When a screenshot is taken, user can decide if image is big enough to be added as link and not as embed image. Another approach that may find users useful is resize the image, so for example with a resize property you can decide that if an image is big enough instead of adding it as a link, resize the image to given percentage/fixed width, and embed inside the document.
In this case we should decide if image is resized and nothing more, or if it is resized and add an option to open the full screen.