发明名称 |
Black level detecting circuit of video signal |
摘要 |
A black level detecting circuit compares an input video signal with a current minimum value of input video signals, then detects a difference between the input signal and the current minimum value when the input value is smaller than the current minimum value, and then outputs the detected difference only during a detecting period of the black level, then corrects the minimum value by using this output for renewing the current minimum value, and finally outputs this renewed minimum value as a new minimum value of the input video signal. The black level detecting circuit also latches the minimum value during the vertical blanking pulse and initializes the minimum value during a vertical blanking period so as to detect a black level of the input signal. As such, the black level detecting circuit measures the black level only during a video period, thereby reducing detection errors due to noises, and also an automatic initialization of the minimum value during a blanking period can contribute to a more stable detection of the black level. The black level detected can be used effectively as a control signal over picture quality for each field or each frame.
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申请公布号 |
US5920351(A) |
申请公布日期 |
1999.07.06 |
申请号 |
US19980034020 |
申请日期 |
1998.03.02 |
申请人 |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,LTD. |
发明人 |
TAKESHIMA, MASAHIRO;KAGEYAMA, ATSUHISA |
分类号 |
H04N17/00;H04N5/16;H04N5/20;(IPC1-7):H04N5/68 |
主分类号 |
H04N17/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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