The Image Manager Extended interface, like all standard 'Manager' plugins (Image Manager, File Manager, Media Manager etc.), consists of 2 sections, the Attributes section, and the File Browser section.
Attributes
This section is divided into 4 parts, each accessible by clicking on the named tab. The default tab display is of the Image section, which contains the fields that represent the main image attributes of the currently selected article image, or the image to be inserted into the article.
Image
Set the most common attributes for the image including URL, Description and Dimensions. See Inserting an image
Advanced
Set advanced attributes for the image. See Advanced Options
Rollover
Create rollover images. See Creating a Rollover image
Popup
Create "lightbox" style image popups. See Creating Popup Images
Responsive
Create device responsive images using the srcset attribute. See Responsive Tab
File Browser
The Image Manager Extended Browser has the same basic features as the core Image Manager, with a few additional features
The Create Thumbnail button 
opens the Thumbnail Editor for creating thumbnails of images.
The Edit Image button 
opens the Image Editorfor resizing, cropping, rotating and applying effects to images.