what is resolution of photo taken by iPhone 4 camera?

In specs,

iPhone 4 screen resolution & pixel density * iPhone 4 has a screen resolution of 960×640 pixels, which is twice that of the prior iPhone models

As we know, when we code like this,

CGImageRef screenImage = UIGetScreenImage();
CGRect fullRect = [[UIScreen mainScreen] applicationFrame];
CGImageRef saveCGImage = CGImageCreateWithImageInRect(screenImage, fullRect);

the saveCGImage will have size 开发者_JAVA百科(320,480), my question is how about iPhone 4 ? Is that (640,960) ?

Another question is about black image in thumb view when you open Photo.app if coding like this,

CGImageRef screenImage = UIGetScreenImage();

CGImageRef saveCGImage = CGImageCreateWithImageInRect(screenImage, CGRectMake(0,0,320,460));  // please note, I used 460 instead of 480

The problem is that when open "Photo.app", in the thumb view, those images are view as black, when clicking it to see details, that is okay. Any solution for this issue now ?

Thanks for your time.

update questions:

When you invoke UIGetScreenImage() to capture screen in iPhone 4, is that also 320x480 ?

From Falk Lumo:

iPhone 4 main camera:

• 5.0 Mpixels (2592 x 1936)
• 1/3.2" back-illuminated CMOS sensor
• 4:3 aspect ratio
• 35 mm film camera crop factor: 7.64
• Low ISO 80 (or better)
• 3.85 mm lens focal length
• f/2.8 lens aperture
• Autofocus: tap to focus

Equivalent 35mm film camera and lens:

• 30 mm f/22

Photo resolution taken by iOS devices,

• iPhone 6/6+, iPhone 5/5S, iPhone 4S(8 MP) - 3264 x
  2448 pixels

• iPhone 4, iPad 3, iPodTouch(5 MP) - 2592 x 1936 pixels

• iPhone 3GS(3.2 MP) - 2048 x 1536 pixels

• iPhone 2G/3G(2 MP) - 1600 x 1200 pixels