Optimizing for Google Image Search 
Firstly, What is Google Image Search?
Most of you are probably quite familiar with the Google Image search feature, and use it often. For others, this is simply a modified version of the Google Search that allows a user to search for relevant images instead of web pages.
Go here to have a test run:
Google Image Search What's the Point?
There are quite a few reasons to optimize your site for the Google Image Search. Firstly Google Images can bring your site "alot" of visitors, especially if your images rank page 1 and they are heavily searched, such as say the term "Paris Hilton". I've known of some sites to receive more traffic from the Google Image search then from the regular search.
The other good reason to optimize for Google Images, is to help define your overall page theme. This can assist in ranking higher in the regular search, display more relevant Adsense ads etc. and further to that, it complies with W3C web design standards.
The W3C states "Alt" text should be used on images to assist visually impaired users who run screen readers to browse your website. Now while the chance of a blind person browsing your website may be remote, poor old Googlebot is basically "blind". He can't sit back and see your site through the monitor like a regular user, he has to "feel out" what's what much like somebody visually impared reads braile.
When optimizing our sites for Google Image Search or doing
Search Engine Optimization in general, it's our job to arrange things in an easily interpret manner with all the important stuff more noticeable then the rest.
What's the Google Image Bot?
This is the bot that crawls the web, indexing images just like the regular Googlebot indexes pages and keywords for the normal search index. Yes the two are different bots, however the Google Image bot is very slow and doesn't visit a site with anywhere near the frequency as a regular Google search bot.
It may take Google Image Bot a full year to even drop by your site... YES that correct, a full year to appear in Google Images. So optimizing for Google Images is a long, slow process to see any results.
Not to worry though, the best thing we can do as webmasters is optimize now then just sit back and wait. Then we can rest assured that when the Google Images bot does eventually come, everything is in place and we stand the highest possible chance to rank high in Google Images.
When you start seeing
images.google.com in your server logs, you know the time has come.
OK, So how do i optimize images?
Because Google can't actually "see" images like we can (yet), it relies on a number of factors to help determine what an image is all about.
These are:
- Alt Text
- File Name
- Surrounding Text
- Page Title
- Page Theme
- Links
From my testing on past websites, the Alt Text followed by the File Name appear to be the biggest factors in determining what an image is about.
Alt Text
This is the text that displays when you "hover" or "mouseover" an image. To include Alt Text in your image code, you simply use:
Quote:
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<img src="filename.gif" alt="Alternative description goes here">
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Try to be descriptive with your Alt Text, however don't over do it. The best thing to put here is what you personally would search for if you were looking for that image. Also try not to include too many "junk" words like, the, and, or, we, are, for, etc. For example use "Apple iPhone Covers" instead of "All the Apple iPhone Covers i have got".
The first example is short, descriptive and is what somebody would actually type in if they were looking for pictures of Covers for the Apple iPhone.
File Name
Always do the same thing with your image File Names. Instead of calling them
pic1234.jpg rename it to something more descriptive such as
apple-iphone-covers.jpg
Try to keep the File Name either the same, or very similar to the Alt Text. Don't try and rank the same image for multiple terms by jamming different keywords in to the Alt and File Names as this will only serve to confuse Googlebot in determining what your image is about.
Also try and keep the path to your image themed, for instance:
domain.com/images/phones/apple-iphone-covers.jpg
Is much better then just throwing it in:
domain.com/mystuff/miscpics/apple-iphone-covers.jpg Surrounding Text
Always try and place a paragraph of descriptive text directly above and below your image, with the keyphrase from your Alt Text and Image Name included in this text.
Page Title
If possible try and include your keywords in your Page Title, and Page Meta Description. This helps Google define a theme for the page which will not only help ranking in Image Searches, but also in the Regular Index as well as display more relevant Adsense Ads if you run them.
Page Theme
Same with this one, it's always a good idea to keep each page within it's own set theme. For instance, try not to mix images and text on Cell Service Providers with content about your Apple Iphone Covers.
