Dual spectral band network camera
The subject of this invention is the network camera sensitive to both visual and near-infrared or infrared spectral bands and comprising two or more image sensors with different spectral responses, one or more image processors, and network interfaces. In the preferred embodiment the network camera disclosed in this invention comprises two image sensors with individual optics, where both sensors have similar fields of view. In the preferred embodiment of the present invention one of the sensors is color image sensor with infrared-cut filter positioned in front of pixel array, while the other sensor is monochrome image sensor with optics characterized by lower f-number than that used for color sensor and without infrared-cut filter in its field of view. In one of the embodiments of this invention, monochrome sensor has larger pixel sizes than color sensor to provide for higher low-light sensitivity.
1. Dual spectral band network video camera comprising:
two or more image sensors characterized by distinctly different sensitivities to the intensity of illumination incident on said image sensors;
a network interface for transmitting image data streams originated by said image sensors to a communication network; and an image processor configured to monitor exposure settings of the image sensors and brightness of respective images from each image sensor, and select an image to be transmitted to the communication network based on the exposure settings and the brightness.
2. Dual spectral band network camera of claim 1 , wherein at least one of said image sensors is a color image sensor and wherein at least one of said image sensors is a monochrome image sensor.
3. Dual spectral band network camera of claim 1 , wherein all of said image sensors have substantially similar fields of view.
4. Dual spectral band network camera of claim 2 , wherein an infra-red cut filter is positioned in front of focal plane array of said color image sensor and wherein there is no infra-red cut filter positioned in front of focal plane array of said monochrome image sensor.
5. Dual spectral band network camera of claim 2 , wherein said monochrome image sensor comprises pixels with larger light sensitive area than light sensitive area of the pixels of said color image sensor.
6. Dual spectral band network camera of claim 2 , wherein said color image sensor is a high-resolution image sensor comprising more than 1 million pixels.
7. Dual spectral band network camera of claim 1 , wherein individual optics or lens is positioned in front of the focal plane arrays of each of said image sensors and wherein said optics or lens positioned in front of more light sensitive image sensor has lower f-number than said optics positioned in front of less light sensitive image sensor.
8. Dual spectral band network camera of claim 1 , wherein said network interface is Ethernet network interface.
9. Dual spectral band network camera of claim 1 , wherein said network interface supports one or more of the group including TCP, UDP, TFTP, and IP protocols.
10. Dual spectral band network camera of claim 1 , wherein said multiplexing of said image data streams is performed on a time-interleaved basis, where transmission of some portion of data stream from one of said image sensors is followed by the transmission of some portion of data stream from another of said image sensors.
11. Dual spectral band network camera of claim 1 , wherein said means of multiplexing of image data streams are configured to allow for selection of the image data streams to be transmitted off camera to be controlled from an external input.