Abstract:
An apparatus and related method for detecting film mode using motion estimation. In the method, a pixel region in each field is sequentially chosen as a target pixel region in a target field to be processed with a motion estimation operation.

Description:
BACKGROUND OF INVENTION 
   1. Field of the Invention 
   The present invention relates to a video system, and more specifically, to a film mode detector of the video system. 
   2. Description of the Prior Art 
   In conventional interlaced scanning, a frame is composed of two fields, which are an odd field, and an even field. The frame is displayed by displaying the two fields in an interlacing sequence. 
   In progressive scanning (non-interlaced scanning), an odd field and an even field are combined into one frame, and then the frame is scanned at double horizontal scan frequency in sequence, so that the quality of the image (frame) is improved. 
   Before combining two fields into one frame, it is necessary to detect the relationship between each field in the video data. This means it is necessary to detect whether the video data is film mode data, for example, the video data can be 3-2 pull down or 2-2 pull down or other. Then, the video data is appropriately de-interlaced according to result of the film mode detection. If the video data is film mode data, it is necessary to appropriately combine two adjacent fields. If the video data is not film mode data, it is necessary to perform an interpolation operation on each field to properly de-interlace each field. Please refer the methods disclosed in U.S. Pat. No. 4,982,280 and U.S. Pat. No. 6,580,463 for the prior art. 
   SUMMARY OF INVENTION 
   It is therefore one of objectives of the claimed invention to provide an apparatus and a method for detecting film mode using motion estimation. 
   According to the claimed invention, an apparatus and a method for detecting film mode are disclosed. The apparatus comprises at least one motion estimation module and a film mode detector. Each the motion estimation module comprises: a pixel motion estimator receiving a first field and a second field in the video data, and performing a motion estimation operation on a target pixel region in the first field and the second field to generate a pixel motion determining value corresponding to the target pixel region; and a field motion estimator coupled to the pixel motion estimator for generating a field motion determining value corresponding to the first field according to the pixel motion determining values. The film mode detector coupled to the at least one motion estimation module is utilized for determining the film mode of the video data according to the field motion determining value respectively corresponding to the first field. 
   These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a functional diagram according to an embodiment of the present invention. 
       FIG. 2 ,  FIG. 3 ,  FIG. 4  and  FIG. 5  are flowcharts illustrating the method according to the embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Please refer to  FIG. 1 .  FIG. 1  is a functional diagram of a film mode detection apparatus  200  according to an embodiment of the present invention. Generally speaking, video data in interlaced scanning is composed of a plurality of fields. The apparatus  200  is utilized for determining film mode of the video data by performing a motion estimation operation on fields. In an embodiment, the apparatus  200  comprises three motion estimation modules  10 ,  20  and  30 , and a film mode detector  40 . The motion estimation modules  10 ,  20  and  30  can have the same structure. The motion estimation module  10  is given as an example and is described as follows. The motion estimation module  10  comprises a pixel motion estimator  11  and field motion estimator  12 . The input end of the pixel motion estimator  11  receives two fields respectively as a first field and a second field. The pixel motion estimator  11  is utilized for dividing the first field into a plurality of target pixel regions. For each target pixel region, the pixel motion estimator  11  performs a motion estimation operation on the target pixel region in the first field and the second field to generate a pixel motion determining value D 1  corresponding to the target pixel region according to the result of the motion estimation operation. In another embodiment of the present invention, the target pixel region can only contain a pixel and can be called a “target pixel”. 
   In an embodiment, the pixel motion estimator  11  comprises a pixel motion estimating unit  13  and a first determining unit  14 . The pixel motion estimating unit  13  is utilized for performing a motion estimation operation on each target pixel in the first field to estimate a possible position of the target pixel region in the second field, and calculate the difference between the possible position and the position of the target pixel region to generate a estimating result of the motion estimation operation. The estimating result comprises motion vector MV_ 1  and a similarity value (or a difference value) S 1 . The first determining unit  14  can be a first threshold  61 . The first determining unit  14  is coupled to the pixel motion estimating unit  13  for generating the pixel motion determining value D 1  corresponding to the target pixel according to the motion vector MV_ 1 , the similarity value S 1 , and a first threshold value. The pixel motion determining value D 1  represents whether the target pixel has motion. If the motion vector MV_ 1  is 0 and the similarity value S 1  is greater than the first threshold value (or the difference value is smaller than the first threshold value), it means the target pixel (region) has no motion. When the pixel motion determining value D 1  is set to be 1, it means the target pixel has motion. 
   The field motion estimator  12  is coupled to the pixel motion estimator  11  for generating a field motion determining value D 2  corresponding to the first field according to each pixel motion determining value D 1  respectively corresponding to each target pixel in the first field. In an embodiment, the field motion estimator  12  comprises a field motion estimating unit  15  and a second determining unit  16 . The field motion estimating unit  15  comprises a counter  17  for generating a first accumulating value C 1  corresponding to the first field according to each pixel motion determining value D 1  respectively corresponding to each target pixel in the first field. The first accumulating value C 1  represents the number of target pixels in the first field that have motion. For example, if a pixel motion determining value D 1  corresponding to a target pixel in the first field is 1, the first accumulating value C 1  is increased by 1; if the pixel motion determining value D 1  is 0, it means the target pixel has no motion, hence, the first accumulating value C 1  is not changed. According to the above-mentioned description, the first accumulating value C 1  can be generated according to all target pixels in the first field. 
