11 April 2009

Color film

The invention:Aphotographic medium used to take full-color pictures. The people behind the invention: Rudolf Fischer (1881-1957), a German chemist H. Siegrist (1885-1959), a German chemist and Fischer’s collaborator Benno Homolka (1877-1949), a German chemist The Process Begins Around the turn of the twentieth century, Arthur-Louis Ducos du Hauron, a French chemist and physicist, proposed a tripack (threelayer) process of film development in which three color negatives would be taken by means of superimposed films. This was a subtractive process. (In the “additive method” of making color pictures, the three colors are added in projection—that is, the colors are formed by the mixture of colored light of the three primary hues. In the “subtractive method,” the colors are produced by the superposition of prints.) In Ducos du Hauron’s process, the blue-light negative would be taken on the top film of the pack; a yellow filter below it would transmit the yellow light, which would reach a green-sensitive film and then fall upon the bottom of the pack, which would be sensitive to red light. Tripacks of this type were unsatisfactory, however, because the light became diffused in passing through the emulsion layers, so the green and red negatives were not sharp. To obtain the real advantage of a tripack, the three layers must be coated one over the other so that the distance between the bluesensitive and red-sensitive layers is a small fraction of a thousandth of an inch. Tripacks of this type were suggested by the early pioneers of color photography, who had the idea that the packs would be separated into three layers for development and printing. The manipulation of such systems proved to be very difficult in practice. It was also suggested, however, that it might be possible to develop such tripacks as a unit and then, by chemical treatment, convert the silver images into dye images.Fischer’s Theory One of the earliest subtractive tripack methods that seemed to hold great promise was that suggested by Rudolf Fischer in 1912. He proposed a tripack that would be made by coating three emulsions on top of one another; the lowest one would be red-sensitive, the middle one would be green-sensitive, and the top one would be bluesensitive. Chemical substances called “couplers,” which would produce dyes in the development process, would be incorporated into the layers. In this method, the molecules of the developing agent, after becoming oxidized by developing the silver image, would react with the unoxidized form (the coupler) to produce the dye image. The two types of developing agents described by Fischer are paraminophenol and paraphenylenediamine (or their derivatives). The five types of dye that Fischer discovered are formed when silver images are developed by these two developing agents in the presence of suitable couplers. The five classes of dye he used (indophenols, indoanilines, indamines, indothiophenols, and azomethines) were already known when Fischer did his work, but it was he who discovered that the photographic latent image could be used to promote their formulation from “coupler” and “developing agent.” The indoaniline and azomethine types have been found to possess the necessary properties, but the other three suffer from serious defects. Because only p-phenylenediamine and its derivatives can be used to form the indoaniline and azomethine dyes, it has become the most widely used color developing agent.Impact In the early 1920’s, Leopold Mannes and Leopold Godowsky made a great advance beyond the Fischer process. Working on a new process of color photography, they adopted coupler development, but instead of putting couplers into the emulsion as Fischer had, they introduced them during processing. Finally, in 1935, the film was placed on the market under the name “Kodachrome,” a name that had been used for an early two-color process. The first use of the new Kodachrome process in 1935 was for 16- millimeter film. Color motion pictures could be made by the Kodachrome process as easily as black-and-white pictures, because the complex work involved (the color development of the film) was done under precise technical control. The definition (quality of the image) given by the process was soon sufficient to make it practical for 8-millimeter pictures, and in 1936, Kodachrome film was introduced in a 35-millimeter size for use in popular miniature cameras. Soon thereafter, color processes were developed on a larger scale and new color materials were rapidly introduced. In 1940, the Kodak Research Laboratories worked out a modification of the Fischer process in which the couplers were put into the emulsion layers. These couplers are not dissolved in the gelatin layer itself, as the Fischer couplers are, but are carried in small particles of an oily material that dissolves the couplers, protects them from the gelatin, and protects the silver bromide from any interaction with the couplers. When development takes place, the oxidation product of the developing agent penetrates into the organic particles and reacts with the couplers so that the dyes are formed in small particles that are dispersed throughout the layers. In one form of this material, Ektachrome (originally intended for use in aerial photography), the film is reversed to produce a color positive. It is first developed with a black-and-white developer, then reexposed and developed with a color developer that recombines with the couplers in each layer to produce the appropriate dyes, all three of which are produced simultaneously in one development. In summary, although Fischer did not succeed in putting his theory into practice, his work still forms the basis of most modern color photographic systems. Not only did he demonstrate the general principle of dye-coupling development, but the art is still mainly confined to one of the two types of developing agent, and two of the five types of dye, described by him.

