The following is part of a multiple part series covering image optimization techniques. This article is intended for beginners through intermediate SEO's; if this doesn't pertain to you, you may want to skim as most of this will probably be review material for you.
Some of the big questions many people ask are why would they even want to perform image optimization? Doesn't it just help people who want to steal or hotlink images? And is there really any meaningful traffic or links that you can get from image optimization? IMHO the answer is yes. Let's say someone is going on a trip to Italy. They might do image searches for things to do or see in Italy and for famous Italian landmarks like the Leaning Tower of Piza, the Trevi Fountain, or St. Peter's Basilica. Thanks to Google's universal search results, images provide a way to get onto the first page (or, in some cases, the top result) and get a click through, an ad view, or adsense impression. It might even get a lead generation completion. Maybe you run a fish store. If a university professor or government agency needs a picture of a fish and your image result appears, and you allow your images to be reused in exchange for a link, this can be huge way to passively build links slowly over time (true story! It happened for a client I used to have). Now that we've got the why out of the way, let's talk about the "how" of image optimization.
This is one of the most basic elements of image optimization. If you have an image of blue widgets, I would name your image "blue-widgets.jpg" or "blue-widgets.gif". You can use other formats like PNG, but I have gotten better results with "jpg" and "gif" files. You can use other characters like underscore as word delimiters, but I get better results with hyphens. You can run the words together if they are separate in other factors. I have found stemming plays a role (ie widget vs widgets), but you can get around it using other factors. I haven't seen capitalization play a role, but I prefer to use all lower case because I usually use Apache servers and case sensitivity matters. If you are going to have multiple images of the same object-type, I suggest adding a "-1″, "-2″ onto the end.
Now, before the hate mail or hate tweets start, it is entirely possible to have an image rank without the keywords being in the file name–IF there are enough other factors in place. However, you should ask yourself why would you give up a chance to give a search engine a signal about what an image is about? If you work on a large ecommerce platform or other large database application, chances are good that your gold diamond earrings will have an image file name like "GDX347294.jpg" that corresponds to the item's SKU or other internal classifier. So, yes, you will have to sacrifice the keyword for business reasons.
Let's get the basic information out of the way: ALT text was designed for screen readers or visually-impaired people to know what they weren't seeing. Your goal is to use it to satisfy the screen readers while being keyword focused enough for the search engines and without being a keyword stuffing spammer. Here's an example of ALT text variations:
Keyword stuffed: discount hotel room paris france
ALT text only: Eiffel Tower
SEO optimized: Eiffel Tower from Louvre Bons Enfants hotel room
Striving to find a balance between pleasing the search engines and text readers can be a juggling act. If you are risky with some of your other SEO techniques, I'd play this on the safe side.
Headings and Bold Text
If image optimization for a particular image is important, I really like to optimize the image with bold or a heading tag of the term I'm chasing right above the image. I've found this really helps give a strong signal to the engines
Image captions like the one to the right are another way I really like to give the search engines a good nudge in the direction I want them to go. Try to place the search term you are trying to optimize for at the front of the caption.
I've found that if you keep your images a reasonable size you generally do better with image optimization. That's not to say really big or really small images won't rank, just that images that are larger than 100×100 and smaller than 1200×1200 work best. Using a thumbnail that links to a larger picture can be helpful.
So what can you expect from image traffic? Like all things, it depends on what you are chasing, but I have one image that ranks on the first page for a single word term that brings in hundreds of views for me every month. The page has adsense on it and, over a single year, it brings in several hundred dollars worth of revenue. It's something to think about before you write off image optimization.
So what are the takeaways from this post:
- Try to name your images with your keywords if possible, using the hyphen as a delimiter.
- Shorter names are better than longer. Avoid using more than 4 words if possible.
- Keep your ALT text keyword focused without being stuffed or spammy.
- If possible use headings or bold tags above or directly next to the image.
- Use captions if at all possible and keep the keywords closer to the front of the caption.
- Keep the images a reasonable size. They should be large enough for people to see but small enough to fit on a screen.
- If you own the image, encourage people to reuse your image in exchange for a link.
- Try to find a way to monetize image traffic with CPM advertising, adsense, or affiliate links.
Originally published at Graywolf's SEO Blog