Collectible Card Game Headquarters

At first i want to say sorry for my bad english

With HQ scans and Photoshop i tried to make XL full card picture including borders!
I did this with zendikar HQ pics! The size for the 269 pictures is insane (369 Mo)

Here is an example of what i did :


Printing result of this is quite good but the scan looks like not really clear on screen!
So i would like to have some advices to make this really better
By advance i say thanks

you are aware, i hope, of the fact that you can't enlarge a digital image and get more details. That's reserved to the Bond movies. The only way to get a good xl image is, well, by starting with one, sorry.