Hi, Folks, I just realize most of us are not talking in the right direction. I know you love instagram and all its funny filter effect and you love you iPhones. But why would you assume your photo will really be sold to some one and use commercially?
No matter what cell phone you are using, the picture quality is really bad as hell if you compare to that of professional cameras. And these cameras are where the majority of stock photos came from. Have you really enlarged your photo from cell phone into 100% view? You'll notice a lot of white spots called "noise" in the photo, unless it's shot under very bright sunlight, outdoor. Photos from instagram won't have any competition power with really professional photos. So I think you don't need to worry too much here.