But i am not sure why Google ignores indexing images when you simply add "noindex" and not "noimageindex". Are you sure that is the reason or is it that you have blocked images for others (except Google) using .htaccess. Can you two pls. confirm?
My images were well indexed when I did not have the "noindex" tag on large image pages, It was my bad that I waited too long to check the image index, all the images were gone! However thumbnail images are still indexed which are in same sub directory (images/thumbnails/cat123/) to (images/media/cat123/)
Also few large images are indexed in bing/yahoo. I also ran a google bot test from webmaster tools and for direct image links I get "Allowed" for googlebot, even fetch as google worked.
Having Google index from an image site-map, wouldn't that result in the image URL's being the ones used? Meaning... a Google visitor comes to the *.jpg url, where there is no HTML at all?
Image sitemaps do not work with simple links to the images. You need to define an html page which is taken as a parent to the images. You can have upto 1000 images per page. Search for "google imagesite map" and follow the google link.