Acorn … clarification on your chunk of code ….

Here comes the sleight of hand.
For each resized and placed image in your design, open its Placeholder Body and insert:
<img id="unique image identifier" src="<source path>/<A nice image filename>.jpg" alt="describe the image" loading="lazy" width=100% height=100% />
Change the id, set the src to 'index_html_files/<master-image>.<ext>, describe the image in alt.

The image <a nice image filename> is the name of my file. No changes to the image id correct? Alt is my description of pic.

This is a fascinating solution.

Thanks
W