Bio-Rad EXQuest Spot Cutter - Manual (Page 16)

Introduction
1-3
Fig. 1-1. Representation of the pixels in two digitally imaged spots 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 ChemiDoc with a white light source, or the
Fluor-S and Fluor-S MAX MultiImagers with white light illumination. Signal
intensity is expressed in counts when using the Personal FX or FX, or in the case of
the Gel Doc, ChemiDoc, Fluor-S, or Fluor-S MAX when using the UV light source.
2-D View
3-D View
Signal intensity of a single pixel
int
ens
ity