Study Of Photometric Measurement System On Screen Image

Photometric property of screen includes luminance, contrast, on/off ratio and uniformity, etc. The current technology estimates the screen quality by sampling some points from the area of screen. This method is subject to sampling area limitation and fortuity, which fails to fully reflect the integrated situation of the whole screen. To detect the photometric property of screen, this thesis designs a measurement system based on area CCD as transducer for photometric property of screen.In this thesis, the following sections are introduced:1.In terms of detection methods and techniques, the current development of image detection based on CCD and photometric property of screen is presented and the feasibility of using area CCD for screen measurement is also included. In addition, we designed a photometric transducer enclosing CCD len and optical filters and the spectral response of photometric transducer must match the spectral luminousefficiency curve V(λ). In order to select the optimal optical filters and verify matchingeffect, we adopt the measurement system of spectral response performance to test the photometric transducer repeatedly. The testing results indicate that the matching accuracy of photometric thansducer reaches the national level standards.2.The photometric detection system based on DSP as core processor is proposed.We mainly analyse the CCD driving scheme, and design the driving circuit with DSP,logical circuit and vertical clock driving circuit. USB interface technology is further developed, which shows realiable performance on high speed data transmission and the portability on many application platforms.3.The software process of image photometric measure is designed, incluing in-depth research on image file and filter algorithm. By considering the special requirement of screen image measuring, a novel method introduced as area diving measurement instead of the tranditional singal point measurement. The main function modules of our system are presented in detail for reference. 4.By applying the luminance calibration based on standard luminance source, we study the separated lens structure of luminance colorimeter used in luminance calibration. Morever, we perform diverse kinds of photometric performance tests in perspectives of concrete screens and test results could satisfy the expected index in practice.In the end, future work is pointed out and the research is still ongoing.