Abstract:
Disclosed herein is a film detection device for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection device including, a frame motion detection section, a field motion detection section, a motion judder detection section, and a film determination section.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    The present invention contains subject matter related to Japanese Patent Application JP 2007-107078 filed in the Japan Patent Office on Apr. 16, 2007, the entire contents of which being incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a film detection device and method for films having pictures recorded thereon, and to a picture signal processing device and method. 
         [0004]    2. Description of the Related Art 
         [0005]    The term “telecine process” refers to the process by which a picture recorded on a film such as movie film is converted into a television signal for broadcasting or other purposes. The telecine process normally converts the frame rate. At the same time, the telecine process splits each frame of the film into two fields because an interlaced signal is primarily used for broadcasting. 
         [0006]    The 2:2 pulldown and 3:2 pulldown techniques are popular as the telecine system. The 2:2 pulldown technique is employed when the television signal&#39;s field frequency is close to twice the film frame rate. Here, this technique provides an interlaced signal by dividing each frame of the film into two fields, one field made up of only even lines and the other made up of only odd lines of the frame. 
         [0007]    In contrast, the 3:2 pulldown technique is used when the television signal&#39;s field frequency is close to 2.5 times the film frame rate. The 3:2 pulldown technique provides an interlaced signal by dividing each frame of the film in the same manner as the 2:2 pulldown technique for the first four fields of the television signal and repeating the third field for the fifth field of the television signal. 
         [0008]    It should be noted that a pulldown technique other than the above may be employed depending on the combination of television signal&#39;s field frequency and film frame rate. 
         [0009]    On the television signal receiving side, a picture signal obtained from the telecine process (hereinafter referred to as a “telecine material”) may need to be distinguished from a picture signal captured by an ordinary television camera (hereinafter referred to as a “video material”). 
         [0010]    One example of such a case is that a television set employs different schemes to perform de-interlacing of telecine and video materials. 
         [0011]    In addition to the above, a picture recording device may detect 3:2 pulldown to remove in advance the field identical in content which appears once every five fields prior to compression and recording of a moving image. In the description given below, the detection of a pulldown picture signal such as 3:2 and 2:2 pulldown detection will be collectively referred to as “film detection.” 
         [0012]    An example of the 3:2 pulldown detection method is given in Japanese Patent No. 2870565 hereinafter referred to as Patent Document 1. The 3:2 pulldown detection relies on the fact that the field image identical in content appears every five fields as described above. 
         [0013]    A calculation of the difference between an input picture signal and a picture signal delayed by two fields from the input picture signal reveals that the difference is smaller once every five fields for a 3:2 pulldown picture signal. This is not likely to occur with a video material. As a result, 3:2 pulldown can be detected by monitoring a periodic change of the difference between the signals distant from each other by two fields. 
         [0014]    On the other hand, an example of the 2:2 pulldown detection method is given in U.S. Pat. No. 6,580,463 hereinafter referred to as Patent Document 2. The detection method in Patent Document 1 relies on the difference between the signals distant from each other by two fields. In contrast, the method in Patent Document 2 calculates the difference between an input picture signal and a picture signal delayed by one field from the input signal. 
         [0015]    With a telecine material, the difference between two field images derived from the same film frame is expected to be smaller than that between two field images derived from different film frames. In the case of a 2:2 pulldown picture signal input, therefore, the field-to-field difference alternates between large and small values every field. 
         [0016]    It should be noted that the 2:2 pulldown detection method disclosed in Patent Document 2 can also detect 3:2 pulldown with a common circuit. A calculation of the field-to-field difference for a 3:2 pulldown picture signal reveals that the field-to-field difference alternates between large and small values every field for the first four fields as with 2:2 pulldown. For the last field, the two field images derived from the same film frame are compared. As a result, the field-to-field difference is small. 
         [0017]    Thus, if the field-to-field difference changes from large to small to large to small and small values in this order at intervals of five fields, the input picture signal can be considered to be a 3:2 pulldown signal. 
         [0018]    Further, the detection method disclosed in Patent Document 2 can detect edit points in a telecine material without delay. One of the two field images derived from the same film frame may be lost near an edit point. 
         [0019]    In de-interlacing in particular, the original film frame cannot be restored by simple overlaying of fields. As a result, the detection of edit points is needed. With an ordinary telecine material, the field-to-field difference is never large for two consecutive fields. In this case, therefore, we can assume that the input picture signal has been changed to a video material by editing. 
         [0020]    Among examples of particular telecine materials is a picture signal containing telecine and video materials in the same field image (hereinafter referred to as a “hybrid material”). 
         [0021]    Japan Patent No. 3389984 (hereinafter referred to as Patent Document 3) describes a technique to choose a de-interlacing method which is as probable as possible even in such a case. Here, the picture signal for each pixel is determined to be a telecine or video material using the field-to-field difference so that a proper de-interlacing scheme is selected. 
         [0022]    That is, the local differences in pixel value are compared between the current, previous and next fields. If the difference is small only in one of the fields, de-interlacing suitable for a telecine material is performed in this area. 
       SUMMARY OF THE INVENTION 
       [0023]    The scheme described in Patent Document 1 performs detection at intervals of five fields, resulting in slow detection. In particular, if the input picture signal changes from a telecine to video material or vice versa, this change can be detected five fields later in the worst case. If film detection is used for de-interlacing, slow detection is apt to lead to degraded image quality due to erroneous de-interlacing. Moreover, this scheme is disadvantageous in that it can only detect 3:2 pulldown. 
         [0024]    On the other hand, the scheme described in Patent Document 2 is advantageous in that it can detect not only both 3:2 and 2:2 pulldown but also edit points. However, the scheme has drawbacks. That is, the scheme is slow to detect the change of the input picture signal from a video material to telecine material. The scheme is less accurate than the scheme in Patent Document 1 in detecting 3:2 pulldown. 
         [0025]    First, the reason for slow detection of the change from a video material to telecine material will be described. Even in a video material, the field-to-field difference may be different between two consecutive fields. To positively detect a telecine material, therefore, it is necessary to monitor a periodic change of the field-to-field difference over a more or less long period of time (e.g., four fields or more). 
         [0026]    Further, the detection accuracy for 3:2 pulldown is low because of the following reason. That is, the scheme described in Patent Document 1 finds the two-field difference. As a result, this scheme calculates the difference between even lines or between odd lines of the film frame. On the other, the scheme described in Patent Document 2 finds the field-to-field difference. As a result, this scheme calculates the difference between even and odd lines. If we assume that the original film frame contains a vertical high frequency component, even and odd lines of a field image derived from the same film frame do not always have exactly the same content. 
         [0027]    The scheme described in Patent Document 1 compares even or odd lines. Even in the above case, therefore, the field identical in content which appears once every five fields can be properly detected. However, even if a field appears which is identical in content to the field preceding the previous field, the scheme described in Patent Document 2 may detect a large field-to-field difference, possibly resulting in erroneous detection of 3:2 pulldown. The difference between field images derived from the same film frame is not always small. Therefore, a similar erroneous detection may occur in the detection of 2:2 pulldown. 
         [0028]    The scheme described in Patent Document 3 relies only on the local difference between field images for detection. On one hand, this provides two advantages, namely, quick response and capability to detect an arbitrary pulldown sequence which includes a hybrid material. On the other hand, the scheme has a drawback that erroneous detection is apt to occur for an image containing many vertical high frequency components. The scheme described in Patent Document 2 does not fail in film detection at least for an image locally containing many vertical high frequency components. Therefore, the scheme in Patent Document 3 is more prone to erroneous detection than that in Patent Document 2. 
         [0029]    According to embodiments of the present invention, it is provided a film detection device and method which is capable of detecting a telecine material having an arbitrary pulldown sequence using a common circuit and which is also capable of handling picture edit points and hybrid materials thanks to high detection accuracy coupled with quick response. It is also another embodiment of the present invention to provide a picture signal processing device and method using the film detection device and method. 
         [0030]    According to an embodiment of the present invention, it is provided a film detection device for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection device including: 
         [0031]    frame motion detection means for detecting, as a scalar or vector value, a frame-to-frame picture motion between previous and next fields, the previous field being a field preceding a current field, and the next field being a field succeeding the current field; 
         [0032]    field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion between the current and previous or next fields; 
         [0033]    motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and field motion detection means; and 
         [0034]    film determination means for calculating the probability that the input picture signal is an interlaced signal generated by the telecine process using at least the detection result of the motion judder detection means. 
         [0035]    According to an embodiment of the present invention, it is provided a film detection device for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection device including: 
         [0036]    frame motion detection means for detecting, as a scalar or vector value, a frame-to-frame picture motion between previous and next fields, the previous field being a field preceding a current field, and the next field being a field succeeding the current field; 
         [0037]    first field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion between the current and next fields; 
         [0038]    second field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion between the current and previous fields; 
         [0039]    first motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and first field motion detection means; 
         [0040]    second motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and second field motion detection means; and 
         [0041]    film determination means for calculating the probability that the input picture signal is an interlaced signal generated by the telecine process using at least the detection results of the first and second motion judder detection means. 
         [0042]    According to an embodiment of the present invention, it is provided a film detection device for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection device including: 
         [0043]    first delaying means adapted to delay the input picture signal by one field; 
         [0044]    second delaying means adapted to delay the input picture signal by two fields; 
         [0045]    frame motion detection means for detecting, as a scalar or vector value, a frame-to-frame picture motion using the input picture signal and an output picture signal of the second delaying means; 
         [0046]    first field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion using the input picture signal and an output picture signal of the first delaying means; 
         [0047]    second field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion using the input picture signal and the output picture signal of the second delaying means; 
         [0048]    first motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and first field motion detection means; 
         [0049]    second motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and second field motion detection means; 
         [0050]    first accumulation means for accumulating the detection result of the first motion judder detection means in the spatial direction; 
         [0051]    second accumulation means for accumulating the detection result of the second motion judder detection means in the spatial direction; 
         [0052]    first film determination means for determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a global image area using at least the accumulation results of the first and second accumulation means; and 
         [0053]    second film determination means for determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a local image area which is part of the global image area using at least the detection result of the first field motion detection means or first motion judder detection means and the detection result of the second field motion detection means or second motion judder detection means. 
