function swapImage(imageElement) {
    var src = imageElement.src;
    var lowSrc = imageElement.lowsrc;

    if (ignoreTab == null || (ignoreTab != null && (ignoreTab != src && ignoreTab != lowSrc)))
    {    
        imageElement.src = lowSrc;
        imageElement.lowsrc = src;
    } 
    else if (ignoreTab != null && (ignoreTab == src || ignoreTab === lowSrc)) 
    {
        imageObject.style.zIndex = 4000;
    }
}