Color film (motion picture)

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35 mm film frames from color film print (positive) with optical sound track (no digital sound tracks present). The frames are hard matted to 1.85:1.

This article discusses the evolution and technology behind color photographic film, with specific focus on motion pictures.

[edit] Tinting and hand coloring

For the history of motion picture film, in general, see 35 mm film

Color movies started nearly as early as film itself in 1895 with Thomas Edison's hand-painted Anabelle's Dance made for his Kinetoscope viewers. George Méliès was utilizing a similar hand-painting process for his films, including the early pioneer A Trip to the Moon (1902), which had various parts of the film painted frame-by-frame by twenty-one women in Montreuil^[1] in a production-line method.^[2] Between 1900 and 1935, dozens of color systems were introduced, some successfully.^[3]

Among the early dye-coloring processes, Pathé Frères invented Pathé Color (renamed Pathéchrome in 1929), one of the most accurate and reliable stencil coloring systems. It incorporated a series of glass stencils, cut by pantograph to correspond to those areas to be tinted in any one of six standard colors^[1] by a coloring machine with dye-soaked, velvet rollers to color films.^[4] After a stencil had been made for the whole film, it was placed into contact with the print to be colored and run at high speed (60 feet per minute) through the coloring (staining) machine. The process was repeated for each set of stencils corresponding to a different color. By 1910 Pathé had over 400 women employed as stencilers in their Vincennes factory. Pathéchrome continued production through the 1930s.^[1]

A more common technique, Film tinting is a process in which either the emulsion or the film base is dyed, giving the image a uniform monochromatic color. This process was popular during the 1920s, with specific colors employed for certain narrative effects (red for scenes with fire or firelight, blue for night, etc.).^[2]

A complementary process, called toning, replaces the silver halide particles in the film with metallic salts or mordanted dyes. This creates a color effect in which the dark parts of the image are replaced with a color (eg. blue and white rather than black and white). Tinting and toning were sometimes applied together.^[2]

The Handschiegl Color Process was a stencil process first used in Joan the Woman (1917) directed by Cecil B. DeMille and used in special effects sequences for films such as The Phantom of the Opera (1925), until Handschiegl was taken over by Harriscolor in 1928.

Eastman Kodak introduced its own system of pre-tinted black-and-white film stocks called Sonochrome in 1929. Sonochrome featured films tinted in seventeen different colors including Peachblow, Inferno, Rose Doree, Candle Flame, Sunshine, Purple Haze, Firelight, Fleur de Lis, Azure, Nocturne, Verdante, Aquagreen, Caprice and the neutral density "Argent", which kept the screen from becoming excessively bright when switching to a black and white scene.^[3]

[edit] Physics of light and color

The principles on which color photography are based were first proposed by Scottish physicist James Clerk Maxwell in 1855 and presented at the Royal Institution of London in 1861. By that time, it was known that light is comprised of a spectrum of different wavelengths which are perceived as different colors as they are absorbed and reflected by natural objects. Maxwell discovered that all natural colors in this spectrum may be reproduced with additive combinations of three primary colors - red, green and blue - which when mixed together equally produce white light.^[1]

[edit] Additive color

The additive color systems were practical because they could be incorporated with black-and-white film stock. The various additive systems entailed the use of color filters on both the photography and projection apparatus. Additive color adds lights of the primary colors in various proportions to the projected image. Because of the limited amount of space to record images on film, and later because the lack of a camera that could record more than two strips of film at once, most early motion picture color systems consisted of two colors, often red and green or red and blue.

Practical color in the motion picture business began with Kinemacolor, first introduced in 1906.^[4] This was a two-color system created in England by Edward R. Turner and George Albert Smith, and promoted by the company of film pioneer Charles Urban beginning in 1908. It was used for a series of films including the documentary With Our King and Queen Through India (also known as The Durbar at Delhi, 1912), depicting the Delhi Durbar as filmed in December 1911. In Kinemacolor, alternating frames of specially sensitized black-and-white film were photographed at 32 frames per second through either the red or green areas of a rotating filter, and the printed film was projected through the same filter at the same speed. The sense of color was achieved through a combination of separate red and green alternating images and the viewer's persistence of vision. ^[2]

William Friese-Greene invented another additive color system called Biocolour, which was developed by his son Claude Friese-Greene after William's death in 1921. William sued George Albert Smith, alleging that the Kinemacolor process infringed on the patents for Biocolour. Both Kinemacolor and Biocolour had problems with "fringing" or "haloing" of the image, due to the separate red and green images not fully matching up.

