Subtractive 3 color: Chromogenic monopack
(Gevaert Photo-Produkten N. V )
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Gevacolor Samples (Kodak Film Samples Collection).
Credit: National Science and Media Museum Bradford.
Photographs of the Gevacolor Prints and Negatives by Josephine Diecke, SNSF project Film Colors. Technologies, Cultures, Institutions and Joëlle Kost, ERC Advanced Grant FilmColors.
Original Technical Papers and Primary Sources
Verpoort, A./Stappaerts, H. (1979): A New Gevacolor Negative Film Type 682. In: Journal of the SMPTE, Vol. 89, Sept. 1980, pp. 650-652.
Bracey-Gibbon, J. (1949): Gevaert Colour Processes. In: The Photographic Journal, 89A, pp. 285-288.
Anonymous (1956): Current Techniques of 35mm Color Film Photography and Printing. In: American Cinematographer, 37,1, January 1956, pp. 26-27 and p. 58.
Beyer, Friedemann; Koshofer, Gert; Krüger, Michael (2010): UFA in Farbe. Technik, Politik und Starkult zwischen 1936 und 1945. München: Collection Rolf Heyne, on p. 54and on p. 55. (in German)
Koshofer, Gert (1966): Fünfundzwanzig Jahre deutscher Farbenspielfilm. In: Film – Kino – Technik, Vol. 20, No. 10, 1966, pp. 259-262, on p. 261. (in German)
Pierotti, Federico (2012): La seduzione dello spettro. Storia e cultura del colore nel cinema. Genova: Le Mani-Microart, on pp. 191–192and on p. 202. (in Italian)
Pinel, Vincent (1992): La forêt des techniques. In: Michel Ciment (ed.): Ciné mémoire. Colloque international d’information (7-9 octobre 1991). Paris: Femis, pp. 17-24, on pp. 21-24. (in French)
Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 190-197.
The Gevacolor process is a three-color subtractive negative/positive process introduced in 1947 by Gevaert Photo-Producten N.V., Mortsel, Belgium. When it was introduced the process consisted of two elements that could be used singly or together. A coupler-incorporated, three-color negative, and a coupler-incorporated, three-color print film. Although these films achieved some degree of success in Europe they were not introduced into the United States until 1965. In the fall of that year the third in a series of print films marketed under the Gevacolor name was described and demonstrated at the 94th S.M.P.T.E. Technical Conference in Boston, Mass. The quality of this film was comparable to other products used for release printing in the United States; however, its use was somewhat limited by the need for a special color developer solution for processing the release films made on this film. The Gevaert Company recognized the need for standardization and developed a new print film having improved sharpness and saturation as well as processing capability; this film was introduced in the spring of 1970.
Some of the features released on Gevacolor print film in the United States have been:
The camera negative films manufactured under the name of Gevacolor Negative are multilayered color films which consist of three light-sensitive emulsions sensitized to Blue, Green and Red light, respectively and coated on a single film support (Fig. 58). Incorporated in the emulsion are dye couplers which react simultaneously during development to produce a separate dye image in each layer complementary to the sensitivity of the layer. The light and dark areas of the image are reversed with respect to those of the original subject. Also the various color areas of the negative are complementary in color to the corresponding areas in the original scene.
Gevacolor Negative—Type6·51 4, 7
A color negative film balanced for use with 3200°K tungsten illumination. The speed of this film was E.I. 16; it was introduced in Europe in 1948. This film was also sold for some time as Type “T-48.”
Gevacolor Negative—Type 6·52 5, 8
A color negative film balanced for use with 3200°K tungsten illumination. The speed of this film was E.I. 32, it was introduced in Europe in 1954 as a replacement for Type 6-51. Its improve characteristics included a one camera stop increase in speed.
Gevacolor Negative—Type 6·53 6, 16
A color negative film balanced for use with 3200°K tungsten illumination. The speed of this film was E.I. 25 Tungsten and 16 Daylight with a Gevacolor CTO-I2 filter. Introduced in 1958 this film replaced the earlier Type 6-52.
Gevacolor Negative—Type 6·54 5
A color negative film balanced for use with 3200°K tungsten illumination. The speed of this film was E.I. 50 Tungsten and 25 Daylight when exposed with an Agfa-Gavaert CTO-12 or a Kodak Wratten 85-B filter. This film was not sold in the United States.
Gevacolor Negative—Type 6·55
A color negative film balanced for use with 3200°K tungsten illumination. The speed of this film was E.I. 100 Tungsten and 64 Daylight when exposed with an Agfa-Gavaert CTO-12-B or a Kodak Wratten 85-B filter. This film was not sold in the United States.
Gevacolor Negative—Type 6·8O 14
A color negative film balanced for use with 3200°K tungsten illumination. The speed of this film was E.I. 100 Tungsten and 64 Daylight with an Agfa-Gavaert CTO-12-B or a Kodak Wratten 85-B filter. This film was introduced in the United States in 1976.
The print films manufactured under the name of Gevacolor Print Film are multilayered color films which consist of three light sensitive emulsions coated on a single support. The first of these films differed from later versions in its emulsion composition and layer orientation. In this film silver bromide was the light sensitive material. The layer orientation was nonsensitized top layer containing a yellow dye-forming coupler, gelatin interlayer, yellow filter layer or a Carry Lea Silver layer, gelatin interlayer, green-sensitive layer containing a magenta dye-forming coupler, gelatin interlayer, red-sensitive layer containing a cyan dye-forming coupler, subbing, Acetate base, Green Dye antihalation backing (Fig. 59). This film suffered from a lack of sharpness and color saturation. A substantial improvement was brought about in subsequent versions of this film by changing the position of the light sensitive layers to the order proposed by Dr Bela Gaspar in his U.S. Patent 2344084. Advantage was taken of the low original sensitivity of silver chloride emulsions which is confined to the far blue and ultra-violet zones of the spectrum. This property is used to avoid the use of a Carry Lea Silver Filter layer and to position the Green-sensitive magenta dye-forming layer which contributes 60% of the final image definition at the top layer where light scatter is low. A gelatin interlayer is next followed by the red sensitive layer which contains a cyan dye-forming coupler and contributes 30% of the final image definition. After another gelatin interlayer a non-sensitized silver bromide emulsion containing a yellow dye-forming coupler is next. This followed by the subbing and the acetate film base which is coated with the same green dye antihalation backing used on the previous film. The color-forming couplers used in all of these films are colorless (Fig. 60).
