US1407875A - Color cinematography - Google Patents

Description

T. A. MILLS.

COLOR CINEMATOGRAPHY.

APPLICATION FILED NOV:13. 1920.

Patented Feb. 28, 1922 UNITED STATESPATENT OFFICE.

THOMAS ALBERT MILLS, OF CLAIPHAM, LONDON, ENGLAND, ASSIGNOR TO ZOECHROME LIMITED, 01? LONDON, ENGLAND, A BRITISH COMPANY.

To all whom it may concern the following is a specification.

This invention relates to an improved method of producing cinematograph films of the type in which each individual picture or element of the film is a complete color rendering of the subjects According to this invention there are produced uponthe negative film (by'the aid of suitable color screens) a set of images of full or normal size which will be referred to hereinafter as key images and interposed sets of small sized color giving images, each preferably of half the linear dimensions of a key image. The small color giving images may be three "in number, corresponding to the usual triple division of colors, and the key image taken without a color screen so as to give the black and white effect only. Or the key image may also be a color image, giving say the blue in' the resulting positive film, either alone or, by a double printing, the blue anda similar black and white ortrue key image, and only two small images may be produced. Each key image and its asso;

ciated small images are taken simultaneously through separate lenses and, as the lens for the large image has to have a correspondingly greater focal length and if employed to give a direct imagewould form an obstruction for the small images, the increased focal length is preferably provided for by a prism or other reflector, allowing all the,

lenses to lie in the'same plane. This displaces the key image from its corresponding colorimages and therefore between the key' and color images of oneexposure. are interposed the key and color images of other exposures.

the original negative the latter is moved at each operation through. a distance equal to a key image and the following small color images,

closlng up the key images on the positive film so thatthey are reproduced in succession without the interposition of the color images, these being afterwardsenlarged and superposed. The reproduction, if the key image is to be in one of the colorsemployed,

COLOR CINEMATQGRAPHY.

k Specification of Letters Patent. Patented F b 28 1922. Application filed November 13, 1920. Serial No. 423,961.

say blue, is suitably colored or dyed, but if the key image is black and white the usual process only is employed. Or the same large image may be reproduced twice, once as a black and white image and once in color. The reproduced key film is then coated with a. sens1t1ve emulsion andone of the color sets of images is then enlarged to the key size and superposed upon the 'key images, the new positive 1mages being colored to the required color, complementary. to that of the color screen employed for the negative. The next set of color giving pictures is similarly superposed and, in the case of'the process employing black and white key images and three colors, the third set of color images is then superposed, with the result that the finished film is a complete color renderingof the subject and can be pro ected by the usual apparatus upon the screen. The apparatus employed for producing the positive may be of the type descrlbed in the specification of British Patent No. 16353 off-1913 (Middleton). It is to be understood that the term key image is used in a wide sense as the image which is 01']. lnally taken of full sizeand thus serves as t e most important image in giving defini= t1on to the picture, but it is not necessarily an opaque or black and white image in the positive picture.

In order that the said invention may be clearly understood and readily carried into effect, the same will be more fully described with reference to the accompanying drawings, in which Figure 1 is a diagram illustrating theproduction of a negative having a set of key images and three sets of color giving images; an

Figure 2 is a similar diagram illustrating the casein which the key image is also one -of the color giving images.

are the camera lenses, of which the larger lens D is of twice the focal length of the smaller lenses D. E is a prism reflector. The lenses are arranged as shown at the right of the figure, the small lenses forming an invertedtriangle belowthe large lens. The reflecting prism E is arranged so that placed in the same plane. The shutter mechanism and thecolor screens are not shown as they may be of ordinary type.

In Figure 2 the key pictures B are produced by the aid of a color screen, say red,

and instead of separating the images by a full picture width as in Figure 1 the separation is of half a picture width only, to accommodate a pair of small color images C taken through the two other, color screens of the set of three. placed symmetrically below the large lens D. Otherwise the arrangement is'as in Figure 1, and the prism reflector E doubles the distance of the path from the lens D to the film.

In producing a positive from the negative film as shown in-either Figure 1 or Figure 2 the key image is thrown-upon the positive film and the negative film is moved for each exposure in the apparatus through the space of two pictures or a picture and a half according to whether the arrangement of Figure 1 or Figure 2 is employed, the positive film being moved one picture space at a time. The positive film with the key images on it is then developed and fixed and may be varnished before sensitizing again. If

the key image is also a color one the positive film is colored to, say, blue. Or a black and white key image may be used and a second printing from the large images taken and colored.