Create a dedicated page for each topic, then optimize each page seperately. Once you have done this,
place Adsense on the page and monitor the Ads with each page load.
Even if you don't want to run ads on the page, this is an excellent tip for being able to visually see what Google believes your page as all about.
If you are seeing Ads for the Apple iPhone, and accessories such as Covers... Success. If not, take not of what Ads are displaying then ammend the piece of content casuing the non-themed Ads and reword it until you have Ads relevant to your content and what you want to rank for.
Links
Ok just like getting your pages to rank higher using backlinks, you can do the same for images. If you use a text link with anchor text on your site, use the keyphrase you want to rank for as the anchor.
So instead of having, "
Click here to view picture" or "
Full Size" use "
Picture of Apple iPhone Covers". As you can see, this tells Googlebot it's a link to a Picture of Apple iPhone Covers.
Also the actual page URL should be descriptive and contain your keywords. So again just like the images File Name, our Page Name should be structured instead of
domain.com/page76.html
Change it to:
domain.com/apple-iphone-covers.html
This can be done using .htaccess and Mod Rewrite. If you are unsure, see our Guide on .htaccess for rewriting your URL's.
Duplicate Content Ok i've never heard anyone talk about duplicate content with images before, and i doubt many SEO's are even aware of this portion of the Algo. Google is dedicated to providing unique content with images just like it does with Web Pages.
When you do a Google Image Search, you will very rarely see duplicate images, ie same file name, same dimensions and same file size. This is how the Google Image algo detects duplicate content with images, as we know the Google Image Bot can't "look" at an images and determine it's content so in order to detect duplicates it relies primarily on the following:
- Image File Size ie Bytes, Kilobytes, Megabytes etc
- Images Dimensions ie 400 x 500 pixels
- Image File Type ie JPG, GIF, BMP etc
- Image File Name ie apple-iphone.jpg
Google's algo is always improving, they are continually improving on it and can even recognize faces however i have found these 4 image characteristics listed above are the primary method of duplicate detection.
So, if your picture is obtained from another site (just like copying text from a web page) you need to make it unique by changing the dimensions, file size, file name or file type.
Now i'm not advocating taking peoples images, there are many legitimate instances where a single image is published on multiple websites. Take for instance a Wallpaper Website where i know many webmasters legitimately purchase "Wallpaper Packs" that are often on 100's of other sites. This could be devestating for a webmaster who's primary source of traffic is intended to be Google Image Search.
You can see what i mean by a search for a
Salvador Dali painting, the third line down there's 3 duplicate images but they are listed due to different file name and file size so Google see's them as unique. If they wern't different like this it's highly unlikely all 3 would be listed.
So if you are legitimately using images that are also published on other websites, altering the Dimensions will also alter the File Size and provide your image with enough "uniqueness" to rank on Google Image Search. You can also take it a step further and alter the File Type and File Name.
I've never heard anyone talk about duplicate image search content before, so there you have it.
Conclusion
As you can see there are a number of things we can do to start ranking for the Google Image Search, and these things can actually assist in higher rankings for the regular search too.
A few things to note, it's not the best idea to optimize all images for Google Image Search such as your Template and Navigation elements, general page backgrounds etc.
For these don't use Alt Text, make their File Names obscure like "bg1.jpg" and also place them in their own folder and block it with Robots.txt
You can either block the whole folder from all bots by using:
Quote:
User-agent: *
Disallow: /Images
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Or just block the Google Image Bot by using:
Quote:
User-agent: Googlebot-Image
Disallow: /Images
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Well hopefully this bit of info helped you out in optimizing your images to appear in Google Image Search. There doesn't appear to be much information around about this, and alot of people asking "How do i" so hopefully this has filled the gap.
Edit December 17th 2007
Here is a video of Matt Cutts, the head of Google's Webspam team discussing the Alt attribute in images.
Optimizing for Google Image Search 
Linear Mode
