Panchromatic
Encyclopedia
Panchromatic film is a type of black-and-white
photographic film
that is sensitive to all wavelength
s of visible light. A panchromatic film therefore produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern photographic film is panchromatic, but some types are orthochromatic
and are not sensitive to certain wavelengths of light. As naturally prepared, silver halide
emulsions are much more sensitive to blue and UV light than to green and red wavelengths. The German chemist Hermann W. Vogel
found out how to extend the sensitivity into the green, and later the orange, by adding sensitising dyes to the emulsion. However, his technique was not extended to achieve a fully panchromatic film until the early 1900s, shortly after his death. Panchromatic stock for still photographic plates became available commercially in 1906. But the switch from orthochromatic film was only gradual: panchromatic plates cost two to three times as much, and had to be developed in darkness, unlike orthochromatic which, being insensitive to red, could be developed under a red light in the darkroom. And the process that increased the film's sensitivity to yellow and red also made it oversensitive to blue and violet, requiring a yellow-red lens filter to correct it, which in turn reduced the total amount of light and increased the necessary exposure time.
Orthochromatic film proved troublesome for motion pictures, rendering blue skies as perpetually overcast, blond hair as washed-out, blue eyes nearly white, and red lips nearly black. To some degree this could be corrected by makeup, lens filters, and lighting, but never completely satisfactorily. But even those solutions were unusable for additive color
motion picture systems like Kinemacolor
and Prizma color
, which photographed on black-and-white stock behind alternating color filters. In those cases, negative film stock after it arrived from the manufacturer had to be passed through a color-sensitizing solution, a time-consuming process which increased the film's cost from 3 cents per foot to 7 cents. Eastman Kodak, the leading supplier of motion picture film, introduced a panchromatic film stock in September 1913, available on special order for photographing color motion pictures in additive systems. Cameramen began using it for black-and-white films too in 1918, primarily for outdoor scenes. The company introduced Kodak Panchromatic Cine Film as a regular stock in 1922. The first black-and-white feature film
to be photographed entirely on panchromatic stock was The Headless Horseman (1922). But panchromatic stock was more expensive, and not until the prices were equalized by competition in 1926 did it become used more widely than orthochromatic stock. Kodak discontinued manufacturing general-purpose orthochromatic motion picture film in 1930.
Digital panchromatic imagery of the Earth
's surface is also produced by some modern satellites, such as QuickBird
and IKONOS
. This imagery is extremely useful, as it is generally of a much higher (spatial) resolution than the multispectral imagery from the same satellite. For example, the QuickBird
satellite produces panchromatic imagery having a pixel equivalent to an area 0.6m x 0.6m, while the multispectral pixels represent an area of 2.4m x 2.4m.
Black-and-white
Black-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...
photographic film
Photographic film
Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...
that is sensitive to all wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s of visible light. A panchromatic film therefore produces a realistic reproduction of a scene as it appears to the human eye. Almost all modern photographic film is panchromatic, but some types are orthochromatic
Orthochromatic
- Orthochromatic photography :Orthochromatic photography refers to a photographic emulsion that is sensitive to only blue and green light, and thus can be processed with a red safelight. The increased blue sensitivity causes blue objects to appear lighter and red ones darker...
and are not sensitive to certain wavelengths of light. As naturally prepared, silver halide
Silver halide
A silver halide is one of the compounds formed between silver and one of the halogens — silver bromide , chloride , iodide , and three forms of silver fluorides. As a group, they are often referred to as the silver halides, and are often given the pseudo-chemical notation AgX...
emulsions are much more sensitive to blue and UV light than to green and red wavelengths. The German chemist Hermann W. Vogel
Hermann W. Vogel
Hermann Wilhelm Vogel was a German photochemist and photographer who made a key discovery of great importance to photography.-Academic career:...
found out how to extend the sensitivity into the green, and later the orange, by adding sensitising dyes to the emulsion. However, his technique was not extended to achieve a fully panchromatic film until the early 1900s, shortly after his death. Panchromatic stock for still photographic plates became available commercially in 1906. But the switch from orthochromatic film was only gradual: panchromatic plates cost two to three times as much, and had to be developed in darkness, unlike orthochromatic which, being insensitive to red, could be developed under a red light in the darkroom. And the process that increased the film's sensitivity to yellow and red also made it oversensitive to blue and violet, requiring a yellow-red lens filter to correct it, which in turn reduced the total amount of light and increased the necessary exposure time.
Orthochromatic film proved troublesome for motion pictures, rendering blue skies as perpetually overcast, blond hair as washed-out, blue eyes nearly white, and red lips nearly black. To some degree this could be corrected by makeup, lens filters, and lighting, but never completely satisfactorily. But even those solutions were unusable for additive color
Additive color
An additive color model involves light emitted directly from a source or illuminant of some sort. The additive reproduction process usually uses red, green and blue light to produce the other colors. Combining one of these additive primary colors with another in equal amounts produces the...
motion picture systems like Kinemacolor
Kinemacolor
Kinemacolor was the first successful color motion picture process, used commercially from 1908 to 1914. It was invented by George Albert Smith of Brighton, England in 1906. He was influenced by the work of William Norman Lascelles Davidson. It was launched by Charles Urban's Urban Trading Co. of...
and Prizma color
Prizma
The Prizma Color system was a technique of color motion picture photography, invented in 1913 by William Van Doren Kelley and Charles Raleigh. Initially, it was a two-color additive color system, similar to its predecessor, Kinemacolor...
, which photographed on black-and-white stock behind alternating color filters. In those cases, negative film stock after it arrived from the manufacturer had to be passed through a color-sensitizing solution, a time-consuming process which increased the film's cost from 3 cents per foot to 7 cents. Eastman Kodak, the leading supplier of motion picture film, introduced a panchromatic film stock in September 1913, available on special order for photographing color motion pictures in additive systems. Cameramen began using it for black-and-white films too in 1918, primarily for outdoor scenes. The company introduced Kodak Panchromatic Cine Film as a regular stock in 1922. The first black-and-white feature film
Feature film
In the film industry, a feature film is a film production made for initial distribution in theaters and being the main attraction of the screening, rather than a short film screened before it; a full length movie...
to be photographed entirely on panchromatic stock was The Headless Horseman (1922). But panchromatic stock was more expensive, and not until the prices were equalized by competition in 1926 did it become used more widely than orthochromatic stock. Kodak discontinued manufacturing general-purpose orthochromatic motion picture film in 1930.
Digital panchromatic imagery of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's surface is also produced by some modern satellites, such as QuickBird
QuickBird
QuickBird is a high-resolution commercial earth observation satellite, owned by DigitalGlobe and launched in 2001 as the first satellite in a constellation of three scheduled to be in orbit by 2008...
and IKONOS
IKONOS
IKONOS is a commercial earth observation satellite, and was the first to collect publicly available high-resolution imagery at 1- and 4-meter resolution. It offers multispectral and panchromatic imagery. The IKONOS launch was called by John E. Pike “one of the most significant developments in...
. This imagery is extremely useful, as it is generally of a much higher (spatial) resolution than the multispectral imagery from the same satellite. For example, the QuickBird
QuickBird
QuickBird is a high-resolution commercial earth observation satellite, owned by DigitalGlobe and launched in 2001 as the first satellite in a constellation of three scheduled to be in orbit by 2008...
satellite produces panchromatic imagery having a pixel equivalent to an area 0.6m x 0.6m, while the multispectral pixels represent an area of 2.4m x 2.4m.