DPI does not mean what you think it means. <i>At all.</i> DPI metadata is completely irrelevant to the web.<p>It's a piece of metadata about an image that says how densely it should be when formatted for print. Unfortunately that's almost completely useless, because you can't just tell someone to give you an image at $X dpi, because what you actually care about is how big you can print it, so you end up specifying 3 pieces of metadata: W x H @ DPI. It's always much better to just ask for an image at a specific pixel size.<p>Even programs for a print workflow have to essentially ignore most DPI metadata, because it's usually set to bullshit values like '72' and '96' by asinine applications doing their best to perpetuate irrelevant platform-specifc details. It's marginally better when new Photoshop documents default to shit like 5" x 7" @ 300dpi, but that's still a pointless artifact of people insisting on using a bitmap photo editor for digital painting.