between the camera result values and the known reference values. When two or more cameras need to be calibrated relatively to each other, to reproduce the same color values, the technique of color mapping can be used. Scanner For creating a scanner profile it needs a target source, such as an IT8-target, an original with many small color fields, which was measured by the developer with a photometer. The scanner reads this original and compares the scanned color values with the target's reference values. Taking the differences of these values into account an ICC profile is created, which relates the device specific color space (RGB color space) to a device independent color space (L*a*b* color space). Thus, the scanner is able to output with color fidelity to what it reads. Display For calibrating the monitor a colorimeter is attached flat to the display's surface, shielded from all ambient light. The calibration software sends a series of color signals to the display and compares the values that were actually sent against the readings from the calibration device. This establishes the current offsets in color display. Depending on the calibration software and type of monitor used, the software either creates a correction matrix (i.e. an ICC profile) for color values before being sent to the display, or gives instructions for altering the display's brightness/contrast and RGB values through the OSD. This tunes the display to reproduce fairly accurately the in-gamut part of a desired color space. The calibration target for this kind of calibration is that of print stock paper illuminated by D65 light at 120 cd/m2. Printer The ICC profile for a printer is created by comparing a test print result using a photometer with the original reference file. The testchart contains known CMYK colors, whose offsets to their actual L*a*b* colors scanned by the photometer are resulting in an ICC profile. Another possibility to ICC profile a printer is to use a calibrated scanner as the measuring device for the printed CMYK testchart instead of a photometer. A calibration profile is necessary for each printer/paper/ink combination. See also Gamma correction List of colors Color chart Color management Color mapping ICC profile IT8 References External links CoCa - www.dohm.com.au/coca/index.html Color Camera Calibrator - an open source scanner and digital camera color calibration (ICC profiling) software by Andrew Stawowczyk Long. Color