Xflow is an utility devoted to display image 2D vector fields in a GTK
window. Image vectors fields are embedded in an Inrimage image data.
inrimage is then required to compile xflow.
xflow can also product graphics in various formats (using fig2dev command
available in transfig or xfig packages).
From http://inrimage.gforge.inria.fr, choose a suitable version of Inrimage for your OS. For instance, an 64-bits Ubuntu/Debian:
$ wget https://who.rocq.inria.fr/Dominique.Bereziat/ftp/inrimage/4.6.5/inrimage_4.6.5-debian_amd64.deb
$ sudo dpkg -i inrimage_4.6.5-debian_amd64.deb`
$ sudo aptitude inrimage
Then, you can compile xflow as usual:
$ git clone https://github.com/bereziat/xflow.git
$ cd xflow; ./configure & make install
Here a simple example with Lena gradient computed using Sobel filter (with Inrimage):
$ wget http://www.iis.uni-stuttgart.de/lehre/ss11/ComputerVision/lena.jpg
$ cnvcol -bw lena.jpg >lena.inr
$ raz >lena.grad `par lena.inr -x -y` -r -v 2
$ echo -1 0 1 -2 0 2 -1 0 1 | cim -x 3 -y 3 -r | conv lena.inr - -dir | melg - lena.grad
$ echo -1 -2 -1 0 0 0 1 2 1 | cim -x 3 -y 3 -r | conv lena.inr - -dir | melg - lena.grad -ivo 2
$ xflow lena.jpg lena.grad