1. A method for imaging an object, comprising: spectrally processing electromagnetic energy emanating from the object through a first dispersive element; forming a spectrally dispersed image of the object on a coded aperture; spectrally processing electromagnetic energy emanating from the coded aperture using a second dispersive element; forming a spectrally modulated image of the object on a detector array; and calculating a spatio-spectral image of the object from the spectrally modulated image measured at the detector array, an effect of the first dispersive element, a coding of the coded aperture, and-an effect of the second dispersive element, wherein the spectrally modulated image is measured in a single time step and the number of measurements in the spectrally modulated image is less than the number of spatio-spectral elements in the spatio-spectral image.