Patent ID: 8203650
Filing Date: 2012-06-19
Classification: H04N

Abstract:
1. A pull-down signal detecting apparatus comprising: a difference-calculating circuit which finds a difference between the present field signal of an input video signal and a signal delayed by one field with respect to the present field signal; an inter-field correlation determination circuit which compares the difference output from the difference-calculating circuit, with a first comparison value, adds the result of the comparison for each field, compares the result of the addition with a second comparison value and determines an inter-field correlation level; a first determination circuit which determines whether the input video signal is one of a first pull-down signal and a second pull-down signal for each field period, on pattern of consecutive inter-field correlation levels obtained by the inter-field correlation determination circuit; a second determination circuit which comprises a first counter configured to count the number of times the first determination circuit determines that the input video signal is the first pull-down signal, and which determines that the input video signal is the first pull-down signal, when the count of the first counter exceeds a first preset value; and a resetting unit which resets the count of the first counter to “0” when the first determination circuit determines that the input video signal is a signal other than the first and second pull-down signals, and which maintains the count of the first counter when the first determination circuit determines that the input video signal is the second pull-down signal, the first pull-down signal is a signal generated by converting a 24-frame-per second progressive-scan video signal representing an image composed of different frame images, to one of a 2-3 pull-down signal and a 2-2 pull-down signal, and the second pull-down signal is a signal generated by converting a 24-frame-per second progressive-scan video signal representing an image composed of frame images including consecutive identical images, to a 2-3 pull-down signal or a 2-2 pull-down signal.