We’ve all heard the expression “blind as a bat” — but bats aren’t blind, they just “see” differently from us. Bats supplement their small eyes and poor visual acuity with echolocation, a radar-like quality that enables them to ping their environment, gather data and use this information to locate prey, fly in the dark, and so forth.
Google’s Web crawlers are popularly known as “spiders,” but they might be more accurately described as bats — particularly when it comes to Google Image Search’s attempts to identify and sort photographs in search results.
Web crawlers are visually impaired when it comes to determining the content of online photos; they can’t “look” at the images they come upon. Instead, like bats, they rely heavily on “pinging the environment” to ascertain the content, relevance and relative importance of the photos they encounter.
That means Google’s bats — I mean, spiders — require you to create an environment around your images that enables them to be “seen.”
Here are eight ways to accomplish this:
1. Give your image file a descriptive name. Image456.jpg doesn’t help Google figure out what your photograph is about. But big-red-car-in-london.jpg does.
2. Create a meaningful image path. The path /photos/cars/ford/mustang/big-red-car-in-london.jpg is much better than the generic /image/big-red-car-in-london.jpg.
3. Fill in your alt tags. The alt tag is where you can insert alternative text to display in place of an image, such as for text-only or audio-based browsing. Tagging your image “alt=big red car in London” is a whole lot better than leaving the alt tag blank, which is what many people do. Just don’t overload your tags with keywords; Google might consider that “keyword spamming,” which would hurt your search positioning.
4. Add a descriptive caption and place the photo amid relevant body copy, headlines, etc. Google looks at your image caption and other nearby content to determine what the image is about. So always caption your photos.
5. Don’t forget your header information. Your Web page title and meta description, located in the header of your site’s source code, can provide further clues about your image’s content.
6. Publish the image as a JPEG. My research shows that Google ranks .jpg images highest — and, in fact, almost completely ignores PNG and GIF images. (A good way to take advantage of this is to give photos you do not want spidered a generic name and a .png file type. This will focus Google’s spiders on the images you want to be noticed.)
7. Go larger rather than smaller. A quick look at Google Image Search results shows that Google rewards larger images with better search visibility.
8. Host the image on your own site. I have no hard evidence of this, but I believe that photos hosted on your own domain are given greater weight than those hosted elsewhere — such as on a hosted storage domain. Photo sharing sites like Flickr seem to provide the least search engine juice.
Of course, while it’s important to help Google “see” your images, you should never forget that your site, first and foremost, is for human eyeballs. Make sure your image optimization doesn’t detract from your visitors’ experience.