Everything You Need to Know About Image Optimization for Google

Author: Rand Fishkin – CEO of Moz, a regular speaker at the world’s largest conferences on SEO and online marketing.

In today’s world, the role of image optimization as an aspect of SEO is undoubtedly important. As of now, a third of all Google queries in the US are related to images.

In one of the recent Whiteboard Friday episodes, Rand Fishkin covered image SEO in detail—from the basics to ranking factors and practical tips.

In this article, you’ll find all the information you need on the topic. Moreover, we’ll discuss optimization not only for Google Image Search, but also for the image block within the main search results.

Image SEO fundamentals

There are a couple of things we should discuss before diving in. First, many webmasters ask:

1. Do we need to bother with image SEO at all?

Years ago, when you clicked an image in Google Image Search, you landed on the site or page where it was published. Now, clicking an image opens its full-size version and indicates which site hosts it. For many people, that’s enough. They perform numerous searches but never visit your site. Google serves your image without your knowledge, and you get no data from it. You don’t know how many impressions it received, etc.

When image SEO is needed

• Visually sold products and services. We’ve talked to many contractors, decorators, hotel owners, renovation specialists, and hand-made sellers. They all believe image search helps people choose their offer. For example, someone searches for “Seattle kitchen remodel” and decides to visit a site based on the images shown.
• Anything created to earn links and mentions. If you do data visualization or work as a photographer and hope people will use your images and link to you, you definitely need image SEO. It helps you get in front of the right audience. When those people use your image in a presentation, publication, or on their site, you earn a link.
• Licensed visual content. Some people earn money by selling images. Google Image Search is a great place to tap into this niche. If you’re a photographer, illustrator, or stock owner, you absolutely need image SEO.

A bit of stats… According to Jumpshot, in the US a third of all Google searches happen in Image Search. According to MozCast, an image block appears for 12.5% of queries in the results.

2. Must you use original visual content?

Or can you license visuals acquired from others? Can you buy a stock image, place it on your site, and still rank for it in Google? The answer is yes.

• Unlike web results, duplicate images are not considered a problem. In most cases, Google picks one version of an image and ranks it above others in image search. It’s not always the original. In many cases, it’s the better-optimized page. Thus, it’s a great opportunity to get extra traffic.
• Just make sure you have the right permissions.

3. How do you decide whether image SEO is worth doing?

For instance, you type “Santa Fe architecture.” At the top you might see an ad, and below it—a block containing several photos. Google shows this block only if people click images frequently or if there are many image searches for that query. Thus, Google itself can indicate demand.

Ranking factors in image search and image blocks

Creating a favorable impression of your website for visitors isn’t an exact science. Still, performance metrics can help developers increase traffic and retain audiences.
Below are the factors that influence image rankings. The list is fairly extensive, but the factors are simple. In our view, that’s because Google focuses more on relevance and satisfying user intent than on link popularity when ranking images. The search engine worries less about spam and manipulation here. Hence, you can see a somewhat “old-school” algorithm at play.

Core factors:

• Image file name.
• Presence of the “alt” attribute. Another very important reason to add alt attributes is image SEO. It also somewhat influences the main results.
• Caption. We’ve noticed this element matters more than alt for image search. Therefore, adding a short caption under the image can help improve its position in Google Image Search.
• Surrounding text. Google analyzes the text around the image to assess its relevance.
• Page title.
• URL of the page where the image is placed. This is one reason image galleries—especially stock sites—rank worse. Those pages have little relevant content. Many photos live on one page, and Google has to pick one or two most relevant to the query. That’s why most high-ranking images in Image Search are the primary image on their page.
• User engagement and popularity. This factor carries significant weight. Tests show that if users search in Image Search and click, say, the 12th image, and many people start doing that, Google will move that image up—just like with web results. In image search, engagement is even more important. Therefore, publish high-quality, interesting, highly relevant images if you want users to like them.
• Image aspect ratio. Google rarely shows images with unusual proportions. Images that are extremely tall or wide rank lower. The search engine primarily favors 16:9, 4:3, and square formats. Others tend to rank worse.
• Image size. In most cases, Google won’t pick very small or excessively large images. However, if someone searches for “desktop wallpapers,” Google understands large images are needed and looks for those.
• Embedded images. If your visual (e.g., an infographic) appears as an embed across many sites and pages, this can positively affect its rankings.
• Traditional URL ranking factors. If the page architecture.com/santafe ranks top 5–7 for “Santa Fe architecture,” chances are images from that page will also rank high in Image Search. The reverse isn’t always true. If you improve the page’s position in main results, the image ranking from that page will likely improve as well—bringing traffic from both channels.
• Visual relevance. Google’s algorithms also analyze an image’s visual match. So even if you have an excellent koala photo and optimized all the above factors, Google still won’t show it for “Santa Fe architecture.”

Recommended steps

1. Define your SEO goals, then compare them to your keyword list.
2. Audit your keyword list for image visibility. Use Keyword Explorer, Moz Pro, or other tools. Upload your keywords and see how many results contain image blocks to reveal opportunities.
3. Prepare guidelines for copywriters and site authors. For example: ensure captions and alt are added; verify aspect ratio and size meet norms, etc.
4. Compile a list of image SEO opportunities. This can be 5, 10, or even 50 keywords that trigger image blocks or have heavy Image Search demand—and target them.
5. Review existing site images for SEO and UX (size, load speed, etc.).

In closing

Image SEO helps improve your website’s overall effectiveness. Don’t miss the opportunities in this area.