What is "diaphanotype"

Diaphanotype \Di`a*phan"o*type\, n. [Gr. ? transparent + -type.] (Photog.) A colored photograph produced by superimposing a translucent colored positive over a strong uncolored one.

n. (context dated English) A colour photograph produced by superimpose a translucent coloured positive over a strong uncoloured one.