More often than not, you will find an array of people discussing content optimisation, and the use of keywords within articles and landing pages, but as image search is becoming increasingly prevalent, as discussed in an earlier article, image optimisation should not be overlooked.

With that in mind, here is’s guide to image optimisation:

Choosing the right image

There’s no doubt that you have to find the right image for any page or blog.

Good quality photographs are key not only for user experience, but Google also shows images as thumbnails in its search results – which means that they will be clicked on by users.

Although many companies use stock images, there is some benefit to using original, high-quality images, especially if you happen to be a powerful brand.

Once you have found the right image for your post or page, ensure that you are on the right side of copyright laws.

Use a stock image service such as Getty, Shutterstock, or Bigstock to avoid infringing copyright laws.

You can also use filters on Google images so that you can see results based on images available for reuse.

Modern apartments in Leeds against a blue sky.
An original image is always good to use.

File size, type, and quality

The type of file that you use is also important as there are best practice guidelines for each kind.


Most sites use JPEG images, which are great for maintaining a quality image once that it is compressed or resized — which they can be to a great extent without compromising quality.

The only issue with JPEGs is the fact that they use lossy data compression, which means quality can actually be lost if an image is compressed and decompressed over and over again.


Thought of as a modern alternative to JPEG formats, the image type offers better transparency and colour range.

They can be saved as a PNG-8 or a PNG-24, with the former being limited to 256 colours, while the latter produces a much higher quality image at the cost of a larger file size; potentially affecting loading times.


It’s quite rare that a brand will use a GIF file format in a page or blog in case the format slows page loading speeds.

You can however compress gifs using lossy or lossless compression to ensure that the file remains small.

Although GIFs are widely used on bookmarking sites and on social media, brand guidelines tend to limit the use of GIFs across websites.

Leeds City Centre in the Evening.
A view down Call Lane on a Summer evening.

Captions and filenames

Filenames are important for images so that search engines can not only find them, but easily understand what they are about.

It’s very easy to upload an image with its original title (think “IMG_256415”), but this is also a place where you can enter valuable keywords.

So, if you happen to be an ecommerce store selling protein shakers, your obvious choice for an image name would be something along the lines of “large protein shaker” or “yellow protein shaker with grid” if that happens to be what the image involves.

It’s worth remembering however, that if you have multiple pictures of large protein shakers, each image title should be unique.

Whatever you do, try and ensure that the file name is short, accurate, and contains naturally placed keywords.

Captions are also important as they provide more information and context to the search engine crawling the page.

According to one study, captions get 16 per cent more readership than text.

Alt text

SEO friendly alt text is important for a number of reasons.

The first is that if for accessibility, so visually impaired users will have the ALT text read to them.

With that in mind, like image titles, it’s key that the alt text describes what is happening within an image, which is especially important for people using screen readers, or for those who have low-bandwidth connections.

Continuing with the protein shaker example, a good alt description would go something along the lines of <img src= “large protein shaker.jpg”  alt=“person drinking from a large protein shaker”>

Although keywords are good for alt text, keyword stuffing, as usual, should be avoided.

Remember to keep the alt text natural and informative for both the user and search engines.

Image compression and tools

Page loading times are important to search engines and quite often a slow page will lag due to large images within it.

If you find that your site happens to be loading slowly, you can use various online compression tools to resize the images without affecting the quality.

It’s worth knowing that the physical size of the image should not be much larger than how it is represented within a page.

So there’s no point having a 1100×1100 image if it’s only shown as 500×500 to the user.

Good image tools to think about include:

Leeds Corn Exchange roof.
A view inside Leeds Corn Exchange.

Image sitemap

If you are a website that relies heavily on images, you can look into creating specialty sitemaps for images, which will list all the images used on your website

Sitemaps offer search engines more information about the images across a website and enables search engines to find images that are even loaded by a JavaScript code.

It’s not too hard to create a sitemap, and Google offers a good example URL in the relevant webmaster support post.

There are also a range of plugins for WordPress websites that can help you create sitemaps for your images.

If you want to know about search optimisation, or image optimisation for your websitefeel free to check out our contact page.