1. A method for large-scale image recognition, comprising: obtaining, by a descriptor engine, a vocabulary including a set of content indices that reference corresponding cells in a descriptor space based on an input set of descriptors; identifying, by the descriptor engine, a plurality of local features of an image based on the vocabulary, the local features being represented by a plurality of local descriptors; determining, by the descriptor engine, an associated visual word in the vocabulary for each one of the plurality of local descriptors; generating, by a signature engine coupled to the descriptor engine, a plurality of global signatures for the image based on the associated visual words, wherein some of the plurality of global signatures are generated using local descriptors corresponding to different cropped versions of the image, two or more of the different cropped versions of the image being centered at a same pixel location of the image; and facilitating, by the signature engine, an image recognition search using the plurality of global signatures to search a document image dataset.