The availability of high quality Spatial Light Modulators (SLMs) and high-resolution cameras have made it technologically feasible to perform many optical signal-processing functions in a relatively inexpensive manner. Furthermore, recent fast algorithms have been proposed to compute Linear Canonical Transforms (LCTs), which may be used to simulate paraxial optical systems. Optical Encryption offers the possibility of high-speed parallel encryption of image data. Such encryption/decryption may involve the capture of full field information, i.e. phase and intensity. Applications of Digital Holography go beyond applications to optical encryption. They include Holographic Interferometry (metrology) and Holographic displays. In this paper we discuss the design and analysis of systems used in the capture, encryption/decryption and display of 2-D (image) data and present our recent experimental and theoretical results.