A plain paper process introduced in 1842 by Sir John Herschel. Cyanotypes did not become popular until the 1880s when low cost and easy processing appealed to amateur photographers. Professional photographers used cyanotypes to proof their negatives and decide which they would use for the final print. Introduced by several practitioners in the 1870s and designed to replace the collodion, or wet-plate, process of making negatives. Engraving The intaglio process of preparing a metal or wood surface for printing by removing material in lines or dots.
Ink is spread into the resulting indentations or furrows and the plate then used in a common press.
Halftone The process introduced by Frederick Ives and Stephen Horgan in the late 1870s that mechanically transfers photographs with text to the printed page. The orignial image is rephotographed through a screen that breaks the continuous lines of the image into a matrix of tiny dots. A photographic image consisting of two nearly identical views, made most often by a single camera with lenses placed approximately two and one-half inches apart. Introduced in England by Sir David Brewster in the late 1840s, based upon experiments by Sir Charles Wheatstone a decade earlier. When viewed with a device called a stereoscope, these twin views provided the illusion of depth.