and robustness due to artifacts from the switching. 
     Accordingly, there is a need in the art for increasing detection accuracy to prevent feather/comb artifacts on moving video object areas and increasing robustness of film and video mode detection to improve picture quality of mixed cadence sources. 
     SUMMARY OF THE INVENTION 
     Accordingly, the invention is directed to an apparatus and method for inverse telecine or video de-interlacing for picture quality improvement that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
     Briefly stated, the present invention involves film and video mode detections at both a global and local level. Film mode can be detected at a global level. Confidence of detection is increased by introducing a two-step check for mixed video content, one at a global level when film mode is detected and another at a local level when mixed video content is detected at a global level. Mixed video content detection methods can be further separately optimized for global and local detection. 
    
    
     
       BRIEF DESCRIPTION 
         FIG. 1  is an exemplary diagram of a video processing system and method for inverse telecine and/or video de-interlacing according to an embodiment of the invention; 
         FIG. 2  is an exemplary diagram of an embodiment of a global video checker according to an embodiment of the invention; 
         FIG. 3  is an exemplary diagram of a global video checker for cadence with repeat field according to an embodiment of the invention; 
         FIG. 4  is a diagram illustrating an example window used by a repeat field motion detector; 
         FIG. 5  is an exemplary diagram of a global video checker for cadence without repeat field unit according to an embodiment of the invention; 
         FIG. 6  is an exemplary diagram of a feathering detector according to an embodiment of the invention; 
         FIG. 7  is a diagram illustrating a processing window of a vertical frequency analyzer; 
         FIG. 8  is an exemplary diagram of a motion adaptiveness unit according to an embodiment of the invention; 
         FIG. 9  is a diagram illustrating an example neighborhood window used in a vertical frequency post-processing unit; 
         FIG. 10  is an exemplary diagram of a tail detector according to an embodiment of the invention; 
         FIG. 11  is an exemplary diagram of a global detail estimator according to an embodiment of the invention; 
         FIGS. 12(   a ) and  12 ( b ) are examples of inter-field motions and global detail levels for explanation of an embodiment of global detail estimator; 
         FIG. 13  is an exemplary diagram of a tail analysis unit according to an embodiment of the invention; and 
         FIG. 14  is a diagram illustrating example neighborhood windows used in tail post-processing. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are hereafter described in detail with reference to the accompanying figures. Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention. 
     The following description with reference to the accompanying figures is provided to assist in a comprehensive understanding of exemplary embodiments of the present invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
     The terms and words used in the following description and claims are not limited to the bibliographical meanings, but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for purposes of illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 
     The present invention involves film and video mode detections at both a global and local level. Film mode can be detected at a global level. Confidence of detection is increased by introducing a two-step check for mixed video content, one at a global level when film mode is detected and another at a local level when mixed video content is detected at a global level. Mixed video content detection methods can further be separately optimized for global and local detection. 
     Reference will now be made in detail to an embodiment of the present invention, an example of which is illustrated in the accompanying drawings. 
       FIG. 1  illustrates a video processing system and method for inverse telecine and/or video de-interlacing according to an embodiment of the invention. 
     The video processing system according to an embodiment of the invention comprises global film mode detection  10 , global video de-interlacing  20 , global video checker  30 , global inverse telecine  40 , local video detection  50 , and local fading between inverse telecine and video de-interlacing  60 . 
     Global film mode detection  10  detects film mode globally at picture or sequence level. An example of global film mode detection  10  is disclosed in U.S. patent application Ser. No. 12/978,154. Global video de-interlacing  20  is applied when no film content is detected globally by global film mode detection  10 . 
     If global film mode is detected by global film mode detection  10 , global video checker  30  detects video mode at a region, picture or sequence level. Global inverse telecine  40  is applied when there is no mixed video and film content detected. 
     If global video mode is detected by global video checker  30 , indicating that there is mixed video and film content detected, local video detection  50  detects local video mode at the pixel level. An example of local video detection  50  is [disclosed in U.S. patent application Ser. No. 13/174,194]. Pixel level local fading between inverse telecine and video de-interlacing  60  is applied based on result of local video detection  50 . 
