One of the many elements which Google will look for when assessing the relevance of a web page is the images on that page. Despite their incredible complexity, however, it’s still hard for machine algorithms to analyse an image and declare: “that’s a blue widget”. So it’ll be a while before Google can say: “that page has photos of blue widgets on it, so it must be a relevant page for searches on blue widgets”.
However, there are ways. Google has a thing called Image Search, as we know. It can see what’s getting clicked-on there, and learn from what people think are the most representative images of blue widgets. If one of those is the photo of a blue widget on your page, then that’s a thumbs-up for your page in standard Google search.
So we need to push our images towards Google in the first place.
One overlooked way of doing this is a really easy win. Just describe the photo in the filename. Even if you don’t do your own web design, I suspect that you prepare the images and send them to the web designers.
Don’t send them “DC457020.jpg”.
Send them “new-faster-blue-widget.jpg”, which you spent a whole 5 seconds renaming.