Daguerreotype
It is said that Daguerre has found the means to collect, on a plate prepared by him, the image produced by the camera obscura, in such a way that a portrait, a landscape, or any view, projected upon this plate by the ordinary camera obscura, leaves an imprint in light and shade there, and thus presents the most perfect of all drawings ... a preparation put over this image preserves it for an indefinite time ... the physical sciences have perhaps never presented a marvel comparable to this one.
A further clue to fixing the date of invention of the process is that when the Paris correspondent of the London periodical "The Athenaeum" reported the public announcement of the daguerreotype in 1839, he mentioned that the daguerreotypes now being produced were of considerably better quality than the ones he had seen "four years earlier".
Hand-colouring of photographs
In an attempt to create more realistic images, photographers and artists would hand-colour monochrome photographs. 
The first hand-coloured daguerreotypes are attributed to Swiss painter and printmaker Johann Baptist Isenring, who used a mixture of gum arabic and pigments to colour daguerreotypes soon after their invention in 1839. Coloured powder was fixed on the delicate surface of the daguerreotype by the application of heat. Variations of this technique were patented in England by Richard Beard in 1842 and in France by Étienne Lecchi in 1842 and Léotard de Leuze in 1845. Later, hand-colouring was used with successive photographic innovations, from albumen and gelatin silver prints to lantern slides and transparency photography.