If you include unique images in your web pages, then you may want to consider including an image sitemap on your site. I emphasis the word “unique” – if you are using images from other websites then an image sitemap may not help. Unique images are a hidden resource for those websites that put in the extra effort to create them. Images appear in search results, and often draw clicks from users in preference to text links.
Google has recently published an short advisory on images and how to ensure they are accurately indexed to rank well in search results. In their article, Google suggest the following when including images you:
- ensure that Google can crawl both the HTML page the image is embedded in, and the image itself;
- only use images where the image is in one of our supported formats: BMP, GIF, JPEG, PNG, WebP or SVG.
- make sure the image filename is related to the image’s content;
- and that the alt attribute of the image describes the image in a human-friendly way;
- and finally, it also helps if the HTML page’s textual contents as well as the text near the image are related to the image.
That will ensure the image itself is optimized. What about the image sitemap? Your image sitemap can be created specifically for images, or you can include image information in your standard sitemap. However, you can only include a maximum of 1000 images per page. Yes, you read right, per page! You can learn more about image sitemaps from Google’s help page here, and more about how Google indexes sitemaps here.
Don’t over optimize images. Google is clamping down on over optimization strategies, however, don’t let that stop you following Google’s own advice. Images do need to have supporting data added to clarify their content. When optimizing your image tags, a simple rule worth following is to consider the user who can’t see images, what information do they need to understand the missing image.