This book covers speckle image formation using a variety of modulated apertures. The central theme revolves around theoretical analyses, specifically the calculation of impulse responses or Point Spread Functions (PSFs) corresponding to these apertures. These calculations provide crucial insights into the resolution inherent in the resulting speckle images. The book begins with an examination of the recognition of the direction of new apertures from elongated speckle images, setting the stage for subsequent discussions. The theoretical analyses extend to diverse aperture designs, including Gaussian, graded-index, and modulated apertures. The book delves into the nuanced dynamics of contrast in speckle images, exploring the Voigt distribution and the effects of modulation on contrast. In addition to aperture-centric discussions, the book addresses the processing of the formed speckle images. The chapters impart a comprehensive understanding of speckle imaging, encompassing discrimination in microscopy using digital speckle images, the utilization of concentric hexagonal pupils, and the exploration of irregular apertures. The book culminates in a detailed exploration of speckle imaging in the context of an annular Hermite Gaussian laser beam. Overall, this book serves as a valuable resource for researchers and academics seeking a profound exploration of speckle image formation, modulation, and processing across a spectrum of apertures and theoretical frameworks.