An improved normalization technique for white light photoelasticity

In white light photoelasticity, the fringe order at a point of interest is resolved by comparing the colour data with a calibration table recorded experimentally. Recently, some researchers have proposed the idea of using a theoretical calibration table if the application image is normalized. In this paper, a systematic study is carried out on the applicability of the theoretical calibration table for fringe demodulation. A novel normalization methodology is developed to improve the dynamic range in both low and high fringe density areas. It is demonstrated that while applying normalization for stretching the dynamic range, one has to use only an experimentally recorded calibration table that is normalized. Specific advantages of using colour adaptation or fringe demodulation by normalization in certain practical situations is discussed.