Since Firefox 4.0, when the user pastes an image from the clipboard on CKEditor it's automatically inserted as a data: URI, that means several things:
It allows other people to see the image (previously it inserted a link to a local file that only worked for that user). This is good.
But there are at least two drawbacks: The image data is inserted into the body, that means a huge increase in size and every reload of the page doesn't use a cached version of the image. Also, old versions of some browser that we should not name aren't able to understand data: url.
This plugin solves those problems: when such an image is pasted it's saved as a new file at the server and that url is used instead of the huge data:
Licensed under the terms of any of the following licenses at your choice: GPL, LGPL and MPL.
ImagePaste version 1.1:
Changes: The 1.1 version is compatible with CKEditor 4. I didn't realize that the 1.0 was compatible only with the CKEditor 3.x paste system.
1. Extract the contents of the file into the "plugins" folder of CKEditor.
2. In the CKEditor configuration file (config.js) add the following code:
config.extraPlugins = 'imagepaste';
3. Set an upload Url for images (just like you might have already done for uploads in the image dialog)
All the details and options are explained in the included install.html.
I improved the basic plugin including the detection of pasted images in Chrome as well as dropped files in most modern browsers, simple toolbar buttons to upload images and files with just one click, etc...
This version is not open source, so you must get a license to use it. You can test it to verify that your browser is correctly supported.