This paper aims at highlighting spatial aspects of the littoralisation process. Behind the general trend of people and activities concentration on the coast, littoralisation dynamics are spatially differentiated and coastal overload fuels new evolutions. As disaggregated data on urbanisation are not always available to make a retrospective analysis, this paper proposes to show how an image analysis method, named Mathematical Morphology, can contribute to determine spatial differentiations with the use of aggregated data. Through the analysis of home-building contrasts at a municipal level, Mathematical Morphology provides a regionalisation of the study area, the French Riviera, and its spatial reshapings during the second half of the twentieth century.