Video signal processing circuit

Abstract

Abstract PURPOSE: To remove the variance in black level, by detecting and storing the level of most black side among input video signals and the level more black side than a given level, and converting the video signals so that this level is in matching with the black level. CONSTITUTION: The video signals fed to an input terminal 1 are fed to a peak hold circuit 6 via a clamp circuit 2, blanking circuit 4 to produce the hold output S 3 corresponding to the most black side peak level within the video period. Since this hold output S 3 is connected to the potential point of V o +V t via a diode 7, it is clamped with the magnitude of V o +V t . Further, the video signal S 1 from the clamp circuit 2 and the hold output S 3 are compared at a comparison circuit 8, and one signal being the white side level among both the signals S 1 and S 3 , is output and fed to a clamp circuit 9. Further, the average level of video signal is detected at an average video level detection circuit 12 and the voltage v t is made variable according to this output. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Atsushi Matsuzaki
• 👤 Mitsuo Kawamata

Bibliographic Details