Gevacolor Print Film—Type 9·51 9
A color positive film balanced for printing with filtered tungsten illumination. Introduced in 1947 subtractive printing was recommended.
Gevacolor Print Film—Type 9·52 9
A color positive film balanced for printing with filtered tungsten illumination. Introduced in 1954 its improved characteristics included a substantial increase in sharpness.
Gevacolor Positive—Type 9·53 9,16
A color positive film balanced for printing with filtered tungsten illumination. Introduced in 1958 its improved characteristics include a further and greater improvement in definition accomplished by the removal of the gelatin interlayers reducing emulsion thickness, incorporation of absorbing dyes to prevent light scatter within the emulsions and the use of an improved antihalation backing composed of a removable resin layer containing Carbon Black.
Gevacolor Positive—Type 9·54 10
A color positive film balanced for printing with filtered tungsten illumination. Introduced in 1967 this film was designed primarily to meet the increased definition needs of the smaller film formats (16 mm and Super 8). Other improved characteristics included finer grain and better dye stability.
Gevacolor Positive—Type 9·85 17
A color positive film balanced for printing with filtered tungsten illumination. Introduced in 1970 the improved characteristics of this film included increased sharpness, finer grain and better color reproduction and dye stability. The introduction of this film also represents a fundamental change in the color developer solution formula. This change was made in the interest of standardization; the new color developer formula is compatible with the Eastman Color, Fuji Color, and Ferrania-color processes. The processing steps and times for the negative process and for the positive process are indicated on page 195.
4 KOSHOFER, G., 130 Years of Modern Color Photography 1935-1965,” The British Journal of Photography, Sept. 1966, pp. 828.
5 VANDEPITTE. Cable from Antwerp, August 1974.
6 Gevaert Motion Picture Films for Professional Use. Mortsel, Belgium: Motion Picture Film Department, Gevaert Co., 1963, p. 9.
7 CORNWELL-CLYNE, ADRIAN, Colour Cinematography. London: Chapman Hall, Ltd., 1951, pp. 743-749.
8 “Elements of Color in Professional Motion Pictures,” Society of Motion Picture and Television Engineers, New York: 1957, pp. 25-37.
9 MERUSSEN, L. A., “The Gevacolor Positive Film Type 953,” Journal of the Society of Motion Picture and Television Engineers, Jan., 1964, pp. 18-21.
10 VERBRUGGHE, R. G. L., “A New Color Print Filmstock,” Journal of the Society of Motion Picture and Television Engineers, Jan., 1968, pp. 29-33.
14 HUYBRECHTS, R. J. H. AND VERBRUGGHE, R. G. L., “Gevachrome II: A New Color-Reversal System for Film Productions and News Gathering.” Presented at 116 th Technical Conference of the Society of Motion Picture and Television Engineers, Toronto, Nov., 1974.
16 Processing Motion Picture Films, Mortsel, Belgium. Motion Picture Film Department, Agfa- Gevaert, 1964.
17 VERSLUYS, E. Correspondence from Mortsel, Belgium, April, 1974.”
(Ryan, Roderick T. (1977): A History of Motion Picture Color Technology. London: Focal Press, pp. 190-197.)
“4. LES PROCÉDÉS SOUSTRACTIFS
Autour des années trente, on assiste à la naissance presque simultanée des principaux procédés modernes qui relèvent tous du système soustractif. Dans ce système, la couleur est matérialisée sur la copie destinée à la projection. Le quasi-monopole exercé par les procédés soustractifs tient à un fait très banal : il ne demande aucune transformation du matériel de prise de vues et de projection. Mais cette simplification d’utilisation résulte d’une complexité accrue au niveau de la fabrication et du traitement des émulsions. C’est là que se situe le problème du point de vue de la conservation : les trois couches qui composent la structure de la plupart des films soustractifs sont composées de matières colorantes beaucoup plus instables que l’argent réduit de l’émulsion en noir et blanc.
e. Les procédés chromogènes négatif/positif : ces procédés apparaissent en 1941 avec le nouvel Agfacolor dont les brevets seront dispersés après la guerre et donneront naissance à tous les procédés modernes (Gevacolor, Ferraniacolor, Fujicolor, Anscocolor, Sovcolor, Eastmancolor…).
La prise de vues s’effectue sur un négatif comportant trois couches argentiques sensibles respectivement au rouge, au vert et au bleu. Au cours du développement chromogène, des coupleurs ancrés dans chaque couche produisent des colorants cyan, magenta et jaune. L’argent est ensuite entièrement éliminé. On obtient ainsi une image négative où couleurs et valeurs sont complémentaires de celles du sujet. Pour le tirage, on utilise un film du même type qui rétablit les couleurs et les valeurs du sujet. Les procédés chromogènes négatif/positif sont quasiment les seuls utilisés aujourd’hui dans le cinéma commercial. Leur traitement est relativement simple mais cet avantage comporte une contre-partie : l’usine n’est plus à l’extérieur du film comme dans le Technicolor ou le Kodachrome, elle est à l’intérieur. La complexité des multiples réactions qui se produisent dans ce très faible volume fragilise le produit final. Les procédés chromogènes ont été longtemps instables. Les fabricants nous promettent maintenant des émulsions susceptibles de durer plusieurs siècles (sous la réserve du respect des procédures de traitement, d’une bonne utilisation et de conditions de stockage correctes). Il reste néanmoins à sauver quarante années de cinéma en couleur et la tâche n’est pas mince.”