         [0054]    According to an embodiment of the present invention, it is provided a film detection device for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection device including: 
         [0055]    first delaying means for delaying the input picture signal by one field; 
         [0056]    second delaying means for delaying the input picture signal by two fields; 
         [0057]    third delaying means for delaying the input picture signal by three fields; 
         [0058]    frame motion detection means for detecting, as a scalar or vector value, a frame-to-frame picture motion using output picture signals of the first and third delaying means; 
         [0059]    first field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion using the input picture signal and the output picture signal of the first delaying means; 
         [0060]    second field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion using the output picture signal of the first delaying means and an output picture signal of the second delaying means; 
         [0061]    third field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion using the output picture signals of the second and third delaying means; 
         [0062]    first motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and first field motion detection means; 
         [0063]    second motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and second field motion detection means; 
         [0064]    first accumulation means for accumulating the detection result of the first motion judder detection means in the spatial direction; 
         [0065]    second accumulation means for accumulating the detection result of the second motion judder detection means in the spatial direction; 
         [0066]    first film determination means for determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a global image area using at least the accumulation results of the first and second accumulation means; and 
         [0067]    second film determination means for determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a local image area which is part of the global image area using at least the detection results of the second and third field motion detection means. 
         [0068]    According to an embodiment of the present invention, it is provided a picture signal processing device for converting an input picture signal, which is an interlaced signal, into a progressive signal, the picture signal processing device including: 
         [0069]    frame motion detection means for detecting, as a scalar or vector value, a frame-to-frame picture motion between previous and next fields, the previous field being a field preceding a current field, and the next field being a field succeeding the current field; 
         [0070]    field motion detection means for detecting, as a scalar or vector value, a field-to-field picture motion between the current and previous or next fields; 
         [0071]    motion judder detection means for calculating the probability that there is a picture motion between frames while there is no picture motion between fields using at least the detection results of the frame motion detection means and field motion detection means; and 
         [0072]    de-interlacing means for changing methods to convert the input picture signal into a progressive signal at least according to the detection result of the motion judder detection means. 
         [0073]    According to an embodiment of the present invention, it is provided a film detection method for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection method including the steps of: 
         [0074]    detecting, as a scalar or vector value, a frame-to-frame picture motion M between previous and next fields, the previous field being a field preceding a current field, and the next field being a field succeeding the current field; 
         [0075]    detecting, as a scalar or vector value, a field-to-field picture motion m between the current and previous or next fields; 
         [0076]    calculating a probability J that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m; and 
         [0077]    calculating the probability that the input picture signal is an interlaced signal generated by the telecine process using at least the probability J. 
         [0078]    According to an embodiment of the present invention, it is provided a film detection method for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection method including the steps of: 
         [0079]    detecting, as a scalar or vector value, a frame-to-frame picture motion M between previous and next fields, the previous field being a field preceding a current field, and the next field being a field succeeding the current field; 
         [0080]    detecting, as a scalar or vector value, a field-to-field picture motion m 1  between the current and next fields; 
         [0081]    detecting, as a scalar or vector value, a field-to-field picture motion m 2  between the current and previous fields; 
         [0082]    calculating a probability J 1  that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m 1 ; 
         [0083]    calculating a probability J 2  that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m 2 ; and 
         [0084]    calculating the probability that the input picture signal is an interlaced signal generated by the telecine process using at least the probabilities J 1  and J 2 . 
         [0085]    According to an embodiment of the present invention, it is provided a film detection method for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection method including the steps of: 
         [0086]    delaying the input picture signal by one field to obtain a one-field delayed signal; 
         [0087]    delaying the input picture signal by two fields to obtain a two-field delayed signal; 
         [0088]    detecting, as a scalar or vector value, a frame-to-frame picture motion M using the input picture signal and two-field delayed signal; 
         [0089]    detecting, as a scalar or vector value, a field-to-field picture motion m 1  using the input picture signal and one-field delayed signal; 
         [0090]    detecting, as a scalar or vector value, a field-to-field picture motion m 2  using the one-field and two-field delayed signals; 
         [0091]    calculating a probability j 1  that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m 1 ; 
         [0092]    calculating a probability j 2  that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m 2 ; 
         [0093]    accumulating the probability j 1  in the spatial direction to obtain an accumulated sum J 1 ; 
         [0094]    accumulating the probability j 2  in the spatial direction to obtain an accumulated sum J 2 ; 
         [0095]    determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a global image area using at least the accumulated sums J 1  and J 2 ; and 
         [0096]    determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a local image area which is part of the global image area using at least the field-to-field picture motion m 1  or probability j 1  and the field-to-field picture motion m 2  or probability j 2 . 
         [0097]    According to an embodiment of the present invention, it is provided a film detection method for determining whether an input picture signal is an interlaced signal generated by the telecine process, the film detection method including the steps of: 
         [0098]    delaying the input picture signal by one field to obtain a one-field delayed signal; 
         [0099]    delaying the input picture signal by two fields to obtain a two-field delayed signal; 
         [0100]    delaying the input picture signal by three fields to obtain a three-field delayed signal; 
         [0101]    detecting, as a scalar or vector value, a frame-to-frame picture motion M using the one-field and three-field delayed signals; 
         [0102]    detecting, as a scalar or vector value, a field-to-field picture motion m 1  using the input picture signal and one-field delayed signal; 
         [0103]    detecting, as a scalar or vector value, a field-to-field picture motion m 2  using the one-field and two-field delayed signals; 
         [0104]    detecting, as a scalar or vector value, a field-to-field picture motion m 3  using the two-field and three-field delayed signals; 
         [0105]    calculating a probability j 1  that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m 1 ; 
         [0106]    calculating a probability j 2  that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m 2 ; 
         [0107]    accumulating the probability j 1  in the spatial direction to obtain an accumulated sum J 1 ; 
         [0108]    accumulating the probability j 2  in the spatial direction to obtain an accumulated sum J 2 ; 
         [0109]    determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a global image area using at least the accumulated sums J 1  and J 2 ; and 
         [0110]    determining the probability that the input picture signal is an interlaced signal generated by the telecine process for a local image area which is part of the global image area using at least the field-to-field picture motions m 2  and m 3 . 
         [0111]    According to an embodiment of the present invention, it is provided a picture signal processing method for converting an input picture signal, which is an interlaced signal, into a progressive signal, the picture signal processing method including the steps of: 
         [0112]    detecting, as a scalar or vector value, a frame-to-frame picture motion M between previous and next fields, the previous field being a field preceding a current field, and the next-field being a field succeeding the current field; 
         [0113]    detecting, as a scalar or vector value, a field-to-field picture motion m between the current and previous or next fields; 
         [0114]    calculating a probability j that there is a picture motion between frames while there is no picture motion between fields using at least the frame-to-frame picture motion M and field-to-field picture motion m; and 
         [0115]    changing methods to convert the input picture signal into a progressive signal at least according to the probability j. 
         [0116]    The embodiments of the present invention allows for detection of a telecine material having an arbitrary pulldown sequence using a common circuit. 
         [0117]    Further, the embodiments of the present invention offer both high detection accuracy and quick response to additionally allow detection of a picture edit point and hybrid material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0118]      FIG. 1  is a view illustrating the overall configuration of a picture signal processing device according to a first embodiment of the present invention; 
           [0119]      FIG. 2  is a view illustrating the internal configuration of a film determination circuit according to the present embodiment; 
           [0120]      FIG. 3  is a view illustrating the internal configuration of a de-interlacing circuit according to the present embodiment; 
           [0121]      FIG. 4  is a view  1  for describing the operation of the picture signal processing device according to the first embodiment; 
           [0122]      FIG. 5  is a view  2  for describing the operation of the picture signal processing device according to the first embodiment; 
           [0123]      FIG. 6  is a view  3  for describing the operation of the picture signal processing device according to the first embodiment; 
           [0124]      FIG. 7  is a view  4  for describing the operation of the picture signal processing device according to the first embodiment; 
           [0125]      FIG. 8  is a view  5  for describing the operation of the picture signal processing device according to the first embodiment; 
           [0126]      FIG. 9  is a view illustrating the relationship between a mixing factor k 2  and an output value F+j of an adder; 
           [0127]      FIG. 10  is a view illustrating the telecine process using the 2:2 pulldown technique; 
           [0128]      FIG. 11  is a view illustrating the image contents of the next, current and previous fields, the values of two registers incorporated in a shift register and a determination result F of the film determination circuit at different times; 
           [0129]      FIG. 12  is a view illustrating the telecine process using the 3:2 pulldown technique; 
           [0130]      FIG. 13  is a view illustrating the detection result of the film determination circuit for a telecine material obtained by the 3:2 pulldown technique; 
           [0131]      FIG. 14  is a view illustrating switching between video and telecine materials; 
           [0132]      FIG. 15  is a view illustrating the detection result of the film detection circuit in response to the input as shown in  FIG. 14 ; 
           [0133]      FIG. 16  is a view illustrating the overall configuration of the picture signal processing device according to a second embodiment of the present invention; 
           [0134]      FIG. 17  is a view illustrating the internal configuration of the film determination circuit according to the second embodiment; 
           [0135]      FIG. 18  is a view illustrating the internal configuration of the de-interlacing circuit according to the second embodiment; 
           [0136]      FIG. 19  is a view illustrating the relationship between an absolute value D 0  and a frame-to-frame picture motion M; 
           [0137]      FIG. 20  is a view illustrating the overall configuration of the picture signal processing device according to a third embodiment of the present invention; 
           [0138]      FIG. 21  is a view illustrating the internal configuration of the film determination circuit according to the third embodiment; 
           [0139]      FIG. 22  is a view illustrating the internal configuration of a de-interlacing circuit  45  according to the third embodiment; and 
           [0140]      FIG. 23  is a view illustrating the overall configuration of the picture signal processing device according to a fourth embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0141]    The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 
       First Embodiment 
       [0142]      FIG. 1  is a view illustrating the overall configuration of a picture signal processing device according to a first embodiment of the present invention. 
         [0143]    As illustrated in  FIG. 1 , a picture signal processing device  100  according to the first embodiment includes an input terminal  1  adapted to receive a picture signal, an input terminal  2  adapted to receive a vertical synchronizing signal, a first field memory  3  adapted to delay the picture signal received from the input terminal  1  by one field, a second field memory  4  adapted to delay the picture signal received from the input terminal  1  by two fields by delaying the picture signal already delayed one field by delaying one more field, a film detection circuit  5  adapted to determine the probability that the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process, a de-interlacing circuit  6  adapted to change de-interlacing methods according to the detection result of the film detection circuit  5 , and an output terminal  7  adapted to output a progressive signal converted from the picture signal by the de-interlacing circuit  6 . 
         [0144]    Hereinafter, for simplicity, the output picture signal of the first field memory  3  will be referred to as the “current-field picture signal”, the picture signal received from the input terminal  1  the “next-field picture signal”, and the output picture signal of the second field memory  4  the “previous-field picture signal.” The previous field is a field preceding a current field. The next field is a field succeeding the current field. 
         [0145]    The dotted line in  FIG. 1  represents the film detection circuit  5 . The area enclosed by the dotted line illustrates the internal configuration of the film detection circuit  5 . 