COBOL computer language

The invention: The first user-friendly computer programming language, COBOL was originally designed to solve ballistics problems. The people behind the invention: Grace Murray Hopper (1906-1992), an American mathematician Howard Hathaway Aiken (1900-1973), an American mathematician Plain Speaking Grace Murray Hopper, a mathematician, was a faculty member at Vassar College when World War II (1939-1945) began. She enlisted in the Navy and in 1943 was assigned to the Bureau of Ordnance Computation Project, where she worked on ballistics problems. In 1944, the Navy began using one of the first electronic computers, the Automatic Sequence Controlled Calculator (ASCC), designed by an International Business Machines (IBM) Corporation team of engineers headed by Howard Hathaway Aiken, to solve ballistics problems. Hopper became the third programmer of the ASCC. Hopper’s interest in computer programming continued after the war ended. By the early 1950’s, Hopper’s work with programming languages had led to her development of FLOW-MATIC, the first English-language data processing compiler. Hopper’s work on FLOW-MATIC paved the way for her later work with COBOL (Common Business Oriented Language). Until Hopper developed FLOW-MATIC, digital computer programming was all machine-specific and was written in machine code. A program designed for one computer could not be used on another. Every program was both machine-specific and problemspecific in that the programmer would be told what problem the machine was going to be asked and then would write a completely new program for that specific problem in the machine code.Machine code was based on the programmer’s knowledge of the physical characteristics of the computer as well as the requirements of the problem to be solved; that is, the programmer had to know what was happening within the machine as it worked through a series of calculations, which relays tripped when and in what order, and what mathematical operations were necessary to solve the problem. Programming was therefore a highly specialized skill requiring a unique combination of linguistic, reasoning, engineering, and mathematical abilities that not even all the mathematicians and electrical engineers who designed and built the early computers possessed. While every computer still operates in response to the programming, or instructions, built into it, which are formatted in machine code, modern computers can accept programs written in nonmachine code—that is, in various automatic programming languages. They are able to accept nonmachine code programs because specialized programs now exist to translate those programs into the appropriate machine code. These translating programs are known as “compilers,” or “assemblers,” andFLOW-MATIC was the first such program. Hopper developed FLOW-MATIC after realizing that it would be necessary to eliminate unnecessary steps in programming to make computers more efficient. FLOW-MATIC was based, in part, on Hopper’s recognition that certain elements, or commands, were common to many different programming applications. Hopper theorized that it would not be necessary to write a lengthy series of instructions in machine code to instruct a computer to begin a series of operations; instead, she believed that it would be possible to develop commands in an assembly language in such a way that a programmer could write one command, such as the word add, that would translate into a sequence of several commands in machine code. Hopper’s successful development of a compiler to translate programming languages into machine code thus meant that programming became faster and easier. From assembly languages such asFLOW-MATIC, it was a logical progression to the development of high-level computer languages, such as FORTRAN (Formula Translation) and COBOL.The Language of Business Between 1955 (when FLOW-MATIC was introduced) and 1959, a number of attempts at developing a specific business-oriented language were made. IBM and Remington Rand believed that the only way to market computers to the business community was through the development of a language that business people would be comfortable using. Remington Rand officials were especially committed to providing a language that resembled English. None of the attempts to develop a business-oriented language succeeded, however, and by 1959 Hopper and other members of the U.S. Department of Defense had persuaded representatives of various companies of the need to cooperate. On May 28 and 29, 1959, a conference sponsored by the Department of Defense was held at the Pentagon to discuss the problem of establishing a common language for the adaptation of electronic computers for data processing. As a result, the first distribution of COBOL was accomplished on December 17, 1959. Although many people were involved in the development of COBOL, Hopper played a particularly important role. She not only found solutions to technical problems but also succeeded in selling the concept of a common language from an administrative and managerial point of view. Hopper recognized that while the companies involved in the commercial development of computers were in competition with one another, the use of a common, business-oriented language would contribute to the growth of the computer industry as a whole, as well as simplify the training of computer programmers and operators. Consequences COBOL was the first compiler developed for business data processing operations. Its development simplified the training required for computer users in business applications and demonstrated that computers could be practical tools in government and industry as well as in science. Prior to the development of COBOL, electronic computers had been characterized as expensive, oversized adding machines that were adequate for performing time-consuming mathematics but lacked the flexibility that business people required. In addition, the development of COBOL freed programmers not only from the need to know machine code but also from the need to understand the physical functioning of the computers they were using. Programming languages could be written that were both machine- independent and almost universally convertible from one computer to another.Finally, because Hopper and the other committee members worked under the auspices of the Department of Defense, the software was not copyrighted, and in a short period of time COBOL became widely available to anyone who wanted to use it. It diffused rapidly throughout the industry and contributed to the widespread adaptation of computers for use in countless settings.