(Pinel, Vincent (1992): La forêt des techniques. In: Michel Ciment (ed.): Ciné mémoire. Colloque international d’information (7-9 octobre 1991). Paris: Femis, pp. 17-24, on pp. 21-24.) (in French)
“Kinefilmmaterialien wie Ansco Color (nur 1950-1956), Ferraniacolor (seit 1950) und Gevacolor (seit 1948) verdanken den Pionierleistungen der Agfa ihr Erscheinen;19 allerdings hatten die ausländischen Hersteller auch bereits eigene Vorleistungen erbracht. Im Vorspann und auf den Plakaten des am 14.11.1951 uraufgeführten ersten deutschen Gevacolor-Spielfilms Grün ist die Heide war daher auch zu lesen: “Gevacolor nach Agfa- und Gevaert-Patenten”; ihm folgten bis 1953 sechs weitere deutsche Gevacolor-Filme.
19 Koshofer, G.: Die Geschichte der modernen Farbfotografie. Bild u. Ton Bd. 2 (1966) Nr. 2, S. 60.”
(Koshofer, Gert (1966): Fünfundzwanzig Jahre deutscher Farbenspielfilm. In: Film – Kino – Technik, Vol. 20, No. 10, 1966, pp. 259-262, on p. 261.) (in German)
“There are several color negative films manufactured by different companies throughout the United States and Europe. These negative films can be used in any ordinary black-and-white camera. They have three emulsion layers superimposed on a cellulose acetate base. These three emulsion layers are differently sensitive to different colors of light. This means that the photo-sensitive silver halide particles in the separate emulsions are exposed by different colors of light. Generally, color negative films have a filter layer between the top two emulsions. Where the color sensitivity is not complete, this filter aids in separating unwanted colors from a particular emulsion.
In the United States the most widely used color negatives are Eastman and Ansco.
Both Eastman Color Negative and Ansco Color Negative have only one strip of film surfaced with three layers of emulsion, each being sensitive to a different primary color. Either film can be used in a conventional 35mm camera.
Similar to color negative, 16mm color positive film has three layers of emulsion, each sensitive to a different primary color – red, green and blue, The commercial film is low in contrast and differs from color negative in that a positive color image is obtained by reversal development rather than a negative.
From it three 35mm separation negatives are made when dye transfer release prints are to be made for 35mm exhibition.
In Europe, there are three additional color negatives, Agafcolor, Gevacolor and Ferraniacolor. These negatives are similar to those used in the United States in that three layers of emulsion are superimposed on a single film base.
The Technicolor laboratories, in both United States and England, manufacture release prints from all of these color negative systems.
When photographing with 35mm Eastman or Ansco color negative, any standard 35mm camera may be used, including the “hand-held” or portable models. Specific “color” cameras are not required. After the negative is developed, positive prints may be made in a manner similar to that for black-and-white film, or by the dye transfer method from the color negative, or from separation negatives, as will be explained later.
Only Technicolor offers the producer the alternative of having film printed on color positive stock or by the dye transfer method. Dye transfer release prints offer a cost advantage when a large number of prints are required for worldwide release. And by dye transfer printing from matrices valuable negative is saved from constant re-use.
Color positive release prints are manufactured only from color negative. Color positive stock is similar to color negative in that it has three super-imposed emulsion layers. Color positive stock is contact-printed by light coming through the color negative. Color negative has different colors correlated to the sensitivities of color positive emulsion layers.
Color positive stock records one color image aspect in each of its three emulsion layers and, after printing, is developed.”
(Anonymous (1956): Current Techniques of 35mm Color Film Photography and Printing. In: American Cinematographer, 37,1, January 1956, pp. 26-27 and p. 58.)
“The Gevacolor Family has two branches: (a) reversal material and (b) negative/positive material.
Reversal development is more intricate and delicate than the standard negative/positive development. It need hardly be pointed out that reversal development should be employed when only one copy is required, and in this event it is worth while following the more exacting reversal method rather than to use both negative and positive material in order to obtain one single copy.
In the application of the negative/positive system a negative image is obtained at the outset and from this a colour positive is made. This system is invariably used when more than one copy is required. It is of course possible to start from a colour image obtained by reversal development and to copy this on reversal material, but this is without doubt a more exacting method of obtaining a copy of the original.
Messrs. Gevaert are now introducing on the British market a reversal film on cut film base intended for taking colour pictures by artificial light and in view of this they are also supplying developing kits with which users will be able to develop Gevacolor Reversal film themselves. Everybody knows the precautions that have to be taken to obtain consistently fair results with black-and-white photography. In processing Gevacolor reversal film, even more rigorous precautions have to be taken because two developments have to be carried out, one immediately following upon the other. Moreover, in both cases the developer has to act on three layers simultaneously.
For your information, I shall now comment in some detail upon the working instructions which are included with Gevacolor film. I shall deal with this matter in the following order, (1) the exposure of the material, (2) its development, (3) the manner in which faults ascertained during the processing can be corrected, (4) methods for correcting processed colour images in a limited degree.
During the exposure of colour material three factors have to be taken into account. The first and most important I will deal with at some length.
