Matlab Vs Scilab vs Octave

A lot of my students want to learn image processing. So i'm working on a course outline that flows like this
acquire - > process - > send data to arduino - > control robot

Now I know its easy to do this in Matlab and have done it. But considering the licensing options, I would like to know if any of the other 2 can do the above as well? A simple search shows that they can but i would love to hear from users here.

Cheers,
Pracas

I don't know about those two but you can certainly do this in Processing and that's free.