Versuch's mal so:
HTML-Code:
<a id="gallery_inside_thumbnail_101" class="button_product_images button_lightbox_gallery active_thumbnail" href="images/product_images/info_images/Bild1.jpg" rel="images/product_images/original_images/Bild1.jpg" title="">
<img alt="Bild1" src="images/product_images/gallery_images/Bild1.jpg" title="" />
</a> Das ist Bild1
<a id="gallery_inside_thumbnail_102" class="button_product_images button_lightbox_gallery active_thumbnail" href="images/product_images/info_images/Bild2.jpg" rel="images/product_images/original_images/Bild2.jpg" title="">
<img alt="Bild2" src="images/product_images/gallery_images/Bild2.jpg" title="" />
</a> Das ist Bild2
Und damit es bei den ID's kein Massaker gibt, kannst die einfach ab 101 fortführen.