How you get iPhone 4 camera to take larger pictures

GSM Model is the AT&T one? Just want to make sure Im in the right spot. I have an AT&T iPhone 4.
Well I notice that when I take photos and I laod them on my computer to color correct them or whatever, they are a very small size (11x8 @ 72dpi) Obviously when you up the dpi the image gets smaller, in this case when you change the dpi to 300 the picture becomes a 1x2 image. Not suitable for printing at all.
How can I change the output picture settings on the iPhone 4? On my older 3GS model it takes pictures at 28x21@ 72 dpi, and when you up the dpi to 300 it makes it roughly a 4x6. Very suitable for printing a clean picture. There has to be a way to change the settings on the iPhone 4.