Adding Alt Tags

Hi all

I’m using the plug-in TESTIMONIAL and it’s works great for what I need. However, when you upload a photo of the person who gave the testimonial, the plug-up doesn’t grab the photo’s ALT tag from the library.

Below is the current code. How can I edit it so it will include the ALT tag too? What do I need to add to the img src call?

{
$html.= '
<div style="max-height:'.$testimonial_items_thumb_max_hieght.';" class="testimonial-thumb">
<img src="'.$testimonial_thumb_url.'" />
</div>';
}