Abstract : This paper deals with a method for mapping the apparent ground brightness on a pixel basis. It makes use of geostationary satellite visible data and generalizes the earlier work of Cano (1982). The detection of clouds larger than one pixel is performed in a time series by comparing the cloud-induced sensor response to the signal which would occur if the pixel were cloud-free by means of an iterative and adaptive filtering. To illustrate the method, Meteosat data either received by means of a WEFAX-type receiver connected to a personal computer or provided by ESOC have been processed. Maps of apparent ground brightness are presented for Europe and Africa with 5 km resolution.