Image Sizes on Demand
·
Creates the new size of an image, if it is requested and does not already exist.
Image Sizes on Demand generates sizes of an image at the moment they are requested. It tries to generate the new size from the original image, if it exists. This means you don’t need to regnerate all your images if you add new iamge sizes.
Arbitrary section
This plugin is available for download for your site.