     One of ordinary skill in the art would appreciate that by introducing a two step check for mixed video content, one at the global level when film mode is detected and the other at the local level when mixed video content is detected globally, confidence of detection is increased. Further, the two step check process could be separately optimized for global and local detection respectively. 
     The video processing system according to an embodiment of the invention is configured to receive a video signal from DVD, cable or satellite TV channel broadcasters, or internet video providers, and outputs a processed video signal for optimal display on modern flat screen panels. 
       FIG. 2  illustrates a global video checker according to an embodiment of the invention. 
     The global video checker unit receives a video input signal  100 , a cadence signal  700  from a global film mode detector in a video processing system such as global film mode detection  10  in  FIG. 1 , and outputs a video fallback mode flag  900 . The global video checker comprises a global video check for cadence with repeat field unit  200 , a global video check for cadence without repeat field unit  400 , a multiplexer  600  coupled to the global video check for cadence with/without repeat field units  200  and  400 , and a temporal control unit  800  coupled to multiplexer  600 . 
     The global video check for cadence with repeat field unit  200 , described in detail below with reference to  FIG. 3 , receives the video input signal  100  and outputs a video fallback mode flag  300  for cadences with repeat field. 
     The global video check for cadence without repeat field unit  400 , described in detail below with reference to  FIG. 5 , receives the video input signal  100  and outputs a video fallback mode flag  500  for cadences without repeat field. 
     The multiplexer  600  selects either video fallback mode flag  300  or  500  according to the type of the cadence, i.e., if the cadence is with repeat field or not, and outputs a video fallback mode flag  650  indicating the existence of mixed video and film content. The cadence signal  700  could be provided by an external global film mode detector in a video processing system such as global film mode detection  10  in  FIG. 1 . By adopting two separate methods of global video check for cadences with and without repeat field, the global video check unit could detect video mixed with various cadences; thus, the robustness of the detection could be improved. 
     In order to avoid temporal instability, the temporal control unit  800  receives the video fallback mode flags  650  from a plurality of fields, and outputs the temporally converged video fallback mode flag  900 . 
       FIG. 3  illustrates a global video check for cadence with repeat field unit according to an embodiment of the invention. 
     The global video check for cadence with repeat field unit  200  receives the video input signal  100 , and provides a video fallback mode flag  300  for cadences with repeat field. According to one embodiment, the global video checker for cadence with repeat field unit  200  comprises an inter-frame motion detector  210 , which could usually be shared with an external global film mode detector or an external de-interlacer, a repeat field motion detector  220  coupled to inter-frame motion detector  210 , a summing unit  230  coupled to repeat field motion detection  220 , and a video fallback mode decision unit  240  coupled to summing unit  230 . 
     The repeat field motion detector  220  receives a repeat field flag  250  from an external global film mode detector and a plurality of inter-frame motion values  215  in a neighborhood window, compares these inter-frame motion values with a motion threshold when the current field is a repeat field, and provides a detected repeat field motion flag for the center pixel of the neighborhood window based on the density of the motion in this local window. An example method of the repeat field motion detector  220  is illustrated with Equation 1 (a) to (d), with the neighborhood window used in this example method shown in  FIG. 4 . 
                     vfreq   k     =     {             freq     k   ,   1       -     freq     k   ,   2                 fielddiff   k     ≥   MonotoneTh             0       otherwise                   Eqn   ⁢           ⁢   1   ⁢     (   a   )                   k   =   0     ,   1   ,   2                         where                           freq     k   ,   1       =       ∑     i   =   0     3     ⁢     (         (       y     k   +   i       -     mean   k       )     ·     (       y     k   +   i   +   1       -     mean   k       )       &lt;   0                 Eqn   ⁢           ⁢   1   ⁢     (   b   )                   freq     k   ,   2       =       ∑     i   =   0     2     ⁢     (         (       y     k   +   i       -     mean   k       )     ·     (       y     k   +   i   +   2       -     mean   k       )       &lt;   0     )               Eqn   ⁢           ⁢   1   ⁢     (   c   )                   mean   k     =       (         (       y   k     +     y     k   +   2       +     y     k   +   4         )     ×   2     +       (       y     k   +   1       +     y     k   +   3         )     ×   3     +   6     )     /   12             Eqn   ⁢           ⁢   1   ⁢     (   d   )                 
The summing unit  230  receives a plurality of the detected repeat field motion  225 , accumulates them in a block, a region, or a field, and provides a repeat field motion sum  235  for the video fallback mode decision unit  240 .
 
