Patent GB-702051-A (GB)
Title: Method for producing true appearance of solid objects from plane pictures thereof
IPC: G02B27/22
Filed: 1950-07-05
Abstract: 702,051. Composite photographic pictures giving an illusion of reality. MONTEBELLO, R. L. De. July 5; 1950 [July 7, 1949], No. 16760/50. Class 98(2) [Also in Group XV]. A process of making a composite picture of plane reproductions of an object comprises photographing the object while it is lit by at least one source of light which by its position provides shadows and contrasts and so creates a good appearance of relief, taking a second photograph of the same zone of the object while it is lit by a source or sources other than that used while making the first photograph, and placing the two photographs in exact register so that when said composite picture is viewed by transmitted light with the presence of said light concealed from the viewer, the viewed composite gives the illusion that the object itself is present. In a modification the second photograph is'taken with the object lit also by the source or sources used when taking the first photograph but at such brilliance as will cause no more than slight shadows on the object, As shown, a polished ball surrounded by a frame 50 having a rough surface is photographed by means of oblique lighting from a concentrated source, lamp A, and also by flat top front lighting B to yield respectively by underexposure and underdevelopment on a film of wide latitude and low gamma a negative A<SP>1</SP>, Fig. 4 (not shown), showing detail in the highlights and shadows, and by overexposure and normal- or slight under-development a negative B<SP>1</SP>, Fig. 6 (not shown), showing detail in the shadows but not in the highlights. A negative A<SP>3</SP>, Fig. 5 (not shown), showing only the highlights is made from A<SP>1</SP> by first making from it an overexposed positive and from this making an underexposed negative A<SP>3</SP>. From the negative A<SP>1</SP> a contrasty positive A<SP>2</SP>, Fig. 11, on a plate P<SP>1</SP> is made, and from the negative A<SP>3</SP> a print WA<SP>5</SP> is made on a white material, which is rendered soluble where exposed to light, e.g. that sold under the registered Trade Mark " Transfax ", by first making a positive A<SP>4</SP> (not shown) which, if the highlights are broad and diffuse, may be a halftone positive, from the negative A<SP>3</SP> and using this positive to expose the " Transfax layer to yield a print WA<SP>5</SP> having transparent highlight areas on a white ground. Alternatively the positive A<SP>2</SP> is made by printing either simultaneously or successively from negatives formed by simultaneously overexposing a front film and underexposing a slow rear film which may be separated from the front film by a thin neutral density filter. A negative B<SP>3</SP>. Fig. 7 (not shown), which is black except in the darkest shadows, is made from the negative B<SP>1</SP> by first making from it an underexposed positive and from this making an overexposed negative B<SP>3</SP>. From this negative an overexposed laterally reversed positive B<SP>4</SP> is made bearing only black areas in the darkest shadows. From the negative B<SP>1</SP> a laterally reversed underexposed underdeveloped thin positive B<SP>2</SP> on a plate P<SP>2</SP> and having detail in the shadows is made. Alternatively the positive B<SP>2</SP> may be made by printing through negatives A<SP>3</SP>, B<SP>1</SP> in register or from a negative B' made with faint illumination from the lamp A, when the positive B<SP>2</SP> has a clear highlight area 53. Over the positive B<SP>2</SP> is printed a layer of very black ink in the very dark shadows 56 only. The positive A<SP>2</SP> is illuminated through its plate P<SP>1</SP> by a rear light source and the positives B<SP>2</SP>, B<SP>4</SP> which are registered therewith with the image bearing faces towards that of A<SP>2</SP> are illuminated by flat lighting reflected from the white translucent layer WA<SP>5</SP>, the highlight 53 being luminous by virtue of transmitted light. In a modification, a very light half-tone negative made by means of an intermediate positive from the negative B<SP>1</SP> is used with the positive A<SP>4</SP> to print on "Transfax", thus yielding a print WB<SP>2</SP>, Fig. 13, having transparent areas in the shadows on negative B<SP>1</SP> and the highlights of the positive A4. This white print is then ink-printed in the dark shadows 56 by a silk-screen process by use of the negative B<SP>3</SP>. To make colour positives, thin colour separation negatives produced either directly or from an integral multilayer reversal colour