A Color Calibration Method for Multispectral Camera of Long Focal Length and Large Aperture

With the development of technology in remote sensing, a lot of multispectral cameras with large aperture and long focal length are widely applied. The traditional color calibration method is no longer applicable for this kind of cameras. A new method of color calibration is introduced. The lighting system of this method is composed of integrating sphere, transmission color standards and collimator. Incident light of different colors can be provided by the system, and the chromaticity coordinates can be measured. There are many adjustable parameters for cameras, for example, gain, integral stage and integral time. The digital number (DN) values of different wave bands can be changed by adjusting these parameters. In this paper, the mathematical model is established by relating the RGB values after color synthesis with equivalent radiance incepted by each wave band of the camera. The difficulty caused by many adjustable parameters which can change the DN values of the camera can be avoided in this way. In this method, the chromaticity coordinates of incident light from the source system must be tested accurately . This method can be used in the space field.