     The video fallback mode decision unit  240  receives the summed repeat field motion  235 , compares it with a user defined threshold, and outputs a binary signal indicating if mixed video and film content exists in the targeted block, region, or field. This binary signal is the video fallback mode flag  300 . 
       FIG. 5  illustrates a global video check for cadence without repeat field unit according to an embodiment of the invention. 
     The global video check for cadence without repeat field unit  400  receives the video input signal  100 , and provides a video fallback mode flag  500  for cadences without repeat field. In one embodiment, the global video checker for cadence without repeat field  400  comprises a feathering detector  410 , a tail detector  440 , and a video fallback mode decision unit for cadences without repeat field  490  coupled to the feathering detector  410  and the tail detector  440 . 
     The feathering detector  410 , described in detail below with reference to  FIG. 6 , receives a plurality of fields of the video input signal  100 , and provides a summed feathering value  430  to the video fallback mode decision unit  490 . 
     The tail detector  440 , described in detail below with reference to  FIG. 10 , receives a plurality of fields of the video input signal  100 , and provides a summed tail value  485  to the video fallback mode decision unit  490 . 
     The video fallback mode decision for cadence without repeat field unit  490  receives the summed feathering value  430  and the summed tail value  485 , compares them with their respective user defined thresholds, and decides if mixed video and film content exist based on the result of the feathering detector  410  and/or the result of the tail detector  440 . 
       FIG. 6  illustrates a feathering detector according to an embodiment of the invention. Feathering detector  410  further comprises an optional inter-frame motion detector  210 , an optional comparator  216  coupled to optional inter-frame motion detector  210 , a field buffer  218  coupled to comparator  216 , a multiplexer  110 , a vertical frequency analysis unit  420  coupled to multiplexer  110 , a motion adaptiveness unit  422  coupled to comparator  216  and field buffer  218 , a vertical frequency post-processing unit  424  coupled to motion adaptiveness unit  422 , and a summing unit  426  coupled to vertical frequency post-processing unit  424 . 
     The inter-frame motion detector  210 , which could usually be shared with a global film mode detector or a de-interlacer in a video processing system as in  FIG. 1 , receives a previous field and a next field of the video input signal  100  at times t−1 and t+1, respectively, and provides an inter-frame motion signal  215 . 
     In one embodiment, the optional comparator  216  compares the inter-frame motion signal  215  with a pre-defined motion threshold, and provides a binary motion value  217  to the field buffer  218  for cost saving purposes. In another embodiment without comparator  216 , the field buffer  218  would have to store the inter-frame motion values at their full precision and this could lead to more hardware costs. 
     The multiplexer  110  receives the previous field and the next field of the video input signal  100 , selects one of them as the coupling field signal  120  according to the phase information  710  received from an external global film mode detector. 
     The vertical frequency analysis unit  420  receives a plurality of pixels from the current field and the coupling field of the video signal  100 , and provides the detected feathering values  421 . An example method of the vertical frequency analysis is illustrated with reference to Equation 2 (a) to (f). The used input pixel window, including the even numbered pixels from the current field and the odd numbered pixels from the coupling field, is shown in  FIG. 7 . 
     
