Insert a title tag in the <h>
Code:
<h1 title="Chapter 1" class="calibre10" id="calibre_pb_12"> <a id="_Toc511571660"><img src="../Images/00005.jpeg" alt="" class="calibre11"/></a> </h1>
When you run the Sigil TOC generator, it will snag the title as you have typed it.
This is also handy if you want the generated TOC to read differently than the text displayed on the page. For example, the page could display
Chapter One - The Beginning,
but if the title only includes The Beginning, the TOC will only show The Beginning.
I think there might be a Sigil plugin that could help you, but am not sure. I must admit, I use an AutoHotkey script in Notepad++ to create titles for chapter headings, using search and replace combined with pre-set text strings.