Video image analysis and direct sampling of the froth surface were combined to investigate the relationship between different imaging parameters accounting for the structural features of the froth, and the separation efficiency of a flotation bank. The bubble solids loading and the air recovery were measured to introduce a new structural parameter, the froth volumetric mineral loading, additionally a new image analysis measurement, the cross correlation peak., was investigated. Both parameters were shown to be linked to the mobility of the bubbles on the froth surface. The cross correlation peak was found to be closely related to the volumetric mineral loading measured on the froth surface. Both parameters were found to follow a drop in froth stability and mineral attachment down the bank, which resulted in a relatively wetter and less viscous froth, and therefore a higher bubble mobility on the froth surface. As a result, the cross correlation peak was shown to be related to the mineral grade in the concentrate, while further analysis highlighted the possible use of a combination of air recovery and cross correlation peak to give a closer prediction of the bank performance. (c) 2006 Published by Elsevier B.V.