It should go without saying that your eCommerce website needs plenty of images in order to succeed. These images need to be big, vibrant, clear and depict the products from every angle. That’s how you convert visitors into customers. However, that’s not all it takes. You need to constantly remind yourself that until search engines see your eCommerce website, visitors never will. Search engines are essentially blind to the images you use, meaning you must describe them to Google, Bing and others.
The first thing you need to do is name all the important images on your eCommerce website. If you’re selling purses, for example, you’ve probably taken many pictures of each model. When you upload them to your computer, it’s easy to leave the files with whatever name they were given—usually it’s a random grouping of letters and numbers.
Search engines can’t make sense of that though. What they can make sense of is a simple, but effective, description like, “red-leather-Gucci-purse.jpg.” Provided this is the order you believe your customers would type those words in when searching for a red leather purse made by Gucci, this tag will help search engines direct traffic to your site. If you don’t know for sure, start spending some time with your analytics and finding out which phrases people are using.
Another way to link up descriptions with your images is by using alt tags. This is simply code you can add to a photo that makes it easier for search engines to identify what it is. In fact, it’s probably the best way to ensure that the picture for your product ends up in a Google image search. Entering in alt codes will be different depending on what you’re using to build your site, but the actual formula is as simple as “alt=’red leather Gucci purse’>” (where actual quotation marks are placed within the ones we used).
Don’t get lazy with alt tags either. Every important image on your website needs one. If you take three pictures of that purse, be sure each has a tag, but make each unique too. Add in words like “strap”, “logo”, “inside”, etc. depending on what’s appropriate to describe the photo.
Lastly, your eCommerce website absolutely must have images large enough that the customer can see all the important details. However, this doesn’t mean putting the biggest possible option on your site, as this will make load times torture. Instead, use a more manageable size and give visitors the option to click on it for a larger display in a pop-up window if they want.
There’s more to the images on a successful eCommerce site than just taking a great photo. You need to tell search engines how great they are too.
Source:
http://www.shopify.com/blog/7412852-10-must-know-image-optimization-tips