Bio-Rad EXQuest Spot Cutter - Manual (Page 535)

PDQuest User Guide
L-10
single gel should be the same since the same physical calibration strip was used to
make each exposure.
L.2 Merging Multiple Exposures
If you are working with 8-bit images and are using calstrips on your scans, you can
merge multiple exposures of the same gel into a single image with a greater dynamic
range.
Note: You can only merge 8-bit images with calstrips. If you are not working with 8-bit
images or are not using calstrips, you cannot merge exposures.
To merge multiple exposures, make sure all your exposures and calstrips are loaded
into the same image window, then simply auto-detect spots as you would normally
(see the following chapter).
Creating Different Exposure Files
To identify different gel scans as different exposures of the same gel, open the scan
files, select Change Version/Exposure from the File menu, and enter consecutive
exposure numbers for the different scans. Make sure that the root names of the scan
files are the same.
Note: You can give different exposures the same root name when you are scanning
them, or you can change them later using the Save As command. After you
change the exposure numbers, you will end up with files named RootName x1,
RootName x2, RootName x3, etc.
Why Merge Exposures?
Because 8-bit scanners have a limited dynamic range, dark spots may saturate on long
exposures, while faint spots may be missed on short exposures, and either extreme
can be missed on medium duration exposures. Therefore, it is frequently necessary to
combine the quantitative data from a number of 8-bit exposures of the same gel
exposed for different lengths of time into a “merged” synthetic image. Merging
creates such an image automatically as you spot detect.