Actually, It is better to use underscores in the file names. Google parses those and will break out each word as a separate keyword. If you use hyphens Google treats it as one big word instead of separate keywords.
Great article though! Thanks!
After receiving a couple of emails regarding SEO (Search Engine Optimization) in relation to images, I thought I would take some time to list out 6 steps you can use to help your images rank higher in image search (such as Google Images, Bing Images, etc.). As an added bonus, these steps will also aid in helping your pages rank higher in normal Web search! This isn’t some rehash of the same run-of-the-mill advice you get on images (or so I hope, at least 
), so, without further ado, here are 6 steps to image-ranking success:
Image Name
This is about as simple as it gets, but it really needs to be mentioned. Please, please, please do not name your images in a non-descriptive manner (e.g. q43fj8qs.jpg)! Likewise, don’t leave your images named as they are when you offload them from your camera, mobile phone, etc. (e.g. IMG01148.JPG, DCIM0001.JPG, et al). You want to name your image something that describes the image within a keyword term or two. For example, if you have a picture with your cat in it, name the image something like “cat.jpg” or — even better — “black-cat.jpg” if it’s a black cat. Better still might be something like “black-cat-running.jpg” or similar. Don’t worry about getting super-descriptive with the image name; just shoot for an overall topic that covers the image. I’ll show you how to go into more specific detail about an image in an upcoming step.
To note, while it’s debatable as to if you should use an underscore (_), a hyphen (-), a period (.), a space ( ), or some other character to separate multi-word-named images (e.g. my-image-name.jpg vs. my_image_name.jpg vs. my.image.name.jpg, etc.), I, personally, like to use hyphens. The reason for that is because I like the way the image name looks in the URL. With that said, the method I see Google using throughout their Web empire is underscores (e.g. hot_tamales.jpg)! Whatever you choose, rest assured that it’s not a huge deal how you separate your words. Don’t use a space, though, because that space gets formatted with a %20 (the HTML code equivalent for a space) in the URL which tends to add additional fluff between words and make a URL look quite nasty.
Image Metadata
Photographers are undoubtedly familiar with the metadata that is added to images taken with any decent camera: Model number, time, date, bit depth, dimensions, et al. But that’s not all that can be added to a photograph. If you’re not a photographer, then you may not be familiar with this, but there’s a whole section that allows you to add information about an image: Title, description, comments, author, et al. Basically, if you right-click on an image and view its properties, there’s a “Details” tab (in Windows, that is — I’m not sure about Mac or Linux) where you can add some additional information to an image. If you can’t see that information, save your image as a JPG instead of whatever format it’s currently in and then try.
It has been a widely-debated topic for quite a while as to if Google pays attention to image metadata, but I’m under the impression that they do. To what extent, though, is unclear. And if they don’t yet, then the time is near when they will. For one, Google’s new WebP image format contains a specific container which preserves metadata. From the WebP help page (bold emphasis added by me):
This section provides information on the RIFF container for WebP users who want to be able to save and parse WebP metadata.
Lastly, for Google to find metadata in an image is simple. As you may or may not know, Google places more emphasis on information located at the top of a Web page. Luckily, an image’s metadata is stored at the *top* of it! If you would like to verify this for yourself, simply right-click on an image you’ve stored metadata in, select “Open with…” and then choose Notepad. As you can see in the image below, the metadata you see in the properties window of the image is exactly what shows up at the top of the image when opened in Notepad (albeit in a different order):
To be clear, adding metadata isn’t about cheating the search engines; it’s about making it easier for them to learn what your image is about (they want to know!). Just don’t be spammy and unnecessarily list keywords. Be smart about it and be fair.
Title and Alt Text
Remember in the “image name” section above when I said I would go more in-depth into ways to add more specific information to your images? Well, in addition to the previousy-discussed image metadata, now it’s time to discuss that. The format is simple; you just need to figure out what you want to populate the fields with. For all of your images, you should link to them either one of two ways:
Display an Image Without Linking It: <img src=”http://www.yoursitegoeshereinthisspot.com/keyword-named-directory/keyword-in-image-name.jpg” title=”Keyword or Keyword-Rich Description Here” alt=”Keyword Here”>
Display an Image While Linking It: <a href=”http://www.yoursitegoeshereinthisspot.com/keyword-named-directory/keyword-in-image-name.jpg” title=”Keyword or Keyword-Rich Description Here”><img src=”http://www.yoursitegoeshereinthisspot.com/keyword-named-directory/keyword-in-image-name.jpg” title=”Keyword or Keyword-Rich Description Here” alt=”Keyword Here”></a>
The former is good for if you want to load a full-sized image within a page while the latter is good for if you want someone to click on a thumbnail to see the full-sized image or to be taken to an outbound link after clicking on an image of any size. Whichever you choose, use the title=”" section to either place your keyword or a keyword-rich description of the image. If you rest your mouse on top of an image with title=”" text, you will see it pop up in a little window:
The alt=”" text is what loads in place of your image instead of a red ‘x’ if the link is broken or if it doesn’t load immediately. Even if a person never sees that text, spiders (the things that crawl the Web for search engines) will, so make sure you put them to good use!
For all that I've kept up with in regards to recent data, Google treats them about the same (with preference seemingly going towards hyphens and not underscores). If you've seen more personal success using underscores, though, then that's awesome!