Frenchman Louis Dufay developed Dufaycolor in 1931, which was a reversal film (producing a positive image on the camera original) that used a mosaic of tiny filter elements of the primary colors between the emulsion and base of the film.^[4]. Dr. Bela Gaspar developed Gasparcolor beginning in 1934, and film artists such as Len Lye and Oskar Fischinger used Gasparcolor for their abstract and stop motion films. The onset of World War II interrupted further development of both Dufaycolor and Gasparcolor.

By the nature of the systems, additive color was not economical. Because of the filters used to project the films, more light was required than was typically projected onto the screen, resulting in an image that was dimmer than the average black and white image. The larger the screen, the dimmer the picture. For this and other case-by-case reasons, additive processes for motion pictures grew out of favor about the time of the Second World War, though a variation of additive color systems are employed for all color video and computer display systems.^[2]

[edit] Subtractive color

Subtractive color largely started with the inventions of William Van Doren Kelley. The first successful subtractive color process was Kelley's Prizma Color, an early color process that was first used in 1917 with the feature, Our Navy. Prizma began as an additive system, similar to Kinemacolor, but eventually Kelley reinvented the process as a subtractive one with The Glorious Adventure (1922) and Vanity Fair (1923), one of the last feature films made in Prizmacolor.

Prizma's design was further duplicated by many other companies after this -- film was shot bi-pack in a standard 35mm camera. One strip was sensitized to red, one to blue. Both negatives were then printed on duplitized stock and each side toned red or blue. Prizma was popular through 1923, primarily in the U.S. and the U.K. Kelley, who held a number of color patents and owned several color photography companies, then sold the company and its patents and it went out of business a few years later. (List of films in Prizmacolor at IMDB [1].)

In 1918 in Marin County, California, the only film made in the NaturalColor process--Cupid Angling [2]--was produced by Leon Forrest Douglass (1869-1940), who was also an early investor in Victor Records.

The first animation film in color, The Debut of Thomas Katt was shot in 1920 by John Randolph Bray and was produced in Brewster Color by the Brewster Color Company of Newark, New Jersey. Percy D. Brewster's system was based on the bi-pack/duplitized stock method, and enjoyed some success in the late 1920s.

In 1926, Kelley and Max Handschiegl co-developed a process known as Kelleycolor. The process used on imbibition printing, included Handschiegl's stencil process. Kelleycolor was bought by Harriscolor in 1928.

Late in 1928, Howard Hughes bought the Multicolor corporation, which used a bi-pack/duplitized printing process. Three years later, Cinecolor was established. It used the same technique, based on patents bought from Kelley, and in 1932, after Multicolor closed down, Cinecolor collected its equipment to their advantage.

After experimenting with more advanced methods of additive systems (including a camera with two apertures (one with a red filter one with green) from 1915 to 1921, Dr. Herbert Kalmus, Dr. Daniel Comstock, and mechanic W. Burton Wescott (who left the company in 1921) developed the subtractive color system for Technicolor. This system used a beam splitter in a specially modified camera to send red and green light waves to separate black-and-white film negatives. From these negatives, two prints were made on film stock with half the base thickness than normal, which were toned accordingly - one red the other green^[4]. Then they were cemented together base-to-base into a single strip of film. The first film using this process was Toll of the Sea (1922) starring Anna May Wong. Perhaps the most ambitious film made with this process was The Black Pirate (1926), starring and produced by Douglas Fairbanks and directed by Albert Parker. The system was refined through the incorporation of dye imbibition, which allowed for the transferring of dyes from both color matrices into a single print, thus avoiding the problems at attaching two prints back-to-back and allowing for multiple prints to be created from a single pair of matrices.^[2]

