| 摘要 |
PURPOSE:To obtain a key signal having good clearing, by compensating the shading with the superposition of a compensating signal having a waveform that compensates the shading. CONSTITUTION:A color selecting circuit 22 has the same structure as a conventional color selecting circuit and therefore has the same operation. The red, green and blue signals delivered from a color TV camera, etc. are supplied to input terminals 23, 24 and 25 respectively. A shading compensating circuit 26 compensates the signal which has an increment or decrement by the shading. The output signal given from the circuit 22 is clipped by a clipping circuit 27 to a set clipping level and then delivered in the form of a key signal. A shaping circuit 28 gives the waveform shaping processes such as a stretching process, an amplifying or clipping process, etc. to the key signal delivered from the circuit 27 and then converts the signal into a desired impedance when necessary to deliver it to an output terminal 29 as a key signal. |
