Images SEO – How to optimize visual website content for search engines

17 min

Arousing emotions can be decisive when it comes to whether a user clicks or not. But during crawling by the Googlebot exactly these are not included. For this reason, it is important to rely on images SEO to also tell the Google algorithm what is to be seen on the image and how it belongs in the context of the text. Below, we give you a guide to the most important image ranking factors, including helpful tips. This way, you will learn how to make your image content run smoothly in the future!

What is image SEO anyway?
How does your website content benefit from images and graphics?
Why is the optimization of images important for search engines, and what are the benefits of image SEO?
Which aspects count as ranking factors in image SEO, and how do you optimize them?
How do you evaluate the success of your image SEO?
Conclusion: Image SEO is work – is it worth the effort?

What is image SEO anyway?

Image SEO or image optimization is an important part of search engine optimization and is one of the measures of OnPage optimization. Optimized visual web content not only influences the visibility of your site, but also enables better rankings in the Google Image Search. The goal is therefore to rank in Google Image Search with your own graphics, illustrations and representations and thereby generate visibility for your own website.

In addition, SERPs are nowadays a mixture of info boxes, fold-out questions, images, videos and websites. In order to have better chances for a good placement in this so-called Universal Search, an optimization of your images is fundamental. Through targeted methods of image SEO, your own visual elements should be placed in the SEPRs.

How does your website content benefit from images and graphics?

Especially from the user’s point of view, images are an effective way to lighten up the text and to present content in a short and comprehensible way. The saying “A picture is worth a thousand words” is more appropriate than ever. Infographics are vivid and support what you wanted to express with your text. In this way, you can reinforce what you’ve written or provide additional information that is difficult to convey in words. Thus, visual content improves your user experience and has a positive effect on the dwell time of your website visitors.

But images are not only important from the user’s point of view. Google also considers your website more relevant if you include images that match the text. By assigning an alt tag, you can tell Google what you see in the image. If you place appropriate keywords and semantic terms here, you convey to the search engine for which search queries the visual content is suitable.

Why is optimization of images important for search engines, and what are the benefits of image SEO?

If users search transactionally, i.e. with a certain purchase intention, it is particularly important to convince with images. Therefore, it is essential to focus on the search engine optimization of your images, especially for this type of search query.

Illustrative example:

If a user searches for “kitchen table large”, it is important to be prominently visible with your table in the corresponding search results – be it via an image directly in a search result, which draws the user’s attention to it, or via Google Image Search. This is the only way to attract the attention of searchers in the flood of offers on the Internet.

The image shows a screenshot of the SERPs for the search query "kitchen table large". Here, the Google Image Search is prominently presented to the user (framed in red). Therefore, it makes sense to optimize images so that they can be placed here.
Example of the search results page for the query “kitchen table large”.

But even with an informational search query, you can position yourself as an expert with your visual content. For example, the user searches for “AIDA model“. A graphic that already roughly explains the structure of this method can attract attention and move the user to click on your article.

The image shows a screenshot of the SERP for the search query "aida model". Here you can clearly see that SEO-optimized images are placed prominently and can thus generate more attention. This is achieved on the one hand via the Featured Snippet and on the other hand via a preview of the images in the respective search results (both framed in red).
In addition to the individual search results, graphics for the search for “aida model” are also displayed directly in the Google Featured Snippet, for example, and are thus prominently placed.

As you can see, image SEO has several purposes. In a nutshell, it serves the following purposes:

Which aspects count as ranking factors in image SEO, and how do you optimize them?

File name

The temptation is high: the photo is already called “IMG_9687.jpg”, so why not keep it for the sake of simplicity? Sure, it wouldn’t change anything about the function of the website, but from a SEO point of view, this is a fatal mistake. For example, if a user searches for “James Bond beach Thailand”, images named “james_bond_beach_thailand.jpg” will rank higher than those with a generic name. This means that you yourself are giving away potential.


When naming your file, you should include appropriate keywords for which you want to rank with the image. In addition to the file name, these should appear in the title tag and the alt tag.

Underscore or hyphen – that is the question here?

You can separate words in your image names with underscore, hyphen or space. However, it doesn’t matter how you do it. Underscores are considered a conjunction by Google, while hyphens are considered a separation. This means “james-bond-beach-thailand” would be counted as 4 separate words, each of which you can rank for separately. The name “james_bond_beach_thailand”, on the other hand, would be considered as one keyword and therefore only fits search queries that are posed in exactly the same way.

In the following video, Matt Cutts, who used to work for Google, explains in detail what underscores and hyphens in image naming are all about.

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File format

The choice of different file formats is large. But especially for use on the web, there are several formats that are particularly common.


A true old-timer of image formats is the JPEG format. It belongs to the raster graphics formats, i.e. images in which the individual pixels are arranged in a grid. These are the advantages and disadvantages of the format:

–        Applicable for many purposes
–        Compression possible
–        Support by almost every browser
–        Suitable especially for colorful and high-contrast photos
–        No transparent areas possible
–        Compression leads to loss of detail
–        Scaling not possible without loss

Even a long-established format like JPEG is being developed further. JPEG 2000 and JPEG XR are successors to the original format. They benefit from a smaller file size without reducing quality. JPEG XR also offers the possibility of inserting transparent areas.


