The purpose of this paper is to allow for high level shape representation and matching in multi-object images by detecting and extracting the envelope of object groupings in the image. The proposed algorithm uses hierarchical clustering to find object groupings based on spatial proximity as well as low-level shape features of objects in the image. Each grouping is then merged using a morphological algorithm. The envelope is extracted by reconstructing the object from its dynamically pruned concavity tree. We test our approach on a set of 45 multi-object trademark images and we report results on object groupings and envelope extraction.