         [0146]    The film detection circuit  5  includes a frame motion detection circuit  8  adapted to detect a frame-to-frame picture motion using the next- and previous-field picture signals, a field motion detection circuit  9  adapted to detect a field-to-field picture motion using the current- and next-field picture signals, a still image determination circuit  10  adapted to detect that there is no picture motion between frames using the frame-to-frame picture motion detected by the frame motion detection circuit  8 , The film detection circuit  5  still further includes a motion judder detection circuit  11  adapted to detect a judder in the picture motion (a judder in the picture motion will be hereinafter referred to as a “motion judder”). The frame-to-frame picture motion detected by the frame motion detection circuit  8  and field-to-field picture motion detected by the field motion detection circuit  9  are used to detect the judder, and a film determination circuit  12  adapted to determine the probability that the input picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process. 
         [0147]    The determination result of the film determination circuit  12  is updated each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . 
         [0148]    Further, the motion judder detection circuit  11  includes a calculator  13  and accumulator  14 . The calculator  13  calculates a motion judder using a transform function which will be described later. The function has a frame-to-frame motion and field-to-field motion as variables. The accumulator  14  accumulates the motion judder, calculated by the calculator  13 , in the spatial direction. The accumulator  14  resets the accumulation result to 0 each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . 
         [0149]      FIG. 2  is a view illustrating the internal configuration of the film determination circuit  12  according to the present embodiment. 
         [0150]    As illustrated in  FIG. 2 , the film determination circuit  12  includes a pattern generating circuit  15  adapted to generate a finite and discrete number of patterns using the time series of the determination result of the still image determination circuit  10  and that of the accumulation result of the accumulator  14 , a pattern ROM  16  adapted to store patterns to be compared with a pattern generated by the pattern generating circuit  15 , and a pattern comparison circuit  17  adapted to compare a pattern generated by the pattern generating circuit  15  with one of the patterns stored in the pattern ROM  16  to find a match. 
         [0151]    Further, the pattern generating circuit  15  includes an identification circuit  18  adapted to identify the status of a picture signal based on the determination result of the still image determination circuit  10  and the accumulation result of the accumulator  14 , a shift register  19  adapted to store the identification result of the identification circuit  18  for a plurality of fields. 
         [0152]      FIG. 3  is a view illustrating the internal configuration of the de-interlacing circuit  6  according to the present embodiment. 
         [0153]    In  FIG. 3 , the de-interlacing circuit  6  includes a motion detection circuit  20  adapted to generate a motion factor which represents the magnitude of picture motion based on the previous- and next-field picture signals, an interpolation circuit  21  adapted to generate a pixel value of a scan line to be interpolated by properly weighting and adding the previous-, current- and next-field picture signals according to the motion factor generated by the motion detection circuit  20 , The de-interlacing circuit  6  still further includes a selector  22  adapted to select the previous- or next-field picture signal based on the calculation result of an adder  23  which will be described later, an adder  23  adapted to add up a motion judder calculated by the calculator  13  which is incorporated in the motion judder detection circuit  11 , a mixing factor generating circuit  24  adapted to generate a mixing factor based on the addition result of the adder  23 , a mixing circuit  25  adapted to generate a pixel value of a scan line to be interpolated by weighting and adding output signals of the interpolation circuit  21  and selector  22 , and an interlaced-to-progressive conversion circuit  26  adapted to generate a progressive signal by interleaving the scan line interpolated by the mixing circuit  25  and the actual scan line of the current field. 
         [0154]    The progressive signal generated by the interlaced-to-progressive conversion circuit  26  is output from the output terminal  7 . 
         [0155]    The operation of the picture signal processing device according to the first embodiment will be described below with reference to  FIGS. 4 to 8 . 
         [0156]    The simplest implementation of the frame motion detection circuit  8  is to find the difference in luminance between pixels distant from each other by one frame. If a luminance signal is contained in the picture signal received from the input terminal  1 , the frame motion detection circuit  8  can be configured only with a subtractor. The subtractor finds the difference between the previous- and next-field luminance signal components. The frame-to-frame motion obtained at this time is a scalar quantity. To avoid the impact of high-frequency noise or find the block-by-block average motion quantity, low-pass spatial filters may be provided, one before and the other after the subtractor. Each block is made up of a plurality of pixels. 
         [0157]    The field motion detection circuit  9  can be configured only with a subtractor as with the frame motion detection circuit  8 . For an interlaced signal, however, there is a half-line offset in the display position of the scan lines between fields. Therefore, if the field motion detection circuit  9  is configured only with a subtractor, the field motion detection circuit  9  finds the difference in luminance between pixels distant from each other by half a line on the screen. To find a more accurate field-to-field motion, it suffices to use two spatial filters. These filters have group delays different by half a line from each other. One of the filters is applied to the current-field luminance signal. The other filter is applied to the next-field luminance signal. The output signals of these spatial filters are subtracted, one from the other, with the subtractor. 
         [0158]    In the description given below, a case is considered in which both the frame motion detection circuit  8  and field motion detection circuit  9  are configured only with a subtractor for simplicity. The output of the frame motion detection circuit  8 , namely, the frame-to-frame motion, will be hereinafter written as M assuming that it is the value obtained by subtracting the next-field luminance signal component from the previous-field luminance signal component. Similarly, the output of the field motion detection circuit  9 , namely, the field-to-field motion, will be hereinafter written as m assuming that it is the value obtained by subtracting the next-field luminance signal component from the current-field luminance signal component. 
         [0159]    The still image determination circuit  10  determines the probability that there is no picture motion between frames using a function which decreases monotonically with respect to the frame-to-frame motion M. More specifically, the still image determination circuit  10  outputs a total sum S of a value s found by the following equation over the entire display screen in relation to positive constants t 1  and T 1 . This total sum S represents the probability that there is no picture motion between frames. 
         [0000]        s =med{0,1,(| M|−t 1)/ T 1} 
         [0160]    In the above equation, “med {x, y, z}” is a function adapted to select the median of x, y and z. On the other hand, “/” is a division symbol. “|x|” is a symbol representing the absolute value of x. “s” is monotonically decreasing, namely, monotonically non-increasing, with respect to M in a broad sense, as illustrated in  FIG. 4 . 
         [0161]    The calculator  13  incorporated in the motion judder detection circuit  11  calculates a motion judder j from the values M and m. As described later, the motion judder detection circuit  11  calculates the motion judder j so that the absolute value of the judder j takes on a large value when the absence of motion is detected between fields despite the fact that a large motion is detected between frames. Such a motion judder is typical of telecine materials and hardly occurs in ordinary video materials. 
         [0162]    The calculator  13  calculates the judder j using a transform function g given below. The transform function g has M and m as variables. 
         [0000]        j=g ( M,m ) 
         [0000]      where 
         [0000]        g ( M,m )=|α M ×(1+2 ×m/M ) 
         [0000]    when −0.5≦m/M&lt;0 
         [0000]        g ( M,m )=|α M |×(1−2 ×m/M ) 
         [0000]    when 0≦m/M&lt;1 
         [0000]        g ( M,m )=−|α M |×(3−2 ×m/M ) 
         [0000]    when 1≦m/M&lt;1.5 
         [0000]        g ( M,m )=0 
         [0000]    when other than the above 
         [0163]    In the above equations, α is a constant, and α×M is abbreviated as αM. 
         [0164]      FIG. 5  illustrates the change of j with respect to m/M. As is clear from  FIG. 5 , the absolute value of j is maximal when m=0 and m=M. That is, the absolute value of j is maximal when the field-to-field picture motion m is 0 or equal to the frame-to-frame picture motion M. In particular, m=0 means that there is no picture motion between the current and next fields. m=M means that there is no picture motion between the current and previous fields. 
         [0165]    When m=0 or m=M, |j|=|αM|. This value increases monotonically with respect to the absolute value of the frame-to-frame picture motion M. This means that the greater the frame-to-frame picture motion, the larger the motion judder. The value j found by the calculator  13  is output to the accumulator  14  and employed by the de-interlacing circuit  6  at the same time. 
         [0166]    The transform function g described above is not limited to function which can find the motion judder j. For example, the motion judder j may be calculated by the transform function h shown below by taking j=h(M,m). 
         [0000]        h ( M,m )=med{−1,1, g ( M,m )} 
         [0167]    If the transform function h is used, the change of j with respect to m/M is as shown in  FIG. 5  when |αM|≦1 and as shown in  FIG. 6  in any other case. At this time, |j| is monotonically increasing, namely, monotonically non-decreasing, with respect to |M| in a broad sense. Even if the transform function h is used, the absolute value of the motion judder j takes on a large value also when there is a picture motion between frames and when there is no picture motion between fields. 
         [0168]    The accumulator  14  accumulates the motion judder j, output from the calculator  13 , in the spatial direction. That is, the accumulator  14  resets the accumulated sum to 0 each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . Each time the new motion judder j is calculated by the calculator  13 , the accumulator  14  adds j to a currently stored accumulation result J. This provides the total sum of the motion judder j over the entire display screen. 
         [0169]    The film determination circuit  12  determines, using the accumulation result J from the accumulator  14 , the probability that the picture signal input from the input terminal  1  is an interlaced signal generated by the telecine process. 
         [0170]    The identification circuit  18  identifies the picture status using a determination result S of the still image determination circuit  10 , the accumulation result J of the accumulation circuit  14  and three positive threshold values Sa, Ja and Jb. Assuming the value output by the identification circuit  18  to be p, the value p can be found as follows: 
         [0171]    p=−2 when S&lt;Sa and −Jb≦J&lt;Ja 
         [0172]    p=−1 when S&lt;Sa and J&lt;−Jb 
         [0173]    p=0 when S≧Sa 
         [0174]    p=1 when S≦Sa and J≧Ja 
         [0175]    p=0 is associated with a still image, p=0 a moving image of a video material, and any other case a telecine material. Considering the fact that the values S and J are finalized when a reference edge of a vertical synchronizing signal is received which represents the start of a next field, the current and next fields are highly likely to be derived from the same film frame when p=1. On the other hand, when p=−1, the previous field and the one before the previous field are highly likely to be derived from the same film frame. In particular, when p=−1, the current and next fields are also highly likely to be derived from the same film frame, on the precondition that the input picture signal remains unchanged as a telecine material. 
         [0176]    The shift register  19  includes two registers. The register value at each stage is updated each time a reference edge of a vertical synchronizing signal is received. That is, the value of the first-stage register is updated to p which is the output of the identification circuit  18 . The value of the second-stage register is updated to that of the first-stage register. The series of values stored in the two registers represents the pattern associated with the status change of the input picture signal over time. 