(1) Colour Temperature
The colour temperature of the light used should always remain the same. It will be clear that if the colour temperature of the light used during the exposure is not the same as the one for which the film is balanced, the various layers will react more or less according to whether the exposure light contains a greater or a smaller quantity of the rays to which the film is balanced. If, for instance, a film balanced to artificial light is used in daylight, it will be understood that the layers which react to blue light will be more strongly affected than by exposure to artificial light. This factor so seriously affects the balance of sensitivities that unusual exposures are obtained. The most convenient way to express the nature of light by means of a figure is provided by the Kelvin unit which determines the colour temperature of the light source. Here are the colour temperatures of a few types of light:
Gevacolor reversal film is adapted to a colour temperature of 3200° which is given by over-run lamps of 100 hours life, for instance the Agaphot.
The higher the colour temperature, the greater the blue content of the light and the smaller its red content. This should be borne in mind in order to avoid the danger of colour casts in the processed image and the use of mixed lighting should be avoided.
To illustrate this, I might mention that ordinary incandescent light has relatively too much red and too little blue. If this light source is used for lighting purposes, the tone of the image obtained will be dominantly brown. If Photoflood bulbs of the two-hour life type (which have a colour temperature of 3400°) are used as a light source, the contrary will occur, as this type, of lamp gives a light containing more blue rays and less red rays than the light source recommended. Exposures made by this type of lighting will give an overall bluish hue. As daylight has even more blue rays and less red rays than Photoflood light, it is not surprising that daylight exposures on material intended for use by artificial light will give an image that is far too blue.
If, for one reason or another, it is not possible to use the light sources recommended with a colour temperature of 3200°, the composition of the light used should be modified so that its quality corresponds to a colour temperature of 3200°. For this purpose, compensating filters are placed before the lens. These filters will be put on the market by Gevaert under the name of C.T. Filters. They will be manufactured in two series:
(a) an orange series by which the colour temperature of the light is decreased;
(b) a blue-green series by which the colour temperature of the light is increased.
Special consideration should be given to the following points with regard to lighting:
It is obvious that the use of different light sources should be avoided when lighting the same subject. If this cannot be avoided, and if practicable, the C.T. filters already mentioned could be used to screen the light sources and so balance colour temperature.
(2) Quantity of Light
The quantity of light to be used for colour work, as well as the time of exposure and the aperture of the lens should be determined by means of a photoelectric meter. Most photoelectric meters give reliable results and can be used for the purpose of determining exposure. We strongly recommend that the instructions given by the manufacturers of these instruments should be followed explicitly, because the exposure of this colour material (which later on will be subjected to reversal development) is critical. Every user of a kine camera knows by experience that this is also the case for black-and-white reversal processes, where the exposure must be determined most accurately in order to obtain positives of a constant and correct density. With Gevacolor reversal material, all three images are obtained by a reversal process and it will be readily understood that the latitude of exposure for this material is less than that of normal black-and-white reversal emulsions.
(3) Distribution of Light
The distribution of light over the subject is also important and it should be as uniform as possible within the limits of good modelling. The choice of flat lighting is a concession which has to be made in order to obtain colours that are pure without the image becoming too hard.
Let us assume that you have taken all this advice and all these precautions into account during the exposure, and that you now wish to develop your film. The way in which this must be done is clearly shown in Fig. 1.
As you see, the film is treated in different baths which are prepared with products taken from the developing kit for Gevacolor Reversal Film as supplied by the Gevaert Company. Included with this developing kit you will find a detailed description of the manner in which all the baths have to be prepared, the first operation is the development of the black-and-white negative image formed in the different layers of the film. This development is stopped at the exact time indicated in the instructions by the use of a stop bath. After treatment in the stop bath, the film is washed and is then strongly exposed on the emulsion side. All the silver bromide that has not been reduced by the first developer is now exposed, so that, by the redevelopment of the emulsion in the colour developing bath, practically all the remaining silver bromide grains are reduced by the colour developer. As mentioned, silver and dyes are formed during this reaction. After the specified development time and in order to stop the colour development, the film is transferred from the third bath to the fourth bath, which both stops the development and transforms the colour developer into a product that can easily be washed out. After the film has been hardened in the bath recommended, it is thoroughly washed and then transferred to a bleaching bath which transforms the silver formed, during the first and during the colour development, into silver ferrocyanide. The film is again washed and then fixed. As a result of the final treatment all silver salts are removed from the film, so that only the three 288 The Photographic Journal dye images remain. The film is now thoroughly washed and dried.
Control during Development
It is important that I lay particular stress on the following points which require special attention during the processing of Gevacolor material.
In the first development and the colour development, the following points are of special importance:
(1) Time – the use of a good darkroom clock, with a luminous dial will reduce errors to a minimum;
(2) Temperature – this should be maintained at 68°F to within half a degree;
(3) Agitation of Bath – the distance covered in moving the film to and fro should be about 1 to 1½ inches, and the tempo one movement per second.
(4) Keeping Quality of the Baths – oxygen in the air attacks the baths and the colour developer in particular is sensitive to the action of air. It is therefore advisable to carry out the first, as well as the colour development, in small tanks in which the frames bearing the films are suspended. When the baths are not being used, the surface should be sealed off by a floating lid.
When applying the second exposure, both the intensity of the light as well as the manner in which the exposure is made, play a part. The standard method we recommend is to expose the film from a distance of about 1½ feet during 2½ minutes with a normal bulb of 500 watts at normal voltage. The film should be placed emulsion side upwards in a dark tray of cool water.
The other operations are less sensitive to deviations in temperature, duration of immersion, exhaustion of baths, etc. Nevertheless, they should be performed with care. For instance, the rinsing between the hardening and the bleaching bath should be sufficiently prolonged to remove all traces of the colour developer. If the slightest trace of this product remains in the film, it would be oxidized by the potassium ferro-cyanide which constitutes the main component of the bleaching bath; the products of oxydization and the dye couplers present in the film would react upon each other, and this would produce a colour cast which would be very difficult to remove.
