Multi-scale analysis of shell growth increments using wavelet transform

Shell increments contain information related to the evolution of the environment in which the organism grew during its biomineralization. To extract the information from variations in shell topography, a new and promising technique is presented, involving multi-scale analysis of the shell topography using a B-spline wavelet transform. An accurate non-contact optical system, based on laser triangulation, is used to map the shell surface. The resulting range image is treated as a grey-level image by using a multi-resolution approach based on the generalization of the cascade algorithm. This method allows reconstruction of non-subsampled images that correspond to the projection onto the space of the chosen scale of detail. This new approach provides an ecient tool for analyzing multi-scale information contained in growth increment rings and/or within quasi-periodic features. In conclusion, this approach can be applied to any 3D object, in order to extract features such as rhythmic information, color variations or object envelope.