         [0177]    The pattern ROM  16  stores four patterns to be compared with the value of the shift register  19 . Each of the patterns stored in the pattern ROM  16  is made up of an arrangement of up to two numbers to match the two registers of the shift register  19 . 
         [0178]    The patterns stored in the same ROM  16  are illustrated in  FIG. 7 . A pattern PTN 1  is made up of 0, a pattern PTN 2  1, a pattern PTN 3  −1 and 0, and a pattern PTN 4  −1 and 1. 
         [0179]    The pattern comparison circuit  17  determines that the pattern PTN 1  in  FIG. 7  matches the pattern represented by the shift register  19  when the value of the first-stage register of the shift register  19  is 0. 
         [0180]    In the same manner, the pattern comparison circuit  17  determines that the pattern PTN 2  in  FIG. 7  matches the pattern represented by the shift register  19  when the value of the first-stage register is 1. The pattern comparison circuit  17  determines that the pattern PTN 3  in  FIG. 7  matches the pattern represented by the shift register  19  when the values of the first- and second-stage registers are −1 and 0, respectively. The pattern comparison circuit  17  determines that the pattern PTN 4  in  FIG. 7  matches the pattern represented by the shift register  19  when the values of the first- and second-stage registers are −1 and 1, respectively. 
         [0181]    When the pattern represented by the shift register  19  matches the pattern PTN 1  or PTN 2 , the pattern comparison circuit  17  outputs a negative value −β considering that it is highly likely that the input picture signal is an interlaced signal generated by the telecine process and that the current and previous fields are derived from the same film frame. When the pattern represented by the shift register  19  matches the pattern PTN 3  or PTN 4 , the pattern comparison circuit  17  outputs a positive value γ considering that it is highly likely that the input picture signal is an interlaced signal generated by the telecine process and that the current and next fields are derived from the same film frame. In any other case, the pattern comparison circuit  17  outputs 0 considering that it is unlikely that the input picture signal is an interlaced signal generated by the telecine process. 
         [0182]    The output value of the pattern comparison circuit  17  is fed to the de-interlacing circuit  6  as the output value of the film determination circuit  12 . Hereinafter, the output value of the film determination circuit  12  will be written as F. The absolute value of F represents the probability that the input picture signal is an interlaced signal generated by the telecine process. The sign of F is used to identify fields which are derived from the same film frame. 
         [0183]    The de-interlacing circuit  6  converts the interlaced signal from the input terminal  1  into a progressive signal using F obtained from the film determination circuit  12  and j obtained from the motion judder detection circuit  11 . The de-interlacing circuit  6  outputs the resultant progressive signal from the output terminal  7 . 
         [0184]    As illustrated in  FIG. 8 , the pixel value of the current field to be interpolated will be written as i, the pixel value one field preceding i as a, the pixel value one field succeeding i as b, the pixel value one line above i on the display screen as c, and the pixel value one line below i on the display screen as d. The values c and d are obtained from the first field memory  3 . The value a is obtained from the second field memory  4 . The value b is contained in the picture signal received from the input terminal  1 . 
         [0185]    The motion detection circuit  20  generates a motion factor k 1  from the previous- and next-field picture signals. In the description given below, the value obtained by transforming the absolute value of the difference between the luminance signal components of a and b with a non-linear monotonically non-decreasing function is assumed to be the motion factor k 1 . That is, the larger the absolute value of the difference between the luminance signal components of a and b, the larger the motion factor k 1 . In particular, when the luminance signal components of a and b match, k 1 =0. 
         [0186]    The interpolation circuit  21  generates an interpolation value suitable for a video material of the input picture signal from the values a, b, c, d and k 1 . Here, v obtained by the following equation is assumed to be the output value of the interpolation circuit  21 . 
         [0000]        v =(1 −k 1)×( a+b )/2 +k 1×( c+d )/2 
         [0187]    The larger the motion factor k 1 , the more apt the interpolation circuit  21  is to select “(c+d)/2” which is the average of the upper and lower lines. Conversely, the smaller the motion factor k 1 , the more apt the interpolation circuit  21  is to select “(a+b)/2” which is the frame-to-frame average. 
         [0188]    The selector  22  generates an interpolation value suitable for a telecine material from the values a and b and an output value F+j of the adder  23 . Here, f obtained by the following equation is assumed to be the output value of the selector  22 . 
         [0189]    f=a when F+j&lt;0 
         [0190]    f=b when F+j≧0 
         [0191]    If it is highly likely that the current and previous fields are derived from the same film frame, the selector  22  is apt to select the pixel value a of the previous field. In any other case, the selector  22  is apt to select the pixel value b of the next field. 
         [0192]    The mixing factor generating circuit  24  generates a mixing factor k 2  from the value F+j. That is, the mixing factor generating circuit  24  outputs k 2 , obtained by the following equation, to the mixing circuit  25  as a mixing factor for two positive constants t 2  and T 2 . 
         [0000]        k 2=med{0,1,(| F+j|−t 2)/ T 2} 
         [0193]      FIG. 9  illustrates the relationship between the mixing factor k 2  and the output value F+j of the adder  23 . k 2  represents the probability that the input picture signal is a telecine material. 
         [0194]    The mixing circuit  25  generates a final interpolation value i with the following function using the output value v of the interpolation circuit  21 , the output value f of the selector  22 , and the mixing factor k 2  generated by the mixing factor generating circuit  24 . 
         [0000]        i =(1 −k 2)× v+k 2 ×f    
         [0195]    The larger k 2 , the more apt the interpolation method suitable for a telecine material is to be selected. The smaller k 2 , the more apt the interpolation method suitable for a video material is to be selected. Thus, the picture signal processing device  100  performs de-interlacing in different manners, one tailored to a telecine material and the other to a video material. 
         [0196]    A description will be given below of the reason why the picture signal processing device  100  configured as described above can detect a telecine material having an arbitrary pulldown sequence using a common circuit. A description will also be given of the reason why the picture signal processing device  100  is resistant to erroneous de-interlacing even in the presence of an edit point or hybrid material while offering quick detection response without sacrificing film detection accuracy.  FIGS. 10 to 15  will be referred to for the description. 
         [0197]      FIG. 10  is a view illustrating the telecine process using the 2:2 pulldown technique. 
         [0198]    Picture frames recorded on film are termed A, B, C and D in order of transmission, from earliest to latest. These are progressive signals. The telecine process using the 2:2 pulldown technique divides each film frame into two fields, one made up of odd lines and the other even lines, thus generating an interlaced signal. Two fields derived from the frame A will be written as Ao and Ae. Although captured at the same time, Ao and Ae are transmitted with a time lag of one field between them when used as a television signal for broadcasting. Here, the field transmitted next to Ao will be written as Ae. In the same manner, two fields derived from each of B, C and D will be written as Bo, Be, Co, Ce, Do and De, in order of transmission from earliest to latest. Further, the times when Ae to De are fed to the input terminal  1  are termed fields n+1 to n+9, respectively. 
         [0199]    Here, a case will be considered in which the film frames are different in image content from one another. At this time, the frame motion detection circuit  8  constantly detects a frame-to-frame picture motion. Therefore, the determination result S of the still image determination circuit  10  is highly likely to be smaller than Sa. As a result, the identification result p of the identification circuit  18  is unlikely to be 0. 
         [0200]    Further, if the current and previous fields are derived from the same film frame, the calculation result j of the calculator  13  incorporated in the motion judder detection circuit  11  is highly likely to be negative. As a result, the accumulation result J, which is the result of accumulating j, is highly likely to be less than −Jb. 
         [0201]    When S&lt;Sa and J&lt;−Jb, the identification result p of the identification circuit  18  is −1 as mentioned earlier. In the same manner, when the current and next fields are derived from the same film frame, the identification result p is highly likely to be 1. This is shown in a diagram in  FIG. 11 . 
         [0202]      FIG. 11  shows the image contents of the next, current and previous fields, the values of the two registers incorporated in the shift register  19  and the determination result F of the film determination circuit  12  at different times. In  FIG. 11 , U in the register value and determination result columns denotes that the value is unknown. 
         [0203]    As an example, the field n+2 will be considered in which the previous, current and next fields are Ao, Ae and Bo. 
         [0204]    The values S and J for the field n+2 are finalized when a reference edge of a vertical synchronizing signal is received which represents the end of the field n+2. At the time of the field n+2, therefore, the value of the first-stage register of the shift register  19  is U. The identification result p=−1 of the identification circuit  18  for the field n+2 is reflected for the first time in the field n+3. The same is true for the field n+3 onward. 
         [0205]    The pattern generated by the pattern generating circuit  15  using the shift register  19  matches the pattern PTN 2  or PTN 4  in  FIG. 7 . Therefore, when the input picture signal is generated by the 2:2 pulldown technique, the determination result F of the film determination circuit  12  is always non-0. As a result, it is determined that the input picture signal is probably a television signal generated by the telecine process. 
         [0206]    Further, as a result of the operation of the pattern comparison circuit  17 , F=−β in the fields n+4, n+6 and n+8. Still further, the current and previous fields are derived from the same film frame in these fields. Therefore, M and m are roughly equal to each other. j is negative. Therefore, we can say that it is highly likely that F+j&lt;0 and |F+j|&gt;t 2 +T 2  in the fields n+4, n+6 and n+8. 
         [0207]    If the conditions F+j&lt;0 and |F+j|&gt;t 2 +T 2  are satisfied, the output value f of the selector  22  is a. In this case, the mixing factor k 2  generated by the mixing factor generating circuit  24  is close to 1. As a result, a is apt to be selected by the mixing circuit  25  as the interpolation value i. 
         [0208]    In the fields n+4, n+6 and n+8, the current and previous fields are derived from the same film frame. Therefore, the operations described above allow the de-interlacing circuit  6  to properly restore the original film frame. 
         [0209]    The same is true for the fields n+5, n+7 and n+9 in which F=γ. That is, when the current and next fields are derived from the same film frame, the two conditions F+j&lt;0 and |F+j|&gt;t 2 +T 2  are highly likely to be satisfied. b is apt to be selected as the interpolation value. As a result, the original film frame can be properly restored. 
         [0210]    Next, a case will be considered in which the input picture signal is generated by the telecine process using the 3:2 pulldown technique. The 3:2 pulldown technique divides a single film frame sometimes into two and other times into three as illustrated in  FIG. 12 . When a single film frame is divided into three fields, the first and third fields are completely identical. 
         [0211]    In  FIG. 12 , the fields (Bo) input to the fields n+2 and n+4 are identical, and the fields (De) input to the fields n+7 and n+9 are also identical. 
         [0212]    If the film frames are different in image content from one another, the detection results of the film determination circuit  12  regarding a telecine material resulting from the 3:2 pulldown technique are as shown in  FIG. 13 . 
