The Eltron Company P310 manual Region Black Body Temperature

CHAPTER 3

color of the print media. In monitors, maximum intensities (maximum additions) result in white, and minimum intensities produce black. Because light reflected from print media depends on ambient lighting, users may get darker images from a printer than they see on their monitor, where a brightness setting exists.

Print illumination (generally from room or outdoor lighting) affects color for all printed images. When a light source emits less in certain parts of the visual spectrum, a print illuminated by such a source by necessity reflects less of the associated colors. This occurs even though the corresponding light reflecting capability remains inherent in the print. Imagine, for example, the effect of placing a color filter in front of a light source. Only the visual spectrum parts passed by this filter can reach the print. Viewers can sometimes see subtle effects of this by observing the same print under sunlight, incandescent lights, and fluorescent lights.

Sunlight radiates fairly evenly over the entire visual spectrum, rising only slightly higher at the center. Incandescent lights radiate far more on the red side than on the blue side of the visual spectrum. Fluorescent lights radiate differently depending on their phosphor blends. Such classifications as “Cool Light” and “Warm Light” refer to blue-rich and red-rich enhancements, respectively.

In scientific terms, the question “How white is my source?” is resolved by a side-by-side comparison between a source in question and a heated black body radiator. The term “black body” refers to a material that produces no color other than that which results from heating. Imagine such a material first appearing reddish and then gradually becoming white hot followed by bluish white as its temperature is pushed higher. These are the whites to which comparisons are made. In the Graphic Arts industry, the following standards for white exist:

Region Black Body Temperature

US.5000°K

Europe6500°K

The NTSC standard for white is 6500°K. However, only a properly adjusted television or monitor can produce a standard white.

When close concern for color is important in displaying prints, users should find similar ambient conditions for a color check. If a color is closely related to identifying a printed feature, users may find themselves dealing with this level of concern, with skin tones typically offering the greatest challenge. However, most applications tend to require a less critical evaluation. Usually, what looks good in one setting tends also to look good in another, despite any subtle differences in ambient lighting.

Color is very much a function of the device either sensing or producing the color. A computer monitor that uses a CRT, for example, can produce very bright images, typically brighter than those produced by a television set. A television set typically can produce a broader range of colors than can a CRT monitor. Television manufactures emphasize color range over brightness; monitor manufacturers emphasize brightness over color range. While the forgoing compromises generally hold true, each device manufacturer, in fact, takes a different perspective when deciding which formulations to use in the red,

980264-001 Rev. B 3-5