document {
     Key => {image,(image, Matrix),(image, ChainComplexMap),(image, GradedModuleMap),(image, RingElement)},
     Headline => "image of a map",
     TT "image h", " -- yields the image of the homomorphism ", TT "h", ".",
     PARA{},
     "The result will be a submodule of the target of h",
     PARA{},
     "If h is a ring element, it is interpreted as a one by one matrix."
     }
