Bio-Rad Quantity One 1-D Analysis Software - Manual (Page 367)

Quantity One User Guide
H-12
Fig.H-10. Options dialog box.
H.6.a Dark Subtraction Type
All CCD cameras accumulate electrons that produce a “signal” that is
indistinguishable from light. This “dark count” adds to the noise in your images. In
most cases, you will want to subtract this dark count from your images.
Normal
The Normal option button selects the default dark subtraction type. In this mode, after
you acquire an image, a “dark” image of the same exposure length will be taken, and
this will be subtracted from your image.
The progress of the dark exposure will be displayed in the Exposure Status bar
following the regular image exposure.
Note: In Normal mode, a dark image is only acquired the first time you perform a scan
with particular application and exposure settings. If you perform subsequent
scans with the same settings, no dark exposure will be taken.