Images are increasingly important to the customer experience and search yet many sites are not optimised to take advantage.

In the early days of the web images were typically small and of low quality. We all remember the little animated men at work icons that littered the web in its infancy.

However, as users have moved from dial-up to broadband connections, the number, size and quality of images on the web has increased significantly. 

The following graph shows this rapid increase:

graph of web images

Some facts about images:

  • 100bn images are captured and made available online each year.
  • 750m camera equipped mobile phones are sold each year.
  • 100m digital cameras are sold each year.

Images are important to search. Increasingly important. Don't just take our word for it though.

R.J Pittman, Google Director of Product Management, Feb 2009:

Image search makes up about 5.7% of all Google Searches and 5% of all search is image related.

However, very few websites are optimised to take advantage. A recent study we conducted on the top 20 websites in a particular industry (thought to have fairly advanced SEO), highlighted that their optimisation in this area was poor, at best.

So what can be done to capitalise on this free traffic?

Cookieless domain

Ideally images should be hosted under a cookieless domain. A cookie is a small piece of data sent from a website and stored in a user's web browser while the user is browsing that website.

Cookies are usually used to maintain session state, etc. Despite being relatively small, it is unnecessary for them to be sent with every image request as it needlessly slows down the user's experience.

This is particularly important for mobile users. For example, if your website is then you should consider or or some other variation as long as the domain does not set cookies.

Of course you need to make sure you own the domain. You may also need to register the domain with the various search engine site master tools.

Image filename

Images should have meaningful filenames. Using an ID, e.g. SKU, is simply not good enough and does nothing to inform search engines about the contents of the image.

Filenames, like the following, are common examples of what should be avoided:

  • 112354_main.jpg
  • Method-01-2011-med.jpg
  • e9b8fb52-6c02-11e0-b36e-00144feab49a.img

Images should have meaningful filenames without overly long paths, e.g.

Don't forget to include location information, if that is relevant too, e.g.

If a website is translated into multiple languages, then image filenames could be too. However, this can prove a challenge for some systems and will often require images to be duplicated, unless a dynamic imaging system is used. 

Ideally you want to be able to change the image filename, without having to re-upload the image. However, make sure that your image URLs cannot be tampered with by malicious people, e.g.

Make sure short-black-dress cannot be replaced and the image is still served correctly


Google has extended its Sitemap capabilities to include support for images. You are now able to provide a caption, title, geo location and license for each image.

It makes sense to use this new capability although Google does not guarantee that it will include your images. It is important to make sure that you are not including thumbnail images and main product images.

Include your main product images rather than thumbnails.


Google uses a special crawler to crawl the web for images. To prevent Googlebot-image from indexing small images (e.g. search result thumbnail images), as opposed to the large images you want them to index, you could sniff the UserAgent string and serve it the large image URL.

That way Google won't accidentally include any small images that are less valuable.

Site speed

In April 2010, Google announced that it was adding site speed as a signal in their search ranking algorithms. Amazon has released research showing that every 100 ms increase in page load time decreased sales by 1%. These are both compelling reasons to improve site speed.

As images typically represent the vast majority of page weight they can have a significant impact on site speed.

This example has been taken from an online shoe store and it's by no means the worst case!

pie charts

There are several techniques to mitigate this:

  • File size reduction, i.e. compression.
  • Intelligent caching.
  • Delivery acceleration.

It is not good enough to implement one or two of these techniques. All should be implemented!


Websites with international customers are often providing a poor user experience because they are not optimised to cope with the distance.

The distance problem comes down to latency:

  • 40 to 80 ms from Europe to UK.
  • 80 to 180 ms from USA to UK.
  • 250 to 300 ms from Japan to UK.
  • 300 to 350 ms from Australia to UK.
  • 500 to 600 ms from China to UK.

As stated above, Amazon research shows that every 100 ms increase in page load time decreases sales by 1%.

We tested the loading time of a designer shoe website from London and Sao Paulo. It took eight seconds for the site to load from London and just over 20 seconds from Sao Paulo. The situation is even worse with China.

With appropriate delivery acceleration (edge caching) in place it should not have taken much longer.

If you have any doubt, as to the purchasing power of these countries, see the table below. At its current growth rate, India would easily have more High Net Worth Individuals than the UK by 2018.

net worth table

Endless aisle

Prior to the internet, retailers were restricted by the location and floor space of their shops. This not only restricted who they could sell to, but which products they could sell.

With the advent of the internet, these physical restrictions have largely been removed. Retailers may stock the top products in their stores, but are able to offer the long tail of products online.

Retailers are also able to offer categories of products that are complimentary to their brand that they wouldn't ordinarily sell in their physical stores, or wish to stock in their warehouses.

Increasingly people are using search engines to find products rather than visiting sites directly.

Long tail products increase your content and the likelihood that people using search engines will find your site.

Discontinued products

Products (and their images) that have been discontinued should not be removed from websites as there will likely be residual links and hence traffic to them.

Visitors should be shown the discontinued product and offered one or more of the following:

  • The replacement product.
  • Products from the same category.
  • Products from the same brand.


Using a Dynamic Imaging solution you are able to optimise images (dimensions and/or file size) for different device models, e.g. PCs, smartphones, tablets, kiosks, ePoS, smart TVs, etc.

For example you may serve a picture at 85% quality (read compression) for a PC, but serve it at 60% quality for smartphones. Whilst 60% may be unacceptable on a PC, smartphones user will not notice and will appreciate the quicker download.

Search engines such as Google are now crawling websites with different mobile user agents to see if they find different content or mobile optimised content.

