Image Optimisation for Websites: Get Found on Google Faster and Higher

Guest post — Mika Vaasala — Digitekoja.fi

Image optimisation is an important part of search engine optimisation (SEO). Well-optimised images improve a website's visibility in search engines and help pages load faster. In this guide, we go through how search engines interpret and index images, as well as the best practices for image optimisation.

The importance of image optimisation in SEO

Images are an important part of web pages, but optimising them for search engines is easily overlooked. Search engines cannot interpret images in the same way as the human eye, so they cannot use images to determine a page's content. Instead, search engines rely on image metadata to understand what is in or happening in the image.

Well-optimised images help search engines understand a page's content and thereby improve the site's visibility in search results. Image optimisation also promotes faster page loading and a better user experience, which is one of the most important ranking factors in Google's search engine.

How search engines interpret and index images

As mentioned, search engines cannot interpret images in the same way as humans, so they rely on image metadata to understand their content. The most important part of image metadata is the alt text. Alt text tells search engines what is shown in the image and helps them understand the image's content. It is important to choose appropriate alt text that describes the content of the image as accurately as possible.

Tip: Write the image alt text as if you were describing the image to someone who is completely blind. Don't write anything that is not in the image or that contradicts it.

Image captions can also provide additional information about the image's content and help search engines understand the context of the image. Captions don't directly affect search engine rankings, but they can improve the site's user experience and help visitors understand the significance of the image.

Image files also have a filename, but it doesn't need to describe the image. In other words, the image filename allows the use of important keywords, even if the image itself has nothing to do with the keyword. This measure can have just the right amount of influence on how a search engine interprets the web page's content and relevance for that particular keyword.

Choosing the right file format for images

The file format of images can have a significant impact on their loading speed and site performance. The most common file formats are JPEG, PNG or GIF, which is well suited for displaying small-scale animations, for example. These file formats are generally good choices for saving photographs, but can be somewhat heavy in terms of loading speed when used on websites.

Large image files slow down web page loading and can worsen the user experience, which has a major impact on discoverability in Google search results. It is therefore extremely important to optimise image file sizes to be as small as possible while still maintaining their quality as high as possible. An excellent alternative file format for website images is WebP. This is a file format released by Google, with the simple purpose of speeding up web page loading times. Converting file formats is often quite straightforward with the right tools, and fortunately there are also free and handy online tools available. Search Google for a suitable image file conversion tool using a search term like "jpeg to webp".

Using free stock images on your website

Using your own images is generally recommended, but it is not always possible. In such cases, you can look for solutions from free stock image libraries. Stock libraries often offer a wide selection of high-quality images that you can use freely on your website.

However, there are risks involved in using stock images. While stock photos can be tempting, always make sure that the images are genuinely free to use on your website. Stock images also lack the uniqueness that is generally particularly important for brand credibility and trustworthiness.

Decorative and supplementary use of stock images can be justified. In these cases, it is worth using generally good and reliable stock libraries such as Pexels, Pixabay, Freepik and Unsplash, as well as Canva, which is an excellent option for image editing.

However, the safest and most reliable approach is to use a professional photographer, because then the images are guaranteed to be unique and no copies of them will be found elsewhere. Duplicated and repetitive content is always a negative factor when it comes to discoverability in search engines.

Monitoring image optimisation and measuring its impact

Image optimisation directly affects a website's discoverability in search engines as well as its loading speed. If you make changes to the images on your website, remember to also monitor and measure the effects of image optimisation.

You can track the development of your website's discoverability using the Google Search Console tool, for example, and monitor loading speed development with Google's PageSpeed Insights tool.

Conclusions

Image optimisation is an important part of search engine optimisation and improving site performance. Well-optimised images improve a website's discoverability in search results and help pages load faster.

Choose the right file format for images, optimise image file sizes, add appropriate alt texts, captions and filenames, use free stock images when necessary, and monitor the effects of your optimisation. By following these practices, you can improve your website's discoverability in search engines while also providing a better user experience for visitors.

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