It is obvious that the paintings which have now been obtained by means of photography will show, better than any other method, the particularities and the limits of our art. The Photograph must not be merely a literal reproduction of the prosaic fact; it must be one of the means of realizing what depends on the imagination, that is to say our art, living art: such has been the only aspiration of my life. To this end, I have tried, in the following Chapters, to get photographers to think for themselves like artists, and to learn to express their artistic thoughts according to the grammar of art.(Henry Peach Robinson, preface)

From the Getty’s Atlas of Analytical Signatures of Photographic Processes... A number of collotype variants were developed and patented since its introduction in the 1860s. They include, among others, Alethetype, Autocopyist, Gelatinotypy, Leimtype, Heliotype, Indotint, Ink-Photo, Lichtdruck, Papyrotype, Photophane, Roto-Collotype, Rye’s, and Sinop. A majority of these differ in technical details that do not have an effect on the final microstructure of the printed image. Even if a typical feature of the printed microstructure is present, such as the more pronounced grain microstructure of the Ink-Photo process, it does not provide the fully reliable visual signatures needed for process identification. The collotype process variants also do not differ in their chemical signatures; the only differences are small but atypical chemical differences in the paper substrate and the stiff oil-based collotype ink. [1]