1. A method for generating an output data set representing a fluorescence image of a sample, the method comprising the steps of: (a) obtaining an input data set comprising a plurality of florescence images of the sample, the plurality of fluorescence images representing fluorescence images of the sample for a plurality of different focal plane depths in the sample and different exposure times, wherein the respective ones of the plurality of fluorescence images comprise image signal values for a two-dimensional array of pixel locations; and (b) combining, with a processor of a computer, image signal values from different ones of the plurality of fluorescence images from the different focal plane depths and different exposure times to form a two-dimensional output data set representing a single resultant fluorescence image of the sample; wherein step (b) comprises the steps of: (b1) deriving an intermediate image for each of the different exposure times from the images for the different focal plane depths for the respective different exposure times, and (b2) combining the intermediate images for the different exposure times to form the single resultant image; and wherein step (b2) comprises determining for each pixel location in the intermediate images a weighted average of the corresponding image signal values in the different intermediate images, and wherein the weightings for each image signal value in the intermediate images are based on a measure of a variation in the image signal values among neighboring pixel locations.