       
         
           
             
               
                 
                   
                     vfreq 
                     k 
                   
                   = 
                   
                     { 
                     
                       
                         
                           
                             
                               freq 
                               
                                 k 
                                 , 
                                 1 
                               
                             
                             - 
                             
                               freq 
                               
                                 k 
                                 , 
                                 2 
                               
                             
                           
                         
                         
                           
                             
                               fielddiff 
                               k 
                             
                             ≥ 
                             MonotoneTh 
                           
                         
                       
                       
                         
                           0 
                         
                         
                           otherwise 
                         
                       
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     ( 
                     a 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     k 
                     = 
                     0 
                   
                   , 
                   1 
                   , 
                   2 
                 
               
               
                 
                     
                 
               
             
             
               
                 where 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     freq 
                     
                       k 
                       , 
                       1 
                     
                   
                   = 
                   
                     
                       ∑ 
                       
                         i 
                         = 
                         0 
                       
                       3 
                     
                     ⁢ 
                     
                       ( 
                       
                         
                           
                             ( 
                             
                               
                                 y 
                                 
                                   k 
                                   + 
                                   i 
                                 
                               
                               - 
                               
                                 mean 
                                 k 
                               
                             
                             ) 
                           
                           · 
                           
                             ( 
                             
                               
                                 y 
                                 
                                   k 
                                   + 
                                   i 
                                   + 
                                   1 
                                 
                               
                               - 
                               
                                 mean 
                                 k 
                               
                             
                             ) 
                           
                         
                         &lt; 
                         0 
                       
                       ) 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     ( 
                     b 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     freq 
                     
                       k 
                       , 
                       2 
                     
                   
                   = 
                   
                     
                       ∑ 
                       
                         i 
                         = 
                         0 
                       
                       2 
                     
                     ⁢ 
                     
                       ( 
                       
                         
                           
                             ( 
                             
                               
                                 y 
                                 
                                   k 
                                   + 
                                   1 
                                 
                               
                               - 
                               
                                 mean 
                                 
                                   k 
                                   ⁢ 
                                   
                                       
                                   
                                 
                               
                             
                             ) 
                           
                           · 
                           
                             ( 
                             
                               
                                 y 
                                 
                                   k 
                                   + 
                                   i 
                                   + 
                                   2 
                                 
                               
                               - 
                               
                                 mean 
                                 k 
                               
                             
                             ) 
                           
                         
                         &lt; 
                         0 
                       
                       ) 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     ( 
                     c 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     mean 
                     k 
                   
                   = 
                   
                     
                       ( 
                       
                         
                           
                             ( 
                             
                               
                                 y 
                                 k 
                               
                               + 
                               
                                 y 
                                 
                                   k 
                                   + 
                                   2 
                                 
                               
                               + 
                               
                                 y 
                                 
                                   k 
                                   + 
                                   4 
                                 
                               
                             
                             ) 
                           
                           × 
                           2 
                         
                         + 
                         
                           
                             ( 
                             
                               
                                 y 
                                 
                                   k 
                                   + 
                                   1 
                                 
                               
                               + 
                               
                                 y 
                                 
                                   k 
                                   + 
                                   3 
                                 
                               
                             
                             ) 
                           
                           × 
                           3 
                         
                         + 
                         6 
                       
                       ) 
                     
                     / 
                     12 
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     ( 
                     d 
                     ) 
                   
                 
               
             
             
               
                 and 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     fielddiff 
                     k 
                   
                   = 
                   
                     
                        
                       
                         
                           
                             ( 
                             
                               
                                 y 
                                 k 
                               
                               + 
                               
                                 y 
                                 
                                   k 
                                   + 
                                   2 
                                 
                               
                               + 
                               
                                 y 
                                 
                                   k 
                                   + 
                                   4 
                                 
                               
                             
                             ) 
                           
                           × 
                           2 
                         
                         - 
                         
                           
                             ( 
                             
                               
                                 y 
                                 
                                   k 
                                   + 
                                   1 
                                 
                               
                               + 
                               
                                 y 
                                 
                                   k 
                                   + 
                                   3 
                                 
                               
                             
                             ) 
                           
                           × 
                           3 
                         
                       
                        
                     
                     / 
                     12 
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     ( 
                     e 
                     ) 
                   
                 
               
             
             
               
                 
                   vf 
                   = 
                   
                     { 
                     
                       
                         
