Localisation de la transition bois initial-bois final dans un cerne de chene par analyse microdensitometrique

Abstract

The ring widths and the earlywood-latewood limits in 96 annual rings of oak (Quercus petraea Liebl.) have been measured by image analysis of cross sections. A microdensitometric analysis has been performed on the same rings. The position of the earlywood-latewood transition has been estimated in each ring by searching the intersection of the density profile with a threshold of density. This threshold has been computed in three ways: l) a fixed threshold, 2) a floating threshold depending on the minimal and maximal densities in the ring and 3) a floating threshold depending on the mean density in the ring. Each method has been tested with several parameters and the estimated values of the earlywood and latewood widths and ratios have been compared with the anatomical observations. The second and third methods are more accurate than the first method. The second method is preferred because the quality of the results is less dependent on the choice of the parameters.