         [0213]    In the field n+4, the next and previous fields are both Bo. Therefore, M detected by the frame motion detection circuit  8  is 0. As a result, the determination result S of the still image determination circuit  10  is highly likely to be greater than Sa. As described earlier, when S≧Sa, p=0. Therefore, the value of the first-stage register of the shift register  19  is 0 in the field n+5. 
         [0214]    In the field n+5, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 1  in  FIG. 7 . In the field n+6, on the other hand, the pattern generated by the same circuit  15  matches the pattern PTN 3  in  FIG. 7 . In the fields n+4, n+7 and n+9, the pattern generated by the same circuit  15  matches the pattern PTN 2 . In the field n+8, the pattern generated by the same circuit  15  matches the pattern PTN 4 . 
         [0215]    As described above, the pattern generated by the pattern generating circuit  15  matches one or more of the patterns in  FIG. 7  for any field. Therefore, the film detection circuit  5  can also handle film detection properly even in the case of the 3:2 pulldown technique. 
         [0216]    The de-interlacing circuit  6  operates in the fields n+7 and n+8 in the same manner as described in the example using the 2:2 pulldown technique. Therefore, a description will be given below of the operation of the de-interlacing circuit  6  for a period from the field n+4 to the field n+6. It should be noted that the de-interlacing circuit  6  operates in the field n+9 exactly in the same manner as in the field n+4. 
         [0217]    First, the operation of the de-interlacing circuit  6  in the field n+4 will be described. 
         [0218]    In the field n+4, the next and previous fields are completely identical. As a result, M=0 and j=0. On the other hand, the value F is −β which is negative. As a result, it is highly likely that F+j&lt;0. 
         [0219]    Therefore, the output value f of the selector  22  is highly likely to be a. On the other hand, the motion factor k 1 , which is the output value of the motion detection circuit  20 , is 0 as described earlier when the next and previous fields match in image content. As a result, the output value v of the interpolation circuit  21  is the average of a and b. In the field n+4, a=b. As a result, the average of a and b is equal to a. 
         [0220]    The input value of the mixing circuit  25  is f=v=a. As a result, the interpolation value i is equal to a irrespective of the mixing factor k 2 . This is correct in terms of the operation of the de-interlacing circuit  6 . 
         [0221]    Next, the operation of the de-interlacing circuit  6  in the field n+5 will be considered. In this field, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 1 . 
         [0222]    In the field n+5, the current and previous fields are derived from the same film frame. As a result, the value j is highly likely to be negative as the value F. Therefore, it is highly likely that F+j&lt;0 and |F+j|&gt;t 2 +T 2 . As a consequence, a which is the pixel value of the previous field is highly likely to be selected as the interpolation value i. 
         [0223]    In the field n+6, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 3 . In this field, the current and next fields are derived from the same film frame. As a result, the value j is highly likely to be positive as the value F. Therefore, it is highly likely that F+j&gt;0 and |F+j|&gt;t 2 +T 2 . As a consequence, b which is the pixel value of the next field is highly likely to be selected as the interpolation value i. 
         [0224]    As described above, the de-interlacing circuit  6  can properly restore the original film frame even in the case of the 3:2 pulldown technique. 
         [0225]    The film detection circuit  5  and de-interlacing circuit  6  according to the first embodiment can handle film detection and de-interlacing properly even for an interlaced signal generated by the telecine process using a pulldown technique other than the 2:2 and 3:2 pulldown techniques. 
         [0226]    The pulldown process always divides a single film frame into two or more fields. If a film frame is divided into three or more fields, the third field and beyond always match the field two fields previous to them. In the third field and beyond, therefore, the detection result M of the frame motion detection circuit  8  is always 0 (M=0). The determination result S of the still image determination circuit  10  is greater or equal to Sa (S≧Sa). As a result, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 1 . 
         [0227]    The pattern generated by the pattern generating circuit  15  does not match the pattern PTN 1  if only the next field is derived from a different film frame. In this case, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 3  as a result of the operation which is exactly the same as in the field n+6 in  FIG. 13 . 
         [0228]    Further, the next and current fields are derived from the same film frame one field later. As a result, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 4 . 
         [0229]    In the succeeding fields, the pattern generated by the pattern generating circuit  15  matches the pattern PTN 1  until a field appears which is derived from a different film frame as described above. Therefore, the film detection circuit  5  can detect an arbitrary pulldown sequence other than the 2:2 or 3:2 pulldown sequence. 
         [0230]    The de-interlacing circuit  6  can restore the original film frame properly when the pattern generated by the pattern generating circuit  15  matches one of the patterns stored in the pattern ROM  16 . This has been already explained using examples of 2:2 and 3:2 pulldown. Therefore, the de-interlacing circuit  6  can also detect an arbitrary pulldown sequence other than 2:2 and 3:2 pulldown sequences. 
         [0231]    Next, highly accurate film detection of the film detection circuit  5  according to the first embodiment will be described. 
         [0232]    A telecine material is characterized in that it is generated by division of a single film frame into a plurality of fields. For this reason, there is no picture motion between fields in all areas where there is a picture motion between frames. This hardly occurs in ordinary video materials. 
         [0233]    The motion judder detection circuit  11  detects the case where there is a picture motion between frames but no picture motion between fields. This allows the motion judder detection circuit  11  to suppress erroneous film detection. In particular, a picture motion between frames can be detected by using even or odd fields. Therefore, erroneous detection is unlikely even if the original film frame contains a vertical high frequency component. Simple detection of a field-to-field picture motion independently of the frame-to-frame picture motion may result in erroneous detection in a still image area containing a vertical high frequency component. 
         [0234]    However, detection of a field-to-field picture motion only in an area having a frame-to-frame picture motion can suppress erroneous detection caused by a vertical high frequency component. This is advantageous if a telecine material contains many vertical high frequency components and if the frame-to-frame picture motion is small. 
         [0235]    The film detection circuit  5  and de-interlacing circuit  6  according to the first embodiment can quickly handle frequent switching between telecine and video materials. This will be described next with reference to  FIGS. 14 and 15 . 
         [0236]      FIG. 14  is a view illustrating switching between video and telecine materials. We assume that, of the nine fields from Ao to He in  FIG. 14 , the four fields De, Do, Ee and Eo are telecine materials generated using the 2:2 pulldown technique and that the other five fields are video materials. Further, we assume that the film frames are different in image content from one another and that the video material fields are different in image content from one another. 
         [0237]    The detection results of the film detection circuit  5  are as shown in  FIG. 15  when the input is as shown in  FIG. 14 . 
         [0238]    That is, the next, current and previous fields are different in image content from one another in the field n+2. For this reason, there is a picture motion between frames and between fields. Therefore, the value s detected by the still image determination circuit  10  is close to 0. As a result, the accumulated sum S obtained by accumulating s is highly likely to be smaller than Sa. 
         [0239]    Further, m/M is in the neighborhood of 0.5. Therefore, the motion judder j detected by the motion judder detection circuit  11  is close to 0. As a result, the accumulated sum J obtained by accumulating j is highly likely to be −Jb≦J&lt;Ja. 
         [0240]    When S&lt;Sa and −Jb≦J&lt;Ja, p=−2 as described earlier. Therefore, the value of the first-stage register of the shift register  19  is −2 in the field n+3. This does not match any of the patterns in  FIG. 7 . As a result, the determination result F of the film determination circuit  12  is 0. 
         [0241]    In the succeeding fields, the determination result F of the film determination circuit  12  is not 0 for a period from the field n+5 to the field n+8. The current field is a telecine material from the field n+4 to the field n+7. This means that the film determination circuit  12  makes a correct determination in one field after the switching of the input picture signal. 
         [0242]    In the field n+4, F=0 despite the fact that the current and next fields are derived from the same film frame. In this field, however, j is highly likely to be positive. Therefore, F+j is also highly likely to be more or less a large positive value. As a result, the value close to b is highly likely to be selected as the interpolation value i. Consequently, the de-interlacing circuit  6  is highly likely to be able to restore the original film frame in the field n+4 as well. 
         [0243]    In the field n+8, on the other hand, F is a non-O value despite the fact that all the fields are video materials. In this field, j is close to 0. Therefore, as long as γ is set to be more or less small with respect to t 2 , |F+j| will not exceed t 2 . As a result, k 2 =0. Consequently, the output value v of the interpolation circuit  21 , which is suitable for a video material, is highly likely to be selected as the interpolation value i. 
         [0244]    As described above, the film detection circuit  5  can achieve film detection in an extremely short period of time, and the de-interlacing circuit  6  can select an appropriate interpolation value quickly in response to the status of the input picture signal. 
         [0245]    In a practical television signal, telecine and video materials may be frequently switched, for example, as a result of editing of telecine materials. However, the film detection circuit  5  and de-interlacing circuit  6  according to the first embodiment can detect telecine materials with many picture edit points as well. 
         [0246]    The de-interlacing circuit  6  according to the first embodiment can detect a hybrid material containing telecine and video materials in the same field image. This will be described lastly. 
         [0247]    A hybrid material often contains a video material in a relatively small area of the display screen. At this time, the detection result F of the film detection result  5  is highly likely to be non-0 because of a telecine material which occupies the majority of the screen. 
         [0248]    In the image area made up of a video material, on the other hand, as long as there is a picture motion between frames, there is a picture motion both between the current and next fields and between the current and previous fields. 
         [0249]    As a consequence, the value j detected in the moving image area made up of a video material is close to 0. As long as β and γ are set to be more or less small with respect to t 2 , |F+j| will not exceed t 2 . As a result, k 2 =0. Consequently, v which is suitable for a video material will be selected as the interpolation value i. 
         [0250]    In the image area made up of a telecine material, on the other hand, the signs of F and j are highly likely to be the same. Therefore, |F+j| will exceed t 2 . Consequently, f which is suitable for a telecine material will be selected as the interpolation value i. 
         [0251]    In the still image area, there is no picture motion between frames. Therefore, j is close to 0 irrespective of whether this area is made up of a telecine or video material. As a result, F+j is determined almost uniquely by F. It should be noted, however, that either f or v may be selected as the interpolation value i for the still image area. In this case, therefore, the value F+j may be arbitrary. 
         [0252]    Therefore, the de-interlacing circuit  6  according to the first embodiment can handle de-interlacing properly even in the case of a hybrid material. 
         [0253]    As described above, the picture signal processing device according to the first embodiment can detect a telecine material having an arbitrary pulldown sequence with a common circuit. The same device is resistant to erroneous de-interlacing even in the presence of an edit point or hybrid material while offering quick detection response without sacrificing film detection accuracy. 
         [0254]    In the first embodiment, a case has been description in which the frame-to-frame and field-to-field picture motions are detected as scalar quantities. However, these motions may be detected as vector values. The gradient method is known as a detection method adapted to detect a picture motion on a pixel-by-pixel basis. The block matching method is known as a detection method adapted to detect a picture motion on a block-by-block basis. 
