Edit (delete) this string:

Windows Registry Editor Version 5.00
*
[HKEY_CLASSES_ROOT\SystemFileAssociations\image\ShellEx\ContextMenuHandlers\ShellImagePreview]
@="{e84fda7c-1d6a-45f6-b725-cb260c236066}"
*
This it the actual entry, so if you want to put it back, just save the section above that is between the asterisks to a whatevername.reg file(I used notepad) then right click it and select merge.