This plugin is used to infer the preferred orientation of structures present in the input image. It computes a histogram indicating the amount of structures in a given direction. Images with completely isotropic content are expected to give a flat histogram, whereas images in which there is a preferred orientation are expected to give a histogram with a peak at that orientation. On top of the histogram, the plugin tries to generate statistics on the highest peak found.

The plugin offers the possibility to generate an orientation map, where the image is colored according to its local directionality, or location orientation. 

The plugin is part of Fiji, can be launched through the menu: Analyze > Directionality

orientation histogram

Evaluates the orientation of fiber orientation pattern and plots the results in the image. It calculates gradient in x and y direction. - then calculates the eigenvector of nematic tensor, which is the orientation of the pattern.