To control all the parameters related to the color intervening in the processes of seizure, visualization on screen and impression, is not simple thing and requires a theoretical comprehension of the colorimetric concepts. Variations of colors noted between an original (document opaque, slide or negative color) and the restitution on screen or various paper media oblige with a qualitative and quantitative color management. In the absolute, the computer must be able to treat these differences in colors and apply coefficients of correction necessary with an aim of restoring colorimetric coherence to the whole of the system.

         With the awakening of such a need, the manufacturers first of all used their own formats to describe the behavior of their peripherals with respect to the colors. The color management thus functioned only in closed system and this made difficult to exchange the image files between the various systems. Need for developing automated and standardized solutions became impossible to circumvent, the ICC established a format of universal profile for the characterization of the various peripherals.

         Each peripheral has its own color space and the goal of a color management system is to provide information to know where a color is precisely in such space. However, many problems remain in this research of colorimetric constancy, and the purpose of this handbook is to propose the theoretical aspects, while approaching the effects of Color Management.

         To approach Color Management from a technical point of view is not sufficient. This is why we have made an effort, with each time that is possible, to propose the economic obviousnesses of a color management system. In past, a very qualified personnel are required for the integration and use of Color Management System, as well as a consequent material investment, which is not any more nowadays. The current tools are easily integrable in a flow of production, and reduces the expenses due to the trowel (papers, inks, films, etc.), but also to carry out a considerable saving of time, thus improving the productivity. Adoption of an open system by the means of ICC adds a range of possibilities for the company which has a color management system based on this international standard.

A return behind on PostScript and a glance on Color Management

         With the first glance, the reader could be astonished that we begin this handbook devoted to the handling of the colors with a return behind on PostScript. Many signs show the technology of color Management, as much will change the work of organization in the graphic field, that could not do it by PostScript these ten or twelve last years. PostScript is a basic technology conceived for the piloting of apparatuses of edition, a universal interchange format for the text, the image and graphics. After the introduction of PostScript, it was necessary a few years so that the software entitled Desktop Publishing makes full use of the possibilities of PostScript. These last years, PostScript was still improved on certain points in order to make it more compatible to the practice. After this phase of startup having known some "infantile diseases", the organization of work in the graphic field started to change radically. Even twelve years after the arrival of PostScript, many of those and those which use it do not control this technology yet fully. Those which already worked in a photo studio are well placed for the knowledge.

         After PostScript Color Management is from now the second large technological wave to break in the graphic field. PostScript vagueness acted particularly on two sectors of the graphic field: creation (agencies and editors) and the production (traditional photocomposition and partly also reproduction). Color Management vagueness includes distinctly more sectors: put aside agencies and editors, just like photocomposition, the world of the reproduction will change more radically than after the introduction of PostScript. They are primarily the traditional impression and the numerical impression. Photographers, them also, will have to give their knowledge in question and to long, Color Management became a basic technology specialized in the exchange of digital images within media connected by the numerical one.

History of PostScript:

PostScript rests on the fundamental elements which existed already before its creation: the representation of graphics and the writing by means of vectors just like the representation of images and photographs by means of pixels. This coding of text, of graphics and image existed already before the existence of PostScript in some systems of very expensive photocomposition. The originators of these systems were responsible for all, to start with the basic software, allowing to have in the computer the text, graphics and image while passing by the software of use for the formation and management of the exposures. Each manufacturer had his own formats of data and was delighted to be able to sell a few thousands of these systems throughout the world. These systems, the peripherals and the software were thus relatively expensive. It was necessary to count for a working station in photocomposition at the beginning of the Eighties on basic equipment an amount of 500 000 F. With PostScript the watershed came then.