Has anyone used the thumb nail generator plugin

I set up everything from http://www.cleverleap.com/ruby-thumbnail-generator/.
In my view I use the code below.

image_tag("thumb/photo.jpg",:h=>20,:w=>20)

this only displays the name of the image and not the image itself. I
can 't find any examples of anyone using this plugin.

Has anyone used this plugin successfully and if so what is the call
used in your view to get the image?

Thanks.