AbstractIn this study, a numerical procedure is proposed to determine the optical contact (peak of the coherence function) in a scanning white light interferential microscope. The Red, Green and Blue image of the correlogram is transformed to the Commission Internationale de l’Eclairage chromatic system with x,y,z coordinates. The key element is to track the orientation of the curve (trajectory) which exhibits changes as it passes through the optical contact. The path described by the interferogram in this chromatic space makes it possible to localize, without ambiguity, the zero-order fringe and from this information to reconstruct the topography of an object of the order of a few tens of nanometres.KEYWORDS: Scanning white light interferometryCIExyz colour systemlow-coherence interferometrycolour CCD Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingCML thanks Ministerio de Ciencia, Tecnología e Innovación (Minciencia-Colombia) for its financial support.