Understanding Correlation Techniques for Face Recognition: From Basics to Applications

This chapter covers some of the latest developments in optical correlation techniques for face recognition using the concept of spectral fusion and placing a special emphasis on its practical aspects and applications for face recognition. Optical correlation is reviewed as a method to carry out instantly a decision on the target form (form to be recognized). A range of relevant practical topics is discussed, such as JTC (Joint Transform Correlator) and the Vander-Lugt architectures. Both of them are based on the "4f" optical setup and on a comparison between the target image and a reference image. The similarity between the two images is achieved by the detection of a correlation peak. The development of suitable algorithms for optical correlation and new technologies in electro-optical interfaces has significantly improved the processing capacity of optical correlators and reduce their sizes. To overcome the limitations of a decision taken by a simple detection of a correlation peak, more complex decision algorithms are required. These algorithms necessitate the integration of new correlation filters and the realization of multiple correlations and reconfigurable multi-channel architectures