Also displayed in the exhibition are some forty images charting the history of the main photographic processes from the late 1830s to the 1920s. The earliest examples are all monochrome. They include photogenic drawings by three English pioneers (Items 64, 65 and 66) and three daguerreotypes (Items 61, 62 and 63). Later monochrome processes represented are wet-collodion in its various guises, including ambrotypes and albumen prints obtained from wet-collodion glass negatives (Items 67 to 74), gelatin dry plates (Items 76, 77 and 78), and cellulose nitrate rollfilm (Items 79 and 80).

Colour photography was slower to develop. In 1861 James Clerk Maxwell demonstrated that colour images could be produced by combining three photographs of the same subject, each exposed through a different primary colour filter, but it was only in the 1890s with the introduction of panchromatic emulsions that this principle could be put into practice. On display are several such three-colour separation photographs (Items 100 to 107), the earliest being an example of F. E. Ives' 'Kromogram' from 1895 which required his own patent 'Kromskop' viewer in order to be seen properly (Item 146).

In 1868 Ducos du Hauron suggested that the three-colour method could be replaced by making a single exposure through a screen of very fine lines drawn in the three primary colours. But again it was only later that the idea was pursued, with the introduction of the Joly, Dufay, Omnicolore and Paget processes from around 1910 (Item 108 and 112 to 114). Such ruled-screen plates, however, were never as successful as emulsions containing potato-starch grains dyed in the primary colours, of which the Lumières' Autochrome plates were by far the most popular (Items 109, 110 and 111).