One aspect of search that doesn’t get discussed often enough is image search. It’s such a huge part of search and the daily habits of web surfers all over the world, it’s amazing how little attention is actually paid to it when it comes to marketing and optimization. Have tips for optimizing for image search? Share them here.

Some Image Search Stats to Chew On

Google Director of Product Management R.J. Pittman dropped some facts at SES. 300 million digital photos are taken every day. 100 billion images are taken per year. There were half a trillion images in circulation by 2009. That’s the past up to the present. Do you think it’s going to slow down? Pittman says there were 800 million camera phones sold last year, and there may be more images online than web pages.

On Google there are hundreds of millions of image searches every day. Eric Enge, President of Stone Temple Consulting says that image search makes up about 5.7% of all Google searches. "We estimate that up to 15% of all search is image related," he says.

Why Image Search is So Important

If the above information wasn’t enough to convince you of the importance of image search, consider this. When images appear in blended search results (such as Google’s universal search), the images affect what is clicked on the results page. Enge says an eye tracking study proved this, but it makes perfect sense if you think about it. The image is obviously going to catch your eye, regardless if it’s the top result or the 5th.

Todd Schwartz, Group Product Manager for Bing says that engagement is quite high when it comes to image search. Consumers looking for images also end up visiting a lot of web pages. In many cases, images can simply speed up the decision process on the consumer’s part. You can see why this would be effective in eCommerce. "When users are expecting images in a search session it actually increases the speed of a searchers task," says Schwartz. "Images simply speed decision making." He would know. Bing <i>is</i> the "decision engine."

Tips for ranking in Image Search

In a post about ranking in "five other Google engines," I cited some tips from Search Engine Journal’s Dev Basu, who recommended the following for image SEO:

- Add images to your Google Local Business profile
- Enable Google Image Labeler in your Google Webmaster Tools account.
- Add images to local business citation sources.
- Add images to blog posts or news articles for syndication in Google news.

Here is some additional info from Google:

Schwartz says for Bing, you should name the images properly and upload product categories for eCommerce images.

Enge suggested some even more basic tried and true SEO tactics that should still be applied. Include alt attributes in <img source> tags. Name files appropriately, and consider the nearby text, overall page context, links, title tags, etc. This stuff is all good, but you should know that the way search engines are handling images is evolving.

How the Search Engines Handle Images

Pittman says it’s no longer just about looking at tags and stuff, at least at Google. "We now use computer vision and search to find similar images, object recognition, and facial recognition," he says. "We look at everything such as exposure data to help determine the quality of an image. If your image quality is low your photos will not rank as high. If you make only a thumbnail of an image it won’t rank as well as a larger image of the same subject." (Emphasis added.)

Back in June, Google released a fascinating research paper that looked at building a web-scale landmark-recognition engine. The goal is to get computers to recognize landmarks (for example, the Eiffel Tower, the Lincoln Memorial, or the example Google shares – the Acropolis). This is no easy task when the engine has to rely on images of the landmarks, which are incredibly varied by angle, lighting, photo quality, etc.

This was just a research paper, and not a Google product, but one can only imagine where this research will lead with regards to how Google handles image searches.

The image filters that search engines use are worth paying attention to. If you’re trying to sell products especially, it could help to consider where you want your images to rank. Google lets users search images by size, type (face, photo, clip art, line drawing), and color (full color, black and white, specific color).

Bing lets users browse results by size, layout, color, style, and people. That is in addition to the query-specific options you get.

As far as regular web searches, Bing and Google both present a number of options for users to refine their searches. Bing of course has the explore window, which for many queries, provides multiple categories. Google has its search options. Images are included in that.

Just like with any content, there is always concern that stolen material will rank higher than the original source. Pitman was asked about this at SES with regards to images. He said that image search ranking is largely dependant on how often that image is clicked on for the search query being done. He says Google is trying to combat "hotlink spam."

Social Media and Images

Social media accounts for a huge amount of the pictures on the web. Not only do you have sites like Flickr and Picasa, but there are so many people uploading so many photos to Facebook and MySpace, not to mention apps like TwitPic for Twitter.

Believe it or not, real-time search plays a vital role in image search, just as in regular search. People want up-to-the-minute information, and that often comes in the form of images. Some real-time search engines are expanding how they handle media like images and video.

Perhaps the more significant part of this equation is the reputation management factor. Real-time search helps in this regard, when you’re trying to protect your reputation, but good old-fashioned Google searches are vital too.

"Think about the pictures that your employees are putting up on social sites," says Liana Evans, Director of Social Media at Serengeti Communications. "Images can hurt your business reputation."

Social media has a direct relationship with search rankings too. Read up on that here .

Conclusion

There are a lot of things to consider when it comes to images on the web. A couple other things that we didn’t really touch on are SafeSearch filters and Creative Commons licensing. These are things you should explore further if you think they will affect you. There is plenty of info out there about both.

One other thing I’d like to mention is that Google’s Insights for Search analytical tool now includes image search data. This could be a very useful tool for anyone looking to improve their performance in image search.

As a searcher, how often do you use image search? How often do you click through? Tell us.