The holographic stereogram, a hologram synthesized from ordinary stereoscopic component photographs, is investigated as an alternative to classical holograms and to previous types of stereograms for three-dimensional perfect imagery. The process is partly holographic in nature, but it provides images of naturally illuminated objects, and its application is not limited by the technology of laser illumination. The pinhole camera stereogram and the fly's eye lens stereogram are also analyzed, since the principles of their operation are similar. Pinhole camera stereogram imagery is shown to have several deficiencies, among which is the necessity for small camera-object distances. The fly's eye lens is much superior, but is limited in practice by aberrations, a difficulty which the holographic stereogram overcomes. Also treated are the full-color, the focused type, and the distortionless-scaled holographic stereogram, and optical spatial filtering of holographic stereogram images. The achromatically imaged Fresnel zone plate is analyzed as a technique of very general applicability which compensates for source incoherency in two-beam type holographic arrangements. The emphasis is on physical interpretation rather than mathematical formulation. Two simple graphical mnemonics are developed for rapid analytical inspection of the effects of, respectively, temporal and spatial incoherence of the source in any achromatically imaged zone plate or Gabor in-line type holographic system. The scalar wave function approximation of physical optics is used throughout.