Recently, there has been a resurgence of interest in multimode optical fibers illuminated by a white light source. Largely, in the anticipation of many integrated applications in the biomedical domain and spectral sensing benefiting from the broad spectral range and high numerical aperture. Along these lines, the output light from these fibers can be captured by the physics of partially coherent sources. Yet, the sheer complexity arising from the interplay between partial coherence and microstructure transfer function has posed fundamental challenges in deciphering their response.