The resensitized positive film is again exposed and' the enlarged images of one of the sets of small color images superposed upon the key images. The lens system employed for copying is arranged to give the required enlargement, while for the key pictures, the original and reproduced images are of substantially equal size. The images B and O having been relatively displaced by the action of the reflector, the color images superposed must be those separated by the intermediate images, as indicated by the dotted lines in the drawings, so that the color images shall be those taken by the same exposures as the key images on which they are superposed. The positive film is colored and resensitized again for the second color set, the operations being repeated where a key Cpicture and three small pictures are employe as in Figure 1. The final result is a positive film fully colored and adapted to be projected by the usual pro- The small lenses D are jecting apparatus. The three color system has been taken as the basis of the method described and illustrated, but it is obvious that other color systems may be used.

Owing to the fact that the key images and the color images are taken simultaneously the original film should be moved more rapidly than is the case with an ordinary film, since the space of two or of one and a half ordinary pictures has to be covered between each exposure, while the colored positive is moved at the normal speed for projection. Since the key image is of full size the projection on the screen gives a clearness of impression substantially as good as that of the ordinary uncolored picture. To obtain this clearness it .is not essential that the color producing images should be so sharp,

so that the smaller scale, on which they are taken does not materially affect the sharpness of the result and the great advantage is obtained that the color effect is given by an addition to the length of the negative film of only 50 or 100 per cent according to the color'system employed. The disturbing rainbow efi'ect produced when color-images are taken successively is also entirely eliminated by the slmultaneous exposure of a complete set of images.

lVhat I claim and desire to secure by Letters Patent of the United States is 1. A method of making einematograph films which consists in producing upon the negative film a set of full sized images with small sized interposed images by simultaneous exposure of a. full sized image and associated small sized images and producing from the said negative film a positive film by superposing in succession upon the said positive film the negative images, all brought to the said dimensions, and suitably color ing the different superposed positive images, for the purpose specified.

2. A method of making a negative film for the production of acolored cinematograph positive film, which consists in producing a succession of alternating key images of. full size and color giving images of small size, A

by a system of lenses and color screens, and providing for the greater focal length required for the full sized images by reflecting the beam between the corresponding lens and the film.

3. A method of making colored cinematograph films which consists in producing upon a negative film a succession of full sized key images and interposed small sized color giving images whereby a plurality of color giving images occupy the length of film not greater than that of a single key image, reproducing from the negative film a positive film by moving the negative film in the posi- 'tive producing apparatus in steps equal to a one image at a time, repeating the succession of reproducing operations for each color employed and enlarging the small sized color giving images of the negative film to the same size as the key images on the positive film, and, after a complete exposure of the positive film, coloring the positive images re-sensitizing the said film and producing a fresh set of images which are also colored repeating the operations until the complete colored picture is obtained. c,

l. A negative vcine matogra-ph film for the production of a colored positive film, which negative film comprises a. succession of key images of full size along with a simultanea ously taken succession of color giving images of small size, whereby a plurality of color giving images-occupies a length of film not greater than that of a single key image, for the purpose specified.

5. A negative cinematograph film for the production of a colored positive film, which negative film comprisesa' succession of key images of full size along with a simultaneously taken succession of color givingimages of half size, whereby a plurality of' color giving images occupies a length of film not greater than that of a single key image. for the purpose specified.

6. A negative cinematograph film for the product-ion of a positive colored film which negative film comprises a succession of full sized key images having interposed between each pair of full sized images a plurality of half sized color giving images obtained by simultaneous exposure with corresponding key images, whereby a plurality of color giving images occupies a length of film not greater than that of a single key image, for the purpose specified.

7 A negative cinematograph film for the production of a positive colored film, which negative film comprises a succession of full sized key images having interposed between each pair of full sized images a group of three half size color giving images obtained by simultaneous exposure with correspondnot greater than that of a single key image,

for the purpose. specified.

9. Apparatusfor the production of a negative film for use in obtaining acolored positive film, which apparatus comprises a. lens of focal length adapted to give cinematographic images of full size, a plurality of lenses of shorter focal length coplanar with the first lens and adapted to give images of smaller size, and a reflector interposed between the film and the said first lens so as to provide for the increased focal length, for the pur ose specified.

, 'FHOMAS ALBERT MILLS.

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