Yesterday I checked in the latest LIRE revision featuring the PHOG descriptor. I basically goes along image edge lines (using the Canny Edge Detector) and makes a fuzzy histogram of gradient directions. Furthermore it does that on different pyramid levels, meaning that the image is split up like a quad-tree and all sub-images get their histogram. All histograms of levels & sub-images are concatenated and used for retrieval. First tests on the SIMPLIcity data set have shown that the current configuration of PHOG included in LIRE outperforms the EdgeHistogram descriptor.
You can find the latest version of LIRE in the SVN & in the nightly builds.
- A. Bosch, A. Zisserman & X. Munoz. 2007. Representing shape with a spatial pyramid kernel. InÂ Proceedings of CIVR â€™07 — [DOI] [PDF]