PICTURE PROCESSING CIRCUIT

摘要

PURPOSE:To attain picture processing compensating fluctuation and attenuation of an input signal by detecting an amplitude of an auxiliary pulse included in the transmitted input signal and setting the obtained detecting voltage to a conversion permissible range setting voltage of an A/D converter. CONSTITUTION:An infrared ray image signal inputted to a terminal 1 is fed to a clamp circuit 2. The back porch of its input signal is clamped to 0V by a clamp pulse applied to a terminal 3, an output of the circuit 2 is inputted to an input terminal 10 of the A/D converter 8 and an FNC pulse gate circuit 4 so as to gate the FNC pulse by a pulse applied to a terminal 5. This output is applied to a pulse peak holding circuit 6 and becomes into a DC voltage and applied to an input terminal 9 for A/D conversion permissible range setting voltage VRB of the A/D converter 8 via a DC voltage amplifier circuit 7. Suppose that input information at the terminal 10 of the converter 8 is inputted while being attenuated to 80% by the attenuation of the transmission system or the like, the FNC pulse value becomes 80% and the A/D conversion permissible range is narrowered. As a result, the converter output 11 is outputted in matching with the 100% input.