Resizing images to the actual size used in the editor?

Is there a way to resize images to the actual size they will be shown in the post? I have users that import a large image and then resize it in the visual editor. This is easy, since they can just drag the image until it is the size they want, without first opening an image editor, resizing the image, saving it, and uploading it as a separate attachment. Of course, this sometimes results in an image that is 100px wide in the post, but 1500px in reality.