In the 1830s, Charles Wheatstone proposed a theory of three-dimensional vision and invented the stereoscope. He demonstrated that a couple of two-dimensional images, each drawn from a slightly different perspective, could be recombined by the brain to provide a three-dimensional image. His original instrument, using mirrors to present one image to the right eye and a separate image to the left eye, is in the London Science Museum. The need to use highly accurate left and right images meant that, initially, only very simple line drawings of shapes, like a cube or a pyramid, could be used.
The late 1830s also saw the invention of photography. Simultaneously, Daguerre, in France, who was refining earlier work by Niépce, and Fox Talbot, in England, were developing ways to permanently fix, using light-sensitive silver salts, the optical images that are obtained in camera obscura-type devices (ie an aperture, a lens (optional) and a viewing plate). Both techniques were publically announced in 1839.
In the 1840s and 1850s, the Daguerrotype met with the greatest initial commercial success because of the preciseness of the image. Its big disadvantage, in addition to expense, was that each image was unique and multiple copies were not feasible. Talbot’s calotype process used a waxed paper negative from which multiple prints could be taken. Its key drawback was the soft focus of the early photographs, caused by the opaqueness of the negative. Scott Archer’s development of the wet collodion glass negative process, published in 1851, allowed images of a precision approaching daguerrotype levels, but with major cost advantages, especially for multiple prints. The Daguerrotype largely faded from the scene during the 1860s.
As photography developed as a commercial medium during the 1840s, it was realised that it was perfect for producing stereoscopic images and daguerrotypes were produced to be viewed using Wheatstone’s apparatus. This was achieved initially by taking one photograph, then moving the camera a few inches and taking a second. In early stereoviews, sometimes the movement of people between the exposure of the left and right images is obvious. Soon, special stereoscopic cameras were developed to take the left and right images simultaneously, with two lenses separated by around the same distance as human eyes.
In late 1840s, David Brewster greatly improved the viewer by using lenses instead of mirrors and this allowed a compact, portable device to be produced. Queen Victoria was amused by his viewer at the Great Exhibition 1851 and helped spawn a craze. Brewster claimed that by 1856 over 500,000 viewers had been sold.
In the 1850s and 1860s, it can be argued that it was stereoscopic views, along with cartes-de-visite (CDVs), that popularised photography and spurred its growth and development. The London Stereoscopic Company was probably the largest manufacturer of photographs in the world during the 1860s, with its slogan ‘a stereoscope in every home’. By the end of the 1860s, this must have been virtually true for the middle class homes of Britain.
Although its popularity ebbed, there was a second growth phase in the 1890s, with Underwood and Underwood becoming a huge publisher of images. They were eventually taken over by Keystone, who continued producing stereoviews into the 1930s.
In addition to the classic stereoview card (approx. 170mm x 80mm), several other smaller side-by-side formats emerged (particularly in France). The Viewmaster disc was probably the best known and is still produced today.
The question of how to show stereoscopic images to a large audience was more complex. A method was needed to project both left and right images simultaneously, but allowing only the right eye to see the right image. This was successfully achieved in 1858, when Joseph d’Almeida began projecting stereoscopic magic lantern slide shows using red and green filters with the audience wearing red and green goggles. This concept was later refined into the anaglyph, a single print of overlapping images in red and green/blue. This was the technique used by Hollywood for very early 3D feature films in the 1920s. Intriguingly, this is over 30 years before the introduction of stereo sound in the movies.
Colour pictures and films are rendered unsatisfactorily using coloured spectacles and the use of overlaid orthogonally-polarised images has become the method of choice for cinema display. For television and computers, as video screen technology has improved, complex eye-shuttering technology has been developed and this is vying for market share with a polarised image approach similar to cinema. Glasses-free viewing technology is available using overlapped rastered images and a lenticular screen, however, the narrow viewing-angle means that this approach is currently not suitable for audiences numbering more than one.