fisher.h implements the Fisher Vectors (FV) image representation [23] [24] . A FV is a statistics capturing the distribution of a set of vectors, usually a set of local image descriptors.

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.

# Getting started

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 [24] by using appropriate Normalization and improved Fisher vectors normalizations. These are controlled by the `flag`

parameter of vl_fisher_encode.