I have this code :
<li class="work-item mix common">
<a href="images/photography/my-portrait.jpg" class="work-lightbox-link mfp-image">
<div class="work-img"><img src="images/photography/my-portrait-thumbnail.jpg" alt="Black and White Photography of man">
</div>
<div class="work-intro">
<h3 class="work-title">Man Portrait</h3><div class="work-descr">This is a h3 description of the photo</div>
</div>
</a>
</li>So picture is shown as thumbnail and popup on click to show larger photo.
SEO wise is it OK that I don’t have to include alt tags for the main image ?
P.S. Am using a HTML template