PhantomJS script to pseudo-retina screenshots

gistfile1.js

var page = require('webpage').create(),
    address, output, size;
 
page.onConsoleMessage = function(msg, lineNum, sourceId) {
  console.log('CONSOLE: ' + msg);
};

if (phantom.args.length < 2 || phantom.args.length > 6) {
    console.log('Usage: rasterize.js URL filename WxH retina ua');
    phantom.exit();
} else {
    address = phantom.args[0];
    output = phantom.args[1];
    size = /(\d+)x(\d+)/i.exec(phantom.args[2]) || [];
    page.viewportSize = { width: parseInt(size[1], 10) || 1280,
      height: parseInt(size[2], 10) || 1024 };
    phantom.args[4] && (page.settings.userAgent = phantom.args[4]);
    page.open(address, function (status) {
        if (status !== 'success') {
            console.log('Unable to load the address!');
        } else {
            page.evaluate(function (retina) {
              console.log(retina);
              if (retina) {
                /* scale the whole body */
                document.body.style.webkitTransform = "scale(2)";
                document.body.style.webkitTransformOrigin = "0% 0%";
                /* fix the body width that overflows out of the viewport */
                document.body.style.width = "50%";
              }
            }, /(?:1|true|yes)/i.test(phantom.args[3]));
            window.setTimeout(function () {
                page.render(output);
                phantom.exit();
            }, 200);
        }
    });
}

Save this gist as rasterize.js and call it like this:
phantomjs rasterize.js http://www.stern.de homepage-stern-de.png 2000x18000 true ua

If your webseite has webfonts use phantomjs in Version 2 or slimerjs (with Moz prefix instead of webkit)

Note that phantom.args has been removed, in favor of system.args.

Add

var system = require('system');
var args = system.args

at the top of the file and then replace all subsequent calls to phantom.args with args (with rasterize.js being args[0])