Min pixel density

[|Voldemort|]

What is the minimum pixel density required for eliminating grainy display? (e.g. I find 154 ppi in samsung champ grainy)

[udu_4u]

Usually 220+ is good enough for a nice sharp display. Above 300ppi human eyes can't detect much issues anyway. Suffice to say resolutions like 854x480 in a 4.0" screen is good for eliminating graininess. Use dpi calculator @ members.ping.de/~sven/dpi.html in situations where ppi isn't shown.

[YouKnowWho]

Actually there is more to those grainy displays other than the low pixel density.
The quality of the display also matters.

One good example is the iPhone 3GS. It has a 3.5" screen with only 165ppi, but still it doesn't look to be grainy.
So if the quality of the display is not that great even a 200+ppi display would appear grainy.