1. A method for extracting an image of a target fluorophore in a biological material wherein a waveband for the target fluorophore emission overlaps a waveband for autofluorescence emission in the biological material, the method comprising: illuminating the biological material with a first excitation light to induce a first fluorescence emission arising from both autofluorescence of the biological material and fluorescence of the target fluorophore and with a second excitation light to induce a second fluorescence emission arising from the autofluorescence of the biological material; acquiring a first fluorescence image from the first fluorescence emission and a second fluorescence image from the second fluorescence emission; and processing the first and second fluorescence images to extract a third fluorescence image representing the target fluorophore, wherein relative intensities of the first and second excitation lights are modulated prior to acquiring the first and second fluorescence images.