Google Image Sitemaps are an extension to XML Sitemaps. Using Google Image Sitemaps can help improve your results in Google Image Search (GIS).
According to Google’s documentation you can include up to 1000 images per page. This limit is high enough that it practically covers every page. Even on a high-speed connection with plenty of RAM there is no way a browser could handle that type of load.
There are two different types of optional text fields that you can associate with an image. These fields are title and caption. I would recommend the title duplicate the image’s alt attribute on the page. The caption field would only apply if the image was a figure with some type of caption.
The other two fields you can apply are the GEO-location and license fields. The former is helpful for location-based SEO. The latter is mostly useful for companies that license the use of their imagery.
Unlike regular sitemaps, you do not need to host these images on your domain. You can use a Content Delivery Network (CDN) — or at the very least a cookie-less domain — to lower load time and still associate them with your site. You just need to associate the CDN/other domain with your account in the Google Webmaster Tools.
Only submit images in BMP, GIF, JPEG, PNG, WebP or SVG formats. Do not submit a data URI. It’s only practical to use a data URI to replace an image that is 2 KB or smaller. Any image with a file size that small is probably not critical to the page. Google is unlikely to index the file so don’t add bloat to the sitemap.
Image Sitemaps in Google Webmaster Tools
Google Webmaster Tools is a recommended resource for improving your website. You can use it for search engine submission to get your new website launch into Google’s index. By submitting an image sitemap you will also submit your images to Google.
The process to submit an image sitemap the same as a regular XML sitemap. You’re just submitting a file with more data in it. Google will display the number of submitted images and web pages as well as the number they indexed. Don’t worry if they’re not the same. This normal and it is outside of your control. You cannot force Google to index all of your content.
You cannot get a list of the indexed pages or images in the current version of Google Webmaster Tools. The best you can do is do a Google search for your domain using:
Where www.example.com is your domain name. This will show the pages (or images in GIS) on your site. You will get Google’s normal search results so this is not terribly helpful. It’s just the best you can do at this time.
Bing Image Sitemaps?
Bing does not support this extension at the time of this writing. Bing ignores all references to images in an XML file. This means that you can safely submit the same sitemap to Google and Bing. Of course can and should are two different things. Many Content Management Systems (CMS) systems can automatically generate the XML sitemap for you live. Depending on your setup it could put a lot of strain on your web server to reference the images. There is no point in straining a web server to send a search engine a result it won’t understand. We recommend limiting image sitemaps to Google until Bing adds support for images.
SiteBrandBuilder Support for Image Sitemaps
Earlier this week we added image sitemap support to SiteBrandBuilder. These image sitemaps are automatically generated for your site. We generate the regular XML sitemap at www.example.com/sitemap.xml, and the image sitemap at www.example.com/image-sitemap.xml. We recommend that you edit your site’s robots.txt file and manually add the sitemap through the Google Webmaster Tool to improve your site’s ranking in search engines. Or you can work with us to improve your site’s Natural Search Optimization.
Have you ever used image sitemaps for your site? How did it affect your site in GIS? Please share your thoughts.