As long as the actual resolution (amount of pixels) doesn't change, who cares what DPI setting the picture is. It doesn't change the picture in any way. The only thing it does is saying how many of the pixels should fit in an inch when printing. So it's only important once you decide to print them, at which time you probably tell the software to print it at a certain size. Problem probably is that with some formats the DPI setting isnt't stored. Or some programs default the setting to 72 like DS said.

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