Popular Science, helmikuu 1923
By Thomas Elway
How an Invertor, by Ingeniously Combining Blue-Green and Red-Orange on Double Photograph, Tricks Our Eyes into Seeing Delicate Shades of All Colors, Vividly Representing Life
When I was told, a few weeks ago, that another new process for taking motion pictures in color had been "perfected," I confess I smiled skeptically to myself.
I had seen many colored movies before. They had left me either unimpressed or thoroughly displeased.
To be sure, I knew that this new method had been invented by a scientist of distinction - Dr. Daniel Frost Comstock, of Boston - and that 10 years of patient research and experiment had gone into its development. I was told that more than $1,000,000 had been spent upon these experiments; that the enterprise had the financial backing of no less a figure than William Travers Jerome, former District Attorney of New York, and that artists and motion picture experts who had seen the film hailed it as a phenomenal improvement, charming in its colorful realism, lessening etestrain, and destined to revolutionize motion picture work.
Here is an exact-size reproduction of a section of the new color motion picture feature film, "The Toll of the Sea," starring the young Chinese actress, Anna May Wong. This lifelike move made possible by the remarkable color process invented by Dr. Daniel Frost Cornstock (inset), is called by the artist, Maxfield Parish, "highly successful from a color point of view and an invention with endless possibilities - a revolution in the moving picture art"
A Colorful Dream Comes True
And, finally, I had fully shared the great dream of motion picture enthusiasts during the past decade - the dream that the movies some day would be shown to us in all the beauty of natural color, enhancing enormously the power of their appeal.
Nevertheless, I did not realize the art had advanced far enough to make this dream a reality. But when I witnessed the private exhibition in New York of this new colored film feature - a play called "The Toll of the Sea," starring the young Chinese girl, Anna May Wong, whose fame has begun to spread eastward from California - I was frankly surprised by the unexpectedly high quality of the color work. Here was a film in which colorful costumes and feminine beauty moved convincingly across the screen, with slight trace of the garishness, flicker, and distracting color fringes that have hurt so many other color films.
Not that this color work is perfect. Some of the reproductions of blues and green are bad. The yellows are even less satistying. But this motion picture does constitute, to my mind, the best color work done so far in the films, and the process used, the new Technicolor process, promises still better things to come. For the first time I have begun to expect something really big from color photography on the screen, something that will affect the fundamentals of motion picture art. It isn't only that we may expect enhanced charm of settings, and still greater beauty of feature in out heroines; or that we shall see them blush real blushes, as we now see them weep real tears; that expressions will be more lifelike, costumes more fascinating, natural scenery more magnificient.
A successful color movie can do something much more fundamental than this. It can give us not merely an improved art, but a new art; a new kind of dramatic production, differing from the present productions in black and white as completely, perhaps, as these differ from the productions of the spoken stage.
How can this be? Because color alone, pure color, has a powerful appeal to the human mind. This is always the great aim of drama - to seize on the emotions, to contrive that you are completely "carried away" by the thrill, sentiment, joy or sorrow of the play.
Light Rays Split and Filtered in New Color camera
This diagram explains in simplified form the ingenious process of color movie phorography perfected by Dr. Daniel Frost Comstock and fully described in the accompanying article. Two phorographs of an object, such as the flag shown above, are taken at the same instant through the single lens of the movie camera. Incoming light is split in half by a perforated mirror just back of the lens, one half being led through a color filter that allows only blue-green light to reach the film negative, the other half led through a second color filter that allows only red-orange light to pass to the film.
Thus the film negative of the flag, shown at the right (slightly reduced), consists of a succession of double images, alternating blue-green and red-orange impressions, but still in black and white. In the positive print of this negative, the blue-green and red-orange images are superimposed, one on the front, the other on the back of the positive film. The positive film then is dyed, the blue-green images taking blue-green dye and the red-orange images red-orange dye.
When projected on the screen, the film gives the effect of reproducing all the original colors of the flag in their natural shades.
There is no doubt that color has this appeal. Red excites and stimulates us; green is restful and sedactive. To play on people's minds with color as we now play on them with moving images or written words, will require, of course, a completely new kind of directing. There will be new lighting, new make-up, a new technique of screen acting.
But first there is a scientific problem - Can it be done? Is the color movie an accomplished fact?
As yet we cannot say that it is. But we can say that it promises to be. The new process we are discussing is a long step toward the fulfilment of this promise.
George Fitzmaurice, Movie Producer, Says: "As to whether color photography will enchance the dramatic quality and realism of the picture - that is rather hard to tell. I cannot see where natural color will detract from the drama so long as the color remains neutral and unobtrusive.
"Still, I think that the great progressive step will be taken when stereoscope photography has been fully developed. And the millennium will come when stereoscopy and color combine to produce the perfect whole.
