page_title: Coded aperture
section_title: Well known types of masks
hierarchical_section_title: Coded aperture / Well known types of masks
caption_attribution_description: This is an image representation of a MURA mask, with (0,1) mapped to (black, white)
context_page_description: Coded apertures or coded-aperture masks are grids, gratings, or other patterns of materials opaque to various wavelengths of electromagnetic radiation. The wavelengths are usually high-energy radiation such as X-rays and gamma rays. By blocking radiation in a known pattern, a coded "shadow" is cast upon a plane. The properties of the original radiation sources can then be mathematically reconstructed from this shadow. Coded apertures are used in X- and gamma ray imaging systems, because these high-energy rays cannot be focused with lenses or mirrors that work for visible light.
context_section_description: Different mask patterns exhibit different image resolutions, sensitivities and background-noise rejection, and computational simplicities and ambiguities, aside from their relative ease of construction.
  FZP = Fresnel Zone Plate
  ORA = Optimized RAndom pattern
  URA = Uniformly Redundant Array
  HURA = Hexagonal Uniformly Redundant Array
  MURA = Modified Uniformly Redundant Array
  Levin
caption: A rectangular MURA mask of size 101
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