function switchOn(img) {
    var imgName = (img.src).split('/');
    img.src = 'images/icons/' + (imgName[7].split('.'))[0] + '_hi' + '.jpg';
}

function switchOff(img) {
    var imgName = (img.src).split('/');
    img.src = 'images/icons/' + (imgName[7].split('_'))[0] + '.jpg';
}