| 摘要 |
The signal processing apparatus described is particularly useful in a graphic arts process simulating system. In a preferred embodiment, the apparatus makes use of a vidicon to generate a video signal in response to light signals. A controlled iris adjusts the intensity of light signals into the vidicon in accordance with the peak value of the video signal, so that the vidicon can operate with a range of light intensities corresponding to its optimum dynamic range. Prior to the iris adjustment, a measurement of the average video signal level is made and the resulting value stored. The stored signal value is used in conjunction with the average video signal level after iris adjustment to generate a pedestal correction voltage, which is used in a clamping circuit to provide an output video signal which is representative of the true characteristics of the image. |