Rupert Hughes, Motion Picture Writer, Says: "It seems to me that color processes in motion pictures will probably follow the same line as in book and magazine illustration: for certain special effects they will furnish great charm, richness, and contrast, but for general use the singletone pictures will enormously prevail. It would be ridiculous to deby the beautiful possibilities of occasional color, though I cannot believe that it will ever drive the monochrome, or one color, process off the screen."
A College Professor's Vision
This process is a professor's dream come true. Ten years ago, Dr. Daniel Frost Comstock was a professor of physics in the Massachusetts Institute of Technology. He knew a good deal about color photography. He dreamed of applying it to motion pictures. With Mr. Herbert T. Kalmus, his partner in an engineering firm, he went to work. They began experiments. They organized the Technicolor Company and gathered a group of able scientists and engineers.
For years the experiments failed. Finally, success began to come. One by one the worst of the technical difficulties were overcome: the difficulty of taking two pictures at once through the same lens; the difficulty of finding the two dyes that were exactly the right ones to use in coloring the film after it had been photographed; the many difficulties that came from the extreme weakness of the light after it had passed through the complicated system of lenses and prisms required for the color camera. Film schrinkage, too, was overcome and the many other obstacles that stood in the way of making the two differently colored images fit exactly one on top of the other when they came to be printed on the same strip of film.
Probably you have heard color photo-graphs described as "two-color" or "three-color." Doctor Comstock's films use only two colors to produce the effect of six. To understand what this means, we must recall a few facts about the nature of color and about color vision.
Ordinary white light like sunlight is made up, you remember, of six primary colors: red, orange, yellow, green, blue, and violet. You can prove this by putting a glass prism into a beam of sunlight, and noting how it splits the white light into a strip of these colors, a spectrum. You see them in a rainbow.
White light is believed to be made up of waves or vibrations of various lengths, each wave length producing a distinct color sensation. Red light from a red glass lamp globe looks red because the waves producing the other five color sensations are held back by the red glass. The orange, yellow, green, blue, and violet waves are absorbed. Only the red waves get through. Similarly a blue globe lets through only blue light, and so on. A red paint or dye is merely a substance that reflects only red ight, absorbing all the others. A yellow paint reflects only yellow light, etc. These are the physical fundamentals of colors.
Facts Explaining How We See Color and How Color Screens Work
Scientists believe we detect colors through minute, sensitive nerve endings, called "rods" and "cones," in the membrane of the retina behind the eyeball. These nerve endings (shown in highly enlarged cross section at upper right) transmit light stimuli to the brain.
How our Eyes Mix Colors
But this color theory is partial. It leaves out the human eye. You look, for instance, at an apple. Something happens in your eye. You have a sensation of redness, and impression that the apple is sending red light into your eye.
This seems straightforward enough. The eye, you say, must contain some mechanism able to perceive red light as such, able to sort out the light of the six different primary colors and recognize each color by itself. What could be simpler?
It is simple, true enough, but it is not what happens. Make an experiment. Take some yellow paint and some blue paint and mix tehm. What do you get? You get green paint.
This fact is so familiar that we are apt to forget how startling it is. Think for a moment of what it really means. There are six primary colors. These are separate physical things - different kinds of light. You mix two of them, yellow and blue. You do not get a mere mixture, a yellowish blue or a bluish yellow. You get a third promary color, totally different from the yellow and blue, another one of the original six!
What is the explanation? Simply this: The mix-up is in the human eye. The eye does not perceive the six primary colors separately and individually. It confuses and blends them in a very complicated way.
Marcus Lowe, Owner of 75 Theaters, Says: "I recently witnessed a showing of a colored moving picture of the Chinese story called, 'The Toll of the Sea,' which was shown by Judge William Travers Jerome. I thoroughly enjoyed the picture and consider the process highly successful.
"The picture was made far more effective and convincing by the soft, wonderful coloring."
Charles Dana Gibson, Artist-Illustrator, Says: "I have see nall the color processes so far, and the new process represented in the picture, 'The Toll of the Sea,' is far and awat tge best. The effect is convincing and most restful to the eyes and altogether irresistible.
"I am looking forward to seeing the picture again.
"It is my belief that this new process will revolutionize the motion picture industry."
Green Isn't Green
Take, for instance, out mixture of yellow and blue paint. Put this in front of a spectroscope, and analyze the light from it. You get yellow light and blue light - no green light at all. Physically, the mixture of paint reflects just the lights that the two separate paints did. The blending of these lights to make green is done, somehow, in the eye. The eye is fooled. It really sees blue plus yellow. It thinks it sees green.
There are innumerable other ways to fool the eye on colors. For instance, mixed red and green (of the proper tints) look white. Certain yellows and certain violets, when mixed, also look white. The eye is simply unable to distinguish between a red-green mixture that looks white, a violet-yellow mixture that looks white, and a true white containing all six spectrum colors.
