var page = new WebPage(),
    address, output, size;

if (phantom.args.length < 2 || phantom.args.length > 3) {
    console.log('Usage: rasterize.js URL filename [paperwidth*paperheight|paperformat]');
    console.log('  paper (pdf output) examples: "5in*7.5in", "10cm*20cm", "A4", "Letter"');
    phantom.exit();
} else {
    address = phantom.args[0];
    output = phantom.args[1];
    page.viewportSize = { width: 600, height: 600 };
    if (phantom.args.length === 3 && phantom.args[1].substr(-4) === ".pdf") {
        size = phantom.args[2].split('*');
        page.paperSize = size.length === 2 ? { width: size[0], height: size[1], border: '0px' }
                                           : { format: phantom.args[2], orientation: 'portrait', border: '1cm' };
    }
    page.open(address, function (status) {
        if (status !== 'success') {
            console.log('Unable to load the address!');
        } else {
            window.setTimeout(function () {
                page.render(output);
                phantom.exit();
            }, 200);
        }
    });
}