| 摘要 |
PROBLEM TO BE SOLVED: To provide a noise amount measurement apparatus adaptable to a video input signal subjected to automatic gain control. SOLUTION: A luminance discrimination circuit 14 compares a luminance level of each of pixels configuring a video input signal VIN for every optional region Ai with a predetermined threshold value and outputs a detection signal DET to the region Ai if even one of the luminance levels exceeds the threshold value. A sum SUMi of luminance level differences for every multiple optional regions Ai outputted from an integration circuit 16 is given to a selection circuit 17, wherein the SUMi is compared with an output signal OUT, the value which is smaller between the SUMi and the output signal OUT is given to a register 18. The register 18 latches an output of the selection circuit 17 with a latch signal LAT received from a pulse generating circuit 22, and the latch signal LAT from the pulse generating circuit 22 is stopped when the circuit 14 outputs the detection signal DET. Thus, the sum of the luminance level differences with respect to the regions with pixels whose luminance level exceeds the threshold value is neglected and excluded from the output signal OUT of a noise amount. COPYRIGHT: (C)2007,JPO&INPIT
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