The use of RGB signals to provide a device for converting composite video signals and computer generated video overlay

摘要

PURPOSE: To prevent the generation of a color artifact by using auxiliary notch filters including notch filters for filtering a keying signal at the time of converting R/G/B signals into a composite video signal. CONSTITUTION: A 1st converter 20 converts a composite video signal into 2nd R/G/B signals. A 2nd converter 32 converts 1st R/G/B signals into a composite overlay signal by using notch filters 37, 38 for filtering a luminance signal in a conversion process. Combination is executed by both of 1st and 2nd switches 22, 33. The 1st switch 22 selects either one of the 1st R/G/B signals and the 2nd R/G/B signals under the control of a keying signal. The 2nd switch 33 selects the composite video signal or the composite overlay signal by using a keying signal filtered by the notch filters 37, 38.