these images are set at 300 DPI  which is good for Printing.
since the height and width are so huge
if you try and add a pic lets say off the web, the web pic will look really small
when you add it,

in photoshop you can resize the image as a smart object but some times that not good enough and if you try and just inlarge the picture it will get all distorted
so what you do is use this plugin&gt;Alien Skin Blow Up v.1.0 for Photoshop
 :arrow:  http://gfxworld.org/plugins/alien_skin_blow_up.html
it will blow up your picture size very good, the plugin will be located under your FILE Tab &gt;automated.