         [0255]    To detect the motion judder j using the frame-to-frame and field-to-field picture motions which are vector values, the transform function g or h need only be calculated by assuming the norm of the frame-to-frame motion vector to be M and that of the field-to-field motion vector to be m. 
         [0256]    In addition to the above, a transform function may be defined so that the motion judder j is dependent upon the direction of the motion vector. Also in this case, the same effects can be achieved as those of the first embodiment if the absolute value of the transform function is maximal when the field-to-field motion vector is 0 or equal to the frame-to-frame motion vector and if the absolute value of the transform function at this time is monotonically non-decreasing with respect to the norm of the frame-to-frame motion vector. 
         [0257]    Further, the first embodiment performs de-interlacing based on the motion judder j and the addition result of the film determination result F. However, de-interlacing may be performed using only the motion judder j. In this case, the operation is the same as when the film determination result F is always 0. If the de-interlacing methods are changed only in response to the motion judder j, the detection accuracy drops slightly for images locally containing many vertical high frequency components. Nevertheless, the same effects can be obtained as those of the first embodiment. 
         [0258]    Further, the shift register  19  of the first embodiment has two stages. However, the present invention is not limited thereto, and the shift register  19  may have more than two stages. 
         [0259]    For example, the shift register  19  may have five stages so that the pattern ROM  16  stores a pattern made up of five numbers, namely, 0, 1, −1, 1 and −1. The value of the first register is 0, the values of the second and fourth registers are 1, and those of the third and fifth registers −1 when the input picture signal is a television signal generated by the 3:2 pulldown technique. As a result, the above pattern allows for detection of a 3:2 pulldown sequence. 
         [0260]    Further, the adder  23  is incorporated in the de-interlacing circuit  6  in the first embodiment. However, the adder  23  may be incorporated in the film detection circuit  5 . In this case, F+j is the film detection result. 
       Second Embodiment 
       [0261]      FIG. 16  is a view illustrating the overall configuration of the picture signal processing device according to a second embodiment of the present invention. 
         [0262]    In  FIG. 16 , the components having the same function as those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted. 
         [0263]    A picture signal processing device  100 A according to the second embodiment includes, a third field memory  27  adapted to delay a picture signal, which has been delayed by two fields, by one more field so as to delay the picture signal received from the input terminal  1  by three fields, a film detection circuit  28  adapted to determine whether the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process, and a de-interlacing circuit  29  adapted to change de-interlacing methods according to the detection result of the film detection circuit  28 . 
         [0264]    The de-interlacing circuit  29  according to the second embodiment differs from the de-interlacing circuit  6  according to the first embodiment in that the circuit  29  uses the picture signals delayed by one or more fields from the picture signal received from the input terminal  1 . The picture signal converted into a progressive signal by the de-interlacing circuit  29  is output from the output terminal  7 . 
         [0265]    Hereinafter, as in the first embodiment, the picture signal received from the input terminal  1  will be referred to as the “next-field picture signal”, the output picture signal of the first field memory  3  the “current-field picture signal”, and the output picture signal of the second field memory  4  the “previous-field picture signal.” Further, as necessary, the output signal of the third field memory  27  will be referred to as a “field N 3  picture signal”, and the previous-, current- and next-field picture signals field N 2 , N 1  and N 0  picture signals, respectively. 
         [0266]    The dotted line in  FIG. 16  represents the film detection circuit  28 . The area enclosed by the dotted line illustrates the internal configuration of the film detection circuit  28 . 
         [0267]    As illustrated in  FIG. 16 , the film detection circuit  28  includes, a frame motion detection circuit  30  adapted to detect a frame-to-frame picture motion using the next- and previous-field picture signals, a first field motion detection circuit  31  adapted to detect a field-to-field picture motion using the current- and next-field picture signals, a second field motion detection circuit  32  adapted to detect a field-to-field picture motion using the current- and previous-field picture signals, a moving image determination circuit  33  adapted to determine the probability that there is a given picture motion between fields for two consecutive fields using the detection results of the frame detection circuit  30 , first field motion detection circuit  31  and second field motion detection circuit  32 , a first motion judder detection circuit  34  adapted to detect a motion judder using the detection results of the frame detection circuit  30  and first field motion detection circuit  31 , a second motion judder detection circuit  35  adapted to detect a motion judder using the detection results of the frame detection circuit  30  and second field motion detection circuit  32 , and a film determination circuit  36  adapted to determine the probability that the input picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process using the determination result of the moving image determination circuit  33  and the detection results of the first and second motion judder detection circuits  34  and  35 . 
         [0268]      FIG. 17  is a view illustrating the internal configuration of the film determination circuit  36  according to the second embodiment. 
         [0269]    As illustrated in  FIG. 17 , the film determination circuit  36  includes, a first threshold circuit  37  adapted to threshold the determination result of the moving image determination circuit  33 , a second threshold circuit  38  adapted to threshold the ratio of the detection results of the first and second motion judder detection circuit  34  and  35 , and an identification circuit  39  adapted to identify the status of the input picture signal based on the output values of the first and second threshold circuits  37  and  38 . 
         [0270]    The identification result of the identification circuit  39  is output to the de-interlacing circuit  29  as the determination result F of the film determination circuit  36 . 
         [0271]      FIG. 18  is a view illustrating the internal configuration of the de-interlacing circuit  29  according to the second embodiment. 
         [0272]    As illustrated in  FIG. 18 , the de-interlacing circuit  29  includes, a motion detection circuit  40  adapted to generate the motion factor k 1  which represents the magnitude of the picture motion using the field N 1  and N 3  picture signals, an interpolation circuit  41  adapted to generate a pixel value of a scan line to be interpolated by properly weighting and adding the field N 1 , N 2  and N 3  picture signals according to the motion factor k 1  generated by the motion detection circuit  40 , a selector  42  adapted to select one of the three options, namely, the output signal v of the interpolation circuit  41  and field N 1  and N 2  picture signals, according to the determination result F of the film detection circuit  28 , and an interlaced-to-progressive conversion circuit  43  adapted to generate a progressive signal by interleaving the picture signal of the scan line to be interpolated which has been selected by the selector  42  and the actual scan line of the current field. 
         [0273]    The progressive signal generated by the interlaced-to-progressive conversion circuit  43  is output from the output terminal  7 . 
         [0274]    Here, the operation of the picture signal processing device according to the second embodiment will be described. 
         [0275]    The frame detection circuit  30  detects, as the frame-to-frame picture motion M, the value obtained by monotonic nonlinear transform of an absolute value D 0  of the difference in luminance between pixels distant only by one frame from each other. 
         [0276]    Similarly, the first field motion detection circuit  31  finds an absolute value D 1  of the difference in luminance between two pixels of the current and next fields which are spatially located at almost the same position. The same circuit  31  detects, as the field-to-field motion m 1 , the value obtained by monotonic nonlinear transform of the absolute value D 1 . 
         [0277]    Further, the second field motion detection circuit  32  finds an absolute value D 2  of the difference in luminance between two pixels of the current and previous fields which are spatially located at almost the same position. The same circuit  32  detects, as the field-to-field motion m 2 , the value obtained by monotonic nonlinear transform of the absolute value D 2 . 
         [0278]    Low-pass spatial filters may be provided, one before and the other after where the difference in luminance is found between pixels distant by one frame or field from each other, as in the first embodiment. 
         [0279]    In the description given below, we assume that the relationships between D 0  and M, between D 1  and m 1  and between D 2  and m 2  are defined respectively by the following equations: 
         [0000]        M =med{0,1,( D 0 −t 3)/ T 3} 
         [0000]        m 1=med{0,1,( D 1− t 3)/ T 3} 
         [0000]        m 2=med{0,1,( D 2 −t 3)/ T 3} 
         [0280]      FIG. 19  is a view illustrating the relationship between the absolute value D 0  and the frame-to-frame picture motion M. The relationships between D 1  and m 1  and between D 2  and m 2  are also similar to the relationship between D 0  and M shown in  FIG. 19 . 
         [0281]    The moving image determination circuit  33  determines the probability that there is a given picture motion between fields for two consecutive fields using the values M, m 1  and m 2 . When the probability detected on a pixel-by-pixel basis is written as z, the total sum Z of z over the entire display screen is assumed to be the determination result of the moving image determination circuit  33 . 
         [0000]        Z=M×m 1× m 2 
         [0282]    The larger the frame-to-frame and field-to-field picture motions, the larger Z. The first motion judder detection circuit  34  detects a pixel-by-pixel motion judder j 1  by the equation shown below. 
         [0000]        j 1= M ×(1 −m 1) 
         [0283]    The motion judder j 1  is maximal when m 1 =0, that is, when there is no picture motion between fields. The maximal value thereof increases monotonically with respect to M. 
         [0284]    The motion judder j 1  takes on a large value in a pixel where there is a picture motion between frames but no picture motion between the current and next fields. As with the motion judder detection circuit  11  according to the first embodiment, the first motion judder detection circuit  34  incorporates a calculator adapted to calculate the motion judder j 1  and an accumulator adapted to find the total sum of the motion judder j 1  over the entire display screen. The same circuit  34  outputs the accumulation result J 1  of the accumulator to the film determination circuit  36  as the motion judder detection result. The accumulator adapted to find J 1  resets the sum to 0 each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . 
         [0285]    The second motion judder detection circuit  35  detects a pixel-by-pixel motion judder j 2  by the equation shown below and outputs the total sum J 2  of j 2  over the entire screen to the film determination circuit  36  as the detection result. 
         [0000]        j 2= M ×(1 −m 2) 
         [0286]    The motion judder j 2  takes on a large value in a pixel where there is a picture motion between frames but no picture motion between the current and previous fields. The accumulator adapted to find J 2  resets the sum to 0 each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . 
         [0287]    The first threshold circuit  37  outputs 0 when the value Z which represents the determination result of the moving image determination circuit is equal to or greater than a positive constant Za. The same circuit  37  outputs 1 in any other case. When Z≧Za, there are supposed to be quite a few pixels where z&gt;0. 
         [0288]    In order for z&gt;0 to hold, the conditions M&gt;0, m 1 &gt;0 and m 2 &gt;0 need be satisfied. In a pixel where z&gt;0, therefore, there are picture motions both between frames and between fields. 
         [0289]    That is, when the output value of the first threshold circuit  37  is 0, a part or the whole of the image area is highly likely to contain a moving image of a video material. 
