Research For Measuring Maritime Background Brightness Based On Color CCD Camera

As the research foundation of light pollution on the sea, the measurement of background brightness value is necessary, however, there exist a variety of limitations of the current intensity measuring tools when dealing with the maritime background brightness measurement. With the development of color CCD camera manufacturing technology and digital image processing technology, the use of color CCD camera combined with digital image processing techniques to obtain the target field intensity distribution information has become the most simple and effective method.Nevertheless, few researches are carried out but the research on the application of measurement of light pollution on the sea.The analysis of the feasibility of using color CCD camera to measure maritime background brightness is made, based on the principle of color CCD cameras, and photometry and color theory. The feasibility of color CCD camera to use on maritime background brightness measurement is analyzed. And a detailed program for the Colorimetric calibration and brightness calibration of camera is determined.Color values of the digital image extracted by Image processing software are used in SPSS, a statistical analysis software to fit a function with the CIE chromaticity values, and color CCD camera colorimetric calibration is completed. Then, based on colorimetry and image-brightness meter principle, the same camera is taken to brightness calibration to obtain the mathematical expressions of the target luminance values based on some parameters of the camera combined with digital image color finally.Through field measurements, with the target brightness value measured by Standard brightness meter as the standard value, the precision analysis of luminance values obtained by color CCD camera is made. The result shows that the accuracy of this system is high and the feasibility of using a color CCD camera maritime background brightness measurement is confirmed.The error sources which may have a great impact on the measurement accuracy of the measurement system are analyzed, and the methods to eliminate or reduce error to improve the accuracy of measurement system are given.In summary, the method of color CCD cameras as maritime background brightness measurement tools is applicable, the accuracy of which is relatively high.