This module is based on a third-party library called FBOW. FBOW is licensed under the MIT license.
FBOW (Fast Bag of Words) is an extremmely optimized version of the DBow2/DBow3, which are open source C++ libraries for indexing and converting images into a bag-of-word representation. The library is highly optimized to speed up the Bag of Words creation using AVX,SSE and MMX instructions. It is used for keyframe retrieval.