We analyze the controllability of interference phenomena between partially coherent fields by introducing the Wigner distribution function (WDF) and entropy, which is defined using the intensity matrix [H. Gamo, J. Opt. Soc. Am. 47, 976 (1957)]. The analytical derivation of the WDF and entropy is presented for a partially coherent imaging system consisting of two pinholes illuminated by a circular source. It is shown that the WDF, defined in the 4D space–spatial frequency region, and entropy can be useful tools to understand how one can freely and quantitatively control the interference when any optical components in the partially coherent imaging system are changed.