Image analysis as a tool for monitoring and controlling flotation froths has become quite widely used in the minerals industry. One of the challenges is to be able to use the image analysis data to predict the performance of a flotation cell. One of the key parameters to be predicted is the water recovery from the froth, since this is intimately related to the gangue recovery and thus the grade. Recent theoretical developments have allowed for the calculation of this water recovery based on the air rate, froth stability and the bubble size distribution. The problem is that all that can be seen of a froth is the bubble films at the top surface. This paper uses physics based simulations of the froth structure to show that the relationship between the size distribution of the films seen at the top surface and the underlying bubble size distribution is a complex one. The paper presents some preliminary results on the statistical relationship between these distributions. (c) 2006 Elsevier Ltd. All rights reserved.