This function is now available on the Gothic Ivories web site.
To do so, you need to:

• Select the images you want to compare and save them into a Folder. You add items to the Folder by clicking the Add to Folder button in the Features toolbar. If you are in a list page (such as the Results Page), do not forget to make a selection (or many selections) first by checking the box to the right of the row in which the thumbnail image appears.
  Important: You will need to click on the Add to Folder on each Results page where you have made a selection button before going on to the next page, otherwise your previous selection will be lost.

• Open the Folder and check the boxes corresponding to the images you want to compare. A new window opens, allowing you to zoom in individually on each image (see image to the right).

Please note that you cannot compare more than four images at a time.

This function is also available within a Set, which is a more permanent version of a Folder. For more information on sets, see see here.