Rapid strides have been made in the use of digital image processing techniques for data acquisition in photoelasticity in the last two decades. Techniques such as fringe thinning, fringe clustering, fringe tracing, phase shifting, polarization stepping and Fourier transform methods have significantly contributed to the automation of data acquisition. The recent developments in colour image processing and development of tricolour light source have added a new dimension. The use of time delay and integration (TDI) camera techniques has extended digital photoelasticity for dynamic analysis. Now the field of Digital Photoelasticity has matured to a level where it could be used to solve problems in industries. Apart from developments in data acquisition techniques, several methods have also come into existence for efficient processing of experimental data. Extensive use of computer graphics has found a unique place in presenting the experimental results in a meaningful way. Though there has been significant developments in data processing and data acquisition in the last two decades, there is no book available yet to present these developments in a comprehensive way. The motivation for this book is based on the experience of teaching the course on Experimental Methods in Stress Analysis at lIT Kanpur for the last 10 years. I have always felt a need for introducing Digital Image Processing in an appropriate way, which will be useful for an experimentalist.