The only time you have to worry about dpi is if you are printing and need particular pixel dimensions to fill the space exactly.  You're printing at 300dpi and the print will be 8x10, that's 2400x3000 pixels.  Voila.  Realistically though, with today's 'blurred' ink printers and thermals, even 240x300 could look decent with the correct algorithms used.

Good ole' Nyquist.  Just a sample of the fun, huh? ;p  (I not ony had to deal with this in pixels a bit but mainly with audio - 'nuf said).

C makes it easy to shoot yourself in the foot. C++ makes it harder, but when you do, you blow your whole leg off.

 -- Bjarne Stroustrup

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