A 2-D shape description using the turning angle is presented 1 . This descriptor is based on a scalogram obtained from a progressive filtering of a planar closed contour. At a given scale, the differential turning angle function is calculated from which, three essential points are derived: the minimum differential-turning angle (α-points), the maximum differential-turning angle (β-points) and the zero-crossing of the turning angle (γ-points). For a continuum of the scale values in the filtering process, a map (called d-TASS map) is generated. As shown experimentally in a previous study, this map is invariant under rotation, translation and scale change. Moreover, it is shearing and noise resistant. The contribution of the present study is firstly, to prove theoretically that d-TASS is rotation and scale change invariant and secondly to propose a new descriptor extracted from the blocks within the scalogram. When applied to shape retrieval from commonly used image databases like MPEG-7 Core Experiments Shape-1 dataset, Multiview Curve Dataset and marines animals of SQUID dataset, experimental results yield very encouraging efficiency and effectiveness of the new analysis approach and the proposed descriptor.