How can I make alphas from my pictures without Photoshop?

Hi
How can I make alphas from my pictures without using Photoshop? Is there a free alternative? It’s kind of waste of money to rent Photoshop (as you do nowadays) just in order to make alphas. The one mont free trial
is no option here.
Thx

Try Gimp - it’s like a free, lightweight version of Photoshop. You can manipulate alpha layers very well in it, and it has some pretty good plugin support.