One misconception about making large prints is that you have to print at 300 dpi. We performed some experiments with print resolution and found that lower resolution prints are acceptable in certain situations. It all depends on viewing distance. For instance, if a 10'x10' mural will be high on a building and only viewed from 40' away or more, then you would probably be fine with 75dpi or something like that (for reference, output for billboards often tends to be 20-30 dpi). This will give you a much smaller file which will be easier to manipulate in Photoshop, put on a thumb drive, send to your printer, etc.
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