Photographic identification of objects by spectral signature - using transparencies of different spectral bands superimposed and viewed by transmitted light

摘要

A photographic method of recognising objects in a viewed area or field in accordance with their spectral signature by multi spectral photography consists of making a series of photographs in different spectral bands, esp. in black-and-white, of the same area. Those regions in the individual photographs are selected where the tone values correspond to the spectral signature of the object in the particular band. A transparent tone value extract is made photographically of each spectral band photograph, showing as transparent all the regions which have a tone value corresp. to the intensity of the spectral signature in the relevant spectral band, all the other regions being black or opaque. These transparent tone value extracts are stacked and evaluated by looking through them. This is pref. realised by stacking a marking photograph of all the super-imposed extracts.