Another fantastic plugin that I’ve been using lately is “Regenerate Thumbnails” from Viper007Bond. This is very handy when working in theme development. If you add or change image sizes in functions.php like in this post, that image size won’t take effect with existing images. Unless of course you use this plugin and say “WordPress, regenerate mah thumbnails right now!”
Located under Dashboard -> Tools you’ll see Regen. Thumbnails. Click it. Now you can regenerate ALL of your thumbnails at the same time. If you just have one or two you would like to regenerate, go to Dashboard -> Media -> Library and check out your images. When you hover over, you can see that you now have an option called “Regenerate Thumbnails.” This single image option will only regenerate the thumbnails for, well, a single image.
It’s that easy. I thank Viper007Bond for creating such a useful development plugin. If I ever meet him I will owe him a handshake and a drink. Go test it out for yourself. It’s free so you’ve got nothing to lose.