The coherence of optical field is an important physical property that should be quantified to produce significant interference phenomenon. Although high spatial and temporal coherence lasers have become an essential tool in traditional interferometry and holography, in many emerging computational imaging fields (such as computational photography and computational microscopy imaging), reducing the coherence of the light source, i.e., using a partially coherent light source, is uniquely advantageous for obtaining high signal-to-noise ratio and high-resolution imaging information. As a result, the importance of “characterization” and “reconstruction” of partially coherent optical fields has become increasing prominent. Therefore, it is necessary to introduce the optical field coherence theory and develop coherence measurement techniques to answer “what light should be” and “what light is” in computational imaging. This paper provides a systematic review in the aforementioned context. The basic principles and typical optical path structures of the interferometric coherence measurement and non-interferometric coherence retrieval methods are described using the classical correlation function and phase space optics theories. Several new computational imaging regimes derived from coherence measurements and their typical applications, such as light-field imaging, non-interferometric phase retrieval, incoherent holography, incoherent synthetic aperture, incoherent cone-beam tomography, are discussed. Further, the challenges faced the current coherence measurement technology are discussed and its future development trend is predicted.