Patent ID: 7728908

Claim:
A pull-down signal detecting apparatus comprising: an interfield motion detecting module that determines whether or not an input image is a moving image by comparing a present field signal of an input video signal with a 1-field delay signal thereof by a block unit formed of small areas, and performs interfield motion determination by comparing an interfield motion block number determined as the moving image with a reference threshold value; an interframe motion determining module that determines whether or not the input image is a moving image by comparing the present field signal of the input video signal with a 2-field delay signal thereof by a block unit formed of small areas, and performs interframe motion determination by comparing an interframe motion block number determined as the moving image with a reference threshold value; a determination module that determines that the input video signal is a pull-down signal when the determination result of the interfield motion determining module and the determination result of the interframe motion determining module both coincide with a pull-down pattern; and a threshold value correcting module that changes the reference threshold value of the interfield motion determining module to correct interfield difference caused by shift of interfield vertical phase, when the determination result of the interframe motion determining module coincides with the pull-down pattern while the determination result of the interfield motion determining module does not coincide with the pull-down pattern.