   The second determining unit  16  is coupled to the field motion estimating unit  15  for generating a field motion determining value D 2  according to the first accumulating value C 1  from the field motion estimating unit  15 . The second determining unit  16  can be a second threshold  62  for comparing the first accumulating value C 1  and a second threshold value to generate the field motion determining value D 2  corresponding to the first field. The field motion determining value D 2  represents whether the first field has field motion. When the field motion determining value D 2  is greater than the second threshold value, it means the first field has field motion, hence, the field motion determining value D 2  is set to be 1. Otherwise, it means the first field has no field motion, and therefore the field motion determining value D 2  is set to be 0. 
   In another embodiment, the apparatus  200  receives three adjacent fields from the video data respectively as a previous field F n−1 , a middle field F n  and a following field F n+1 . As shown in  FIG. 1 , the motion estimation module  10  receives the field F n  and the field F n−1  respectively as the first field and the second field in the previous description. The motion estimation module  10  further generates a field motion determining value D 2  according to each pixel motion determining value D 1 . In the same manner, the motion estimation module  20  receives the field F n  and the field F n+1  respectively as the first field and the second field in the previous description and generates a field motion determining value D 4  according to each pixel motion determining value D 3 . The motion estimation module  30  receives the field F n−1  and the field F n+1  respectively as the first field and the second field in the previous description and generates a field motion determining value D 6  according to each pixel motion determining value D 5 . 
   The film mode detector  40  is coupled to the motion estimation modules  10 ,  20  and  30  for generating a seventh determining value D 7  and an eighth determining value D 8  according to field motion determining values (D 2 , D 4 , D 6 ). The seventh determining value D 7  represents whether the field F n  of video data is film mode data (eg: a 3-2 pull down film mode or a 2-2 pull down film mode or other). The eighth determining value D 8  represents whether it is appropriate to combine the field F n  with the field F n−1  or the field F n+1 . 
   The above-mentioned description illustrates a preferred embodiment of the present invention. Additionally, in another embodiment of the present invention, it is applicable to implement the function for film mode detection with only one motion estimation module  10  and the film mode detector  40 . Meanwhile, the first field F n  and the second field F n−1  are received as input. In the present embodiment, it is applicable to determine whether the video data comprising the first field F n  is film mode data. It is also applicable to determine whether it is appropriate to combine the first field F n  and the second field F n−1 . 
     FIG. 2 ,  FIG. 3 ,  FIG. 4  and  FIG. 5  are flowcharts illustrating the method according to the present invention. The three procedures in  FIG. 2  are respectively shown in  FIG. 3 ,  FIG. 4  and  FIG. 5 . The present method comprises receiving three adjacent fields from the video data respectively as a previous field F n−1 , a middle field F n  and a following field F n+1 . As shown in  FIG. 2 , steps from step  202  to step  216 , steps from step  302  to step  316 , and steps from step  402  to step  416  are respectively utilized for implementing a motion estimation procedure. A motion estimation procedure is described as follows: 
   Step  202 : Receive the field F n  and the field F n−1  from the video data as input; 
   Step  204 : Choose a pixel (region) in the field F n  containing M 1  pixels as a target pixel (region), and N 1  is an assigned number of the target pixel (region); set N 1  to be 1; 
   Step  206 : Perform a motion estimation operation on the target pixel and the field F n−1  to estimate the possible position of the target pixel in the field F n−1 ; 
   Step  208 : For each target pixel, generate a pixel motion determining value D 1  corresponding to the target pixel. The pixel motion determining value D 1  represents whether the target pixel has motion; 
   Step  210 : Count the pixel motion determining value D 1  to produce a first accumulating value C 1 ; 
   Step  212 : Determine if N 1  is equal to M 1 ; if so, go to step  216 ; if not, go to step  214 ; 
   Step  214 : The value of N 1  is increased by 1; go to step  206 ; 
   Step  216 : Determine whether the field F n  has field motion. 
   Each step from step  302  to step  316  is respectively similar to each step from step  202  to step  216 . Step  302  is used to receive the field F n  and the field F n+1  as input. Each step from step  402  to step  416  is also respectively similar to each step from step  202  to step  216 . Step  402  is used to receive the field F n−1  and the field F n+1 . The following steps of the method are described as follows: 
   Step  218 : Determine the film mode of the video data according to the field motion determining values D 2 , D 4  and D 6 . 
   It is applicable to implement the function for film mode detection with only one motion estimation procedure, such as steps from step  202  to step  216 , and step  200 , step  218  and step  220 . Step  202  is used to receive the field F n  and the field F n−1  as input. Therefore, it is applicable to determine whether the video data comprising the field F n  is film mode data. It is also applicable to determine whether it is appropriate to combine the field F n  and the field F n−1 . 
   The present invention can more properly determine whether video data is film mode data, and further choose the appropriate de-interlacing method to process the video data properly. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.