Resizing UIimages pulled from the Camera also ROTATES the UIimage?

Question

I am getting UIimages from the camera and assigning them to UIImageViews to be displayed. When I do this the camera gives me a 1200 x 1600 pixel image which I then assign to a UIImageView in my Application. The image is displayed as expected in the image view under this condition. However, when I attempt to RESIZE the retrieved UIImage before assigning it to the UIImageView, the image is resizing as expected but there IS a problem in that somewhere (in the RESIZING code?) my UIImage is getting ROTATED... As a result, when I assign the resized UIImage to a UIImageView the image is rotated 90 degrees and appears stretched as the aspect ratio (1200 x 1600 pixels) was unchanged...

I am using this to get a UIImage from the Camera:

- (void) imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info
{

     myImg = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
     myResizedImg = [self resizeImage:myImg width:400 height:533];
     [myImageView setImage:myResizedImg];

}

I am using this to resize it:

-(UIImage *)resizeImage:(UIImage *)anImage width:(int)width height:(int)height
{

    CGImageRef imageRef = [anImage CGImage];

    CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);

    if (alphaInfo == kCGImageAlphaNone)
    alphaInfo = kCGImageAlphaNoneSkipLast;


    CGContextRef bitmap = CGBitmapContextCreate(NULL, width, height, CGImageGetBitsPerComponent(imageRef), 4 * width, CGImageGetColorSpace(imageRef), alphaInfo);

    CGContextDrawImage(bitmap, CGRectMake(0, 0, width, height), imageRef);

    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage *result = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return result; 
}

QUESTION: How do I RESIZE a UIImage pulled from the Camera WITHOUT rotating the pixels?

Answer 1

I had this problem too with some of the code out there, i found this code that works, check it out, let me know what you find

+ (UIImage*)imageWithImage:(UIImage*)image 
               scaledToSize:(CGSize)newSize;
{
   UIGraphicsBeginImageContext( newSize );
   [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
   UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();

   return newImage;
}

Answer 2

The reason your code doesn't work is because the imageOrientation on the code that you have is not being taken into account. Specifically, if the imageOrientation is right/left, then you need to both rotate the image and swap width/height. Here is some code to do this:

-(UIImage*)imageByScalingToSize:(CGSize)targetSize
{
 UIImage* sourceImage = self; 
 CGFloat targetWidth = targetSize.width;
 CGFloat targetHeight = targetSize.height;

 CGImageRef imageRef = [sourceImage CGImage];
 CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
 CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

 if (bitmapInfo == kCGImageAlphaNone) {
  bitmapInfo = kCGImageAlphaNoneSkipLast;
 }

 CGContextRef bitmap;

 if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
  bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

 } else {
  bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

 } 

 if (sourceImage.imageOrientation == UIImageOrientationLeft) {
  CGContextRotateCTM (bitmap, radians(90));
  CGContextTranslateCTM (bitmap, 0, -targetHeight);

 } else if (sourceImage.imageOrientation == UIImageOrientationRight) {
  CGContextRotateCTM (bitmap, radians(-90));
  CGContextTranslateCTM (bitmap, -targetWidth, 0);

 } else if (sourceImage.imageOrientation == UIImageOrientationUp) {
  // NOTHING
 } else if (sourceImage.imageOrientation == UIImageOrientationDown) {
  CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
  CGContextRotateCTM (bitmap, radians(-180.));
 }

 CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef);
 CGImageRef ref = CGBitmapContextCreateImage(bitmap);
 UIImage* newImage = [UIImage imageWithCGImage:ref];

 CGContextRelease(bitmap);
 CGImageRelease(ref);

 return newImage; 
}

This will resize your image and rotate it to the correct orientation. If you need the definition for radians, it is:

static inline double radians (double degrees) {return degrees * M_PI/180;}

The answer Daniel gave is also correct, but it suffers from the problem that it is not thread-safe, since you're using UIGraphicsBeginImageContext(). Since the above code only uses CG functions, you're all set. I also have a similar function to resize and do proper aspect fill on images - let me know if that's what you're looking for.

Note: I got the original function from this post, and did some modifications to make it work on JPEGs.