The instrument overview provided here is the abstract from
[MALINETAL2007]; for more details, see that paper.
 
  Instrument Overview
  ===================
    The Context Camera (CTX) on the Mars Reconnaissance Orbiter (MRO)
    is a Facility Instrument (i.e., government-furnished equipment
    operated by a science team not responsible for design and
    fabrication) designed, built, and operated by Malin Space Science
    Systems and the MRO Mars Color Imager team (MARCI).  CTX will (1)
    provide context images for data acquired by other MRO instruments,
    (2) observe features of interest to NASA's Mars Exploration
    Program (e.g., candidate landing sites), and (3) conduct a
    scientific investigation, led by the MARCI team, of geologic,
    geomorphic, and meteorological processes on Mars.  CTX consists of
    a digital electronics assembly; a 350 mm f/3.25 Schmidt-type
    telescope of catadioptric optical design with a 5.7-degree fiels
    of view, providing a ~30-km wide swath from ~290 km altitude; and
    a 5000-element CCD with a band pass of 500-700 nm and 7 micron
    pixels, giving ~6 m/pixel spatial resolution from MRO's nearly
    circular, nearly polar mapping orbit.  Raw data are transferred to
    the MRO spacecraft flight computer for processing (e.g., data
    compression) before transmission to Earth.  The ground data system
    and operations are based on 9 years of Mars Global Surveyor Mars
    Orbiter Camera on-orbit experience.  CTX has been allocated 12
    percent of the total MRO data return, or about >= 3 terabits for
    the nominal mission.  This data volume would cover ~9 percent of
    Mars at 6 m/pixel, but overlapping images (for stereo, mosaics,
    and observation of changes and meteorological events) will reduce
    this area.  CTX acquired its first (instrument checkout) images of
    Mars on 24 March 2006.