you can set some sizes for thumbnails in WordPress - yes. But what if there are some sizes which are not set within WordPress Media settings, but through a plugin? For example I am using a function that automatically generates a new image depending on the set sizes. Example: A picture shall be shown in 627x489px - when loading the page the function recognizes the need for an image with 627x489 and generates this file "on the fly" (example: testfile_627x489.jpg).
Is it possible that such images (also stored in the images-folder together with all the standard-size-pictures) are also regenerated with Smush-it?