| 摘要 |
PROBLEM TO BE SOLVED: To provide an interphone system capable of detecting a brightness of a surrounding environment of a visitor or a house entrance in real time, and precisely adjusting the brightness in response to the detection result, thereby enhancing visibility of an output video and giving no discomfort to the visitor.SOLUTION: Depending on a difference between light-on and light-out states of an infrared illuminating lamp 120 to be lit for a prescribed time when calling from an entrance slave unit to a room master unit 2, a contour detection part 104 detects first and second contour information held by a video signal generated by a video imaging part 101. According to a comparison result between a degree of approximation calculated by a comparison part 105 on the basis of the contour information, and a preset threshold value corresponding to the degree of approximation that enables identifying a photogenic subject or a visitor, any of the following controls is repeatedly conducted until the degree of approximation agrees with the threshold value: an AE control for the video imaging part conducted by a video image control part 106; a frame rate control; and a while light control for gradually adjusting the brightness level of a white illuminating lamp 121. |
