var removeOverlay = function(re) {
    this.href = this.getAttribute('onclick').match(re).pop();
    this.removeAttribute('onclick');
    this.setAttribute('target', '_blank');
};

$('a.img_filename, a.expand_image').each((i,v) => {
    switch(v.className) {
        case 'img_filename':
            removeOverlay.call(v, /'(.*)'/)
            break;
        case 'expand_image':
            removeOverlay.call(v, /','(.*)',/)
            break;
    }
});