Just as an FYI when moving from sharePoint 2010 to SharePoint 2013. The images folder is now accessed via _layouts/15/images. SharePoint 2010 was just _layouts/images!

Since the move to SharePoint 2013 requires that every reference to the “Hive” be prefixed with 15, and 16 for SharePoint 2016 etc, I have moved all logos and references to images to reference the images in the Style Library of each Site collection so that they will not break with consequent upgrades.