This is the currently selected image. You can change the image shown by clicking in the main duplicate files list, or on one of the group thumbnails below.
There is additional information about the image in the top right:
Image resolution (e.g. 1024x768)
Image format (e.g. JPG)
Orientation : The orientation symbol ()will be displayed if the picture is shown rotated according to it's Camera tags.
ZIP : The image is from a compressed (Zip) archive.
The Show tags checkbox will show or hide the image tag information pane.
These are the image tags (also know as Exif tags) associated with the currently selected image. The tags shown will vary depending on the source of the image, and may have been created by the camera, or image processing software.
This shows the images in the same group as the currently selected image, along with resolution and other information as in the main image.
You can hover the mouse pointer over the images to see the full filename and path, and clicking on an image will show it as the main image. You can also mark or unmark an image by clicking in the checkbox.
If there are more images in the group than thumbnail slots you can use the forward and back buttons to page through the thumbnails.