Monday, December 1, 2008

Computer Anarchy And Color Chaos

I would guess the casual consumer when confronted with images displayed on computer screens probably assumes there is some color standard involved that regulates what red, blue or yellow should look like that governs the manufacture of these displays. But that is an incorrect assumption as all color reproduction devices are what the industry calls “device independent”. In other words it is a “free market” and a maker of display screens, as well as printers and scanners, in fact any device that reproduces color information, is not held to any standard in terms of the observed color reproduced as the result to the specific RGB computer data sent to or received from the device.

When the World Wide Web as an extension of the Internet was first envisioned a handful of influential companies realized to obtain any color uniformity in color perceived on-screen by individual computer users would require a way to regulate color at the source. The solution of Microsoft, Intel and Hewlett-Packard was to limit the gamut of color from the source to that of an average CRT monitor(circa early ‘90’s), in other words the lowest common denominator of color by making the number of possible colors from the source small. The result is the sRGB color space that only contains at most 65% of the color variants possible in a total of 1.7 million different colors a computer can record and reproduce from an 8-bit RGB file.

But even before that there was afoot some schemes to make computers reproduce consistent color called Color Management. At first these were primarily attempts spearheaded by companies like Agfa and Kodak and were proprietary and only useful to regulate color reproduction with the company’s products and software. Then a large representation of computer companies with a vested interest in color reproduction like Apple and Adobe got together and formed the International Color Consortium. Eventually a color standard was agreed upon and both physical print and film targets as well as computer reference files were promulgated. All of this became a widely accessible function for users with Adobe Photoshop version 5.5 which supported Color Management not just between devices on a single system but between computers and all platforms, Microsoft Windows, Apple Computer, and eventually Linux.

Some liken Color Management to being an arcane ritual, too complex and poorly regulated to be easily useful. But in concept it is really a simple scheme. Because computer components are manufactured in an international free market environment, then each display, scanner or printer is device independent and reproduces color uniquely; so the first function of Color Management is the measurement of the device’s color reproduction, which is referred to as calibration. Then the calibration is compared to the ICC color standard, and any differences are written into a text file that is called a Profile, with either an .ICC or .ICM suffix usually. These profile files provide your computer with the specific knowledge (description) of what color each device reproduces. For instance without a calibrated and profiled display your computer is unaware of what colors are on screen you are looking at. In addition to the three types of device profiles, display, input and output, a fourth type of profile is a workspace profile which provides the configuration of color on screen for a color managed application like Photoshop. The workspace profile is standardized like sRGB and Adobe RGB (1998), and when used in an application becomes the source profile for any image file that is generated or open in that application; and if embedded in a file saved from the application, that file then can be opened in any computer with a color managed application and if viewed in the space of the embedded profile, will look the same as it did on the display of the computer that generated it.

The complexity and possible confusion Color Management causes users comes from its implementation in various applications, printer drivers, scanner software and operating systems. In addition very often the installation of a scanner driver, or that of a printer, may result in numerous and often unneeded superfluous profile files being added to the Color folder (Windows) or the Colorsync/Profiles folder on an Apple Mac.

Problems ensue when a user sets up to use color management, for instance in an application like Photoshop, as to which profiles to select for RGB, grayscale and CMYK workspaces, or with a scanner which profile is actually the one to use with a particular model scanner if several have been installed with similar names. With printers it is often even more confusing as there may be a profile for each of the papers the printer supports using. All this is made worse by the fact every operating system when installed loads a bunch of standard generic profile files most users will never need. Sadly, nether printer/scanner companies nor software applications, much less operating systems, provide any documentation that fully identifies the profile files installed and their use or associated hardware. All anyone can do is be diligent in searching out which profiles are necessary and needed in association with your system and hardware, and then move all the rest to a newly made folder and call it Profile Purgatory.

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