A method for background illumination regularization, which requires only one image and a single-stage correction, is presented. The method yields in the exact computation of the background illumination and the local visibility of the fringes from the envelopes of the intensity distribution. The approach is clear, elegant, and easy to implement. The results of the method are compared with another recent approximation, proving itself competitive enough. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.OE.51.9.095601]