New answers tagged prints
Since I do photo restorations I frequently see the results of others efforts of trying to separate the photo from the glass.I personally do not try separating them. I do a high resolution flat bed scan through the glass and then rebuild the photo on my computer. This way my customer has both.
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.
I don't think compansation is a good choice - maybe Krylon Acrylic Satin Finish ? http://photo.net/bboard/q-and-a-fetch-msg?msg_id=0019O1
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