scrollCapture.js

var page   = require('webpage').create(),
    system = require('system');

page.viewportSize = {width: 1280, height: 1024};

if (system.args.length === 1) {
    console.log('Usage: scrollCapture.js <some URL>');
    phantom.exit();
}

var url = system.args[1];

var filename = url.replace(/(https|http):\/\//gi, '')
    .replace(/[^a-z0-9]/gi, '_').toLowerCase();

page.open(url, function (status) {
    if (status !== 'success') {
        console.log('Unable to load the address!');
        phantom.exit();
    } else {
        var capname1 = filename + '--1.jpg';
        page.render(capname1);
        console.log(capname1);
        window.setTimeout(function () {
            page.scrollPosition = {top: 512, left: 0};
            window.setTimeout(function () {
                var capname2 = filename + '--2.jpg';
                page.render(capname2);
                console.log(capname2);
                phantom.exit();
            }, 500);
        }, 500);
    }
});