1. A method for extending the dynamic range of an imaging system having a detector with a linear response, the method comprising: acquiring a plurality of images of a sample using the detector, each image being acquired with a different exposure time, each image having a plurality of pixels, each pixel having an intensity value; subtracting from each acquired image a calibrated dark image corresponding to the exposure time for each acquired image to produce a plurality of dark-corrected images; and on a per pixel basis, determining a merged pixel value using values of the corresponding pixel from each of the plurality of dark-corrected images.