I'm learning iPhone development and a friend will be doing the graphics/animation. I'll be using cocos2d most likely (if that matters).

My friend wants to get started on the graphics, and I don't know what image resolution or dpi or formats are recommended.

This probably depends on if something is a background vs. a small character.

Also, I know I read something about using @2x in image file names to support high res iphone screens. Does cocos2d prefer a different way? Or is this not something to worry about at this point?

What should I know before they start working on the graphics?

  • 1
    \$\begingroup\$ Step One is to accept answers.. your percentage is pretty low... it doesn't encourage others to answer your questions. \$\endgroup\$
    – Nate
    Feb 6, 2011 at 20:46

1 Answer 1


I can't speak to anything Cocos2D related, but for UIKit you want your images to be 72 DPI. The iPhone, iPhone 3G and iPhone 3GS have a native resolution of 320 x 480. The iPhone 4 has a native resolution of 640 x 960, which is exactly double the size of the older devices.

To make it easier for developers, they play a trick with how graphics are handled in iOS. You don't deal in Pixels, you deal in "points". The iPhone screen is 320 x 480 points, no matter what model it is. If you have an image that's 320 x 480 pixels, it's drawn at native resolution on the iPhone 3G, and it's doubled to fill the size of the iPhone 4.

To get even more clear images on the iPhone 4, you can also provide @2x images that are the correct size to match the native iPhone 4 screen. As an example, if you have an image called AvatarIcon.png on your app that's 100 x 50 pixels. You could also create on called [email protected] that's 200 x 100 pixels. Now you get a crisp image on both the iPhone 3G and the iPhone 4.

Make sense?


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