I had added images in my sitemap a week ago, but the number of images indexed in the Google Webmaster Tools has not displayed any tendency to increase. The number of images submitted is about 200,000 but the number of images indexed keeps floating around 10,000.
I hosted my images on AWS S3, and I used different URL
.s3.amazonaws.com instead of my domain, but I provide a
robots.txt file in the root directory of the bucket (per this instruction). In the sitemap XML the images are grouped in each content page
<loc>, but the images filenames doesn't give any relevant information about the content of the page. They are just a bunch of random numbers.
Is there any way I can do to increase the number of indexed images in the Google Webmaster Tools?