How to Optimize Images for Search
SEO is not a magic formula to drive customers to your site, but you can increase the chances that they find you in a search by optimizing your images for search.
There are several tags you can apply to optimize images for SEO: Title, Description, Alt Text and Caption. Here is a quick primer on what each of these items are and how they factor into SEO for your images.
Image Alt Text
This is the text that the search engine uses to understand images. Google officially confirmed that it mainly focuses on an alt text when trying to understand what an image is about. The alt text should describe what the image is about and get those visitors interested to see it.
In addition, alt text is meant to be an alternative information source for those people who have chosen to disable images in their browsers and those user agents that are simply unable to “see” the images (such as certain mobile devices, those on dial-up internet or on devices for the visually impaired).
One more note on alt text. Alt text can be particularly important when using an image as a spacer or as bullets for a list. Giving formatting images an alt text of “ “ will keep web readers from identifying them by the name of your file (which may be something like linespacer1.jpg).
Image Title Optimization
The title of the picture is not as important as the alt text, but you should fill it in nonetheless. Both title and alt text are primarily meant for visitors (though alt text seems more important for crawlers) – so provide explicit information on an image to encourage them to view it or get them interested.
Captions are Important for Search
There is not a direct relation between image captions and search engine rankings. However, captions can lower your bounce rate (which does affect your ranking) because they are one of the first things people look at on a web page.
Search engines downgrade pages that have a high bounce rate (see more on bounce rate here) to prevent web developers from stuffing sites with false keywords to draw in searchers. If someone comes to your page and then immediately leaves (which counts as a “bounce”), the search engine assumes that your page is either a poorly designed page or a scam page.
Well-written captions that explain the page and that draw readers in. When people arrive at a page, the first things they look at are headers and captions. This quick scan helps them decide if your article is worth reading. When posting photos on your page, make it your mission to include engaging captions when possible.
File Names can Affect Image Search
One last element to pay attention to is the name of your image file. If possible, name images according to what is in the photo. If you have a picture of an owl, name the source file owl.jpg as opposed to something like IMG11255.jpg.
As I mentioned, there is no magic formula to guarantee SEO success beyond creating great content and getting it to the right audiences. However, these steps can help your site on its way to search engine success.