For image analysis, the dynamic range (or grey level resolution) refers to the actual range of grayscale levels being used by the image which will be less than the available range of values. For example: with a 16-bit image there are 65,536 available values and your data will lie somewhere inside that range.
Our recommendation:
If possible, only scan the area of the gel you are interested in. Perform any cropping at the time of scanning to remove blank parts of the scanner plate, labels etc.
To find out more, download our image capture guide: http://totallab.com/cms/pdf/imagecaptureebook.pdf