Technicolor's system was extremely popular for a number of years, but it was a very expensive process: shooting cost three times that of black and white photography and printing costs were no cheaper. By 1932, general color photography had nearly been abandoned by major studios, until Technicolor developed a new advancement to record all three, primary colors. Utilizing a special dichroic beam splitter equipped with two 45-degree prisms in the form of a cube, light from the lens was deflected by the prisms and split into two paths to expose each one of three black and white negatives (one each to record the densities for red, green, and blue).

The three negatives were then printed to gelatin "matrices" which also completely bleached the image, washing out the silver and leaving only the gelatin record of the image. A "receiver print", consisting of a 50% density print of the black and white negative for the green record strip, and including the soundtrack, was struck and treated with dye mordants to aid in the imbibition process (this "black" layer was discontinued in the early 1940s). The matrices for each strip were coated with their complementary dye (yellow, cyan, or magenta), and then each successively brought into high-pressure contact with the receiver, which would imbibe and hold the dyes which collectively were able to render a wider spectrum of colors than the previous technologies.^[5] The first animation film with the three-color (also called three-strip) system was Walt Disney's Flowers and Trees (1932), the first short live-action film was La Cucaracha (1934), and the first feature was Becky Sharp (1935).^[4] These films and their prints have extremely high long-term sustainability because both the black and white negatives and the dye-based prints are very resistant to fading, unlike modern one-strip color films which eventually fade towards pink as the dye couplers continue to chemically degrade over time. In order to counteract this inevitable process with modern color films, the three-strip process is essentially reverse engineered to create separation masters, which are three black and white negatives, one each sensitized for red, green, and blue, that can be reliably used to preserve the color record of modern films.

[edit] Monopack color film

A strip of undeveloped 35 mm color negative.

Modern color film is based on the subtractive color system, which filters colors from white light through dyed or color sensitive layers within a single strip of film. A subtractive color (cyan, magenta, yellow) is what remains when one of the additive primary colors (red, green, blue) has been removed from the spectrum. Eastman Kodak's tripack color film incorporated three separate layers of color sensitive emulsions into one strip of film. Kodachrome was the first commercially successful application of monopack multilayer film, introduced in 1935.^[6]

Eastmancolor, introduced in 1952, was Kodak's first, economical, single-strip 35 mm negative recording system, incorporated into one strip of film. This rendered the three-strip photography relatively obsolete, even though for the first few years, Technicolor's quality control in printing produced colors that were more precise than monopack film and the dye-transfer print would maintain its color much longer than an Eastman print, which would fade over time, mostly due to poor processing and improper storage.^[3]

Technicolor continued to offer the dye-imbibition print process for projection prints until 1975, and even briefly revived it in 1998. As an archival format, Technicolor prints are one of the most stable color print processes yet created, and prints properly cared for are estimated to retain their color for centuries.^[7] With the introduction of low-fade (LPP) films, properly stored (at 45 °F or 7 °C and 25 per cent relative humidity) monopack color film is expected to last, with no fading, a comparative amount of time. Kodachrome tranparency film stored at 0^oF (−18 °C) is predicted to last a similar length in time without noticeable picture degradation. Improperly stored monopack color film from before 1983 can incur a 30 per cent image loss in as little as 25 years.^[8]

[edit] How modern color film works

A representation of the layers within a piece of developed modern color 35 mm negative film. When developed, the dye couplers in the blue, green and red sensitive layers turn the exposed silver halide crystals to their complimentary colors (yellow, magenta, cyan). The film is made up of (A) Clear protective topcoat (B) UV filter (C) "Fast" blue layer (D) "Slow" blue layer (E) Yellow filter to cut all blue light from passing through to (F) "Fast" green layer (G) "Slow" green layer (H) Inter (subbing) layer (I) "Fast" red layer (J) "Slow" red layer (K) Clear triacetate base (L) Antihaliation (rem-jet) backing.

