Google just sent out their first newsletter via the new Google News Publisher Center and in that newsletter, they announced publishers can now host images off their website domain and the image will still be crawled, indexed and potentially used in the Google News search results.
In the past, if your images were hosted off your website’s domain, it was very unlikely we’d crawl them for Google News.
We recently implemented an update to our image crawl algorithm, and are now able to crawl off-domain images. If it works better for your team to host your images on a different domain than your news website, you can now feel free to make that change!
Many publishers use CDNs (content delivery networks) or host images on third-party domain names, so this looks like a good change to their image crawl process and I expect a lot of the sources for the images to change in the upcoming days/weeks.