Similar problem here but the problem occurs on google sitemap. I just realized I have been wasting 10s of hours writing descriptive alts in the back end and they're not even in the sitemap.
Actually I am getting the image alt I want from the backend 'legend' section but there is STILL a problem in the sitemap as the sitemap generates the 'title' of the image as the product name.
The sitemap generated from gsitemap.php - and the line with the problem seems to be
'title_img' => htmlspecialchars(strip_tags($product->name)),
As the product title is already mentioned in the sitemap, and there is no image alt field in the sitemap, only image title, I am assuming that this should be the 'legend' which I have so carfully included on every photo in the back-end in vain.
As I know nothing about databases, can someone please tell me what I should change my php to (this line) to point to the alt/legend image title field?
ALSO
How the hell get gsitemap to display not just the cover photo of each product but all the images? I see there's a module on this but I can't go to the hassle of intalling a module (risk of patchy disaster from my experience) just for a few lines of code in gsitemaps... HELP anyone?