(Some slides were then shown to illustrate the influence of these various factors on the results obtained with Gevacolor. The transparencies received the same exposure, but were processed in different ways.)
It will be gathered from what we have seen on the screen that:
(1) All factors which strengthen the action of the first developer tend to produce bluish hues, especially in the lighter parts of the image. This is the case with too high a temperature, too strong an agitation of the bath, the use of a smaller quantity of water than specified, and too long development.
(2) All factors which weaken the action of the first developer give rise to images with a brownish hue. This occurs when the development is too short, when the bath is exhausted or is too cold, or when the film is not sufficiently agitated in the developer.
(3) All factors tending to increase the developing strength of the colour developing bath cause an excess of blue in the processed film. Furthermore, the contrast is then higher than normal. This result is to be expected if development is protracted or if the bath is too warm, and also when an insufficient quantity of water is used in preparing the colour developing bath, or when the film is agitated too strongly.
(4) A weakened colour developing bath will bring about too low a density in all parts of the image, a shifting of the colour balance towards brown, and lowered colour contrast.
(5) Too strong an exposure of the film after the first development will result in an excess of blue-green in the lower densities. Too weak an exposure will lower the maximum density with a loss of blue-green. In the latter case, the image will consequently be too weak and too brown.
Correction of Hue
I cannot here deal in detail with my last point, yet in colour photography this point is of great importance. What is to be done in order to remove a dominant hue from a given image? It will be realized that there are a wide variety of cases which have to be dealt with in different ways and it would be monotonous to read all the formulae that can be applied.
(Some slides were then shown to illustrate the most interesting chemical solutions found to date.)
I have, with special intent, described rather extensively the Gevacolor Reversal Film on Studiofilm base, in view of the fact that developing kits have been made available to enable users to process this material themselves.
In addition to Gevacolor Reversal Flat Film, we also intend to place on world markets as soon as conditions permit, Gevacolor Roll Film and Miniature Film, also Gevacolor Reversal Film in 16mm, 9.5mm, and 8mm sizes.
With regard to the Gevaert negative/positive processes, the following products are available and can be briefly described:
(1) The Gevacolor negative 35mm and positive 35mm and 16mm materials for professional use. Gevacolor negative can be used in any normal kine camera – both the negative and the positive material can be processed by laboratories with slight modifications to existing plant, and, from the negative material, as many three-colour positive copies as required can be produced.
(2) The Gevaert-Chromart Process. This is a much improved Bicolor process, available in 35mm and 16mm negative and positive for professional use, which has been produced in conjunction with Anglo-American Photographic Industries Ltd. This material requires less light than is necessary for other colour processes and produces a colour rendering which for a two or bi colour system can truly be described as amazing.
(3) Last but not least amongst the Gevaert negative/positive processes, I come to Gevacolor Paper. Gevaert intend to release this highly interesting product in the near future. With the use of Gevacolor paper, it will be possible to make colour prints on paper directly from a colour negative which may be either roll film, cut film, or miniature camera film.”
(Bracey-Gibbon, J. (1949): Gevaert Colour Processes. In: The Photographic Journal, 89A, pp. 285-288.)
“Dank als Kriegsbeute beschlagnahmter Patente und mitgenommener Rezepturen sowie der Mitwirkung von Agfa-Fachleuten bei Konkurrenzunternehmen eroberte das in Deutschland ausgearbeitete Farb-Negativ/Positiv-Verfahren auch andere Länder: Aus Belgien kamen die sehr ähnlichen Gevacolor-Filme, aus Italien Ferraniacolor, aus der Schweiz Telcolor, in den USA folgten Ansco-Color und Kodak Eastman Color, in Japan Fujicolor.31
LITERATUR- UND QUELLENANGABEN
31 Gert Koshofer: Die Agfacolor Story, in: Weltwunder der Kinematographie, 5. Ausgabe, Potsdam 1999, S. 69ff.; Gert Koshofer: COLOR Die Farben des Films (1988), S. 109ff., 119ff.”
(Beyer, Friedemann; Koshofer, Gert; Krüger, Michael (2010): UFA in Farbe. Technik, Politik und Starkult zwischen 1936 und 1945. München: Collection Rolf Heyne, on p. 54.) (in German)
“Im selben Jahr, 1964, nannte der VEB Filmfabrik Wolfen in der DDR seine Farbfilme entsprechend seiner handelspolitisch veranlassten Warenzeichenumstellung in “Orwocolor” um und fusionierte die westdeutsche Agfa AG, Leverkusen, mit der belgischen Gevaert Photoprodukten N. V. zur Agfa-Gevaert-Gruppe. Die Zuständigkeit für die farbigen Kinofilme konzentrierte sich auf den belgischen Betriebsteil, wo Gevacolor weiterentwickelt wurde.”
(Beyer, Friedemann; Koshofer, Gert; Krüger, Michael (2010): UFA in Farbe. Technik, Politik und Starkult zwischen 1936 und 1945. München: Collection Rolf Heyne, on p. 55.) (in German)
“L’introduzione del film a colori nelle cinematografie europee è infatti accelerata dalla progressiva disponibilità delle nuove tecnologie a supporto unico derivate dall’Agfacolor. Dopo la fine del conflitto, i brevetti del sistema tedesco diventano parte del bottino di guerra degli Alleati, e, nel giro di alcuni anni, tutte le principali industrie di materiali sensibili sono in grado di lanciare i propri marchi: Sovcolor e Anscocolor (1945), Gevacolor (1947), Ferraniacolor (1949), Eastmancolor (1951), Fujicolor (1955)3. Queste nuove pellicole impiegano un po’ di tempo prima di essere naturalizzate all’interno di contesti produttivi istituzionali, ma dopo alcuni anni di sperimentazioni, nella prima metà degli anni cinquanta esse sono in grado di dar corso a una produzione sempre meno occasionale di film a colori, come vedremo nella seconda parte del capitolo, esaminando le spinte progressive alla diffusione del colore nel cinema italiano.
