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1. A photomechanically produced plate for pictures or type made by exposing a gelatin film under a negative, hardening it with chrome alum, and printing directly from it.
2. also he·li·o·typ·y (-tī′pē) The process of producing a heliotype.
he′li·o·typ′ic (-tĭp′ĭk) adj.
the process of making pictures by printing directly from gelatin film that has been exposed under a negative and fixed with chrome alum.See also: Photography