Image optimisation

What is image optimisation?

Image optimisation is the process of adjusting images so they take up less space without any visible loss of quality. The aim is to make your website faster, more user-friendly and easier for search engines to understand. You work with both the technical properties of the image file itself and the data that describes the image – so it's a question of both performance and SEO.

When you optimise an image, it's not just about making the file smaller. It's also about choosing the right file format and the right dimensions, and giving the image a context that search engines can read. In other words, you create better conditions for both your users and Google's algorithm at the same time.

How do you use image optimisation?

You use image optimisation by adjusting your images before you upload them to your website. The first step is choosing the right format. JPEG is best suited to photos, while PNG, SVG or WebP are often a better fit for graphics or illustrations. A modern format like WebP gives far higher compression than JPEG without any visible loss of quality.

Next, reduce the file's dimensions so the image isn't larger than necessary. If, for example, you only display an image at 800 pixels wide, you don't need to upload a 1600-pixel file. You can also use compression tools that reduce the file size without degrading the image's visual impression. Many CMSs or plugins handle this automatically, but you should still check the result manually.

Optimising your images has a direct effect on your visibility on Google. A precise file name and a descriptive alt text help search engines understand what the image shows. That means you should name the file “black-ceramic-cup.jpg” instead of “IMG_1234.jpg”. The same goes for the alt text, which should describe the subject in a natural way. This kind of optimisation works closely with SEO and content marketing, where relevance and user experience are inseparable.

Why you should use image optimisation

Ultimately, image optimisation is about speed and experience. Every time a user visits your website, the browser has to fetch all the elements – and images are typically the heaviest files. The faster the page loads, the lower the risk of the user leaving again. Google also treats speed as a ranking factor, which makes image optimisation an important part of your overall SEO effort.

Fast-loading images improve your conversion rate, because users experience smoother navigation. That means image optimisation isn't just a technical matter but a strategic move in digital marketing. If you work with both paid and organic traffic, an optimised website can also mean a lower CPC in your ads, because Google rewards fast landing pages.

On top of that, image optimisation reduces the load on your hosting. Smaller files mean lower bandwidth use, which in the long run can save both resources and costs. So you're working both more sustainably in digital terms and more efficiently in business terms.

What types and variants are there?

Image optimisation covers several approaches that you can combine depending on your needs:

• Technical optimisation: You compress images, change their dimensions and choose the right file format – typically JPEG, PNG, GIF, SVG or WebP.
• SEO optimisation: You add descriptive file names, alt texts and captions. You can also use schema markup and an image sitemap if you work with lots of visual elements.
• Advanced techniques: You implement lazy loading, so images only load when the user scrolls down to them. You can also use responsive images that scale automatically to the screen size, or caching for faster display.

How do you use image optimisation in practice?

In practice, you start by analysing your existing images. Use a tool like Google PageSpeed Insights to see which files can be optimised. You'll typically get recommendations on formats, sizes and compression levels. You can then process the images in an image editor or via a plugin, depending on where you publish the content.

If you work with e-commerce, you can, for example, optimise product images so they load quickly, even when the customer swipes between variants. In content marketing, image optimisation makes it easier to deliver visually rich articles without hurting page performance. And in social media marketing, you can use optimised images for faster display on platforms where users quickly scroll on.

A simple example workflow:

By repeating this process consistently, image optimisation quickly becomes a natural part of how you produce and publish digital content.

What should you watch out for?

In particular, you need to watch the balance between quality and file size. If you over-compress images, the result can be grainy or blurry, and that harms the user experience. Make sure you test the images on different screen sizes so they look sharp on both mobile and desktop.

Also remember that each platform and medium can have different requirements. An image that works perfectly on your website won't necessarily suit social media, where file compression and format play a big role. So coordinate your image optimisation with your other marketing channels to ensure a consistent visual experience across platforms.

Finally, you should keep an eye on new technologies and file formats. Standards like WebP and the newer AVIF are evolving quickly, and they can give you a head start on performance and SEO if you implement them early. In other words, image optimisation isn't a one-off task but an ongoing process that you should integrate into your overall digital strategy.