Index of illustrations
FOR many years photographers, amateur and professional, of a scientific turn of mind, have been trying to solve the problem of colour photography.
But to reproduce the actual colours of Nature by any process at all similar to that employed in black and white photography is physically impossible, and like the problem of perpetual, motion, might as well be once and for all abandoned as insoluble. For consider for one moment the composition of a photographic print, whether silver or platinum. It is simply a deposit of the metal in a finely divided state, distributed according to the light and shade of the original object. Such a metallic deposit can only have its own peculiar monochromatic (one colour) tints, and cannot under any circumstances assume the varied colours of the rainbow.
Many attempts have been made in other ways to obtain by mechanical means photographs in colour, but, till the coming of Mr. Frederic Ives from America, very little success had been attained. This gentleman, however, has perfected a method of photography, or, rather, of recording by means of photographic films the actual colours of the objects before the camera. Through the agency of the Krõmskõp, an optical instrument designed by Mr. Ives, these records can be so arranged that when viewed through the instrument the objects photographed are presented to the eye in their natural colours, with the added realism of stereoscopic relief. In fact,they are absolutely lifelike. They may be exhibited at any time, and are permanent for all time.
The value of this invention is at once apparent. Travellers in foreign lands can bring back permanent records in colour of scenery, flowers, plumage, the costume of the inhabitants and other features of interest, which in the ordinary photograph, for want of colour, lose half their charm.
Exact reproductions of all the noted pictures of the world may be made with very little trouble and at comparatively trifling expense; a National Gallery in miniature may thus be set up in every village; and in a thousand other ways the possibility of obtaining a fixed record in colour of any desired object will prove most valuable.
In any but a purely scientific magazine, it would be out of place to enter into the technicalities of the construction or the-working theories of the camera, by which the natural colours of the objects are recorded, or of the Krõmskõp, through which these photographs are exhibited. just a general outline must here suffice.
The theory of colour-vision promulgated nearly one hundred years ago by Professor Young, and elaborated more than half a century later by Helmholtz and Clark-Maxwell, forms the scientific basis of the system to the perfection of which Mr. Ives has devoted many years.
By this theory the eye sees all colour by means of three distinct sets of organs, sensitive respectively to red, green, and blue light, or to the rays which produce the sensation of red, green, and blue. When all three are excited equally, the result is white; when mixed shades are reflected to the eye, the organs are excited unequally; where black exists in the field of view, no light is reflected and such parts are seen as black by contrast.
Light, when analysed by the prism, is seen to be made up of many colours, but there are three particular kinds of rays, red, green, and blue, which equally combine to produce white, and these correspond to the three fundamental colour sensations of Young's theory.
All the varied hues in Nature can therefore be obtained from mixtures in various proportions of the three simple colours, red, green, and blue; and if more or less of one or other of these colours be admitted, it is possible to produce every shade and every delicate graduation of colour.
How, then, is the Ives colour photograph made?
By the aid of a special camera, fitted with an arrangement of mirrors, prisms, and light filters, three pairs of images of the object are thrown on the sensitised plate at the same time. One pair is made by the red and such other rays as excite the red sensation on the eye, all other rays being excluded from this pair of images from the filtration of the light through specially tinted glass and other transparent substances; another pair is made in the same way by the rays which excite the green sensation, and the third by the rays which excite the blue sensation.
A pair of images of each colour, it may be explained in passing, is taken, so that in the viewing instrument - the Krõmskõp - the colour photographs may be observed with both eyes, and the picture consequently seen with the relief and perspective familiar to ordinary vision.
The sextuple negative having been made and developed in the ordinary way, a photographic dry plate is put in contact with it, exposed to gas light for a few seconds, and developed in the usual manner. The positive when dry is cut into three parts, and mounted in a folding cardboard frame, thus forming the Kromogram.
The three images of the Kromogram, which are similar in appearance to ordinary lantern slides, represent, by differences in their light and shade, the distribution and proportions of the three simple colours in the object photographed. These three transparencies, therefore, though themselves of no colour, form a true colour record, just as the wax cylinder of the phonograph, although emitting no sound itself, preserves the record of sound, and the Kinetoscope or Kinematograph ribbon contains the record of motion.
The cylinder must be placed in the phonograph before the sound recorded can be reproduced, the ribbon with its myriad images must pass through the Kinetoscope in order to visually reproduce the moving scene, and in like manner the Kromogram must be seen in the Krõmskõp in order to reproduce in colour the object photographed, which it does so perfectly that all suggestion of photography vanishes, and the object itself, be it flowers, fruit, portrait, landscape, or a work of art, seems to be actually before the eyes.
This wonderful effect, which must be seen to be fully appreciated, is obtained by an ingenious arrangement of mirrors and coloured glass screens in the Krõmskõp, so fitted that the three images, illuminated respectively by red, green, and blue light, are blended in such a way that the observer at the viewing lenses of the instrument sees the object in all its perfect reality of colour.
Our illustrations show the form and general appearance of the Krõmskõp and of a Kromogram. In the larger representation of the Kromogram images, the upper pair shows the amount of red, the middle the amount of blue, and the lower Pair the Proportion of green, which combine to produce one of those brilliant iridescent blue Brazilian butterflies.
There is no kind of colour which is not reproduced. in the Krõmskõp; the bloom of grapes, the velvet of the peach, the shiny red cheek of the apple are all faithfully rendered; while the iridescence of glass, the delicate shades of the opal or mother of pearl, the dull gleam of gold or silver, all of them tints most difficult to reproduce, are displayed with perfect naturalness. Nor will any colour recorded by the Krõmskõp ever fade. For time has no effect on the images of the Kromogram and light is always the same.
No special scientific skill or tedious training is required in taking the colour photographs. The operation is as simple as ordinary photography, and the development is just the same. Some practice will, of course, be necessary, but any amateur who understands the art of photography will quickly acquire the skill to successfully carry through the new colour process.
Before long there is every probability that the invention will be extended to life portraiture. The only obstacle at present to this development is the length of exposure required for portraits -- about a minute in a good light. Unfortunately but few mortals can keep perfectly still for so long a period as sixty seconds, but Mr. Ives is quite confident that sufficiently rapid plates can be prepared, and it will then be possible to have photographs of one's family and friends in the true colours of Nature and in all the reality of life.
The Krõmskõp and Kromograms can be obtained from the manufacturers, 121, Shaftesbury Avenue, London, but the camera is complicated, and will not be obtainable just yet. When certain difficulties in its construction have been overcome, simplifying its operation, and making it possible to produce the camera at a popular price, careful amateurs will be able to make their own colour photographs, and a new pleasure will at once be attainable by all who are familiar with ordinary photographic manipulation.
Colour stereograms produced from the Kromograms accompanying the article. These pictures did not accompany the original text.
For various reasons the six component pictures of each image are not perfectly aligned, by position or angle, and there is some distortion of width and height between images that should be identical, leading to colour fringing and other problems when the colours are combined.
To obtain a stereoscopic image sit well back from the screen and try to overlap the two frames by crossing your eyes.
Robert Thorpe created these pictures from the Kromagrams in December 1999, and they are a considerable improvement on my attempts to fuse the images.