Bio-Rad Quantity One 1-D Analysis Software - Manual (Page 13)

Quantity One User Guide
1-2
1.2 Digital Data and Signal Intensity
The Bio-Rad imaging devices supported by Quantity One are light and/or radiation
detectors that convert signals from biological samples into digital data. Quantity One
then displays the digital data on your computer screen, in the form of gray scale or
color images.
A data object as displayed on the computer is composed of tiny individual screen
pixels. Each pixel has an X and Y coordinate, and a value Z. The X and Y coordinates
are the pixel’s horizontal and vertical positions on the image, and the Z value is the
signal intensity of the pixel.
Fig. 1-1. Representation of the pixels in two digitally imaged bands in a gel.
For a data object to be visible and quantifiable, the intensity of its clustered pixels
must be higher than the intensity of the pixels that make up the background of the
image. The total intensity of a data object is the sum of the intensities of all the pixels
that make up the object. The mean intensity of a data object is the total intensity
divided by the number of pixels in the object.
The units of signal intensity are Optical Density (O.D.) in the case of the GS-700™
imaging densitometer, GS-710™ calibrated imaging densitometer, and GS-800™
calibrated densitometer, the Gel Doc™ system, ChemiDoc™ system, ChemiDoc
XRS™ system with a white light source, or the Fluor-S™ MultiImager system,
Fluor-S™ MAX MultiImager system, Fluor-S™ MAX2 MultiImager system and
VersaDoc™ imaging systems with white light illumination. Signal intensity is
expressed in counts when using the Personal Molecular Imager™ system or the
Molecular Imager FX™ system, Molecular Imager FX Pro™ fluorescent imager,
2-D View
3-D View
Signal intensity of a single pixel
In
te
n
s
it
y