1. A method for enhancing contrast in fluorescence imaging, comprising: providing a patterned illumination source for illuminating one or more regions corresponding to a scan step; scanning at least a portion of a surface of a subject using a plurality of scan steps; collecting an emitted light from an illuminated region as well as from an area of interest away from the illuminated region; acquiring image frames corresponding to two or more scan steps; deducting a background fluorescence from the image frames corresponding to the two or more scan steps to form one or more processed image frames, wherein the background fluorescence is based on an excitation spread function; and reconstructing an image using one or more of the processed image frames.