Even though photo blankets don’t require super-high DPI to make a quality print, they are very large. Every manufacturer is different, but you’ll want something relatively high-res to make the image look as good as it can. Most smartphones pump out 12-megapixel images and they should be just fine in terms of resolution. Most advanced cameras offer more than that, so you should be fine there, too, as long as you don’t crop severely.  Don’t expect to pull down a photo from Facebook or another social media site and print it onto a huge blanket, though. If you don’t have a high-res image, we recommend sticking with the smaller sizes.