film such as " Kodachrome " (Registered Trade Mark), are used to make yellow, magenta, cyan, and black printing plates which are used to produce ink prints A<SP>2</SP>c, Fig. 15, on a transparent sheet P<SP>4</SP>. A white ink print WAc is then made with a plate produced by means of a negative A<SP>3</SP>c (not shown), similar to negative A<SP>3</SP> used in the black-and-white photographic method above, prepared from the colour separation negative which best shows the highlights. Overexposed colour separation negatives B<SP>1</SP> c  (not shown) produced directly or from a "Kodachrome" film of the original under flat top lighting B are employed to make yellow, magenta, cyan, and black printing plates with which a thin composite ink print B<SP>2</SP>c is made on top of the white print WAc, and over which print B<SP>2</SP>c is made a thin print B<SP>2</SP>bk with dense ink in the dark shadows only by means of a plate made by means of a negative B<SP>3</SP>c (not shown) similar to the negative B<SP>3</SP> and made from the colour separation negative which best shows the dark shadows. If desired, the two black printings for the scene B are combined by preparing a black printing plate from both the negative B<SP>3</SP>c and the black key record B<SP>1</SP>c. In a further alternative the white ink print and the black key print. are replaced by a modified white ink print from a plate made by the combined use of a positive of the black key negative and the negative A<SP>3</SP>c, the modified plate printing white ink except in the highlights and deep shadows so that in the final assembly the highlights are bright and the deep shadows are not illuminated by reflected light. The ink prints A<SP>2</SP>c, B<SP>2</SP>c may be made on opposite faces of a sheet of white translucent paper which then replaces the white ink print. To produce colour positives by photographic or imbibition dye printing, an underexposed '' Kodachrome " having good highlight contrast but insuflicient depth and detail in the shadow together with a positive print of an overexposed black and white negative which supplies the missing shadows, are used to form the 'A' views component of the picture, the " Kodachrome " covered if necessary with a grey filter and the black-and-white negative film being exposed simultaneously. Over this is arranged a white layer of lacquer or translucent material or a " Transfax " layer prepared as previously described so as to yield clear highlights. The 'B' view may comprise dye imbibition colour prints supplemented by a black dye print in the dark shadows, the imbibition printing matrices being made in a manner similar to that employed in making the negative for printing the black-and-white positive B<SP>2</SP> or the separation negatives for making the plates which produced the composite colour print B<SP>2</SP>c. If desired, the " Kodachrome " record in the part picture A may be replaced by imbibition prints which may be made from matrices hand-touchedup so as to be of such density as to render the black-and-white shadow-providing print unnecessary. The composite picture 1, Fig. 22, surrounded by reflecting strips 22 which abut against the picture is illuminated by a lamp 31 in a ventilated housing and having a diffuse reflector 32 which may be formed of asbestos sheets. A heat shield formed of heating-resisting glass plates 28, 30 with an air layer between them protects the picture from intense heat while an air passage 25 is left between the picture and the heat shield. An ornamental frame 20, 21 surrounds the picture and overhangs the reflecting strips 22. In an alternative form reflecting strips are disposed to form an inwardly facing U-shaped reflecting channel around the periphery of the picture. If the general lighting at the place where the picture is to be shown is not too strong, the.'B' view may be taken with illumination including one concentrated source of light, and a lamp may then be placed in the corresponding position during display. To heighten the illusion of reality, the intensity of the rear light may be varied rapidly or switched on and off rapidly giving the illusion that the highlight illumination is varying while if a concentrated front source of light is used during display this may be varied with a similar effect. Alternatively both the rear and front sources may be varied or switched on and off rapidly to heighten the illusion still further, providing that both lamps are not switched off together. For creating the illusion of theatrical effects the lights may be coloured to give the effect of changing coloured spot-lights. Specification 702,125 is referred to.