15'' is 2880×1800. Most NASA images are high resolution enough that they should be available. Related, but if you like the Mars HiRISE images I can highly reco

15'' is 2880×1800. Most NASA images are high resolution enough that they should be available. Related, but if you like the Mars HiRISE images I can highly recommend this book: http://aperture.org/shop/books/this-is-mars-books http://aperture.org/shop/books/this-is-mars-books It's nothing that you can't find elsewhere, but it's really something else to see them printed in large-format. They're absolutely phenomenal photographs. What got to me is the sheer variety in the Martian landscape. Really incredible.