Color and Calibration

Additive Color
The additive primary colors are red, green and blue. These additive primaries represent the three main components of white light. Used individually or together, these three colors of light can be mixed to create nearly all colors. Additive color is used in scanners and computer displays.
The act of adjusting equipment so that it performs in accordance with an established standard. Calibration is necessary when equipment is installed and continues to be a necessary part of on-going use and maintenance.
A device independent color space that can be used to describe the entire visual spectrum. This color space is being used in modern color management software to facilitate conversion of data from a scanner to a display, or from a display to an output device.
Closed Loop Calibration
A method of scanner calibration where a factory provided file is printed on the desired printer and then scanned back in. The scanned result is compared with the original file data and a compensation setting is stored. This compensation setting is used as a filter for all future scans to be output on that particular output device.
The process printing colors. Cyan, Magenta, Yellow, Black.
Color Management System
Abbreviated CMS. A CMS is a set of software designed to increase the accuracy and consistency of color between a scanner, display and printer. A CMS consists of: "Device profiles" which document the performance of the particular scanner, display and printer you may own. A "device transformation engine" that coverts data between the scanner, display and printer. A "gamut compensation mechanism" that addresses differences between the capabilities of the scanner, display and printer. And a "device independent color space" through which all color transformations occur.
Color Space
A color space is a particular language used to describe color. Examples of color spaces are: RGB, CMYK, HSB, CIE LAB.
Device Dependent Color Space
For example RGB. A device dependent color space is one in which the same color values will give different results on different devices. This is why the same scan file will appear different when viewed on different computer displays.
Device Independent Color Space
For example CIE LAB. A device independent color space is one in which a particular color value is considered absolute and not subject to interpretation. CIE LAB is the central color space in color management systems and is used to translate between different device dependent color spaces such as scanner RGB and display RGB.
Device Profile
A file used as part of a Color Management System. A device profile contains information documenting the unique characteristics of that brand and model of device. There are device profiles for scanners, computer displays and printers
Gamma Adjustment
An adjustment that makes the Tonal Distribution lighter or darker. A Gamma Adjustment may be made to a monitor, a scanner or to an image during the scanning or image editing process.
A term referring to the range of available color on a display or printer. A particular color is either in or out of the gamut of the device. If outside, it cannot be accurately shown on that display or printed on that output device. (Each device has its own gamut capabilities.)
Gamut Alarm
A software function that tells the user if a color falls outside the Gamut of the currently targeted printer.
Gamut Transformation
A function of Color Management Systems where out of Gamut colors are converted to colors within the Gamut of the targeted printer. For photographs, the gamut transformation progressively transforms all color in the image so the image retains a realistic appearance. For line-art, only the colors falling out of gamut are changed and the rest of the art is left intact.
A color space with the three variable of Hue. Lightness. Saturation. See HSB.
A color space with the three variables of Hue. Saturation. Brightness. Hue means color (as in the color wheel.) Saturation is an indication relating to the richness or vibrancy of the color. Brightness is a term best related to the intensity of light illuminating the object.
Lightness is a term referring to the lightness or brightness of an image. Also, as part of the HSL color space, it refers to the imagined amount of light illuminating a viewed color.
Output Simulation
A term used in some Color Management Systems to describe the function whereby the computer display is used to predict the results achievable on a particular printer.
The CIE based device independent color space used to store images on a Kodak PhotoCD disc.
Red, Green, Blue. These Additive Primary colors are the basic elements of white light. By mixing them in a computer monitor or in a scanned image file, other colors can be made. For instance, Red and Green light make Yellow light. and equal amounts of all three make grey.
Saturation is one attribute of color in the color space called HSB. (Hue Saturation, Brightness) Saturation is a characteristic indicating the vibrancy or intensity of a hue. A color with high saturation will appear more intense than the same color with less.
Subtractive Color
A term used to describe the subtractive primary colors: Cyan, magenta, yellow. As ink applied to a piece of paper by a printing press, these colors absorb light and alter the colors seen by one looking at the press sheet. Cyan ink absorbs the red third of the spectrum, magenta ink absorbs the green third, and yellow ink absorbs the blue third. This should theoretically cause the viewer to see a black color, (with three thirds absorbed, no light is reflected) but due to unavoidable impurities in the inks, there is still light reflected and the viewer sees a muddy brown.
Tonal Distribution
Tonal Distribution describes the distribution of various bright or dark tones within an image. During the scanning or image editing stage, tones can be redistributed lightening a dark image or darkening a light one.
Viewing Conditions
A term used to describe the lighting conditions surrounding a computer display or color proof viewing area. The intensity and type of light have a dramatic impact on the colors perceived by the viewer.