I chose to use gm node module on one of my project. It works pretty well.
See : http://aheckmann.github.com/gm/
It's basically a wrapper around imageMagick or graphicsmagick binaries.
Here is a simple example :
var gm = require('gm');
gm('/path/to/image.jpg')
.resize(353, 257)
.autoOrient()
.write(writeStream, function (err) {
if (!err) console.log(' hooray! ');
});