(iphone) how much memory UIImage takes up?

Question

I'm having trouble with UIImage memory size.

1. When you have 320*320 resolution image data(png), when you load the image onto memory,
   using [UIImage imageWithData:], the resulting UIImage will take up 320*320*4?

2. does a screen size(resolution) affect the memory usage of an image?

3. Would the code below take up twice memory size of myImage or just single image memory size? (320*320*4) * 2 vs (320*320*4)? or something else?

   UIImage* myImage = [UIImage imageWithData:];    
   myImage = [myImage scaleToSize:];
   

   when scaleToSize is defined as

   - (UIImage*)scaleToSize:(CGSize)size
   {
     // Create a bitmap graphics context                                                                                              
   
   
     // This will also set it as the current context                                                                                                                                                                                                                             
     UIGraphicsBeginImageContext(size);
   
     // Draw the scaled image in the current context                                                                                                                                                                                                                             
     [self drawInRect:CGRectMake(0, 0, size.width, size.height)];
   
     // Create a new image from current context                                                                                                                                                                                                                                  
     UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
   
     // Pop the current context from the stack                                                                                                                                                                                                                                   
     UIGraphicsEndImageContext();
   
     // Return our new scaled image                                                                                                                                                                                                                                              
     return scaledImage;
   }
   

Answer 1

TO CHECK MEMORY ALLOCATION

If you want to test for specific images, run your application in the iPhone/Simulator while using Instruments.

Make sure you choose the appropriate target. When you run the program, you'll see the memory space taken by a specific allocation.

---

WHILE RUNNING

You'll see the objects allocated in the window. Like this one, to which I attached iTunes.

Answer 2

Obviously the larger the image the more memory you will use, same goes for the amount of images you load into memory at once.