User guide

User Guide | 231
Glossary
Aspect ratio The ratio of the width to the height of an image.
CCD (Charge-coupled device) A light-sensitive silicon chip used as a
photodetector in ChemiDoc™ MP and ChemiDoc XRS+ camera
systems.
Colormaps Different color representations of a gel image.
Electrophoresis A technique for separating molecules based on the differential
movement of charged particles through a matrix when subjected to an
electric field.
Example precision The number of decimal places chosen for displaying a measurement.
Flat fielding An average intensity computation that compensates for
nonuniformities generated by an instrument.
Histogram A graphed representation of the brightness, or gray value, of an image.
Native charge
density
The inherent electrical charge of a protein without the addition of SDS.
pl Isoelectric point; the pH at which a protein molecule carries no net
charge.
Rf Relative front value of the band. In Image Lab™ software, Rf has a
value between 0 and 1 and indicates the relative movement of the
band from top to bottom.
Quantitative
imaging
Determines the quantity of a protein’s components through analysis of
the pixel values in a digital image of the sample.
UV-B The range of ultraviolet light used by the system.
UV
transilluminator
The part of the imager that transmits UV light through a sample.