1. A spatial-domain low-coherence quantitative phase microscopy apparatus, comprising: an imaging system that collimates a white light from a light source; a component that tunes a wavelength of the white light to a spectral resolution shared by multiple imaging contrasts; a device that projects the tuned light onto a sample, wherein the sample scatters at least a portion of the tuned light back; a camera that records the scattered portion of the tuned light; and an image registration module that co-registers images.