It's not perfect but one idea is that you could use the Line tool to make roman numerals in the bottom corner of the image and reference it as (image III) for example.
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'''EDIT'''
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I figured out a CSS solution to add numbers to the image icons.
It's not perfect but one idea is that you could use the Line tool to make roman numerals in the bottom corner of the image and reference it as (image III) for example.