Image SEO

Image SEO refers to the practice of improving the readability, indexability, and quality of images used on a website, in order to improve user experiences, and achieve better rankings in web and image search. The usage of images on webpages are manifold: they assist with describing more complicated topics, they enrich product pages on eCommerce sizes, images help illustrate articles and break up heavy walls of text, and much more. Falling under the content umbrella, it is always advised to provide high-quality images that are performance-optimized, i.e. compressed and resized to not slow down the page too much. 


A website is comprised of many different elements. Some of these are visible for the users and others, such as the source code, are not. Images are the major visible components of a website, apart from the text. In e-commerce in particular, the quality and design of product images have a decisive influence on the purchasing behavior of customers. Large stores, such as Zalando, routinely optimize their images. Visible and invisible factors play an equally important role in image optimization.

While the goal of conventional search engine optimization is oriented toward a website, image SEO aims to achieve a good ranking for the image file. Image SEO is very important within the scope of a holistic search engine optimization.


Google Image Updates

In 2017

In 2017, the new Google Image Search was introduced. In the earlier version, Google used iFrames within which the images were displayed. If you clicked on an image in the search results, you were taken directly to the web page or blog where the image was used. This allowed website administrators to generate traffic with images and thus improve their ranking in the SERPs with smart image SEO. 

Since the introduction of the new image search, this iFrame has been omitted. The images are no longer displayed in their full size as they were on the original page. Instead, users see so-called thumbnails, i.e. small preview in uniform sizes. If a thumbnail is clicked on, it opens against a black background within the search results. Google has added two buttons to the right of the image. One button takes you to the website that displays the image, the other button allows you to share the image directly.

Usability was greatly improved by the 2017 update. Users no longer had to open the original page to view the image in full size, so they no longer had to open multiple tabs to switch between individual thumbnails. However, legal experts and website administrators criticized the share button for making it easy to infringe copyright.

Before the big update, only two links referred to the actual image source, with the update, this became four: the image title, the URL below, the image itself, and the button to the right. This was supposed to ensure that the traffic of the image-source pages would not decrease. Nevertheless, the new format caused many website operators to lose traffic.

Critics of the new image search attribute this negative effect to the fact that users would no longer have any reason to visit the original website, since Google immediately displays the image in full size when clicking on a thumbnail.

According to critics, this would make the author lose both content-related and aesthetic control over their image, because they would not be able to determine the context in which the image would be displayed and used. Google's image search would have lost its character as a search engine whose purpose would be to communicate websites to users. Since the new image search means that it is no longer necessary to visit the website that produced the image, this characteristic has been lost.

In 2018

In September 2018, Google introduced a further update to the image search. The number of thumbnails displayed was reduced by a quarter. Previously, information about the image, especially the page title and the domain, only became visible when the user clicked on a thumbnail image. Since the optical update at the end of September 2018, this information is placed directly below the image. As a result, only the images in the SERPs whose SEO images are particularly strong are displayed. Images with medium rankings run the risk of slipping to the following pages.

With the picture search update of 2018, traffic for highly ranking pictures increased compared to the update from 2017. The immediate presence of the source information below the thumbnails increases the probability that users will view the original version of the image on the original website.

Further updates

  • As part of the 2018 image search update, Google introduced a reference to the originator of each image, known as image credits.[1]
  • In the SERPs of the image search, advertising images are also now displayed in searches with transactional keywords
  • By providing metadata in the binary file of the image, it became possible to assign the images to their rightful authors. The IPTC information must be filled in to correctly represent the originator, copyright owner, and attribution. Google wants to strengthen the rights holders and prevent an illegal use of the images from the SERP.[2]

Significance of Google's image updates for SEO

The reduced number of preview images and the (new) possibility to generate traffic via images used on the website is significant for the SEO images.

  • The image data, such as meta information, title and file name, must be in the context of the article within which the image is used. Google prefers images from content whose keyword best matches the user's search phrase.
  • The best thing for site operators is to optimize the image in the visible area. Google is increasingly weighting the position of the image on the original page. Users who are interested in the image should be able to see it immediately when they access the website.
  • The topicality of an article can have a short-term influence on the positioning of the corresponding image in the image SERPs. However, the best case scenario is evergreen content, which is updated as regularly as possible.

