SEO Image Optimisation Guide

Through our SEO Agency Optimize 360

If you want to boost your natural referencing and improve theuser experience on your websitethen it is essential to pay particular attention to theoptimising images for SEO.

These visual elements are essential for capturing visitors' interest and facilitating their understanding.

In this article, we're going to explore the different techniques that can be used to optimise your images and maximise the impact of your SEO strategy.

Make your images lighter

Images are often the main factor slowing down page load times. Long loading times can reduce the quality of the user experience and lower your ranking in search results. It is therefore essential to compressing and reducing the weight of your images.

Choosing the right image format

Image format is an essential criterion for reducing image size without compromising quality. The image formats most commonly used are :

JPEG: this format supports lossy compression, but retains good visual rendering for photographs.
PNG JPEG: a lossless format that offers better image quality, but is generally heavier than JPEG.
GIF: ideal for simple animations and images with few colours, but not suitable for photographs.
SVG: a vector format for displaying images or icons clearly and lightly, regardless of the size of the container.
WebP WebP is a modern format designed to deliver high-quality images on the Web. It supports lossless and lossy compression.
It is generally more efficient than JPEG for lossy compressed images and PNG for lossless images, while supporting transparency (like PNG) and animation (like GIF). This format is optimised for the web, offering better performance in terms of loading speed and bandwidth usage.

It is important to choosing the right format for the type of content to achieve a good compromise between visual quality and image weight.

Compressing images

There are many online tools and software packages that can be used to compress your images without any significant loss of quality. Some even allow you to compare several levels of compression to determine which is best for your situation. Don't forget to check the final quality of the image after compression and adjust accordingly if necessary.

Using alt and title tags

The use of tags alt and title tags play a crucial role in optimising images for SEO. These tags make it possible to add descriptive text about the image, making it easier for search engines and the visually impaired to understand. What's more, this textual information is also taken into account by search algorithms, improving your natural referencing.

The alt tag: a relevant description for your images

Attributes altAlternative texts, commonly known as "alternative texts", describe the content of an image when it is not accessible or cannot be displayed correctly. They can be essential for visually impaired people who use screen readers to browse the web.

To write an effective alternative text, it is advisable to :

Describe the content of the image precisely and succinctly.
Include relevant keywords, without overusing them or resorting to "spam".
Avoid common mistakes such as using generic phrases or descriptions that are too long.

The title tag: refining the description of your images

The attribute title displays a tooltip containing explanatory text when the mouse cursor is positioned over the image. Although it doesn't have as much impact as the alt tag in terms of SEO, this attribute can help to improve the user experience.

We recommend that you use concise, informative text that complements the alt tag to maximise the use of the title attribute.

Adopting an optimised naming strategy

Another essential aspect of optimising images for SEO is the choice of file names. Search engines also take this information into account when assessing the relevance of your content. Adopting a optimised naming strategy can help you improve your ranking in search results and attract more visitors to your site.

Use relevant keywords

Remember to include keywords related to the content of the image as well as with the general theme of the page. In this way, you will be able to strengthen the coherence of your content and improve its natural referencing.

Creating descriptive file names

Avoid generic file names or names made up simply of random numbers and letters. Instead, opt for titles that clearly describe the content of the image and enable Internet users and search engines to quickly understand its purpose.

Adjust the dimensions of your images

The final key point in optimising images for SEO: thedimensional adjustment. Adapting the size of your images to suit the different media and screen sizes used by your visitors is essential if you are to offer a satisfactory user experience while maintaining a good balance between visual quality and loading speed.

Setting up responsive images

It is essential to use techniques for automatically adapting the size of images according to the medium and screen resolution. This ensures that content is easy to read and that images are not distorted.

Implementing lazy loading

This technique involves loading images only when the user really needs them, i.e. when they scroll down the page. The lazy loading speeds up the initial page load time and saves server resources, while optimising SEO.