3 Tutti questi sistemi sfruttano il principio della sintesi sottrattiva e la tecnologia del supporto unico a triplo strato di emulsione, introdotta con il Kodachrome e con l’Agfacolor risp. nel 1935 e nel 1936. Il negativo è composto da tre strati di emulsione, sensibili risp. al blu, al verde e al rosso. Ciascuno strato contiene elementi in grado di produrre, per sviluppo cromogeno, un colorante complementare a quello per cui lo strato stesso è sensibilizzato (risp. giallo, magenta e ciano). Il negativo così ottenuto presenta i colori complementari a quelli del soggetto. Una volta stampato su un positivo caratterizzato dalla medesima struttura, si ottiene un’immagine che riproduce i colori del soggetto. Nell’Eastmancolor (1951), questa stessa procedura viene resa più stabile grazie all’introduzione di un sistema di masking (che ottimizza le aree di assorbimento spettrale dei tre strati) e una diversa disposizione degli strati stessi (cfr. Limbacher 1969, pp. 53–72; Ryan 1977, pp. 113–212; Koshofer 1988, pp. 119–130).
Koshofer, Gert (1988), Color. Die Farben des Films, Wissenschaftsverlag Volker Spiess, Berlin.
Limbacher, James L. (1969), Four Aspects of the Film, Brussel & Brussel, New York.
Ryan, Roderick T. (1977), A History of Motion Picture Color Technology, Focal Press, London-New York.”
(Pierotti, Federico (2012): La seduzione dello spettro. Storia e cultura del colore nel cinema. Genova: Le Mani-Microart, on pp. 191–192.) (in Italian)
“La stagione del Ferraniacolor si era aperta nell’aprile del 1952 con l’uscita di Totò a colori, che concludeva una fase sperimentale durata alcuni anni. Il film presentava un assemblaggio dei migliori numeri che Totò aveva già presentato sui palcoscenici di rivista e di avanspettacolo, prima ancora che sullo schermo20. L’attore napoletano risultava un sicuro antidoto contro i rischi della nuova tecnologia, tanto che la sua presenza fu spesso sfruttata per diversi film girati con Ferraniacolor o Gevacolor.
20 Sul film, cfr. Deriu 1996; Caldiron, a cura di, 2003; Pierotti 2009, pp. 211–212.
Caldiron, Orio, a cura di (2003), “Totò a colori” di Steno. Il film, il personaggio, il mito, Edizioni interculturali-FICC, Roma.
Costa de Beauregard, Raphaëlle, a cura di (2009a), Cinéma et couleur. Film and Colour, Houdiard, Paris.
Deriu, Fabrizio (1996), Comico. “Totò a colori“. Una rivista cinematografica, in Quaresima, a cura di, 1996, pp. 251–260.
Pierotti, Federico (2009), Totò, Antonioni, and America: Trends in Italian Filmakers’ Adoption of Colour Technology, in Costa de Beauregard, a cura di, 2009a, pp. 207–218.
Quaresima, Leonardo, a cura di (1996), Il cinema e le altre arti, Marsilio, Venezia.”
(Pierotti, Federico (2012): La seduzione dello spettro. Storia e cultura del colore nel cinema. Genova: Le Mani-Microart, p. 202.) (in Italian)
“Today 16mm systems have become more and more important. Their use has steadily increased in all fields. These systems, however, demand higher requirements in film definition than the 35mm systems. In order to meet the requirements of these smaller film formats, a new Gevacolor positive material, T. 9.54, was designed. Owing to better knowledge of the optical and chemical properties of the multilayer color system, together with recent improvements in the technology of manufacturing photographic emulsions, this film has become a reality. In this type it was possible also to include better contrast and dye stability.
T. 9.54, as well as T. 9.53, is a multilayer color film for printing release prints and television prints from color negatives, with or without a mask, either directly or via duplicating stock. This film consists basically of three separate emulsions, each containing an appropriate color coupler.
T. 9.54, as compared to the T. 9.53, has a nonclassical layer orientation. The bottom layer is sensitive to blue light, the middle layer to red light and the top layer to green light.
The dyes are formed by reaction of the oxidized products of the developer with the color couplers, which are incorporated in the emulsion layer.
Figure 1 compares the structure of the T. 9.54 with that of the T. 9.53. The structures are basically the same. The difference between them lies primarily in the optical qualities of the layers.
By considering the light scattering functions of the single layers, these optical qualities can be evaluated. These functions imply the determination of diffuse and specular light for reflection and transmission at different angles.
The method, in use at Gevaert-Agfa, for measuring the light scattering functions, was devised for the study of optical modulation transfer functions of photographic layers.2
In Fig. 2 the light scattering function for a coarse-grain emulsion is given. The apparatus in use in obtaining the data is shown in Fig. 3. It is composed of a high-intensity light source with a proper band selection filter, a high-resolution goniometer and a recording photometer.
The light scattering functions for blue light transmission of each layer of T. 9.54 and T. 9.53 are shown in Fig. 4. These curves indicate clearly that the green, red and blue sensitive layers of T. 9.54 transmit the blue light more specularly than those of T. 9.53. This results in a higher definition in the underlaying blue sensitive layer.
Figure 5 gives the transmission functions for green, red and blue light, for the green sensitive top layer of T. 9.54. The relation between the transmitted specular light and the transmitted diffuse light is very high for green light. This results in a very sharp magenta dye image, which is of great importance. The magenta layer contributes approximately 60% of the total image definition. The specular transmittance relative to the total transmittance for red and blue light should approach 1 in order to preserve the definition of the red and blue sensitive layers lying below.