Image SEO Best Practices

Similar to on-page optimization for websites, image SEO has different levels, which can be worked on and optimized – the visible level, the meta level, and the image itself.

Search engines such as Google may have improved their ability to recognize images through artificial intelligence and machine learning, but they still cannot read all types of image content. For this reason, the context in which the image material is integrated as well as the meta elements are very important for image optimization.

The following aspects are important for the optimization of images:

  • File format: The common file formats for images are JPG or JPEG, PNG and GIF. Formats such as SVG are rather unsuitable for images in a website context. New formats are currently being developed to guarantee high quality even for images with small file sizes. These include FLIF, HEIF or Google's current WebP project, in which images can be displayed up to 34 percent lower without losing their SSIM index. The common file format is JPG. However, PNG is also suitable for graphics. These types of image files can be easily compressed to a good file size.[3]
  • File size: For an image url or file to be included in the index more quickly and easily by the Googlebot, it is advisable to work with moderate web-optimized file sizes. High-resolution images, compressed to a file size of about 150 kB, optimize the page speed of a website. As the loading time of a website counts as a ranking factor, the optimization of the image file size is very important.
  • Filename: This plays an important role for the subsequent ranking in the image search. It should accurately represent what is seen on the screen. At the same time, the picture will be considered in the entire context of a website. For Google and other search engines, the name offers an important orientation point in recognizing the topic of the website.

Example: An image of a fir tree. Filename: fir.jpg

Additional data is added with dashes.

Example: Image of a green tomato. Filename: Green-tomato.jpg

  • Image Size: It is commonly agreed upon in SEO circles that small images such as thumbnails or previews do not have much of a chance to rank well in the images search. A benchmark of a minimum 300 pixels has been established for at least one side of the image.
  • Image format: Images which are displayed in landscape or exact 4:3 format are clicked more often, and, since the last update, are also preferred by Google.
  • Source: The URL of the image plays a role in image SEO. It is advisable to use a thematically relevant folder structure.


If you want to promote the indexing of image files, you can save all image URLs in a separate XML sitemap and upload it to the Google Search Console.

The following aspects should be considered when embedding an image and relating metadata:

  • Surroundings: the content surrounding an image is important for its ranking. The use of relevant keywords is especially a factor.
  • ALT attribute: The classic function of alt tags is to describe an image in case it cannot be displayed in the browser due to technical problems. Therefore, the alt tag should accurately reflect the content of the image and contain the main keyword.
  • Title tag or image title: The meta title should also be used to fit in a relevant keyword. The title is however primarily for the improvement of usability and less as an SEO factor.
  • Markups: with the help of and other markup languages, Images can be overlooked with structured data which the search engines can read. This data makes it easier for bots to crawl and order.


The benefits of image SEO can be outlined in the following bullet points:

  • Strengthening of visibility: as images of high relevance can be shown directly in the organic google SERPs, websites with optimized pictures can increase their presence in the search results.
  • Indirect traffic boost by ranking well with images: if images are clicked on in the google images search, more users will come to the website. Therefore, traffic can be increased with image SEO.
  • Possibility of top rankings on universal search: it's possible that a website won't be found with the URL in the top rankings, but with an image.
  • Improvement of topic relevance: if pictures are described with important tags, the entire thematic context of a website can be improved. Therefore, the chances of being able to target better rankings in the google search increase.
  • Improvement of usability: if images are condensed appropriately and are of high quality, the usability of the website increases. Condensing an image is important above all within the scope of mobile optimization, because smartphones often don't have a high band width when out and about. Large image files can cause the page to load slowly.
  • More traffic for e-commerce websites: if potential customers search for a product, they often use image search. If a company is present there because of image SEO, the changes increase of more users, and therefore more conversions.

Extended Benefits

Optimized image files do not support a website only in terms of search engine optimization. For example, adjusted file sizes reduce the loading time of a website and thereby affect the user experience positively. Optimized image data is also ideal in terms of accessibility, to give blind users the opportunity to learn all the content of a website, for example.


  1. Bildrechte-Metadaten in Google Images Accessed on November 13, 2018.
  2. Guide to IPTC Photo Metadata and Google Images Accessed on November 13, 2018
  3. A New Image Format for the Web Accessed on November 13, 2018.

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