                           
                             max 
                             ⁡ 
                             
                               ( 
                               
                                 
                                   vfreq 
                                   0 
                                 
                                 , 
                                 
                                   vfreq 
                                   1 
                                 
                               
                               ) 
                             
                           
                         
                         
                           
                             currfield 
                             = 
                             top 
                           
                         
                       
                       
                         
                           
                             max 
                             ⁡ 
                             
                               ( 
                               
                                 
                                   vfreq 
                                   1 
                                 
                                 , 
                                 
                                   vfreq 
                                   2 
                                 
                               
                               ) 
                             
                           
                         
                         
                           
                             currfield 
                             = 
                             bottom 
                           
                         
                       
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   2 
                   ⁢ 
                   
                     ( 
                     f 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG. 8  illustrates a motion adaptiveness unit according to an embodiment of the invention. The motion adaptiveness unit  422  receives the detected feathering value  421 , the recursive inter-frame motion values  217  and  219  at times t and t−1, respectively, and provides a moving feathering signal  423 . The motion adaptiveness unit  422  further comprises a max operator  427  and a multiplexer  428  coupled to max operator  427 . The max operator  427  receives the recursive inter-frame motion values  217  and  219 , and outputs the maximum motion value  429  to the multiplexer  428 . The multiplexer  428  then outputs the detected feathering value  421  if the maximum motion value  429  is classified as motion, or else outputs ‘0’ as the moving feathering value  423 . The motion adaptiveness unit  422  improves the accuracy of the feathering detection since video pixels exhibit feathering artifacts only at moving areas. 
     The vertical frequency post-processing unit  424  in  FIG. 6  receives a plurality of the moving feathering values  423  in a local neighborhood window and provides a post-processed feathering value  425 . An example method of the vertical frequency post-processing is illustrated with reference to Equation 3 (a) to (e), with the used input neighborhood window as shown in  FIG. 9 . 
     
       
         
           
             
               
                 
                   
                     vf 
                     ″ 
                   
                   = 
                   
                     { 
                     
                       
                         
                           
                             vf 
                             ′ 
                           
                         
                         
                           
                             
                               
                                 ( 
                                 
                                   
                                     vf 
                                     
                                       0 
                                       , 
                                       0 
                                     
                                     ′ 
                                   
                                   &gt; 
                                   VFTh 
                                 
                                 ) 
                               
                               &amp; 
                             
                             ⁢ 
                             
                               ( 
                               
                                 ( 
                                 
                                   
                                     ( 
                                     
                                       sum 
                                       ≥ 
                                       VFSumTh 
                                     
                                     ) 
                                   
                                   &amp; 
                                 
                               
                             
                           
                         
                       
                       
                         
                           
                               
                           
                         
                         
                           
                             
                               
                                 
                                   
                                     ( 
                                     
                                       rcnt 
                                       = 
                                       true 
                                     
                                     ) 
                                   
                                   ) 
                                 
                                 | 
                                 
                                   ( 
                                   
                                     
                                       c 
                                       0 
                                     
                                     ≥ 
                                     
                                       VFColTh 
                                       × 
                                       4 
                                     
                                   
                                   ) 
                                 
                               
                               ) 
                             
                             ) 
                           
                         
                       
                       
                         
                           0 
                         
                         
                           otherwise 
                         
                       
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                   ⁢ 
                   
                     ( 
                     a 
                     ) 
                   
                 
               
             
             
               
                 where 
               
               
                 
                     
                 
               
             
             
               
                 
                   sum 
                   = 
                   
                     
                       ∑ 
                       
                         j 
                         = 
                         
                           - 
                           2 
                         
                       
                       2 
                     
                     ⁢ 
                     
                       c 
                       j 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                   ⁢ 
                   
                     ( 
                     b 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     c 
                     j 
                   
                   = 
                   
                     
                       ∑ 
                       
                         i 
                         = 
                         
                           - 
                           2 
                         
                       
                       2 
                     
                     ⁢ 
                     
                       vf 
                       
                         i 
                         , 
                         j 
                       
                       ′ 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                   ⁢ 
                   
                     ( 
                     c 
                     ) 
                   
                 
               
             
             
