Using javascript, you can set tooltips for all the images on the page.
<!DOCTYPE html>
<html>
<body>
<img src="http://sushmareddy.byethost7.com/dist/img/buffet.png" alt="Food">
<img src="http://sushmareddy.byethost7.com/dist/img/uthappizza.png" alt="Pizza">
<script>
//image objects
var imageEls = document.getElementsByTagName("img");
//Iterating
for(var i=0;i<imageEls.length;i++){
imageEls[i].title=imageEls[i].alt;
//OR
//imageEls[i].title="Title of your choice";
}
</script>
</body>
</html>