1. A method for assisting a user in taking photographs comprising: receiving a query photograph comprising an image; with a processor, extracting an image signature from the query photograph based on content-related features extracted from patches of the image, the extracting of the image signature including extracting a descriptor from each patch, each descriptor comprising a feature vector or histogram, the image signature comprising a vectorial representation of the descriptors; querying a database of photographs based on the image signature to retrieve photographs similar to the query image; presenting at least a subset of the retrieved photographs for the user to select a model photograph from among the presented photographs; based on a user-selected model photograph, generating instructions for taking a target photograph; and presenting the instructions to the user for taking the target photograph.