Screen capture a webpage with phantomjs

capture.js

//
// Screen shot a webpage using phantomjs
//
// phantomjs capture.js url filename.png
//
var page = require('webpage').create(),
	system  = require('system'),
		 url, img_filename_output;

if (system.args.length < 3) {
	 console.log('Usage: capture.js URL filename');
	 phantom.exit(1);
} else {
    url = system.args[1];
    img_filename_output = system.args[2];
	page.open(url, function() {
		page.render(img_filename_output);
		phantom.exit();
	});
}