Social media


The Facebook Like button is incredibly powerful. See below for an example of how it can be added

jewellery product page

In this example the social media buttons only appear when the user hovers their mouse over the thumbnail in the search results.

When a user clicks a Facebook Like button, Facebook downloads a copy of the image. The following graph shows for August the % of image Bot requests that Facebook accounts for with a website that uses Facebook Like buttons with their product images.

As you can see it is a very high percentage!

bot requests chart


Pinterest is a virtual pinboard which allows users to organize and share things they find on the web. Users can browse pinboards created by other people to discover new things and get inspiration from people who share their interests.

Pinterest's Pin It Button can be easily added to your website.


As with Facebook and Pinterest you can add a Twitter button so users can tweet about the products they like.

earrings product page

Google SERP images

Google increasingly displays images in its search results. For example:

serp evening earring

When users click on an image Google displays a page such as the following:

google image

The user's web browser makes a request for the original image with Google set as the referrer.

The following graph shows the number of image requests where Google is the referrer.

google image requests chart

Over 1% of the image requests on a daily basis are now referrals from Google and this percentage is increasing!

This highlights the importance of images as part of an SEO strategy.

Richard Yeo

Published 24 September, 2013 by Richard Yeo

Richard Yeo is CEO at Elasticera and a contributor to Econsultancy. 

1 more post from this author

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Comments (14)

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Robin Spira

As one of the earliest adopters of Elasticera at Chemist Direct I can concur with everything Richard states in the above article. It took only a few hours of dev time to integrate Elasticera and we saw an immediate improvement of our page speed over our previous CDN. We were then able to experiment with different levels of jpeg compression really easily by just changing the compression attribute on the call to Elasticera. By doing this we were able to reduce the file sizes by up to 30% while retaining the required level of quality – with no effort on our side - literally just changing a value in the method that calls the images. Elasticera has made image processing and serving for us a snip. Keep up the good work!!

almost 5 years ago



Terrific post. Thanks for your various example.

almost 5 years ago



Thanks for the info and numbers. Good summary of SEO for images.

Would be great to see 1y trend and seasonality on Google/Facebook referrals and referral numbers before/after making these changes.

almost 5 years ago


Ben Cole

We use elasticera on 2 of our websites as a cdn and it has without a doubt improved the speed of our page load. The installation was very simply as most of the needed technical code was provided for us in the example.
The seo benefits are also very clear to us, if i search for a generic term related to our products on google images a few of our product images show on the first page.
The ability to change the image quality simply by changing the param in the url request is also very useful

almost 5 years ago

Andreas Pouros

Andreas Pouros, Co-founder & COO at Greenlight

I'm in 100% agreement with the other comments here. We've recommended Elasticera for some time now and when you stack it up against the current market leaders it is incredibly compelling, and not just for SEO. I think images are one of those areas that are often overlooked when people launch new websites - they assume that there's not much you can really do to optimise them when in fact there is a huge difference to be had when done properly!

almost 5 years ago

Richard Yeo

Richard Yeo, CEO at Elasticera

Hi Roger

When I get some more time I will write another guest blog post covering the questions you raise.


almost 5 years ago

Lenka Istvanova

Lenka Istvanova, Consultant at Seven League

Hi Richard,

Nice post! Images are truly important for any website as the visual content is what counts on Social Media. Businesses should therefore pay attention to effective image optimisation as well as how they can use these images off-site.

I've recently written a blog post on how to increase traffic with the help of images which features also off site ideas. I've also included a Google Analytics advanced segment that will help you find out the traffic your website is getting through Google Image search results

Would love to hear your thoughts on this

almost 5 years ago


Trevor Voss

Very Good article. Images and the way we process images is incredibly important these days as we have to cater for so many different devices and resolutions. Elasticera easily enables the ability for responsive as well as compression to devices and enables considerable savings in studio time.

almost 5 years ago


Michael Bian

I have'nt thought about this before .. Thanks for this post, good point!

almost 5 years ago



I agree with using the alternative name attributes on images as an optimization method. Though i can't see the point on optimizing for google image search. What is the conversion rate of people who searched explicitly for an image?
Focus on your customers, not google. I found a nice page analyzer tool at - it picks apart your content and focuses on logical and understandable site structure.

almost 5 years ago


Richard Yeo

Hi Tim

We are not suggesting optimising purely for Google Image Search.

In the graph titled "Image requests where Google is the referrer" about 98%+ of the traffic is from normal Google Search Results Pages.

Google is increasingly displaying images in normal search results pages.


almost 5 years ago


Ajay Prasad, Manager at Amco solutions

This article provides a lot of great information, especially the technical stuff in image marketing. Image is very important in display marketing. Images are now very important as evidence by the popularity of image social media like Pinterest, Twitter and Facebook. I will be implementing this on my blog

over 4 years ago


Chetan Patel, CEO at iCan Web

Hello i have problem with Google image search its index my thumbnail instead of full size image. I used wordpress and also use Images sitemap and submitted to Google. You say to Sniff the Useragent string to force to index large image. Explain me more detail about this. I will trying for this problem. My site

about 4 years ago


Clemency Wright, Director at Clemency Wright Consulting

Hi Rich. Thanks for pulling all this helpful info and the stats together. Image optimisation is core to our business. Have you done any research/written any posts on image metadata such as IPTC fields (eg image caption, keywords) embedded into the image or associated with the jpeg uploaded directly to a website? This is something we seek clarification on, as an additional optimiser for long tail image names. If we could know how major search engines index metadata in this way then we could further improve SEO alongside our current on-site SEO services.

Thanks for your helpful input

Clemency Wright

over 2 years ago

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