Efficient local feature descriptor filtering

A method for searching for a similar image among a plurality of stored images, comprising the steps of:

• for each stored image, calculating only one feature vector representing the content of the stored image,
• calculating distance measures between each stored image of the plurality of stored images by using the one feature vector calculated for each image,
• clustering the plurality of stored images into one or more clusters of stored images based on the calculated distance measures, wherein each cluster comprises one or more stored images,
• for each cluster comprising a plurality of stored images,
• for each stored image in the cluster, calculating a plurality of feature vectors, each representing the content of the stored image,
• performing a matching operation between at least some of the plurality of feature vectors for all of the stored images in the cluster, and
• based on a result of the matching operation, filtering feature vectors which are matched between at least a threshold number of the stored images, and
• storing the filtered feature vectors,
• retrieving an image for which a similar image should be found,
• calculating a plurality of additional feature vectors for the retrieved image,
• finding a similar image among the plurality of stored images by using the stored filtered feature vectors for at least one of the one or more clusters, and the additional feature vectors.