Help resizing mages

I have a web in development. I need to upload some images and to resize
them in a form. I am able to upload some imags thanks to paperclip, but
I have problems resizing this images. I am becaming mad trying to make
work ImageMagik and Rmagick and I think it will became a lot worse once
I find a host a put the web in production. So I wonder if its another
way to resize images.
I have used other option in a PHP web. It uses a mix of flash and PHP.
The flash gives a tool to resize the image exactly like the user wants,
and the PHP makes the reak work.
I will appreciate any help.

This is simple trumpet blowing but there is a gem I wrote called
thumbnailer (as in ‘gem install thumbnailer’) that resizes images into
boxes with out without transparency, it can also scale images down to
a maximum width or height.

The project is here

and the docs can be seen here

At some point I intend to announce that I have written it but there is
so much to be worked on. Requires gd2 and exifr.