Pull-down detection apparatus and pull-down detection method
A pull-down detection apparatus includes a pixel comparator at least performing pixel comparison between a subsequent field and a present field and determining a presence of a pixel change between the subsequent field and the present field, a field comparator compiling a determination result in the pixel comparator and determining a presence of an image change between the subsequent field and the present field based on the determination result in the pixel comparator, and a pull-down determinater determining if the input video signal is a pull-down signal based on a determination result in the field comparator. The pull-down determinater changes a condition for determining a difference in pixel in the pixel comparator and/or a condition for determining a change in image in the field comparator based on a history of determination if the input video signal is a pull-down signal.
1 . A pull-down detection apparatus for detecting that an input video signal is a pull-down signal generated by pull-down processing, comprising:
a pixel comparator at least performing pixel comparison between a first field contained in the input video signal and a second field that is one-field before the first field and determining a presence of a pixel change between the first field and the second field;
a field comparator compiling a determination result in the pixel comparator and determining a presence of an image change between the first field and the second field based on the determination result in the pixel comparator; and
a pull-down determinater determining if the input video signal is a pull-down signal based on a determination result in the field comparator,
wherein a condition for determining a presence of a pixel change in the pixel comparator and/or a condition for determining a presence of an image change in the field comparator are changed based on a history of determination if the input video signal is a pull-down signal.
2 . The pull-down detection apparatus according to claim 1 , wherein if the determination history indicates a variation between detected state and non-detected state of a pull-down signal, the condition for the determination in the pixel comparator and/or the condition for the determination in the field comparator are changed so that detection of the pull-down signal becomes difficult.
3 . The pull-down detection apparatus according to claim 1 , wherein if the determination history indicates continuation of a state where a pull-down signal is detected, the condition for the determination in the pixel comparator and/or the condition for the determination in the field comparator are changed so that detection of the pull-down signal becomes difficult.
4 . The pull-down detection apparatus according to claim 1 , wherein if the determination history detects continuation of a state where a pull-down signal is not detected, the condition for the determination in the pixel comparator and/or the condition for the determination in the field comparator are changed so that detection of the pull-down signal becomes easy.
5 . The pull-down detection apparatus according to claim 1 , wherein the pixel comparator further performs horizontal pixel comparison in the first field and/or the second field to determine a presence of a pixel change between the first field and the second field.
6 . The pull-down detection apparatus according to claim 1 , wherein the pixel comparator further compares pixels between the first field and a third field that is two-field before the first field to determine a presence of a pixel change between the first field and the second field.
7 . The pull-down detection apparatus according to claim 1 , wherein the field comparator compiles the determination result of the pixel determinater by dividing the result according to pixel location in the fields and determines a presence of an image change between the first field and the second field based on the divided and compiled determination result.
8 . A pull-down detection method for detecting that a video signal is a pull-down signal generated by pull-down processing, comprising:
measuring a difference in pixel between a first field contained in the video signal and a second field that is one-field before the first field and comparing the difference with a first threshold value;
determining a presence of a pixel change between the first field and the second field based on a comparison result with the first threshold value;
determining a presence of an image change between the first field and the second field based on the determination result of a presence of a pixel change;
determining if the input video signal is a pull-down signal based on the determination result in the presence of an image change; and
changing a condition for determining a presence of a pixel change and/or a condition for determining a presence of an image change based on a history of determination if the input video signal is a pull-down signal.
9 . The pull-down detection method according to claim 8 , wherein if the determination history indicates a variation between detected state and non-detected state of a pull-down signal, the condition for determining the presence of a pixel change and/or the condition for determining the presence of a image change are changed so that detection of the pull-down signal becomes difficult.
10 . The pull-down detection method according to claim 8 , wherein if the determination history indicates continuation of a state where a pull-down signal is detected, the condition for determining the presence of a pixel change and/or the condition for determining the presence of a image change are changed so that detection of the pull-down signal becomes difficult.
11 . The pull-down detection method according to claim 8 , wherein if the determination history detects continuation of a state where a pull-down signal is not detected, the condition for determining the presence of a pixel change and/or the condition for determining the presence of a image change are changed so that detection of the pull-down signal becomes easy.
12 . The pull-down detection method according to claim 8 , further comprising:
measuring a difference in pixel horizontally in the first field and/or the second field and comparing the difference with a second threshold value; and
determining a presence of a pixel change between the first field and the second field based on a comparison result with the first threshold value and the second threshold value.
13 . The pull-down detection method according to claim 8 , further comprising:
measuring a difference in pixel between the first field and a third field that is two-field before the first field and comparing the difference with a second threshold value; and
determining a presence of a pixel change between the first field and the second field based on a comparison result with the first threshold value and the second threshold value.
14 . The pull-down detection method according to claim 8 , comprising:
compiling the determination result of a presence of a pixel change by dividing the result according to pixel location in the fields and determining a presence of an image change between the first field and the second field based on the divided and compiled determination result.