Image SEO: Optimizing images for search engines

If you are, for instance, a blogger or you write articles for an online magazine or newspaper, you might encounter this question on a daily basis: should I add an image to my article? The answer is “Yes”. Images make an article more vivid and can contribute to the SEO of your article. In this post, I’d like to explain the steps that you should take to fully optimize an image for SEO.

When you optimize an image, make it as small as possible – in terms of download size – by using the right image compression. A well-optimized image also has the right name and alt text, so it’s optimized for search engines too.

Use images

Images, when added with a certain consideration, will help readers understand your article better. “A picture is worth a thousand words”. Yeah, well, probably not for Google, but it can spice up a 1,000 dull words, illustrate what you mean in a chart or data flow diagram, or simply make your social media posts more enticing for sure.

It’s a simple recommendation: add images to every article you write online. They’ll make it more appealing.

Finding the right image

Image SEO: This image isn't saying 'welcome to our company', it's saying 'welcome to a company'.If you have the opportunity to add your own image, please do so. Your team page needs pictures of your team, not this dude on the right or one of his stock photo friends. Off topic: let alone that the dude needs a haircut.

Your article needs an image that has the same subject as your article. If you would use an image just to use an image and get a green bullet in our SEO plugin, you are doing it wrong. The image should reflect the topic of the post, or have illustrative purposes within the article, of course.

There is a simple image SEO reason for that: an image that is surrounded by related text, ranks better for the keyword it is optimized for. More details on image SEO later.

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Alternatives

If there is no way to use images of your own, there are other ways to find unique images and refrain from using stock photos. Flickr.com is a nice image source for instance, as explained in this article: How to Use Creative Commons Images from Flickr. I also like the images provided by sites like freeimages.com (formerly known as sxc.hu). Check here for more image resources. You should stay away from the obvious stock photos, and rather pick the ones that look (ok, just a bit) more genuine. It almost seems like images with people always look like stock photos, unless taken by yourself. In the end, that is still the best idea.

Obvious alternatives for photos could be illustrations, like we use, or graphs, of course. An honorable mention should go to animated GIFs, as these seem to become more and more popular these days.

Image SEO: Animated GIFs are popular these days

Even with Animated GIFs being very popular these days, don’t go overboard. It’ll make your post less attractive to read, as your reading will be interrupted by the movement of the image, of course. Like in the post where I found the image above.

Preparing images for use in your article

When you have found the right image to use, either an illustration, chart or photo, the next step is to optimize that image for use on your website. There are a number of things that you should think about:

Choose the right file name

Image SEO starts with the right file name. Of course, this is the first location to use that keyword. Without even looking at the actual image, you want Google to know what the image is about. It’s simple: if your image is a sunrise in Paris showing the Notre Dame, the file name shouldn’t be DSC4536.jpg, but notre-dame-paris-sunrise.jpg. The main keyword would be Notre Dame, as that is the main subject of the photo, that is why I added that at the beginning of the file name.

Scale for image SEO

Loading times are important for UX and SEO. The faster the site, the easier to visit and index a page is. Images can have a huge impact on loading times, especially when you load a huge image and show it really small, like using a 2500×1500 pixels image and showing it at 250×150 pixels size. The entire image still has to be loaded. Scale the image to the size you want to show it. WordPress helps by providing the image in multiple sizes after upload already. Unfortunately, that doesn’t mean the file size is optimized as well, that’s just the image size.

Use responsive images

This one is essential for SEO as well. Images might ruin the mobile experience and could increase bounce rate. Go check Bruce Lawson‘s talk at WordCamp London (2015) about responsive images and the use of the picture attribute. He also brought this plugin to my attention as an alternative: RICG Responsive Images For WordPress. The plugin adds the srcset attribute to your images, making it possible to serve a different image per screen width. Note that WordPress adds this behavior by default from version 4.4 and they urge you to update the RICG plugin to the latest version in that same article. If we can automate this process like that, it might be the future of web images, IMHO. I like it.

Reduce file size

The next step in image SEO should be to make sure that scaled image is served in the smallest file size possible. There are tools for that. Of course, you could just export the image and test what percentage of quality is acceptable, but I prefer (especially with retina and similar screens) to use 100% quality images.

Image SEO: Optimize image file size using JPEGMini

Optimize image file size, for instance using JPEGMini

You can still reduce the file size of these images by, for instance, removing the EXIF data. We recommend using tools like ImageOptim or websites like JPEGMiniPunyPNG or Kraken.io.

Next to using tools like the ones mentioned above, please use tools like YSlow to check if your image optimization succeeded.

Adding the image to your article

Don’t just stuff it in somewhere. I already mentioned adding it close to related textual content. That simply helps a lot. It makes sure the content is relevant for the image as well, as it is the other way around. 

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Captions

The caption of the image is the text that accompanies the image. If you look at the images in this article, it’s the text in the gray box below it. Why is that text important for image SEO as well? People use that text in scanning an article. Next to headings, people tend to scan the image and include the caption as well in that scan. Nielsen actually wrote back in 1997: “Elements that enhance scanning include headings, large type, bold text, highlighted text, bulleted lists, graphics, captions, topic sentences, and tables of contents.” In 2012, KissMetric even stated that “Captions under images are read on average 300% more than the body copy itself, so not using them, or not using them correctly, means missing out on an opportunity to engage a huge number of potential readers.”

