Board Thread:The Reference Desk/@comment-165.228.133.90-20130213061834/@comment-188432-20130216165621

At the risk of belabouring the minor point, I dunno that you can "tell straight away". There's not much visual difference between a greyscale scan of a page directly from a colour magazine and a scan of a black-and-white copy — especially when the page in question bears handwriting in black ink.

Since the colour information wasn't important, a greyscale scan of the original would have been logical, because of the consequent reduction in filesize.