Originally posted by ckiang
No, the file can be tagged with whatever dpi by the camera. it has NO EFFECT on quality. A 1600x1200 file can be tagged at 600dpi, 300dpi, or even 1dpi and it will have the same quality on screen.
dpi (or more accurately PPI) is only relevant when printing, or when a output size is specified. That 1600x1200 will print at 300dpi at around 4x5.33333", if at 150dpi, you can get 8 x 10.666".
This dpi thing is the single most misunderstood thing in digital photography. This must be the dunno-how-many-th time I explain liao, should really get a FAQ going.... ;p
Regards
CK