Renamed my images for SEO

I've just improved my SEO (I hope) by spending a few hours renaming my images. They were uploaded when I didn't know what I was doing (still don't really) and had incomprehensible names involving the stock photo sites and their cumbersome numbering systems. While you can rename the image title and its url in WordPress, you can't rename the image jpeg/png name without a plugin. I like Media File Renamer which isn't one on offer from wordpress but which you can buy from the developer (apps.meow.fr) and pay $10 to upgrade to the pro version (3 site license) which automatically renames jpegs for you. Having uploaded it, I had to contact support to validate the activation key but they wer super quick i doing this. I also found a free plugin that lets you do something similar, manually, called Rename Media Files which you can download here. I hope the Google Bots spot the three extra places where each image showcases my keywords (image title, image url and image-jpeg name) and reward me so my visitor counts go up!