Getting started demonstrates how to use the C API to compute the FV representation of an image. For further details refer to:
- Fisher vector fundamentals - Fisher Vector definition.
- Fisher vector derivation - Deriving the Fisher Vectors as a Fisher Kernel.
- Fisher kernel - The Fisher Kernel in general.
The Fisher Vector encoding of a set of features is obtained by using the function vl_fisher_encode. Note that the function requires a Gaussian Mixture Model (GMM) of the encoded feature distribution. In the following code, the result of the coding process is stored in the
enc array and the improved fisher vector normalization is used.
The performance of the standard Fisher Vector can be significantly improved  by using appropriate Normalization and improved Fisher vectors normalizations. These are controlled by the
flag parameter of vl_fisher_encode.