In one aspect, methods of imaging are described herein. In some embodiments, a method of imaging described herein comprises disposing an ultrasound-switchable fluorophore in an environment； exposing the environment to an ultrasound beam to create an activation region within the environment； disposing the fluorophore within the activation region to switch the fluorophore from an off state to an on state； exposing the environment to a beam of electromagnetic radiation, thereby exciting the fluorophore； detecting a photoluminescence signal at a first location within the environment, the photoluminescence signal comprising at least one of an ultrasound fluorescence signal emitted by the fluorophore and a background signal； correlating the photoluminescence signal with a reference signal to generate a correlation coefficient for the first location； and multiplying the photoluminescence signal by the correlation coefficient for the first location to generate a modified photoluminescence signal for the first location.
