Speckle time evolution characterization by the co-occurrence matrix analysis

We describe some aspects of the measurement of dynamic speckle activity. We propose the use of the co-occurrence matrix of the time history of the int ensity of a speckle pattern. Then we suggest a measure of the activity base d on the use of one of its second order moments. Some numerical simulations were performed for testing purposes. The method was applied to the study o f the drying of paint and was compared with gravimetric measurements. Exper imental results obtained are shown and a good correlation is obtained. (C) 1999 Elsevier Science Ltd. All rights reserved.