               
                 and 
               
               
                 
                     
                 
               
             
             
               
                 
                   rcnt 
                   = 
                   
                     ( 
                     
                       
                         
                           
                             
                               
                                 
                                   
                                     
                                       ( 
                                       
                                         
                                           r 
                                           
                                             - 
                                             2 
                                           
                                         
                                         ≥ 
                                         VFRowTh 
                                       
                                       ) 
                                     
                                     &amp; 
                                   
                                   ⁢ 
                                   
                                       
                                   
                                   ⁢ 
                                   
                                     ( 
                                     
                                       
                                         r 
                                         
                                           - 
                                           1 
                                         
                                       
                                       ≥ 
                                       VFRowTh 
                                     
                                     ) 
                                   
                                 
                                 &amp; 
                               
                               ⁢ 
                               
                                 ( 
                                 
                                   
                                     r 
                                     0 
                                   
                                   ≥ 
                                   VFRowTh 
                                 
                                 ) 
                               
                             
                             &amp; 
                           
                           ⁢ 
                           
                               
                           
                           ⁢ 
                           
                             ( 
                             
                               
                                 r 
                                 
                                   - 
                                   1 
                                 
                               
                               ≥ 
                               VFRowTh 
                             
                             ) 
                           
                         
                         &amp; 
                       
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       
                         ( 
                         
                           
                             r 
                             2 
                           
                           ≥ 
                           VFRowTh 
                         
                         ) 
                       
                     
                     ) 
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                   ⁢ 
                   
                     ( 
                     d 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     r 
                     i 
                   
                   = 
                   
                     
                       
                         ∑ 
                         
                           j 
                           = 
                           
                             - 
                             2 
                           
                         
                         2 
                       
                       ⁢ 
                       
                         
                           ( 
                           
                             
                               vf 
                               
                                 i 
                                 , 
                                 j 
                               
                               ′ 
                             
                             &gt; 
                             VFTh 
                           
                           ) 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         i 
                       
                     
                     ∈ 
                     
                       [ 
                       
                         
                           - 
                           2 
                         
                         , 
                         2 
                       
                       ] 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   3 
                   ⁢ 
                   
                     ( 
                     e 
                     ) 
                   
                 
               
             
           
         
       
