Moving Picture News (Jan-Jun 1912)

12 THE MOVING PICTURE NEWS THE KINEMACOLOR PROCESS By Wm. E. Smith, E. E. ]\Iuch has been written and said both in this country and in Europe in praise of kinemacolor pictures, and but little in reference as to how they are produced and the type of machine used to project them. For the proper realization of the great advancement made by kinemacolor over the ordinary black and white pictures of motion photography, it must be clearly emphasized that the colors obtained are due to the agency of light only. No painting, brush work, stenciling or similar devices are employed. The colors are, as it were, lying latent in the photographic film and are brought into visibility at the moment of exhibition. In the older methods of color motion photography as employed by Pathe, Gaumont and others, colored moving pictures are obtained by the costly process of employing numerous girls to paint the pictures, a process often taking weeks to color, and even then only certain classes of subjects are capable of being dealt with. By the kinemacolor process the colors of nature are photographically recorded simultaneously with the taking of the picture; the complete picture with all its glowing richness of color can be exhibited within a few hours after taking. In order to give a clear and comprehensive explanation as to how this is made possible we shall have to learn how still pictures are made in their natural colors; first, we shall endeavor to learn something about light; secondly, about color and the combining of light and color: thirdly, the production of pictures in their natural colors by the aid of light alone. Light Luminous Bodies. — Bodies, like a gas jet or the sun, which emit light of their own, are said to be luminous. Light is now believed to originate in extremely minute and rapid vibrations of the atoms of matter. These vary in rapidity from about 400 billion to about 760 billion a second. The atoms of all luminous bodies are supposed to be vibrating at this enormous rate. When a body is heated its atoms are thrown into more and more rapid vibrations, and when their rate of vibration reaches 400 billion a second the body begins to become luminous. In the case of a candle flame or gas jet, these rapid vibrations are produced by the clashing of the atoms of oxygen, hydrogen and carbon as they rush into combination. A' blacksmith may heat a nail red hot by vigorously hammering it. Each blow of the hammer throws the atoms of the nail into more rapid vibration, until they finally vibrate fast enough to develop light. The number of vibrations and the wave length determine in the case of sound, the key note, and in light, the color. Ingenious experiments have made it possible to ascertain the number of vibrations of colored light, and it has been found that 400 billion impingments per second create the sensation of red, and that by increasing this number, we obtain the yellow, green, blue, and finally violet sensation which corresponds to 760 billion vibrations per second. The most important source of light is the sun, and we term its light "white," while every other quantitively different sensation of light is termed ''colored." Where sunlight passes through a prism of a spectroscope it is dispersed, and on a suitably placed white screen a colored band will be visible, this being the familiar spectrum. In the spectrum all variations from red to yellow, green and blue to violet are represented, and the question as to the number of colors in the spectrum, and the division of the spectrum into six or seven color bands is quite arbitrary. We find the sensation of "white" is caused by the simultaneous action of ether waves of different wave lengths upon the retina of the eye, and further, that white light is composed of all the colored rays visible in the spectrum. If any component is removed, the rest, although composed of different colored lights, will only impress our eye with a single color sensation. If we abstract, for instance, the green rays from white light, the remaining red, yellow, blue and violet parts will combine to form the sensation of red light. If light strikes a body it can be absorbed or reflected, or it can pass through. In most cases all three phenomena can be observed. It can. for instance, occur that the absorption is solely confined to certain wave lengths, whereas, the rest can pass or be reflected. If the reflected rays reach our eye, they will give rise to the sensation of color; the body in question cannot appear white, because one of the components of white light is absent, it will therefore appear colored. If, for instance, a glass plate absorbs all green rays the penetrating rays will make us perceive "red." This glass we will call red, because it has absorbed the green rays. Paper coated with Eosine will appear red, because the light reflected from its surface is devoid of green rays. If we cover the Eosine paper with a green, a red, or a blue glass plate and expose it to strong sunlight, the paper will be bleached under the green glass, and will retain its color under the other two. This decomposition has only been caused by the green part of the white light, and the Eosine molecules are destroyed by the impinging ether waves, and we term it green sensitive. Cyanine is orange sensitive, it bleaches only under the influence of orange rays, because it absorbs the same; chloride, iodide, and bromide of silver are blue sensitive, because they retain the blue rays and appear in the transmitted light of an orange color. The vibration theory of light has given us the following principles which are photographically of the highest importance. 1. A substance can only be chemically altered by rays which it absorbs. 2. Not necessarily every colored body must be chemically altered by these rays. 3. Every light-sensitive substance requires a certain intensity of light for its decomposition. Color The Three Primary Colors. — It is found that all possible hues of color can be obtained by mixing in various proportions the three hues, red, green and violet. Hence these three hues are called the three primary colors. By mixing the hues red and green in various proportions, all the hues from red to green can be obtained. In this admixture the proportion of the red must steadily decrease and that of the green increase in passing from red to green. By a similar admixture of green and violet we can obtain all the hues that lie between the green and violet, and of violet and red, all the hues of purple which lie between the red and violet opposite the green. FIGURE 1. Difference Between Mixing Hues and Mixing Pigments Fill two glass cells having parallel sides, one with a solution of aniline yellow, the other with an ammoniacal solution of sulphate of copper and place each in front of a projection lantern, so as to project two colored discs on a screen. One of these will be yellow and the other blue. Turn the lanterns till the two colored discs overlap or coincide. The result will be a disc of white (Fig. l). In this case the hues are mixed without any mixture of substance. Now mix the two solutions by pouring some of each into a third cell, place this cell before one of the lanterns. The disc on the screen will be green. The