Calibration(redirected from calibration of radiography unit)
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calibration(kal-ă-bray -shŏn) A procedure carried out on a measuring instrument, such as a radio telescope, by means of which the magnitude of its response is determined as a function of the magnitude of the input signal. The calibration of a radio telescope provides an absolute scale of the output deflection against antenna temperature.
a metrological operation by which an instrument of measurement (a standard or measuring device) is equipped with a scale or a calibration chart (curve). The graduations on the scale must correspond with the required accuracy to the values of the quantity being measured; the chart (curve) must reflect with similar accuracy the connection between the magnitude produced at the output of the device and the magnitude affecting the input—for example, the dependence of the electromotive force of a pyrometer’s thermocouple on the temperature of the operating junction. Calibrations are made by means of measurement that are more precise than the means of measurement being calibrated; the actual values of the measured quantity are established from the more precise means of measurement. Accurate means of measurement are calibrated individually; the less accurate ones are supplied with a standard scale printed beforehand or a standard calibration chart (curve). The use of such scales and standard calibration charts may at times make it necessary to regulate the means of measurement in order to reduce the error to some established norm.
K. P. SHIROKOV
verification of a measure or set of measures by taking a group of measurements.
Calibration consists in determining the error or correction of a group of gauges (such as a set of weights) or of a single multivalent gauge (such as a linear scale) for various combinations of the gauge or for various ranges of the scale. A comparison is made of the measures or of the sections of the scale in which one of the measures or scale values is taken as the basis of comparison.
REFERENCESMalikov, M. F. Osnovy metrologii, part 1. Moscow, 1949.
Amatuni, A. N. “Kalibrovka podrazdelenii shtrikhovykh mer.” In En-tsiklopediia izmerenii, kontrolia iavtomatiki (EIKA), issue 6. Moscow-Leningrad, 1966. Page 33.
calibrateTo adjust or bring into balance. Scanners, CRTs and similar peripherals may require periodic adjustment. Unlike digital devices, the electronic components within these analog devices may change from their original specification. See TV calibration, color calibration and tweak.
color calibrationThe matching of colors to a base color, such as a Pantone color, or from one device to another. Color calibration is widely used in print publishing in order to display on screen an accurate representation of the colors that will be printed on paper. Monitors use red, green and blue (RGB) to display the color gamut, while printers use cyan, magenta, yellow and black (CMYK) inks. See TV calibration, color gamut and color correction.
|Light Source's Colortron Color System includes this color calibrator, which is used to accurately determine the color from a sample. Using suction cups, it attaches to the monitor screen to calibrate the monitor so that designers see true representations of the final colors on screen. (Image courtesy of Light Source, Inc.)|
TV calibrationAdjusting the color and contrast on a flat panel TV that has been in use approximately 100 hours. In order to display content as originally intended, separate adjustments must be made for each source, typically the cable box and the DVD or Blu-ray player.
Calibration Discs and ISF Certification
Calibration DVDs are widely available for consumers and professionals. By following the instructions on the disc, adjustments can be made. However, the TV's setup menus can be complicated, and the wrong adjustment can render the TV inoperable.
Consumers often opt for a professional calibration by people who have been certified by the Imaging Science Foundation (ISF). They come into the home with analyzer and test pattern equipment and are able to make fine adjustments that the user cannot. See color calibration.