         [0290]    On the other hand, the second threshold circuit  38  compares the ratio of J 1  and J 2  and a positive constant λ (&gt;1). The second threshold circuit  38  outputs 1 when J 1 ≧λ×J 2  holds. The second threshold circuit  38  outputs −1 when J 2 ≧λ×J 1  holds. The second threshold circuit  38  outputs 0 in any other case. 
         [0291]    In a moving image of a telecine material, if the current and next fields are derived from the same film frame, and if the previous and next fields do not match in image content, m 1 =0 holds for many pixels. Therefore, J 1 ≧λ×J 2  is likely to hold. 
         [0292]    Conversely, if the current and previous fields are derived from the same film frame, and if the previous and next fields do not match in image content, m 2 =0 holds for many pixels. Therefore, J 2 ≧≧λ×J 1  is likely to hold. 
         [0293]    If neither J 1 ≧λ×J 2  nor J 2 ≧λ×J 1  holds, the input picture signal is probably either a still image of a telecine material or a video material. 
         [0294]    The identification circuit  39  calculates the product of the output values of the first and second threshold circuits  37  and  38  when a reference edge of a vertical synchronizing signal is received. Identification circuit  39  outputs the obtained product as the film determination result F. 
         [0295]    In the second embodiment, therefore, F takes on one of the values −1, 0 and 1. F=−1 when the output values of the first and second threshold circuits  37  and  38  are 1 and −1, respectively. As a result, it is highly likely that the input picture signal is a moving image of a telecine material and that the fields N 2  and N 3  are derived from the same film frame. 
         [0296]    Further, F=0 when the output value of the first or second threshold circuit  37  or  38  is 0. As a result, it is highly likely that the input picture signal is a video or hybrid material or a still image of a telecine material. 
         [0297]    Still further, F=1 when the output values of the first and second threshold circuits  37  and  38  are 1. As a result, it is highly likely that the input picture signal is a moving image of a telecine material and that the fields N 1  and N 2  are derived from the same film frame. 
         [0298]    The de-interlacing circuit  29  changes methods to convert the input picture signal into a progressive signal according to the value F. 
         [0299]    The motion detection circuit  40  and interpolation circuit  41  operate exactly in the same manner as the motion detection circuit  20  and interpolation circuit  21  according to the first embodiment. The same circuits  40  and  41  differ from their counterparts in that they use the field N 1 , N 2  and N 3  picture signals rather than the previous-, current- and next-field picture signals. 
         [0300]    The selector  42  selects the output value of the interpolation circuit  41  as the interpolation value when F=0, the field N 3  picture signal when F=−1, and the field N 1  picture signal when F=1, thus generating a pixel value of the scan line to be interpolated. 
         [0301]    A description will be given below of the reason why the picture signal processing device configured as described above can detect a telecine material having an arbitrary pulldown sequence using a common circuit. A description will also be given of the reason why the same device is resistant to erroneous de-interlacing even in the presence of an edit point or hybrid material while offering quick detection response without sacrificing film detection accuracy. 
         [0302]    First, a description will be given of the reason why the film detection circuit  28  according to the present second embodiment can detect a telecine material having an arbitrary pulldown sequence. 
         [0303]    In a telecine material, at least two of the three consecutive fields are derived from the same film frame. The film frames are different in image content from one another when one of m 1  and m 2  is close to 0 and the other larger than 0. As a result, Z is close to 0. One of J 1  and J 2  is close to 0, and the other larger than 0. 
         [0304]    For this reason, when the input picture signal is a telecine material, it is highly likely that Z&lt;Za holds and that the output value of the first threshold circuit  37  is 1. Similarly, if J 1  and J 2  differ significantly from each other, it is highly likely that J 1 ≧k×J 2  or J 2 ≧λ×J 1  holds and that the output value of the second threshold circuit  38  is non-0. 
         [0305]    On the other hand, when the film frames are identical in image content to one another, M=0 for all pixels. Therefore, Z=J 1 =J 2 =0. As a result, the film determination result F=0. However, a still image of a telecine material is not distinguishable from that of a video material. Therefore, such a determination does not practically pose any problem. 
         [0306]    In fact, when the input signal is a still image, selection of any of the three options, namely, the output value of the interpolation circuit  41  and the field N 1  and N 3  picture signals, will ensure proper interpolation. Therefore, the value F may be arbitrary, and film detection is not particularly required. 
         [0307]    As a result, we can say that the film detection circuit  28  can detect a telecine material having an arbitrary pulldown sequence. 
         [0308]    A description will be given next of the reason why the film detection circuit  28  according to the second embodiment can handle film detection with high accuracy. 
         [0309]    The motion judder j 1  detected by the first motion judder detection circuit  34  is large when there is a picture motion between frames but no picture motion between the current and next fields. 
         [0310]    On the other hand, the motion judder j 2  detected by the second motion judder detection circuit  35  is large when there is a picture motion between frames but no picture motion between the current and previous fields. The presence of a picture motion between frames with no motion between fields is a phenomenon typical of a telecine material. This hardly occurs in a video material. As a result, high accuracy can be achieved if film detection is based on the motion judders j 1  and j 2 . 
         [0311]    Further, the film detection circuit  28  and de-interlacing circuit  29  according to the second embodiment can quickly handle frequent switching between telecine and video materials. This is obvious considering the fact that the determination result of the identification circuit  39  incorporated in the film determination circuit  36  is always finalized in one field after the input of a picture from the input terminal  1 . 
         [0312]    The de-interlacing circuit  29  performs de-interlacing using a picture signal delayed by one field from the input picture signal. As a result, the same circuit can perform de-interlacing using the finalized film determination result. Therefore, the same circuit can quickly change de-interlacing methods according to the status of the input picture signal even if the signal status changes frequently because of many picture edit points. 
         [0313]    Further, the de-interlacing circuit  29  according to the second embodiment is resistant to erroneous de-interlacing even if the input picture signal is a hybrid material. The reason for this is that if the input picture signal may be a hybrid material, the film determination result F is set to 0 by the moving image determination circuit  33  so that the output value of the interpolation circuit  41  adapted to perform interpolation tailored to a video material is used as the interpolation value. At this time, the output value of the interpolation circuit  41  is also selected for the display screen area derived from a telecine material. However, the degradation in de-interlacing performance resulting from this is confined to the degradation in vertical resolution in the moving image area containing a vertical high frequency component. 
         [0314]    On the other hand, performing de-interlacing by assuming a hybrid material to be a telecine material causes images captured at different times to be superposed one on the other. This produces a double image artifact in the moving image area, significantly degrading the de-interlacing performance. 
         [0315]    We can say, therefore, that the de-interlacing circuit  29  according to the second embodiment is resistant to erroneous de-interlacing even for a hybrid material. 
         [0316]    It should be noted that although the second embodiment performs film detection based on the ratio of J 1  and J 2 , the same effects can be achieved by performing film detection based on the difference between J 1  and J 2 . 
         [0317]    Further, the second embodiment detects the motion judders using frame-to-frame and field-to-field picture motions. However, the motion judders may be detected using a similarity in pixel value between frames and similarities in pixel value between fields. 
         [0318]    For example, if a similarity in pixel value between frames Q is defined to be Q=1−M and similarities in pixel value between fields q 1  and q 2  are respectively defined to be q 1 =1−m 1  and q 2 =1−m 2 , the motion judders j 1  and j 2  can be calculated using Q, q 1  and q 2 . 
       Third Embodiment 
       [0319]      FIG. 20  is a view illustrating the overall configuration of the picture signal processing device according to a third embodiment of the present invention. 
         [0320]    In  FIG. 20 , the components having the same function as those in the first and second embodiments are denoted by the same reference numerals, and a description thereof will be omitted. 
         [0321]    A picture signal processing device  100 B includes, a film detection circuit  44  adapted to determine whether the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process, and a de-interlacing circuit  45  adapted to change de-interlacing methods according to the detection result of the film detection circuit  44 . 
         [0322]    The dotted line in  FIG. 20  represents the film detection circuit  44 . The area enclosed by the dotted line illustrates the internal configuration of the same circuit  44 . The frame motion detection circuit  30 , first and second field motion detection circuits  31  and  32  and moving image determination circuit  33  are the same as those according to the second embodiment. 
         [0323]    The film detection circuit  44  includes, a still image determination circuit  46  adapted to detect that there is no picture motion between frames using the frame-to-frame picture motion detected by the frame motion detection circuit  30 , a first motion judder detection circuit  47  adapted to detect a motion judder using the detection results of the frame motion detection circuit  30  and first and second field motion detection circuits  31  and  32 , a second motion judder detection circuit  48  adapted to detect a motion judder using the detection results of the frame motion detection circuit  30  and first and second field motion detection circuits  31  and  32 , a first accumulator  49  adapted to accumulate the detection result of the first motion judder detection circuit  47  in the spatial direction, a second accumulator  50  adapted to accumulate the detection result of the second motion judder detection circuit  48  in the spatial direction, and a film determination circuit  51  adapted to determine the probability that the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process. The determination results of the moving image determination circuit  33  and still image determination circuit  46 , the detection results of the first and second motion judder detection circuits  47  and  48  and the accumulation results of the first and second accumulators  49  and  50  are used to determine the probability. 
         [0324]      FIG. 21  is a view illustrating the internal configuration of the film determination circuit  51  according to the third embodiment. 
         [0325]    The film determination circuit  51  includes three film determination circuits. 
         [0326]    As illustrated in  FIG. 21 , the film detection circuit  51  includes a first film determination circuit  52  adapted to determine the probability that the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process for a global display screen area. The determination result of the still image determination circuit  46  and the accumulation results of the first and second accumulators  49  and  50  are used to determine the probability. The film detection circuit  51  further includes a second film determination circuit  53  adapted to determine the probability that the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process for a local display screen area. The detection results of the first and second motion judder detection circuits  47  and  48  are used to determine the probability. The film detection circuit  51  still further includes a mixing factor generating circuit  54  adapted to generate a mixing factor using the determination result of the moving image determination circuit  33 . The film detection circuit  51  still further includes a third film determination circuit  55  adapted to produce a final film determination result by weighting the determination results of the first and second film determination circuits  52  and  53  by the mixing factor generated by the mixing factor generating circuit  54 . 
         [0327]    The determination result of the third film determination circuit  55  is output to the de-interlacing circuit  45  as the determination result F of the film determination circuit  51 . 
         [0328]    It should be noted that the first film determination circuit  52  has the same configuration as the film determination circuit  12  according to the first embodiment shown in  FIG. 2  except that a subtractor  56  is provided which is adapted to find the difference in accumulation result between the first and second accumulators  49  and  50 . 
         [0329]      FIG. 22  is a view illustrating the internal configuration of the de-interlacing circuit  45  according to the present third embodiment. 
         [0330]    The de-interlacing circuit  45  is almost identical in internal configuration to the de-interlacing circuit  6  according to the first embodiment shown in  FIG. 3  except that the adder  23  and mixing factor generating circuit  24  are not provided. 