Do we add captions to all images? No. As mentioned, sometimes images just serve another purpose. Decide whether the image at hand is an image you want to use for SEO as well or not. Keeping over-optimization in mind, I’d say you should add a caption if it would make sense to the visitor if that caption is added. Think about the visitor first, don’t add a caption just for image SEO.

Alt text and title text

The alt text (or alt tags) is added to an image so there will be a descriptive text when the image for whatever reason can’t be displayed to the visitor. I can’t put it any better than Wikipedia: “In situations where the image is not available to the reader, perhaps because they have turned off images in their web browser or are using a screen reader due to a visual impairment, the alternative text ensures that no information or functionality is lost.” Be sure to add alt texts. Make sure the alt text includes the SEO keyword for that page and relates to / describes the image.

When hovering an image, IE shows the alt text as a ‘tooltip’. Chrome shows the title text like it was intended. Title text for images is similar and a lot of people that use these simply copy the alt text. More and more people simply leave these out. What is it for? “The title attribute can be very useful, but it is not a safe way of providing crucial information. Instead, it offers a good way to provide non-essential information, for example, the mood of the image, or what it means in context.” it’s nice to have information indeed, and isn’t taken into account for image SEO.

Read more: ‘Read more about alt tag and title tag optimization’ »

OpenGraph and Twitter Cards

I mentioned using the image for social sharing. If you add the right image tag to your <head> section like this:

<meta property="og:image" content="http://example.com/link-to-image.jpg" />

That will make sure the image is included in your share on Facebook (and OpenGraph is also used for Pinterest, for instance).

Social preview for Facebook sharing

Our WordPress SEO plugin has a Social section where you can set and even preview your Facebook post when you use Premium. Make sure to use a high-quality image, like the original image you use in the post, as higher quality / larger images tend to be used by the social platforms more often. If you have set this up correctly, and it doesn’t work, try to flush Facebook’s cache in the URL Debugger.

Twitter Cards do the same for Twitter and are also generated by our plugin.

Alignment

Let me be honest, this is a pet peeve of mine. Images shouldn’t break the left reading line. I’m sure there are studies about this but I’m taking full responsibility for this myself: I just really don’t like it when text starts on the right of an image, only to jump below the image later:

Maintain the left reading line; don't align images to the left

Maintain the left reading line; don’t align images to the left

If an image is used that is the same width as your textual column, that would be no problem. It will even help emphasizing the image more.

Note that this has absolutely nothing to do with image SEO, but I saw an opportunity to express my opinion and used it 🙂 I think it’s bad for user experience. Just to please me: don’t. Thanks a lot for that.

XML image sitemaps

If you are a web developer, you might wonder about XML image sitemaps. I’d rather say images in XML sitemaps. Google is pretty clear about this:

To give Google information about images on your site, you’ll need to add image-specific tags to a sitemap. You can use a separate sitemap to list images, or you can add image information to an existing sitemap. Use the method that works for you!

Every now and then, people ask us about XML image sitemaps. We don’t generate these in our plugin, but as Google states, instead, these images are included in the page or post sitemaps. Just scroll down in our post sitemap and find that we have added images to all our latest posts (there is a column telling you that). Adding images to your XML sitemaps help Google index your images, so be sure to do so for better image SEO.

TL;DR

Image SEO is the sum of a number of elements. With Google being able to recognize elements in the image better every day, it makes sense to make sure the image and all elements contribute to user experience as well as SEO. It would be foolish to try to fool Google.

Take these things in mind when adding an image to an article:

  • Use a relevant image that matches your text
  • Pick the right file name for your image
  • Make sure image dimension match the image size as displayed
  • Use srcset if possible
  • Reduce file size for faster loading
  • Add a caption for easier scanning of the page
  • Use an image alt text, title text is optional
  • Add OpenGraph and Twitter Card tags for the image
  • Don’t break the left reading line using an image
  • Use images in your XML sitemaps

Besides contributing to SEO and user experience, images can also play an important role in conversion!

Keep reading: ‘Visually direct and captivate your visitors’ »

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Author: Search Engine Optimisation Company

Our team have been offering SEO expert services to clients since the early days of the internet. Whilst the tactics have evolved over the years, our overall goal by no means has and thats making sure our users web pages to rank on page 1 for appropriate keywords at the same time only using honest and long term strategies. Plan to Dominate the Search Engines? While many agencies are convinced that they have to resort to black hat SEO tactics to get results, we can get the 1st page rankings for all of our customers despite the fact that constantly guaranteeing we stick to strategies that are not frowned upon by the the search engines. What happens when you turn to black hat strategies? Without a doubt, you will get some early success, however the internet search engines will quickly discover what you are doing and you can face severe penalties which includes having your website banned with the google search results altogether. We work within guidelines of leading search engines such as Google, Yahoo and Bing! so you never need to be concerned about receiving any penalties as a result of the work we carry out for you.

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