Modern color film is made up of many different layers all working together to create the color image. In color negative films there are three main color layers: the blue record, green record and red record; each made up of two separate layers. Each layer contains silver halide crystals and dye-couplers. A cross-sectional representation of a piece of developed color negative film is at right. Each layer of the film is so thin that the composite of all layers, in addition to the triacetate base and antihaliation backing, is less than 0.0003" (8 µm) thick.^[9]

The three color records are stacked as shown at right with a UV filter on top to keep the non-visible ultraviolet radiation from exposing the silver halide crystals, which are naturally sensitive to UV light. Next, the fast and slow blue sensitive layers, which, when developed, form the latent image. When the exposed silver halide crystal is developed, it is coupled with a dye grain of its complementary color. This forms a dye "cloud" (like a drop of water on a paper towel) and is limited in its growth by developing ingibiting releasing (DIR) couplers, which also serve to refine the sharpness of the processed image by limiting the size of the dye clouds. The dye clouds formed in the blue layer are actually yellow (the opposite or complimentary color to blue).^[10] There are two layers to each color; a "fast" and a "slow." The fast layer features larger grains that are more sensitive to light than the slow layer, which has finer grain and is less sensitive to light. Silver halide crystals are naturally sensitive to blue light, so the blue layers are on the top of the film and they are followed immediately by a yellow filter, which stops any more blue light from passing through to the green and red layers and biasing those crystals with extra blue exposure. Next are the red sensitive record (which forms cyan dyes when developed), and at the bottom, the green sensitive record, which forms magenta dyes when developed. Each color is separated by a gelatin layer which prevents silver development in one record from causing unwanted dye formation in another. The bottom of the whole stack (film base) is an antihaliation layer that prevents bright light from reflecting off the clear base of the film and passing back through the negative to double-expose the crystals and create "halos" of light around bright spots. In color film this backing is rem-jet, which is a black-pigmented non-gelatin layer on the back of the film base and is removed in the developing process.^[9]

Eastman Kodak manufacturers film in 54 inch (1,372 mm) wide rolls. These rolls are then slit into various sizes (65 mm, 35 mm, 16 mm) as needed.

[edit] Modern manufacturers of color film for motion picture use

See also List of motion picture film stocks

Motion picture film, primarily because of the rem-jet backing, requires a different developer bath than standard color film. The developer necessary is ECN-2 (Eastman Color Negative 2). If motion picture negative is run through a standard C-41 color film developer bath, the rem-jet backing will destroy the integrity of the developer and, potentially, ruin the film.

There are two main companies manufacturing color film for motion picture use: Eastman Kodak and Fuji Films.

[edit] Kodak color motion picture films

In the late 1980s Kodak introduced the T-Grain emulsion, a technological advancement in the shape and makeup of silver halide grains in their films. T-Grain is a tabular silver halide grain that allows for greater overall surface area, resulting in greater light sensitivity with a relatively small grain and a more uniform shape which results in a less overall graininess to the film. This made for sharper and more sensitive films. The T-Grain technology was first employed in Kodak's EXR line of motion picture color negative stocks.^[11] This was further refined in 1996 with the Vision line of emulsions, followed by Vision2 in the early 2000s.

[edit] Fuji color motion picture films

Fuji films also integrate tabular grains in their SUFG (Super Unified Fine Grain) films. In their case the SUFG grain is not only tabular, it is hexagonal and consistent in shape throughout the emulsion layers. Like the T-grain, it has a larger surface area in a smaller grain (about one-third the size of traditional grain for the same light sensitivity. In 2005 Fuji unveiled their Eterna 500T stock, the first in a new line of advanced emulsions, keeping competitive with Kodak's innovations.

[edit] References

[edit] See also

• 135 film
• 35 mm film
• Cinecolor
• Color photography
• Film base
• Kinemacolor
• List of color film systems
• List of film formats
• List of motion picture film stocks
• Multicolor
• Photographic film
• Technicolor

[edit] External links

• The American Widescreen Museum has a thorough treatise on early motion picture color processes.