Figure 6 gives the reflection of the blue sensitive layer for red and green light for different angles. The diffuse reflection should be as low as possible. Comparison of T. 9.54 with T. 9.53 shows that this has been achieved to a higher degree in T. 9.54.
Improvement of the optical characteristics of multilayer materials can be achieved by:
(1) Changing emulsion characteristics such as silver halide/gelatin ratio, emulsion thickness, grain dispersion, etc.
(2) Incorporating dyes in separate nonsensitive layers.
(3) Adding sharpening dyes to the emulsion layers themselves.
In Gevacolor Positive T. 9.54 film, as well as in the former type, sharpening dyes are also added; however, in T. 9.54 the concentration of the dyes has been increased. The spectrophotometric curves of the sharpening dyes of both types are compared in Fig. 7. The peak density lies in the green region of the spectrum at the wavelength of 545 mµ.
As far as sharpness is concerned, the response of the different layers to incident light may be analyzed by the techniques of modulation transfer. The procedure used by Gevaert-Agfa3 has the following advantages:
(1) Density dependency of the modulation transfer function (MTF) is immediately detected, since the function is measured over the entire density range.
(2) The statistical significance of the results is high, since the modulation transfer function is obtained from a large number of independent measurements.
Figure 8 gives the MTF curves for Gevacolor Positive films T. 9.53 and T. 9.54. They have been computed from readings of images of sinusoidal targets that have been printed to a neutral gray. The measurements were made selectively, using red, green and blue filters. It may be noted that the new type has been substantially improved, as compared with T. 9.53.
As the granularity of a color film depends on the size of the measuring aperture, when the root-mean-square analysis is applied (σρ), another measuring technique was chosen. In the Gevaert-Agfa laboratories, the photographic granularity of color films is analyzed by means of the Wiener spectrum of its density fluctuations.
In Fig. 9, the Wiener spectra are given for T. 9.53 and T. 9.54, referring to a neutral density of 1.00. Inasmuch as the general sensitivity of T. 9.54 has been in creased by 0.15 log exposure, the result may be regarded as quite satisfactory.
The spectral sensitivity characteristics of the T. 9.54 are given in Fig. 10. The overall sensitivity of the T. 9.54 is slightly higher than that of the T. 9.53. The general form is similar for both types.
Spectral Density Curves
As shown in Fig. 11, the spectral density curves for the new film are slightly different from those of the T. 9.53, because of the new cyan color coupler, which was chosen for the excellent stability of the cyan dye. The peak absorbance for both dyes remains the same.
Compared with that of the T. 9.53, the contrast of T. 9.54 is increased for the higher portions of the sensitometric curves. The toe portions remain unaltered.
Figure 12 shows the integral density versus log E curves for T. 9.54 exposed to white light.
The speed has been slightly increased by 0.15 log exposure, while the speed balance is adjusted so as to give minimum correction with masked negatives.
The most suitable light source remains the sodium-vapor lamp. The peak output of this lamp corresponds to the minimum sensitivity between the green and red regions of the spectrum. The unwanted wavelengths of the sodium-vapor lamp are eliminated by the use of the Agfa-Gevaert 09 filter, formerly X 592.
For optimum reproduction, it is recommended that the soundtrack be confined to the top layers. This is achieved by any selective yellow filter, such as Agfa-Gevaert G 5. After bleaching, the rehalogenated silver of the top layers is redeveloped by selective application of a viscous soundtrack developer bath, GP 82.
The same solutions are used for processing both Type 9.53 and Type 9.54. Table I shows the processing sequence, together with the suggested temperatures and times of treatments. The processing formulas are given in the Appendix, where the numbers 1, 3, 4, etc., correspond to the step numbers in Table I. Compared with the formulas by Mr. Meeussen published in the Journal, January 1964, only the color developer has been slightly modified, as follows:
N,N-diethylparaphenylenediamine hydrochloride: from 3 to 2.7 g;
Sodium carbonate (anhydrous): from 50 to 25 g;
Potassium bromide: from 2.5 to 2.2 g.
2 M. De Belder, J. De Kerf, J. Jespers and R. Verbrugghe, “Light diffusion in photographic layers: Its influence on sensitivity and modulation transfer,” J. Opt. Soc. Am., 55: 1261–1268, Oct. 1965.
3 M. De Belder, J. Jespers and R. Verbrugghe, “On the evaluation of the modulation transfer function of photographic materials,” Phot. Sci. Eng., 9: 314–318, Sept.-Oct. 1965.”
(Verbrugghe, R. G. L. (1968): A New Color Print Filmstock. In: Journal of the Society of Motion Picture and Television Engineers, 77,1, pp. 29–33.)
India: Matri Bhumi (ITA/FRA 1959, Roberto Rossellini)
“La rencontre du motif de l’Inde et la théorie implicite de la couleur chez les maîtres des années cinquante
J’ai toujours été frappé que deux des plus grands films en couleur des années cinquante aient été le résultat de la rencontre avec l’Inde des deux cinéastes européens qui ont le plus compté pour la Nouvelle Vague: Le Fleuve en 1951 pour Jean Renoir et India en 1957 pour Roberto Rossellini. Comme si la rencontre avec le motif de l’Inde – au sens que Cézanne donne à l’idée de rencontre –, avait été, pour les deux cinéastes, une rencontre décisive avec la couleur. C’est la nouveauté du motif, son étrangeté pour des non-Indiens qui a provoqué chez les deux hommes, en même temps qu’un choc sensoriel qui les sortait de leurs habitudes perceptives, un désir de couleur.
