function showCategories () {
         document.getElementById('photo-show').style.display='none';
         document.getElementById('categories').style.display='block';
}
function showPhoto (ImageURL,titleText) {
         getImage (ImageURL);
         //document.getElementById('photo_title').innerHTML=titleText;
         document.getElementById('photo-show').style.display='block';
         document.getElementById('categories').style.display='none';
}
function getImage(ImageURL){
    var pExistingImageID = 'photo-placeholder';
    var img = document.createElement('img');
    img.onload = function (evt) {
        document.getElementById(pExistingImageID).src=this.src;
        document.getElementById(pExistingImageID).width=this.width;
        document.getElementById(pExistingImageID).height=this.height;
    }
    img.src = ImageURL;
    return false;
}