Providing the proper descriptive name for your images helps your SEO in the following way:
Images are another chance to get your keyword in a strategic position of the website! In many cases, the header of the page is an image and the leftmost corner shows the logo of the company. Having keywords in such strategic places can improve your page’s relevancy to searches being made. This is so easy to do and reap major rewards from, yet it gets ignored by most webmasters.
In many websites, the header of the page will be the same across all the pages so you will be naming the same image in each page. In such cases, the keyword you have used in one page may not suit the other page. This is a great chance to get more of your keywords in very easily without having to clutter up your text as much – particularly if your keywords are long-tail and awkward to get in.
You can save the image under multiple names and use the image on each page as it fits; in this case, the online user will see the same image but for the search engines, the keyword will keep changing with each page in a way that matches with the content of the page. If you have limited hosting space, however, you may not be able to follow this practice, and in that case should simply use a main keyword for your site, or even your brand/company name. This is something you’ll definitely need to explore thoroughly before going this route.
For large websites or those that have many images on each page, you are better advised to make sub-folders within the images folder. Once that has been done, categorize images according to the subject matter of each image. When you create subfolders, make sure that you use your keywords for folder names as well to find them easier later. If your keywords are made of more than one word (if they are key phrases instead of keywords) then you can use hyphens or underscores to separate words. Whatever you do, be consistent to avoid confusion later.
As we stated above – be consistent! Optimize your image names in a systematic way and stick to it. You should be able to handle your images with ease anytime you want to make any changes to your website. It seems like a chore to many because that don’t start on the right foot with a plan, but really, it is easy if you are consistent. Your SEO firm should be in synch with your web designer, with optimization suggestions passed on to the web design team to set up your website for the best possible search engine performance. Do it right from the start and you’ll be a winner to the end!