     
       FIG. 10  illustrates tail detector  440  according to an embodiment of the invention. 
     The tail detector  440  comprises an optional pre-filter  101 , an optional inter-field motion detector  103  coupled to pre-filter  101 , a global detail estimator  450  coupled to inter-field motion detector  103 , a tail analysis unit  460  coupled to global detail estimator  450 , a tail post-processing unit  481  coupled to tail analysis unit  460 , and a summing unit  483  coupled to tail post-processing unit  481 . 
     The optional pre-filter  101  is often able to be shared with a global film mode detector in a video processing system as described in  FIG. 1 , and is configured to correct the phase of the input video signal vertically based on the top/bottom parity of the field and provides a phase-corrected video signal  102 . 
     The inter-field motion detector  103  is also able to be shared with a global film mode detector in a video processing system as described in  FIG. 1 , and is configured to receive a plurality of fields of the phase-corrected video signal  102 , and provide the detected inter-field motion between consecutive fields  104  to the global detail estimator  450 . 
     The global detail estimator  450 , described in detail below with reference to  FIG. 11 , is configured to receive a plurality of the existing inter-field motion signal between consecutive fields  104 , and provides an estimation of the global detail level  459  for the tail analysis. 
     The tail analysis unit  460 , described in detail below with reference to  FIG. 13 , receives a plurality of fields of the video signal  102  and the global detail level  459  and provides a global detail adaptive tail signal  480 . Being global detail level adaptive, the tail analysis is robust to vertical details of the picture content which often affects the accuracy of the tail motion detection. In a preferred embodiment, the video signal  102  is received from an optional pre-filter  101 . 
     The tail post-processing unit  481 , described in detail below with reference to  FIG. 14 , receives the tailing motion  480 . Optionally, it also receives the feathering value  421  to aid the tailing motion detection and provides a post-processed tail motion  482 . 
     The summing unit  483  then accumulates the post-processed tail motion in a block, region, or field and outputs the summed value  485  to the video fallback mode decision for cadence without repeat field  490 . 
     Referring now to  FIG. 11 , an exemplary diagram of a global detail estimator is depicted in accordance with an embodiment. The global detail estimator  450  comprises an average operator  451 , a min operator  453  coupled to average operator  451 , and a thresholding unit  455  coupled to min operator  453 . The average operator  451  receives the existing inter-field motions  104  at times t−3 and t−1 and outputs the average of them  452 . The min operator  453  receives the average of the inter-field motion at times t−3 and t−1 and the inter-field motion at time t−2 and provides the minimum value  454  of the two, namely m12_static. Finally, the thresholding unit  455  compares the minimum value  454  with a set of thresholds such as the HighDetailTh  456  and the MidDetailTh  457  and provides the classified global detail level  459 . 
     As understood by one of ordinary skill in the art, the inter-field motions  104  of a film source exhibit high when the two fields are from different progressive frames and exhibit low when the two fields are from the same progressive frame. The calculated min value  454  (m12_static) is actually the lower value of the inter-field motions, which also represents the vertical detail level of a picture.  FIGS. 12(   a ) and ( b ) illustrate examples of inter-field motions along the time and the respective m12_static. The example in  FIG. 12  ( a ) could be from a picture with a lot of vertical details whereas the example in  FIG. 12  ( b ) could be from a picture with little vertical details, as could be told by the value of m12_static. 
       FIG. 13  is an exemplary diagram of tail analysis unit  460  according to an embodiment of the invention. The tail analysis unit  460  comprises two multiplexers  461  and  462 , two adders  465  and  466  coupled to multiplexers  461  and  462 , respectively, multiplexer  478 , a comparator and sign unit  469  coupled to adder  465  and multiplexer  478 , a sign unit  471  coupled to adder  466 , a sign comparator  473  coupled to comparator and sign unit  469  and sign unit  471 , an absolute operator  475  coupled to adder  465 , and a multiplexer  477  coupled to sign comparator  473  and absolute operator  475 . 
     The multiplexer  461  receives the video signals  102  at times t−1 and t+1, and selects one of them as the coupling field  463  of the current field at time t according to the phase information  710  from an external global film mode detector. The multiplexer  462 , in contrary to  461 , selects the other field that has not been selected by  461 , which is the field  464 . 
     The adder  465  provides the difference  467  between the field at time t and the field  463 . The other adder  466  provides the difference  468  between the field  464  and the field at time t. 
     The comparator and sign unit  469  compare the difference  467  with a threshold IntraFrameMotTh  479  and decide the sign  470 , where the threshold  479  is selected by the multiplexer  478  from a set of thresholds based on the global detail level  459 . The sign unit  471  decides the sign of the difference  468 . 
     The sign comparator  473  compares the received signs  470  and  472  and provides output  474  indicating whether the differences  467  and  468  are of the same sign. 
     The multiplexer  477  provides the absolute value  476  of the difference  467  from the absolute operator  475  if the differences  467  and  468  are of the same sign and outputs zero when they are not. 
     One of ordinary skill in the art would appreciate that the sign comparator  473  with the comparator and sign unit  469  and the sign unit  471  is used to detect tailing motion, indicated by the same sign of the motion differences  467  and  468 . Tailing motion is especially useful to detect continuous motion in one direction and, hence, false alarms of motion, i.e. those motions in random directions, would be excluded from the detected tail  480 . 
       FIG. 14  illustrates example neighborhood windows used in the tail post-processing unit  481  of  FIG. 10 . An example method of the tail post-processing is illustrated with Equation 4 (a) to (e). One of ordinary skill in the art would appreciate that the tail post-processing method is used to detect the strength and the density of the tail motion and of the feathering value in a local neighborhood window for a re-enforced decision of tail motion. 
     