         [0331]    A description will be given below of the picture signal processing device according to the third embodiment. 
         [0332]    The still image determination circuit  46  calculates s=1−M using the frame-to-frame picture motion M detected by the frame motion detection circuit  30  to find the total sum S of s over the entire display screen. 
         [0333]    The first motion judder detection circuit  47  calculates j 1  as follows using the frame-to-frame picture motion M detected by the frame motion detection circuit  30  and the field-to-field motions m 1  and m 2  detected respectively by the first and second field motion detection circuits  31  and  32 : 
         [0000]        j 1 =M ×(1 −m 1)×(1 +m 2)/2 
         [0334]    j 1  takes on the maximum value when M=1, m 1 =0 and m 2 =1. These conditions are satisfied when there is a large picture motion between frames and between the current and previous fields and when there is no picture motion between the current and next fields. 
         [0335]    Similarly, the second motion judder detection circuit  48  calculates j 2  as follows using M, m 1  and m 2 . 
         [0000]        j 2 =M ×(1 −m 2)×(1 +m 1)/2 
         [0336]    j 2  takes on the maximum value when M=1, m 1 =1 and m 2 =0. These conditions are satisfied when there is a large picture motion between frames and between the current and next fields and if there is no picture motion between the current and previous fields. 
         [0337]    The first accumulator  49  outputs the value J 1 , obtained by accumulating the value j 1  in the spatial direction, to the film determination circuit  51 . The value J 1  is reset to 0 each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . 
         [0338]    Similarly, the second accumulator  50  outputs the value J 2 , obtained by accumulating the value j 2  in the spatial direction, to the film determination circuit  51 . The value J 2  is reset to 0 each time a reference edge of a vertical synchronizing signal is received from the input terminal  2 . 
         [0339]    The first film determination circuit  52  incorporated in the film determination circuit  51  feeds J 2 −J 1 , which is the subtraction result of the subtractor  56 , to the identification circuit  18 . The identification circuit  18  identifies whether the input signal is a telecine or video material using the subtraction result J 2 −J 1  rather than the accumulation result J of the accumulator  14  according to the first embodiment. The pattern comparison circuit  17  operates exactly in the same manner as in the first embodiment and outputs −β or γ. The output value of the pattern comparison circuit  17  is fed to the third film determination circuit  55  as the determination result of the first film determination circuit  52 . 
         [0340]    Hereinafter, the determination result of the first film determination circuit  52  will be written as F 1 . 
         [0341]    When F 1 &gt;0, the current and previous fields are highly likely to be derived from the same film frame. When F 1 &lt;0, the current and next fields are highly likely to be derived from the same film frame. When F=0, the input picture signal is highly likely to be a video material. 
         [0342]    The second film determination circuit  53  determines on a pixel-by-pixel basis whether the input picture signal is a telecine material using the detection results j 1  and j 2  of the first and second motion judder detection circuits  47  and  48 . 
         [0343]    More specifically, we assume the value obtained by multiplying j 2 −j 1  by a positive constant to be the film determination result. Hereinafter, the determination result of the second film determination circuit  53  will be written as F 2 . 
         [0344]    When F 2 &gt;0, the current and previous fields are highly likely to be derived from the same film frame. When F 2 &lt;0, the current and next fields are highly likely to be derived from the same film frame. 
         [0345]    The mixing factor generating circuit  54  generates a mixing factor k 3  using the detection result Z of the moving image determination circuit. Here, we assume the value obtained by transforming Z by a monotonically non-decreasing function to be k 3 . 
         [0346]    The third film determination circuit  55  outputs the absolute value and sign of F 3  obtained by the following function to the de-interlacing circuit  45  as the final film determination result F. 
         [0000]        F 3=(1 −k 3)× F 1 +k 3 ×F 2 
         [0347]    The value k 3  is monotonically non-decreasing with respect to Z. As a result, if Z is large and the input picture signal is highly likely to be a hybrid material, the value F 3  is strongly affected by the value F 2 . On the other hand, if Z is small and the input picture signal is unlikely to be a hybrid material, the value F 3  is strongly affected by the value F 1 . 
         [0348]    The de-interlacing circuit  45  operates exactly in the same manner as the de-interlacing circuit  6  according to the first embodiment except that the de-interlacing circuit  45  uses the film determination circuit F of the film detection circuit  44  rather than the value F+j obtained by the adder  23  according to the first embodiment. 
         [0349]    That is, when F 3 &lt;0, the selector  22  selects the previous-field picture signal using the sign of F 3  which makes up the film determination result F. When F 3 ≧0, the selector  22  selects the next-field picture signal. The mixing circuit  25  determines the pixel value of the scan line to be interpolated using the absolute value of F 3  as the mixing factor k 2 . 
         [0350]    The third embodiment offers the same effects as the first embodiment and allows for more appropriate de-interlacing for a hybrid material than the first embodiment. These features will be described below. 
         [0351]    The first film determination circuit  52  according to the third embodiment includes almost the same circuit components as the film determination circuit  12  according to the first embodiment. 
         [0352]    Therefore, the film detection circuit  44  according to the third embodiment can detect a telecine material having an arbitrary pulldown sequence. This makes it possible to relate the film detection result quickly to the switching of the input between telecine and video materials. 
         [0353]    Further, both the first and second motion judder detection circuits  47  and  48  according to the third embodiment detect a pixel where there is a picture motion between frames but no picture motion between the current and previous fields. This is a phenomenon typical of a telecine material. As a result, the same circuits  47  and  48  are capable of film detection with high accuracy. 
         [0354]    Still further, in the third embodiment, the first film determination circuit  52  performs global film detection whereas the second film determination circuit  53  performs local film detection on a pixel-by-pixel basis. This makes it possible to select a proper de-interlacing method for each display screen area even if a hybrid material is input. 
         [0355]    In particular, the film determination circuit  51  according to the third embodiment changes the weighting of global and local film detection according to the determination result Z of the moving image determination circuit. If the input picture signal is highly likely to be a hybrid material, the film detection circuit  51  operates so that the result of local film detection has a stronger impact. This prevents failure to detect the display screen areas derived from a video material. 
         [0356]    On the other hand, if the input picture signal is unlikely to be a hybrid material, the film detection circuit  51  operates so that the result of global film detection has a stronger impact. This prevents erroneous determination of a telecine material containing many vertical high frequency components to be a video material. 
         [0357]    It should be noted that although the second film determination circuit  53  uses the motion judders j 1  and j 2  in the third embodiment, the field-to-field motions m 1  and m 2  may be used rather than j 1  and j 2 . 
         [0358]    If the input picture signal does not contain any vertical high frequency component, the current and previous fields are highly likely to be derived from the same film frame when m 1 −m 2 &gt;0. The current and next fields are highly likely to be derived from the same film frame when m 1 −m 2 &lt;0. 
       Fourth Embodiment 
       [0359]      FIG. 23  is a view illustrating the overall configuration of the picture signal processing device according to a fourth embodiment of the present invention. 
         [0360]    In  FIG. 23 , the components having the same function as those in the first and third embodiments are denoted by the same reference numerals, and a description thereof will be omitted. 
         [0361]    A picture signal processing device  100 C according to the fourth embodiment includes the third field memory  27  adapted to delay the picture signal received from the input terminal  1  by three fields as with the picture signal processing device according to the second embodiment. The fourth embodiment differs from the third embodiment in that the de-interlacing circuit  45  uses the fields N 1 , N 2  and N 3  rather than the fields N 0 , N 1  and N 2  for de-interlacing. 
         [0362]    In addition to the configuration of the picture signal processing device according to the third embodiment, the picture signal processing device  100 C according to the fourth embodiment includes a film detection circuit  57  adapted to determine whether the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process. The picture signal processing device  100 C further includes a third field motion detection circuit  58  adapted to detect a field-to-field picture motion using the output picture signals of the second and third field memories  4  and  27 . The picture signal processing device  100 C still further includes a film determination circuit  59  adapted to determine the probability that the picture signal received from the input terminal  1  is an interlaced signal generated by the telecine process. The accumulation results of the first and second accumulators  49  and  50  and the detection results of the second and third field motion detection circuits  32  and  58  are used to determine the probability. 
         [0363]    Except for the above, the picture signal processing device  100 C is identical in configuration to the picture signal processing device according to the third embodiment. 
         [0364]    Hereinafter, the field-to-field picture motion detected by the third field motion detection circuit  58  will be written as m 3 . 
         [0365]    Although identical in internal configuration to the film determination circuit  51  according to the third embodiment shown in  FIG. 21 , the film determination circuit  59  differs from the circuit  51  in that the second film determination circuit  53  uses the field-to-field motions m 2  and m 3  rather than the motion judders j 1  and j 2 . 
         [0366]    Further, the pattern comparison circuit  17  outputs γ rather than −β when the pattern represented by the shift register  19  matches the pattern PTN 1  or PTN 2 . The pattern comparison circuit  17  outputs −β rather than γ when the pattern represented by the shift register  19  matches the pattern PTN 3  or PTN 4 . This is intended to accommodate the fact that the three fields used by the de-interlacing circuit  45  are each delayed by one field from those used in the third embodiment. 
         [0367]    As described above, the determination result F of the film determination circuit  59  is positive when the fields N 1  and N 2  are derived from the same film frame. The determination result F is negative when the fields N 2  and N 3  are derived from the same film frame. 
         [0368]    The picture signal processing device  100 C according to the fourth embodiment is configured so that the picture signals delayed by one or more fields are used for de-interlacing. This has been done in consideration of the fact that at least one field is required before the accumulation results of the first and second accumulators  49  and  50  are finalized. 
         [0369]    The third embodiment detects that the fields N 2  and N 3  are derived from the same film frame when F&gt;0. Based on this, the third embodiment estimates that the fields N 0  and N 1  are derived from the same film frame. 
         [0370]    In contrast, the fourth embodiment does not need to make such an estimation because the fields N 1 , N 2  and N 3  are used for de-interlacing. This ensures more reliable film detection. 
         [0371]    Although cases have been described in the first to fourth embodiments in which film detection and de-interlacing are performed by hardware, the present invention is not limited thereto. Alternatively, film detection and de-interlacing may be performed by software. 
         [0372]    As described above, the first to fourth embodiments are configured to perform film detection by detecting an image area where there is a picture motion between frames but no picture motion between fields. This makes it possible to detect a telecine material having an arbitrary pulldown sequence, providing high film detection accuracy and quick response at the same time. 
         [0373]    Further, the first to fourth embodiments are configured to perform film detection for both global and local screen areas. This makes it possible to determine, for each screen area, whether the input picture signal is a telecine or video material. 
         [0374]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.