Checklist for Image Search Optimization

October 8th, 2009

Dear Reader,

This issue of SEO MixTour is special. From now on, we will include a new section dedicated to SEO experiments performed by SEO MixTour analysts. Read on to familiarize yourself with our research.

Web CEO Editorial Team

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Checklist for Image Search Optimization

Nowadays, professional search engine optimizers give much greater attention to image search visibility. Image search optimization is especially interesting to website owners or publishers with a particularly visual product (for example, art galleries, clothes designers, or furniture manufacturers). What is more, everyone knows a picture is worth a thousand words.

There are a limited number of factors that influence image positioning. Print out the below check list and be sure you’ve done all you can to have your images well-optimized.

  • First of all, your image should be an inherent part of a page and share the same theme. I.e. the page’s title, headings, body text must tell visitors the same story that the image tells.
  • Create an Images folder on your server to save all your pictures there. Make sure search engine crawlers are allowed to index it.
  • Use descriptive keywords in your image files’ names. Separate words in the file names with a hyphen, not an underscore.
  • Provide a small description of an image in the alt attribute of the img tag, but do not fill the alt attribute with tons of keywords, even if they are relevant.
  • Think of also using a short image title with keywords in them.
  • Place the keyword-rich text in the body around the image that describes it.
  • If the image constitutes a link, its anchor text is quite powerful in terms of optimization for high image-search rankings.
  • On the other hand, if you have other pages of your site linking to the page with important images, create keyword-rich link anchor texts to such pages with images.
  • Use high resolution images, if available. Provide different resolutions of images.
  • Avoid putting a ‘click to see larger image’ link inside of a JavaScript link. Scripts may cause difficulties in the link indexing.
  • Check how your image looks in thumbnail size. Stronger contrast is needed to better discern an image, which might lead to more people clicking on and linking to the image.
  • Save photos as .JPG files, and other graphic image types as .GIF. Search engines tend to interpret a GIF image as a standard graphic image with 256 colors, while JPGs as photos with millions of colors.
  • Re-upload your pictures from time to time, since image freshness is a contextual clue for the search engines and might affect relevancy.
  • As promotional tactics, you may watermark your images with your site address — if they are linked to, people on other sites will learn about yours.

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Analysis of Backward Links Information Provided by Google, Google Caffeine, Yahoo! and Exalead

First, we’ve tried to find out which of the search engines gives more information on the number of pages linking to a site.

To make the test more interesting and representative, we’ve analyzed three groups of websites from the top 1,000,000 sites list ( assuming such groups will represent well 1) the most popular sites, 2) sites of medium popularity and 3) less popular sites.

So, our three groups each consisting of one thousand sites belong to: 1) 1-1,000 (top 1,000), 2) 500,000-501,000 (middle 1,000) and 3) 999,000 – 1,000,000 (last 1,000).
For each site in those groups, we have requested Google, Google Caffeine, Yahoo! and Exalead for a number of backward links.

To our surprise (as we bet on Yahoo! :), Exalead left others far behind having indexed the largest number of links, i.e. 76% (top 1,000), 63% (middle 1,000), and 56% (last 1,000).
In our eyes, Yahoo! lost its reputation as the most extensive indexing engine and came second with 21%, 23%, and 26% correspondingly.

Google and Google Caffeine show us the smallest numbers of backward links — from 1 to 5% in all cases.

What’s interesting: An additional analysis shows that Google’s index does include most pages that place links to the analyzed sites (as we know from Yahoo! and Exalead results), but Google didn’t report such pages as linking pages.

Which means, Google indexes many more links than it reports to us. Is this a big surprise to us? No. We understand very well why Google is hiding the backward link information from its users. And Exalead can — if not arm the reverse engineers with valuable info — but at least give us the signals we need to obtain to understand if our sites progress well.

Web CEO Metrics

Here we are sharing the generalized numbers from our HitLens Web Analytics service. It covers 300,000+ websites from all over the world.


Global Search Engines (%)

This chart gives the idea of the market share of each of the three major search engines. The situation of search engine referrers is predictable. Google with its 79% remains the leading referrer and strenghtens its position by improving search options. Yahoo does not make progress, and Bing keeps its position.


Visitor Referrers (%)

You can see how visitors are being referred to websites. September 2008 is remembered as a critical point of the world economic depression. Since that time we’ve been watching a constant decrease of paid advertising. Instead, search engines and bookmarking became more popular visitor referrers.

Experts comment on image search optimization

“The more control you have over the images on your site the better. You can brand them with your logo, url or trademark. It also allows you as the retailer to present the product in the best possible way that will convert with your own audience, not to mention allowing you to present the features in a different way than other competitors.”

Liana Evans
Search Marketing Gurus

One Response to “Checklist for Image Search Optimization”

[...] image should also be relevant to your keyword. Image optimization has been described in detail in one of our newsletters during the past [...]

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