Show full size imgs for postimg.org instead of thumbs

postimg.user.js

// ==UserScript==
//
//Displayable Name of your script 
// @name           Postimg handler
// @include        *extreme-board.com/*
//
// ==/UserScript==

function get_further(rt) {
    var mt = /<img[^<>]*src='([^<>']+)'[^<>]*\/>/;
    var ra = rt.match(mt);
    return ra[1];
}

function get_full(sh, cbk) {
    var mth = /postimg\.org\/([a-z0-9]+)\//;
    var th = sh.match(mth);
    if (!th || th.length < 2) { return; }
    th = th[1];
    var url = 'http://postimg.org/image/' + th + '/';
    var xhr = new XMLHttpRequest();
    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4 && xhr.status == 200){
            cbk(get_further(xhr.responseText));
        }
    };
    xhr.open('get', url, true);
    xhr.send(null);
}

var all_imgs = document.getElementsByTagName('img');

for(var i = 0; i < all_imgs.length; i++) {
    (function(imgo) {
        get_full(imgo.src, function(x) { imgo.src = x; });
    })(all_imgs[i]);
}