New answers tagged ppi
The big problem you have here is that your aspect ratio is wrong. A0 (or any other A size paper) has an aspect ratio of 1:sqrt(2) or 1:1.414 or so. Your image has an aspect ratio of 2048/1152 = 1.777. You're going to have to decide whether to crop your image, or print it "letterboxed". Other than that, see the question linked by mattdm.
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