The MST (Minimum Spanning Tree) is an effective structure for representing images in applications such as image matching and image retrieval. However, previous methods only use MST to connect the structural elements in images and are unable to quantitatively analyze the capability of the elements in describing the image. A method for structural description of images based on MST is proposed in this paper. The MST constructed from the structural elements extract from the image supports the image

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... like the skeleton of the image, which reflects the structure of image. Three indexes for evaluating the distribution uniformity, the distinctiveness and the spanning degree of a set of image structural elements are defined based on the MST. The evaluating indexes can be used to analyze the structural information of an image and can also be used to evaluate the capability of a set of structural elements to describe the structure of an image. Experiments on simulated points and real images validate the proposed indexes. The indexes can be used to classify the structures of image scene and to evaluate the difficulty of image matching.