Pull-down detection apparatus and pull-down detection method
View Patent ↗A pull-down detection apparatus includes a pixel comparator at least performing pixel comparison between a subsequent field and a present field and horizontal pixel comparison in the subsequent field and the present field to determine a presence of a pixel change between the subsequent field and the present field, a field comparator determining a presence of an image change between the subsequent field and the present field based on a determination result in the pixel comparator, and a pull-down determinater determining that the input video signal is generated by pull-down processing based on a history of a determination result in the field comparator.
1. A pull-down detection apparatus for detecting that an input video signal is generated by a pull-down processing, the pull-down detection apparatus comprising:
a pixel comparator performing at least a pixel comparison between a first field included in the input video signal and a second field that is one-field before the first field and a pixel comparison between the first field and a third field that is two-fields before the first field to determine 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 that the input video signal is generated by the pull-down processing based on a history of a determination result in the field comparator,
wherein the pixel comparator measures a difference in pixel value between a first pixel included in the first field and a third pixel included in the third field and located in the same coordinate as the first pixel and, when the difference is less than a predetermined threshold value, the pixel comparator excludes the first pixel from the determination of a presence of a pixel change.
2. The pull-down detection apparatus according to claim 1 , wherein the pixel comparator further compares the first pixel with a second pixel contained in the second field and located adjacently over or under the first pixel.
3. The pull-down detection apparatus according to claim 2 , wherein the pixel comparator further compares the first pixel with a pixel located horizontally and adjacently to the first pixel to determine a presence of a pixel change between the first field and the second field.
4. The pull-down detection apparatus according to claim 1 , wherein the pull-down determinater changes a condition for determining a presence of a pixel change in the pixel comparator based on a history of determination if the input video signal is generated by pull-down processing.
5. The pull-down detection apparatus according to claim 1 , wherein the pull-down determinater changes a condition for determining a presence of a pixel change in the field comparator based on a history of determination if the input video signal is generated by pull-down processing.
6. A pull-down detection method for detecting that a video signal is generated by a pull-down processing, the method comprising:
measuring a difference in pixel between a first field included 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;
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;
determining a presence of a pixel change between the first field and the second field based on a comparison result between the first threshold value and the second threshold value;
compiling a determination result of a presence of a pixel change for one field and determining a presence of an image change between the first field and the second field based on the compiling result; and
determining that the video signal is generated by the pull-down processing based on a history of a determination result of a presence of an image change,
wherein the measuring of the difference in pixel between the first field and the third field further comprises measuring a difference in pixel value between a first pixel included in the first field and a third pixel included in the third field and located in the same coordinate as the first pixel, and
wherein the comparing of the difference with the second threshold value further comprises when the difference is less than the second threshold value, excluding the first pixel from the determination of a presence of a pixel change.
7. The pull-down detection method according to claim 6 , wherein the determination result of a presence of a pixel change is compiled by dividing according to pixel location in the fields and a presence of an image change between the first field and the second field is determined based on the divided and compiled determination result.
8. The pull-down detection method according to claim 6 , wherein the first threshold value and/or the second threshold value are changed based on a history of determination if the video signal is generated by pull-down processing.
9. The pull-down detection method according to claim 6 , wherein a condition for determining a presence of a image change between the first field and the second field is changed based on a history of determination when the video signal is generated by pull-down processing.