With no input argument, digitize() first prompts the user to
select an image file to display, otherwise the given image is displayed.
The user is then asked to graphically identify the location of
the origin, the X and Y axes of the plot.
The user is asked if rotation must be taken
in account in the processing.
If there is a rotation, the axes must cross the origin,
otherwise the output data will be wrong.
The user then graphically selects an arbitrary number of data points
from anywhere on the image using the right mouse button.
Data acquisition is terminated by clicking the left mouse button.
The function returns in the first argument the data as a matrix
(each row contains the coordinates of a point).
Optionally (if the user has specified a second output argument)
the user is prompted to select a file, to save the data in that file as text,
and the path to this file is returned in the second output argument.
Ported by Scilab Enterprises from original digitize2 function (author: A.
Note: this function requires the Scilab Computer Module to be installed