Six ans après, Rossellini fait la même expérience de la rencontre avec les couleurs naturelles de l’Inde qui sont, bien évidemment, les mêmes que chez Renoir. Et lui aussi, passant peut-être par la même intuition quant à la force esthétique et émotionnelle du surgissement du rouge dans cet univers aux couleurs naturellement épurées, va inscrire dans son film un parcours du rouge, qui n’est pas le même que celui de Renoir mais traverse une autre barrière, laquelle structure India, entre espèce animale et espèce humaine, dont l’hypothèse rossellinienne est qu’elle prend une toute autre signification en Inde qu’en Occident, et qu’il y a là une voie royale pour comprendre l’altérité indienne. Ce sera le grand sujet d’India. Le rouge n’apparaît que très erratiquement dans la première moitié du film (dans le spectacle de marionnettes, lors de l’arrivée d’un bus dans un village de la jungle) dominée par une bichromie de verts boueux et de bruns. C’est dans les deux derniers épisodes, celui du vieil homme et du tigre et celui du singe savant, que le rouge va devenir à le fois un élément du scénario et envahir progressivement l’écran. Tout commence avec les taches de sang du tigre blessé sur le sol monochrome qui font redouter le pire au vieil homme: que l’animal s’attaque à l’homme. C’est ce qui va arriver la nuit suivante au cours de laquelle un homme du village – dont on retrouvera le vêtement ensanglanté (du rouge sur du blanc dans la nuit noire) – se fait dévorer par l’animal blessé. Pour sauver le tigre de la battue qui s’organise, le vieil homme met le feu à la jungle et Rossellini filme les flammes en avant-plan, comme un envahissement progressif du vert de la végétation par le rouge du feu. Au début de l’épisode suivant, et final, un montreur de singe meurt en traversant un désert monochrome, aux portes de la ville où se prépare une fête. Son singe, habillé d’un gilet rouge, son “costume de scène”, arrive seul dans la foule et la première image, visuellement inoubliable, que Rossellini nous montrera de cette fête est celle d’une petite fille qui danse, “exhibée” à l’entrée d’un chapiteau: elle est vêtue d’une robe dont le rouge éclate devant un calicot du plus pur jaune. Rossellini la désigne visuellement en une fraction de seconde comme le symétrique exact, dans l’espèce humaine, du singe savant au gilet rouge. Suit une séquence documentaire: une course de boeufs caparaçonnés d’amples tissus jaunes et rouges que Rossellini, lui non plus, n’a pas eu à inventer. Finalement le singe dressé, qui a fait entre temps la rencontre d’un singe sauvage, se retrouve dans un cirque où il regarde de son regard de singe un de ses congénères voltiger en l’air devant la toile du chapiteau dont le rouge vif envahit la totalité de l’écran. Pour quelqu’un qui s’est toujours tenu farouchement éloigné du péché d’esthétisme, il y a dans la dernière demi-heure de ce film un traitement plus que vigoureux, et magistral, de la couleur, entre réel (documentaire) et structure fictionnelle, qui est tout sauf plaqué et décoratif, très proche des conceptions de son prédécesseur en Inde, Jean Renoir.
Rossellini pourrait à l’évidence reprendre ce discours à son compte. Son film India est sans doute un des plus chimiquement hétérogènes qui aient jamais été montés en couleur: il y a utilisé au moins trois pellicules (Gevacolor, Ferraniacolor, Kodachrome) et deux formats (le 16 mm gonflé et le 35 mm), ce qui est réputé plus que nuisible, rédhibitoirement attentatoire à l’unité visuelle et chromatique d’un film. C’est pourtant un des films de l’histoire du cinéma où l’on éprouve le plus vivement à la fois le sentiment de l’existence non pas de la couleur mais d’un monde coloré qui s’appelle l’Inde, et le sentiment que la couleur était non seulement nécessaire, mais constitutive du film, de son émotion, de ses récits, de son discours. Godard s’émerveillait en 1959 que “le champ sur le tigre soit en 16 mm agrandi, et le contrechamp sur le vieillard en 35 mm”. Rossellini, en effet, finira par monter dans son film tourné en 35 mm des images documentaires, tournées en 16 mm, sur les animaux, instituant de ce fait un de ces faux-raccords ontologiques dont il a été l’inventeur. “India, écrivait Godard – prend le contre-pied de tout le cinéma habituel: l’image n’est que le complément de l’idée qui la provoque. India est un film d’une logique absolue, plus socratique que Socrate. Chaque image est belle, non parce qu’elle est belle en soi, comme un plan de Que viva Mexico, mais parce qu’elle est la splendeur du vrai, et que Rossellini part de la vérité.”20 Entre la vérité et le réel, l’image de Rossellini peut être hétérogène, son exécution bâclée, elle n’a plus de comptes à rendre à l’esthétique picturale: la couleur n’est plus un de ses attributs, elle est consubstantielle à sa réalité, c’est son essence et sa force. Bresson ne dit pas autre chose: “[La couleur] est un moyen de rendre plus vrai le réel. Mais pour peu que ce réel ne le soit pas tout à fait (réel), elle accuse son invraisemblance (son inexistence).”21
20 Cahiers du Cinéma, n° 96, juin 1959.
21 Robert Bresson, Notes sur le cinématographe, Gallimard, 1975.”
(Bergala, Alain (1995): La couleur, la Nouvelle Vague et ses maîtres des années cinquante. In: Jacques Aumont (ed.): La Couleur en cinéma. Milan: Mazzotta, pp. 126–136, on pp. 131–133.) (in French)
India: Matri Bhumi (ITA/FRA 1959, Roberto Rossellini):
Bergala, Alain (1995): La couleur, la Nouvelle Vague et ses maîtres des années cinquante. In: Jacques Aumont (ed.): La Couleur en cinéma. Milan: Mazzotta, pp. 126–136, on pp. 131–133. (in French)