Toao.net

Sometimes, it’s not necessary to keep copies of full resolution images on your web server. But, when you solicit images from many sources, you may not be able to rely on users to size images to your specifications. Here’s a very simple plugin that removes the full resolution image and replaces it with an image resized to your preference.
The plugin makes no changes to your database and is written with just 17 lines of code.

Maximum Image Size

When extremely large images are uploaded to the Media Library, replace it with the Large size image, configured in Settings >> Media.

Milan Dinić

Matt Mullenweg

<a href="http://blog.milandinic.com/wordpress/plugins/cache-images/" rel="nofollow ugc">Plugin homepage</a> | <a href="http://blog.milandinic.com/" rel="nofollow ugc">Plugin author</a>
Cache Images is a plugin that gives users option to sideload images that are hosted on other domains to their own site. Sideloaded images are added to WordPress media library so you can use all tools related to images that you can use with images uploaded through WordPress. Image will be added as an attachment of first post where it is found, and every post where original URL is occurring will be updated with new URL. User can select from which domains to sideload images, including Blogger’s domains.
It uses AJAX so it means you can sideload large number of images even on slow servers. (AJAX functions are made by fork of code from plugin <a href="https://wordpress.org/extend/plugins/ajax-thumbnail-rebuild/" rel="ugc">AJAX Thumbnail Rebuild</a>)
This plugin is fully internationalized. You can find .pot file in languages folder where you should place your translation. Current translations are Serbian, Spanish, and Persian. Please send your translation by <a href="http://blog.milandinic.com/contact/" rel="nofollow ugc">contacting author</a> so that it can be included it in next releases.
Read more information about usage on <a href="http://blog.milandinic.com/wordpress/plugins/cache-images/" rel="nofollow ugc">author’s site</a>.

Cache Images

Goes through your posts and gives you the option to cache all hotlinked images from a domain locally in your upload folder

Maximum Image Size vs Cache Images