| 摘要 |
PURPOSE:To obtain the detection level of maximum sensitivity by having multiplication between the detection level of a chroma detecting circuit obtained by processing the output of a function converting circuit and the output of a compensation quantity converting circuit. CONSTITUTION:The function converting circuit 22 supplies both color selection control signal theta and a sampling range control signal + or -alpha from a color selection input terminal 11 and a sampling range control input terminal 12 respectively and are then converted into the product signal of sine and cosine functions to theta+ or -alpha. A chroma detecting circuit 21 supplies R-Y and B-Y signals from an R-Y input terminal 1 and a B-Y input terminal 2 respectively and then performs processing with an output signal supplied from the circuit 22 to obtain a detection level (b). A compensation quantity converting circuit 24 produces a compensation quantity from the signal alpha sent from the terminal 12. A multiplying circuit 23 performs multiplication between the level (b) and said compensation quantity to obtain the detection level (a) of the maximum sensitivity. A chromakey signal processing circuit 26 supplies the signal (a) and converts it into a chromakey signal of a rated level to deliver it through a chromakey signal output terminal 4. |