The theory for all this is very uncertain. In the membrane that lines the back of the eyeball - the retina - there are two kinds of minute nerve endings - the rods and the cones. It is supposed that we detect colors through the sensitiveness of these nerve endings to different light vibrations. It used to be believed that the rods saw red and green and the cones saw blue and yellow. This was disproved. Then it was believed that the cones saw all colors, while the rods saw only light intensity, that is, differences between light and dark. Now even this is doubtful. The plain fact is that we don't know how we see. We know only that the mechanism is extremely complicated, that color vicion is especially so, and that, somehow or other, the nerve endings in the retina are variously stimulated by various lengths of light, and transmit the stimulus to the brain, where the consequent perception of varying colors is produced.
But perhaps you are asking what all this has to do with color movies. It has everything to do with them. Color movies are possible at all only because we are able to fool the eye about colors.
The new Technicolor process, for instance, is a "two-color" process. This means merely that we dye the films with two colors only, but by mixing them in different proportions we are going to try to represent all colors. A mixed red and green, you remember, will look like white. We are going to extend this. We are going to choose two colors, make various mixtures of these two colors and fool the eye, if possible, into thinking that it recognizes in these mixtures all of the six primary colors.
The best proof that this can be done is that it has been done. As you view a two-color film like "The Toll of the Seam" you think you see all the colors. With a few exceptions to be noted later, the eye is fooled successfully enough.
How Constance Talmadge Would Make Up for Color Movies
On the right side of this popular star's portrait are indicated the points in her make-up for black-and-white movies. See how entirely different is the make-up she will be likely to use in color movies, indicated on the left side of the picture. This probable make-up s based on results of recent experiment.
In this particular feature, as in most other color movie processes, the two colors selected are a reddish orange and a bluish green. These colors are represented by two dyes, carefully chosen from more than 200 dyes that were tried. As I shall explain later, the original photograph consists of two separate images. One image, printed on one side of the film used in projection, is dyed blue-green; the other, printed on the reverse of the film, is dyed red-orange. Where the images overlap, these dyes blend. In projection onto a screen the light is colored byt the dyed images, the colors blend likewise, we see both images together, and the eye does the rest.
What we really see are various shades and mixtures of blue-green and red-orange. What we think we see are all the colors of the spectrum. It all depends upon the capacity of the eye for being wrong about colors. it is just like the rabbit that you think you see coming out the conjurer's hat.
This is what the two-color photograph is, but how is it taken? In exactly the same way. You take two photographs at the same time, one through a screen that lets pass only the blue-green color, absorbing all others; the second through a screen that abdorbs all but the red-orange. Suppose you are photographing a red and blue dress. The red parts "take" only on the photograph made through the red-orange screen. They will not show on the other photograph. The blue parts, on the other hand, take only through the blue-green screen. Now we dye one phorograph red-orange and the other one blue-green. The first represents the red parts of the dress, the second the blue parts. We put them together, one on top of the other (of course both are transparent), and we have a color photograph of the dress.
All this is simple enough, but when we come to apply it to motion pictures, there are difficulties. The greatest is to discover some way of taking two photographs at the same instant, through the same lens.
This problem Doctor Comstock solved in a very ingenious way. Just back of the lens of the camera he placed a silver mirror with holes in it. Half of its surface is polished silver, the other half is holes. It stands at an angle of 45 degrees to the beam of light. What happens to the light can be seen immediately from the diagram on page 59. One half of the light is reflected at a right angle. The other half goest straight on. The light beam from the lens is thus split into two beams, exactly alike. One of these beams is led through the blue-green color screen, to make the blue-green image at one point on the film. The other is led through the red.orange screen and makes the red-orange at the same instant on a lower portition of the film. Then the film moves and two new images are made again, one above the other.
The film consists, then, when removed from the camera and developed, of a succession of double pictures (one below the other) all still in black and white. One picture of each pair corresponds to a blue-green image, the other to a red-orange image. This film, of course, is a negative.
The next step is to make the positive print from this negative. On this print the pair of images taken at the same instant and that are separate on the negative must be brought together and superposed. The blue-green one of a pair is printed on the front of the positive film, the red-orange one is printed on the back of the same film. They must now be dyed.
In this process the positive film is run through one dye bath that contains in solution the blue-green dye and the red-orange dye. The dyes are taken up selectively by the two images on the film; the blue-green dye "takes" only on the blue-green image; similarly, the red-orange colors only that image.
The result of this selective dyeing is a colored positive print ready for projection.
Aside from the technical difficulties involved win the perfection of color movies, there remain other sill more interesting problems - problems of directing, of acting, of the psychology of audiences. At present the movie actress's make-up, for instance, is a horrible looking mess of yellow cheeks and blue chin and forehead; blues for what is to be white, yellow for healthy flesh. For color movies all this must change.
An effective make up, I believe, may prove to be greenish or violet, with reds inclining to orange, instead of the yellows and blues now used. Certainly, when the color movie make-up technique is so perfected as to simulate a beautiful star's natural color of complexion, hair and eyes, we shall have more fascinating photo plays than ever.