That seems to be a solution for individual posts. I am thinking of a way to do it in a template or script file do that can bring about a universal adaptation for all existing and new posts. Or are you suggesting I can adapt that for any particular theme template by using another <div> to bracket an image? Which template file are you thinking of?
Before your answer, I have been fiddling with templates and post-types files but couldn’t quite get it. There is a solution for making use of the second array variable in the_post_thumbnail function, but the Hueman theme uses the Responsive Lightbox plugin to regenerate all post images so that original WordPress function has been quite dramatically modified and extended. I am clueless now.