Patent ID: 8422814

Claim:
An image quality improving apparatus, comprising: a low-pass filter circuit that extracts low-frequency components from an input video signal; a subtractor circuit that subtracts the low-frequency components extracted by said low-pass filter circuit from said input video signal to obtain high-frequency components; and an adder circuit that adds the high-frequency components obtained by said subtractor circuit as a correcting signal to said input video signal, wherein said input video signal includes blanking signals that do not contain any video information, wherein said low-pass filter circuit starts extracting the low-frequency components after a lapse of a predetermined unit time from when said input video signal is changed from said blanking signal to the signal containing said video information, and wherein said low-pass filter circuit comprises: a vertical recursive filter circuit which, based on a vertical synchronization signal that regulates a vertical period as a display period of a field or a frame of an image to be displayed in accordance with said input video signal and based on a horizontal synchronization signal that regulates a horizontal period as a display period of each of multiple horizontal lines that form said image, extracts the low-frequency components.