A method based on image segmentation for the analysis of the orientation of rod-like objects

Here we show a method of image processing, which can be applied to the measurement of the orientation of rod-like objects. The method is based on an image segmentation recently developed and used for the analysis of micrographs. The segmentation allows to determine specific objects in the image, the orientation of which can be measured with respect to the axes of the image frame. The orientation is determined by means of the elements of a matrix of inertia. Two lengths are associated to the elements of the diagonal of the matrix. Their ratio is giving the arctangent of an angle, between 0 and 90 degrees; the element outside the diagonal is giving the sign of this angle, which is measuring the orientation of segmented rod-like objects.