Tooltip on image

You can use the standard HTML title attribute of image for this:

<img src="source of image" alt="alternative text" title="this will be displayed as a tooltip"/>

I am set Tooltips On My Working Project That Is 100% Working

<!DOCTYPE html>
<html>
<style>
.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted black;
}

.tooltip .tooltiptext {
  visibility: hidden;
  width: 120px;
  background-color: black;
  color: #fff;
  text-align: center;
  border-radius: 6px;
  padding: 5px 0;

  /* Position the tooltip */
  position: absolute;
  z-index: 1;
}

.tooltip:hover .tooltiptext {
  visibility: visible;
}
.size_of_img{
width:90px}
</style>

<body style="text-align:center;">

<p>Move the mouse over the text below:</p>

<div class="tooltip"><img class="size_of_img" src="https://babeltechreviews.com/wp-content/uploads/2018/07/rendition1.img_.jpg" alt="Image 1" /><span class="tooltiptext">grewon.pdf</span></div>

<p>Note that the position of the tooltip text isn't very good. Check More Position <a href="https://www.w3schools.com/css/css_tooltip.asp">GO</a></p>

</body>
</html>

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>