Image SEO: What is it and How to Optimise for it

One often overlooked area in SEO is image optimisation. But should it be? How important is it really, and can it actually deliver results?

The answer: yes!

Google has 3.5 billion searches a day—3% of these 3.5 billion (100.5 million) are image searches.

But what’s 3% - nothing, right…

Well, it isn’t a lot, you’re right. However, this is just for image searches. This isn’t image SEO as a whole.

Proper image SEO boosts CTR through snippets (for example, AI overviews) and can even get you more backlinks.

What is Image SEO?

Image SEO (Search Engine Optimisation) is all about tweaking the images on your website to boost their visibility and ranking in search results.

It’s a process that helps search engines better understand your images while also enhancing the overall experience for users.

Where can Images Appear in the Search?

Most website owners think that image SEO is when images uploaded to a website appear in the “Image” tab of Google.

However, image SEO is much more powerful than that. In the US, 39% of keywords have an image pack. This is where images also appear in the SERPs.

What makes this so powerful is the digital real estate you gain. By occupying more space on the SERPs, you boost your chances of getting someone to click on your listing.

Not only that, AI Overviews also sometimes use images in their snippets. This is a new feature, but again, it allows you to take up more digital real estate, increasing the likelihood of a click.

Without proper image SEO, Google doesn’t understand these images (well, not entirely). They sometimes do, especially now with their Vision AI, but image SEO makes it easier for them to understand - improving crawlability, indexability, and rankings.

How to Optimise Image for SEO

If you’re thinking about optimising your images for SEO, following the tips below will help you tenfold.

Create or Find Relevant Images

The first step to image SEO is creating or finding relevant images to optimise. By relevant, we mean:

Images that showcase products
Images that break the flow of text
Images that convey ideas (infographics)
Images that display complex data (graphs, tables, etc.)
Images that represent your company (a logo)
Images that provide clear instructions (screenshots, etc.)

If you can, try to use your own unique images. Some stock imagery is okay if it benefits the page. However, unique and personalised photos work the best.

Select the Appropriate Image Formats

Google only supports the following image formats: BMP, GIF, JPEG, PNG, WebP, and SVG.

We recommend that you use the following:

SVG: Best for small icons and logos. It can be resized without loss of quality.

WebP: Best for all other images. It’s supported by search engines and loads quickly.

JPEG: For standard images.

PNG: For images with transparent backgrounds.

GIF: For animated images.

For the most part, stick with SVG and WebP for images. If you’re using animated images, use GIF.

Use Clear and Descriptive File Names

Google does understand images a little. However, not fully. Sometimes images can look the same but mean something else—for example, mistaking cheese for butter or butter for cheese.

To combat this, you want to set clear and descriptive file names (and alt texts; more about this below). This helps search engines understand your image on a text-based level, not only a visionary level.

Good Example: apple-airpod-4-white-case-side-view.webp
Bad Example: apple-product-4-airpod-white-case-super-clean-2205325-.webp

Like anything with SEO, be clear, keyword-focused and descriptive. This is the best type of formula to follow.

Write Effective Alt Text

On top of clear and descriptive file names, write an image alt text. Simply put, an alt text is a written description for an image that’s stored on the web code.

For example:

<img src="image-file-example.jpg" alt="Alt text goes here">

Alt text plays a key role in text-to-speech tools. For someone who’s visually impaired, the alt text provides a description of the image, allowing them to understand what’s being displayed. Plus, it also helps search engines grasp what the image is about.

When writing Alt text:

Use a max of 125 characters
Only use it for functional images, not decorative images
Avoid using words like “photo of” or “image of”
If additional information is needed for all readers, put it underneath the image, not in the alt text.

There are also a load of free AI image ALT text generators. One of the best is from Ahrefs. This seems to be pretty accurate compared to other generators available.

Adjust Image Sizes

Image files shouldn’t be too big or too small - Too big, and it will be a large file and not optimised for small devices, too small, and it won’t have a big file size, but it won’t appear properly for big devices.

The best thing to do is to use a tool. You can use image editing tools like Photoshop. However, it takes too long. If you use WordPress, we recommend that you use the Resize Image After Upload plugin. It automates the process for you.

Reduce Image File Sizes

If, after adjusting the image size, the image file size is still too big, compress it. You may lose a bit of quality, but it’ll perform better regarding image SEO.

There are many too you can use. Optimole, Compress Now, Online Image Tool, JPEG Optimize, Tiny PNG, just to name a few.

Make Images Responsive

You should also use responsive images. These are images that automatically adjust to the size of a user’s screen.

You can also hide images on certain devices. For instance, not showing a certain image on mobile and only on desktop. However, just remember that mobile-first indexing is now a thing.

Luckily, most website builders (such as WIX) have the responsive image scale as a default feature. If you don’t use WIx, however, there are plenty of plugins you can use.

Use Lazy Loading for Faster Pages

Moving forward, you can also use lazy loading to increase website loading speed and your Core Web Vitals.

Lazy loading is an attribute you can add to image tags. The attribute is “loading=lazy”.

Once added, it’ll load other images, images without a lazy load attribute, first and then load the lazy loading images.

Build an Image Sitemap

A normal XML site map is the architecture of a website and mentions its pages and hierarchy. An image sitemap words in a similar fashion - it’s just for images, however.

Creating an image-specific sitemap ensures that bots, like GoogleBot, don’t miss any images while crawling.

When building an image sitemap, we recommend you use tools like ChatGPT. They do this very well.

Once created, add it to your server's sitemap file.

Use a Content Delivery Network (CDN)

You should also use a CDN. A CDN allows you to host images on multiple servers around the world, thus reducing the load time for users (and search engines)

Instead of having a single server the user accesses, they have multiple. This allows them to use the closest server to gain faster access to the webpage.

[caption id="attachment_5872" align="alignnone" width="918"] Reference: Example of a CDN by GTMetrix[/caption]

Enable Browser Caching for Images

In simple terms, browser caching is when a browser (like Google Chrome) stores certain files (like Images) on a visitor's browser.

You can cache all image files—for example, your logo. You can also have different cache durations, for example, one week, one year, etc.

Follow On-Page SEO Guidelines

You should also follow all on-page SEO guidelines—for example, page speed, optimised meta tags, and quality content.

These, like with traditional SEO, will impact how well your image SEO performs. SEO works together. If you have good on-page SEO and image SEO, then you’ll get better image performance.

Add Structured Data to Your Site

Lastly, you should add structured data. Structured data, also known as schema markup, is a way to get images to appear on the SERP (search engine results page).

The type of image structured data you use will depend on your goals. For an e-commerce store, for instance, the structured data will be different than “event” structured data.

You can find all the types of structured data on Google Search Central. You’ll also find a guide on how to perform the different types of structured data depending on your goals/content.

Final Word

After reading the above, you should have a better understanding of image SEO. Though often overlooked, it really shouldn’t be, as it can provide some results.

It can improve CTR, improve traffic, and even improve the number of backlinks to your content assets (If the images are unique and benefit the user).

It’s a win-win all around, both for image SEO and traditional SEO, so we recommend that you focus on it.

Get in touch today for a FREE SEO audit of your website and see where you could be improving your organic traffic.