high memory usage when resizing uiimage - ios

Question

Heavy memory usage when resizing and drawing UIImage in rect.
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
UIImage *selectedImage=[info objectForKey:UIImagePickerControllerOriginalImage];
// COMPRESSING IMAGE
NSData *selectedImageData=UIImageJPEGRepresentation(selectedImage, 0.5);
UIImage *selectedImageFromData=[UIImage imageWithData:selectedImageData];
//SCALING UIIMAGE
UIImage *scaledImage=[[UIImage alloc]init];
if (((selectedImageFromData.size.width>3264) && (selectedImageFromData.size.height>2448)) || ((selectedImageFromData.size.height>3264) && (selectedImageFromData.size.width>2448)))
{
CGFloat originalWidth=selectedImageFromData.size.width;
CGFloat originalHeight=selectedImageFromData.size.height;
CGFloat myWidth=2048;
CGFloat widthRatio=myWidth/originalWidth;
CGFloat dynamicHeight=widthRatio*originalHeight;
CGImageRef CoreGraphicsImage=selectedImageFromData.CGImage;
CGColorSpaceRef colorSpace = CGImageGetColorSpace(CoreGraphicsImage);
CGBitmapInfo bitmapInfo=CGImageGetBitmapInfo(CoreGraphicsImage);
CGImageGetBitsPerComponent(CoreGraphicsImage);
CGContextRef context=CGBitmapContextCreate(NULL, myWidth, dynamicHeight, CGImageGetBitsPerComponent(CoreGraphicsImage), CGImageGetBytesPerRow(CoreGraphicsImage), colorSpace, bitmapInfo);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextDrawImage(context, CGRectMake(0, 0, myWidth, dynamicHeight), CoreGraphicsImage);
CGImageRef CGscaledImage=CGBitmapContextCreateImage(context);
UIImage *CGLastimage = [UIImage imageWithCGImage: CGscaledImage];
NSLog(#"%f",CGLastimage.size.width);
NSLog(#"%f",CGLastimage.size.height);
VisualEffectImageVIew.image=CGLastimage;
BackgroundImageView.image=CGLastimage;
ForegroundImageView.image=CGLastimage;
}
else
{
NSLog(#" HEIGHT %f",selectedImageFromData.size.height);
NSLog(#" WIDTH %f",selectedImageFromData.size.width);
VisualEffectImageVIew.image=selectedImageFromData;
BackgroundImageView.image=selectedImageFromData;
ForegroundImageView.image=selectedImageFromData;
}
if(UI_USER_INTERFACE_IDIOM()==UIUserInterfaceIdiomPhone)
{
[picker dismissViewControllerAnimated:YES completion:nil];
}
else
{
[popoverController dismissPopoverAnimated:YES];
[self popoverControllerDidDismissPopover:popoverController];
}
}
Here's an image below, in the image you can see the above mentioned code is using too much memory. Would like to know why it's using too much memory and would appreciate any solutions.

Answer 1

When it comes to images, i've always been a big fan of Brad Larson's GPUImage, it can do anything you want and uses GPU instead of CPU, which leave you with plenty of power to avoid crashes due to memory pressure.
And also it's pretty good.
This stackoverflow question might also help you achieve what you want once you're done setting up the project.
Hope this helps :)

Answer 2

You're using CPU for drawing data into a frame, i suggest you use CGImage for draw in GPU Context
- (UIImage *) scaleToSize: (CGSize)size
{
// Scalling selected image to targeted size
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, size.width, size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
CGContextClearRect(context, CGRectMake(0, 0, size.width, size.height));
if(self.imageOrientation == UIImageOrientationRight)
{
CGContextRotateCTM(context, -M_PI_2);
CGContextTranslateCTM(context, -size.height, 0.0f);
CGContextDrawImage(context, CGRectMake(0, 0, size.height, size.width), self.CGImage);
}
else
CGContextDrawImage(context, CGRectMake(0, 0, size.width, size.height), self.CGImage);
CGImageRef scaledImage=CGBitmapContextCreateImage(context);
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
UIImage *image = [UIImage imageWithCGImage: scaledImage];
CGImageRelease(scaledImage);
return image;
}