Canon EOS-1D X Manual (en)

Viewing Images in the Main Window (Thumbnail Layout)
Images downloaded to your computer are displayed as a thumbnails list 
in the main window (thumbnail layout). You can double-click an image to 
open the preview window 
 and display the image at large size.
For information on icons displayed on the frame of a thumbnail, 
see “Image Frame Information in the Main Window and Edit 
Image Window” 
Main window
Rotate image
Check marks 
If you double-click on the movie file, the movie playback 
application specified with the computer’s OS settings will start up 
and play back the movie. Note that edited movies will not be 
played back.
When aspect ratio information is attached to the shot image, the 
image is displayed as a cropped image 
In the main window, in addition to this view (thumbnail layout), 
you can select multi-layout. Multi-layout allows you to check the 
image in detail 
You can change the size of the thumbnail images displayed in the main 
window and select the information displayed for thumbnails.
Select the [Thumbnails] menu 
 desired item.
The display changes to the selected item.
To display thumbnails with shooting information attached, select 
the [Tools] menu 
 [Settings for thumbnails with shooting info].
Changing the Thumbnail Display