User guide

Quantity One User Guide
1-2
images can be easily converted into TIFF format for compatibility with other
Macintosh and Windows applications.
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 and GS-710 densitometers, the Gel Doc and Chemi Doc with a white
2-D View
3-D View
Signal intensity of a single pixel