Why Does this Cropping Code Result in a Rotated Image? - iphone

Question

The title to this question should be rather clear. The code below performs a cropping operation and then displays the new cropped photo in an Image View. The problem is that the image, once cropped, is displayed with a different orientation than the original source image. Why is that? And what should I do about it?
-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
[self.popoverController dismissPopoverAnimated:true];
NSString *mediaType = [info
objectForKey:UIImagePickerControllerMediaType];
[self dismissModalViewControllerAnimated:YES];
if ([mediaType isEqualToString:(NSString *)kUTTypeImage]) {
UIImage *image = [info
objectForKey:UIImagePickerControllerOriginalImage];
CGRect rect = CGRectMake(0, ((image.size.height - image.size.width) / 2), image.size.width, image.size.width);
CGImageRef subImageRef = CGImageCreateWithImageInRect(image.CGImage, rect);
CGRect smallBounds = CGRectMake(rect.origin.x, rect.origin.y, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef));
UIGraphicsBeginImageContext(smallBounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, smallBounds, subImageRef);
croppedImage = [UIImage imageWithCGImage:subImageRef];
UIGraphicsEndImageContext();
imageView.image = croppedImage;
*EDIT
Based on the comments suggesting that root cause of the issue is the removal of the EXIF tag I attempted to correct the orientation with the following code. This still doesn't fix the problem but I think it is a step in the right direction. Perhaps it will help someone to propose a new answer to the question.
if (image.imageOrientation == UIImageOrientationLeft) {
NSLog(#"left");
CGContextRotateCTM (context, radians(90));
} else if (image.imageOrientation == UIImageOrientationRight) {
NSLog(#"right");
CGContextRotateCTM (context, radians(-90));
} else if (image.imageOrientation == UIImageOrientationUp) {
NSLog(#"up");
// NOTHING
} else if (image.imageOrientation == UIImageOrientationDown) {
NSLog(#"down");
CGContextRotateCTM (context, radians(-180.));
}
See https://stackoverflow.com/a/5184134/549273

Answer 1

I think your best bet will be to get the orientation from the incoming image, and then create your new image with the appropriate rotation.
Grab the metadata from the info dictionary passed in:
NSDictionary *metadata = [info objectForKey:UIImagePickerControllerMediaMetadata];
NSNumber *orientation = [metadata objectForKey:#"Orientation"];
Then when you create your UIImage:
croppedImage = [UIImage imageWithCGImage:subImageRef
scale:1.0
orientation:[orientation intValue]];
Hope that's a starting point for you, at least.

Answer 2

What you should do is fix the image orientation before coping it, I had the same problem, I'm using swift so I had to change this answer:
iOS UIImagePickerController result image orientation after upload
But the code works just fine. Just remember that it returns an image and its not editing the image, I struggled to get it right just because of that simple mistake. And by the way you should not use UIImageOrientation but UIImageOrientation.rawValue, at least in swift.
I'll leave the code for swift here, HOPE IT HELPS:
extension UIImage {
public func fixOrientation() -> UIImage?{
if self.imageOrientation.rawValue == UIImageOrientation.Up.rawValue {
return self
}
var transform : CGAffineTransform = CGAffineTransformIdentity
switch self.imageOrientation.rawValue {
case UIImageOrientation.Down.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height)
transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
case UIImageOrientation.DownMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height)
transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
case UIImageOrientation.Left.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.width, 0)
transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
case UIImageOrientation.LeftMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.width, 0)
transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
case UIImageOrientation.Right.rawValue:
print("working on right orientation")
transform = CGAffineTransformTranslate(transform, 0, self.size.height)
transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
case UIImageOrientation.RightMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, 0, self.size.height)
transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
case UIImageOrientation.Up.rawValue: break
case UIImageOrientation.UpMirrored.rawValue: break
default: break
}
switch self.imageOrientation.rawValue {
case UIImageOrientation.UpMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.width, 0)
transform = CGAffineTransformScale(transform, -1, 1)
case UIImageOrientation.DownMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.width, 0)
transform = CGAffineTransformScale(transform, -1, 1)
case UIImageOrientation.LeftMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.height, 0)
transform = CGAffineTransformScale(transform, -1, 1)
case UIImageOrientation.RightMirrored.rawValue:
transform = CGAffineTransformTranslate(transform, self.size.height, 0)
transform = CGAffineTransformScale(transform, -1, 1)
case UIImageOrientation.Up.rawValue: break
case UIImageOrientation.Down.rawValue: break
case UIImageOrientation.Left.rawValue: break
case UIImageOrientation.Right.rawValue: break
default: break
}
let bitmapInfo = CGImageGetBitmapInfo(self.CGImage)
let ctx = CGBitmapContextCreate(nil, Int(self.size.width), Int(self.size.height), CGImageGetBitsPerComponent(self.CGImage), 0, CGImageGetColorSpace(self.CGImage),
bitmapInfo.rawValue)
CGContextConcatCTM(ctx, transform)
switch self.imageOrientation {
case UIImageOrientation.Left:
CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
case UIImageOrientation.LeftMirrored:
CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
case UIImageOrientation.Right:
CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
case UIImageOrientation.RightMirrored:
CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.height, self.size.width), self.CGImage)
default:
CGContextDrawImage(ctx, CGRectMake(0, 0, self.size.width, self.size.height), self.CGImage)
}
let cgimg = CGBitmapContextCreateImage(ctx)
let image = UIImage(CGImage: cgimg!)
return image
}
}