Research On Measuring Method Of Luminance Based On CMOS Digital Camera

The use of digital imaging technology to measure the luminance of target objects has a wide range of applications in display product quality inspection,lighting technology measurement,and highway and tunnel luminance inspection.Compared with the traditional single-point luminance measurement technology,the image luminance measurement technology based on digital cameras has the advantages of short measurement time,high efficiency,and strong practicability,but its low measurement accuracy limits its further application.Therefore,it is of great practical value to examine how to improve the accuracy of imaging method luminance measurement.According to actual application requirements,based on extensive review of domestic and foreign related documents and market research,this paper analyzes the principle and structure of digital cameras,and derives the formula for the transmission of radiation energy in the central field of view of the optical imaging system of digital cameras;In the photoelectric conversion and signal processing process,the relationship between the output gray value of the image sensor and the brightness is obtained,and the theoretical calculation formula of the digital camera to measure the brightness is finally derived.In order to verify the correctness of the theoretical derivation,this subject designed a CMOS digital camera,introduced the camera design scheme,the selection of the main device and the peripheral circuit design of the corresponding device,and made a prototype of the digital camera and wrote the corresponding software,tested the basic functions of the digital camera.On this basis,an experimental device was built,which consists of an integrating sphere,a monochromatic LED light source,an optical guide,a standard luminosity meter and a digital camera.The control variable method was used to investigate the relationship between the gray value of the digital camera output and the luminance,the measuring distance,the exposure time and the wavelength of the light source.The experiment verifies the accuracy of the theoretical formula proposed in this article for measuring the luminance of digital cameras,and provides theoretical and experimental support for improving the accuracy of measuring the luminance of imaging techniques.