The compositional and content attributes of images carry information that enhances the performance of image retrieval. Standard images are constructed by following the rule of thirds that divides an image into nine equal parts by placing objects or regions of interest at the intersecting lines of the grid. An image represents regions and objects that are in a spatial semantic relationship with respect to each other. While the Bag of Features (BoF) representation is commonly used for image retrieval, it lacks spatial information. In this paper, we present two novel image representation methods based on the histograms of triangles, which add spatial information to the inverted index of BoF representation. Histograms of triangles are computed at two levels, by dividing an image into two and four triangles that are evaluated separately. Extensive experiments and comparisons conducted on two datasets demonstrate that the proposed image representations enhance the performance of image retrieval.
['Nouman Ali', 'Khalid Bashir Bajwa', 'Robert Sablatnig', 'Zahid Mehmood']
Image retrieval by addition of spatial information based on histograms of triangular regions