We are using in point (x,y) of image I the horizontal gradient defined by [delta]I (x,y)/[delta]x = I (x - 1, y) -I(x+1,y) and the vertical gradient defined by [delta]I(x,y)/[delta]y = I(x,y-1) -I(x,y+1) Index of confidence of the 2D local orientation An index of confidence on the estimated orientation is given from the ratio [[lambda].

Tanks for the 12 replicates of the five treatments were randomly allocated using Lain square randomization in both vertical and horizontal gradients, and all experimentation was run blind of treatments.