The PNG format also belongs to the raster graphic formats. The big difference to the classic JPEG, however, is that transparent areas are possible. A special feature of PNGs is that there are two variants of the format:

  1. PNG8 – this format can render only 256 colors
  2. PNG24 – this format is comparable to JPEG and can reproduce up to 16.7 million colors

The PNG format has the following advantages and disadvantages:

–        Applicable for many purposes
–        Lossless compression possible
–        Transparent areas
–        Large size of files for more complex graphics
–        Scaling not possible without loss


Unlike PNG and JPEG, SVG files are vector graphics. This means that the image is composed of graphical elements, such as lines, circles, etc. SVGs have the following advantages and disadvantages:

–        Any scaling possible
–        Transparent areas possible
–        Animatable via JavaScript
–        Large size of files for more complex graphics
–        No use for photos, only for graphics and logos


The file format was invented by Google and is mainly suitable for lossy or lossless compression. It was developed specifically for use on the Internet and also supports transparent areas. Thus, WebP combines the advantages of the above formats. But it also brings a disadvantage: not all browsers support this format so far.


You should definitely avoid file formats that unnecessarily inflate the file size. This is the case with TIFF, for example. This file format is therefore not suitable for use on the web – and, by the way, not even intended.

Image size and file size

Apart from the file format, the image size is of course a crucial factor, as it affects the loading speed of the website. We talk about the image size when we talk about the dimensions of the visual content that it will occupy on the website. Therefore, if an image on your website has a width of 600px, you should scale it in advance so that it is not bigger or smaller. Therefore, the image size should be adjusted exactly to the space used in order to work without any problems.

Unlike image size, file size is about the amount of memory on the server that your image takes up. This also affects the loading time of your website. Compressing large files is therefore advisable. However, you should keep in mind that this is often accompanied by a loss of quality. So make sure that the quality of your images does not suffer from the compression.

TIP: Use Lazy Loading

Content that is in the visible area of a website is loaded immediately. Everything that is not yet above the fold at this point is loaded downstream and delayed. WordPress 5.5 has this feature built in to save website owners from having to work with plugins.


Normally, the file name is automatically inserted into the title tag. From an SEO point of view, it has little meaning, but users can see it when hovering the mouse over the image. Therefore, use it to increase usability for your website visitors and ideally use the main keyword there.


If an image cannot be loaded or your website is visited by a person with visual impairment, the alt tag is an important tool. Because whenever the image cannot be loaded correctly for the website, the alt text will be displayed instead. For this reason, it is important to maintain it as detailed as possible. Describe what’s in the image. Another plus: It promotes the accessibility of your website, because also visually impaired people have the possibility to have the image “read out” to them.


As a little treat on top, Google can read the alt tag to better understand how the image relates to the rest of the text.

Surrounding Text

Google is increasingly determining the interrelationships of the individual building blocks of a website in order to better evaluate how sensibly a post is structured and how valuable it is accordingly for users. Therefore, the text surrounding the image also plays an important role. Make sure that the keywords from the image description match the previous body text. If Google recognizes meaningful connections after crawling, this can increase your ranking.


Images that you place on a product page should always fit exactly to the previously described product and be optimized.


With the help of the caption, you have the possibility to provide information directly below the image that is relevant for the user. Here you can find, for example, information about the image content, the text context or the copyright. Especially when scanning a post, the caption stands out. So use this option to succinctly tell the reader how the image relates to the text, thus increasing user-friendliness. In addition, the information provided here is also transmitted to Google and therefore helps to increase relevance.

TIP: Images Sitemap

An XML sitemap created specifically for your images informs Google and Co. which visual content is contained on which subpage. This makes crawling easier, conveys connections between images and text, and increases the relevance of your images.

How do you evaluate the success of your image SEO?

Of course, you can optimize as much as you want – but it’s useless if you don’t know if it’s working. Therefore, the Google Search Console gives you a good opportunity to evaluate the success of your image SEO. To do this, you change the search type from “Web” to “Image” in the “Performance” section and get all the information about clicks, impressions, CTR and average position of the respective visual content.


Only calls via the actual image search are evaluated via the “Image” search type. All events that occur via Universal Search are not included here. However, if a user clicks on an image from there, he or she enters Google Image Search. As a result, the  is included in the statistics for the “image” search type.

Here, you can change the search type in the service area of the Google Search Console

Unfortunately, Google Analytics is of no great help to you in the evaluation, since traffic generated via the image search is classified there under “google / organic”.

Conclusion: Image SEO is work – is it worth the effort?

Definitely! Even if your top priority isn’t necessarily ranking in image search, optimized images that match your text content will help your overall ranking. Importantly, image SEO often starts before images even reach the web. You can adjust scaling, compression and image naming before you upload your visual content. This way, you will be able to perform image SEO as efficiently as possible.


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