       
         
           
             
               
                 
                   
                     tail 
                     ′ 
                   
                   = 
                   
                     { 
                     
                       
                         
                           1 
                         
                         
                           
                             
                               
                                 ( 
                                 
                                   t 
                                   &gt; 
                                   0 
                                 
                                 ) 
                               
                               &amp; 
                             
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             
                               ( 
                               
                                 v 
                                 &gt; 
                                 0 
                               
                               ) 
                             
                           
                         
                       
                       
                         
                           0 
                         
                         
                           otherwise 
                         
                       
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     ( 
                     a 
                     ) 
                   
                 
               
             
             
               
                 where 
               
               
                 
                     
                 
               
             
             
               
                 
                   t 
                   = 
                   
                     
                       
                         
                           
                             ( 
                             
                               
                                 tail 
                                 
                                   i 
                                   , 
                                   j 
                                 
                               
                               &gt; 
                               0 
                             
                             ) 
                           
                           &amp; 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         
                           ( 
                           
                             
                               
                                 ∑ 
                                 
                                   i 
                                   = 
                                   
                                     - 
                                     2 
                                   
                                 
                                 2 
                               
                               ⁢ 
                               
                                 r 
                                 i 
                               
                             
                             ≥ 
                             TailCntTh 
                           
                           ) 
                         
                       
                       &amp; 
                     
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       ( 
                       
                         
                           
                             ∑ 
                             
                               i 
                               = 
                               
                                 - 
                                 2 
                               
                             
                             2 
                           
                           ⁢ 
                           
                             ( 
                             
                               
                                 r 
                                 i 
                               
                               &gt; 
                               0 
                             
                             ) 
                           
                         
                         ≥ 
                         TailCntInRowTh 
                       
                       ) 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     ( 
                     b 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     r 
                     i 
                   
                   = 
                   
                     
                       
                         ∑ 
                         
                           j 
                           = 
                           
                             - 
                             2 
                           
                         
                         2 
                       
                       ⁢ 
                       
                         
                           ( 
                           
                             
                               tail 
                               
                                 i 
                                 , 
                                 j 
                               
                             
                             &gt; 
                             0 
                           
                           ) 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         i 
                       
                     
                     ∈ 
                     
                       [ 
                       
                         
                           - 
                           2 
                         
                         , 
                         2 
                       
                       ] 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     ( 
                     c 
                     ) 
                   
                 
               
             
             
               
                 and 
               
               
                 
                     
                 
               
             
             
               
                 
                   v 
                   = 
                   
                     
                       
                         ( 
                         
                           
                             
                               ∑ 
                               
                                 i 
                                 = 
                                 
                                   - 
                                   2 
                                 
                               
                               2 
                             
                             ⁢ 
                             
                               s 
                               i 
                             
                           
                           ≥ 
                           TailVFCntTh 
                         
                         ) 
                       
                       &amp; 
                     
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     
                       ( 
                       
                         
                           
                             ∑ 
                             
                               i 
                               = 
                               
                                 - 
                                 2 
                               
                             
                             2 
                           
                           ⁢ 
                           
                             ( 
                             
                               
                                 s 
                                 i 
                               
                               &gt; 
                               0 
                             
                             ) 
                           
                         
                         ≥ 
                         TailVFCntInRowTh 
                       
                       ) 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     ( 
                     d 
                     ) 
                   
                 
               
             
             
               
                 
                   
                     s 
                     i 
                   
                   = 
                   
                     
                       
                         ∑ 
                         
                           j 
                           = 
                           
                             - 
                             2 
                           
                         
                         2 
                       
                       ⁢ 
                       
                         
                           ( 
                           
                             
                               vf 
                               
                                 i 
                                 , 
                                 j 
                               
                             
                             &gt; 
                             TailVFTh 
                           
                           ) 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         i 
                       
                     
                     ∈ 
                     
                       
                         [ 
                         
                           
                             - 
                             2 
                           
                           , 
                           2 
                         
                         ] 
                       
                       . 
                     
                   
                 
               
               
                 
                   Eqn 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   4 
                   ⁢ 
                   
                     ( 
                     e 
                     ) 
                   
                 
               
             
           
         
       
     
     Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the spirit and scope of the invention, as hereinafter claimed.