Image Optimization Tips for Today’s Search
Search Engine Optimisation

Image Optimization Tips for Today’s Search

21st March 2019

In recent months image optimization has been a hot topic within the SEO community.

Google is continuously introducing new features in its SERPs and has repeatedly reminded how, in this context, images are gaining more and more importance on the Internet.

SEO for images is changing fast, Google’s attention on the topic is high and optimizing images for search represents now more than ever a great opportunity for those involved in search engine optimization.

In this article I would like to provide a practical and fast method to understand how much image optimization is important for you right now and what you can do to get the best for your site from Google images vertical.

Evaluate image search opportunities

First, fundamental, step to understand if image SEO can be interesting for you is to verify the current contribution that images give to your site in terms of traffic and visibility.

To do this you can just open the Performance report within Google Search Console, apply a filter to the Search type considered for data and select “Images”.

The metrics you get (impressions, clicks, etc..) are now related to image search only and show you how your current content assets are performing on Google.

Once verified how the images of your site are displayed in organic results and how many clicks form images searches your pages are receiving, the next step is to identify the queries for which relevant images have more chances to appear in SERP.

One tool you can use at this purpose is SEMrush.

    • Open SEMrush, go to the Keyword Magic tool and perform a couple of searches for keywords relevant for a particular topic covered on your site
    • Collect and download the tool results, then filter them by SERP features containing “images”.
  • According to SEMush “Image results appear for searchers where visual aid is deemed relevant by Google and can appear in any position on a SERP”. This is not a feature specifically related to image search vertical, but let you understand which queries Google is considering “eligible” to contain images results and that, probably, have more chances to be searched also in Google Images

Now you have an idea of how important image search is currently for your site and for which queries there is a concrete opportunity in image optimization.

Next step is to work on your content assets, starting right from the image files.

Optimization of Images for Search in 3 steps

1. Optimize image files

A well-optimized image file for today’s organic search on Google should have at least the following features:

    • File format: use a file format that search engines can understand, index, and download fast. Depending on needed image quality you can rely on PNG (larger files but no impact on quality), JPEG (smaller files but a loss of quality when you save the file) or GIF (perfect for animations). Today also new image formats like WebP are available, ensuring higher quality and optimal compression
    • Descriptive File name: it is very important that the filename is descriptive of the content without being excessively long. It is much simpler for the search engine to “understand” an image of a sheepdog if the file name is sheepdog.jpg rather than IMG0098765.jpg
  • Dimensions: resize images to be no larger than they’ll be displayed and use compression to reduce file size as much as possible.

2. Optimize content and context

Once you have optimized image files you can now proceed to align the context in which images are used, ensuring you are doing your best to let Google understand what images are about.
A couple of things you can do at this purpose:

    • Use Structured data: Wherever is possible add on your web pages markup containing information about images. Structured data represent the new “fuel” of Google, the way through which the search engine is able to collect detailed information about different properties and associate them to particular “search entities” in order to enrich its organic results. Google is currently supporting image markup through structured data as a required attribute for products, videos, recipes, articles (AMP) and more.

    • Add Textual context: the assumption is that an image inserted in a web page is thematically close to the content around it. If I use the image of a cat within a textual content it is very likely that the text near the image is about cats, and not dogs. Making sure there is homogeneity between textual content on the page and the images used is therefore another very effective way to help the search engine understand the content of our photos.
    • Make use of ALT text in HTML: ALT is an attribute of the IMG tag and is very important from an SEO point of view. It represents the replacement text (ALT stands for “alternate”) that used to be shown (and it still is) instead of the image itself in case the browser can not download it. When the image is linked, the ALT attribute works as anchor text of the link. This attribute is fundamental when trying to position an image for a specific keyword: it is generally advisable to use a short sentence (4-5 words) containing a reference of the image itself and the keyword describing it better.
    • Use original images: try to use high quality, original and previously unpublished images in your pages, exactly as you would do for textual content. It is therefore preferable to use images for which you have exclusive rights (no stock photos), maybe pictures taken directly by yourself. If this is not possible, always cite the credits as metadata within the image file (Google reads them and, in some cases, decides to show them in search results).
  • Make images responsive, use srcset attribute to specify different versions of the same image for different screen sizes. By specifying how much space any image is going to take you’ll let the browser load the surrounding page content while the image is requested.

3. Let Google know

Last but not least, the technical part.
As for any type of search, also for images Google needs to be able to properly crawl resources before indexing them, so:

    • Consider using an XML Sitemap specifically for images ( according to Google it helps a lot). If you cannot, ensure that images URLs are included in the XML Sitemap you are using for web pages.
    • Ensure that, especially if your images are hosted on a CDN, robots.txt (both of your site and of the CDN) is not blocking access to URL paths in which images have been placed
  • In case of migration of your images to another hosting / location – remember that images URLs – as any other URL – should be redirected 301


Image optimization is a very important topic in relation to how search on Google is evolving.

From an SEO point of view you can get advantages in this sense both from the positioning of your images in Google’s dedicated vertical (for which you can easily identify your current performance and opportunities through some common SEO analysis tools) and in optimizing them in a broader strategic context, allowing the search engine to gather information on the visual content of your site in order to build “rich results” that can be proposed in different and new forms in the SERPs.

All you have to do, in order not to miss this opportunity, is to be sure you let Google crawl, index and understand your images in the best possible way.


Written By
Marco Megali is an Italian SEO consultant and digital marketing strategist. He's Head of SEO & SEA at AvantGrade, a digital marketing agency based in Switzerland (formerly Bruce Clay Europe).
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