UIImagePickerController returning incorrect image

问题:

I'm using UIImagePickerController to capture an image and then store it. However, when i try to rescale it, the orientation value i get out of this image is incorrect. When i take a snap by holding the phone Up, it gives me orientation of Left. Has anyone experienced this issue?

The UIImagePickerController dictionary shows following information:

{
    UIImagePickerControllerMediaMetadata =     {
        DPIHeight = 72;
        DPIWidth = 72;
        Orientation = 3;
        "{Exif}" =         {
            ApertureValue = "2.970853654340484";
            ColorSpace = 1;
            DateTimeDigitized = "2011:02:14 10:26:17";
            DateTimeOriginal = "2011:02:14 10:26:17";
            ExposureMode = 0;
            ExposureProgram = 2;
            ExposureTime = "0.06666666666666667";
            FNumber = "2.8";
            Flash = 32;
            FocalLength = "3.85";
            ISOSpeedRatings =             (
                125
            );
            MeteringMode = 1;
            PixelXDimension = 2048;
            PixelYDimension = 1536;
            SceneType = 1;
            SensingMethod = 2;
            Sharpness = 1;
            ShutterSpeedValue = "3.910431673351467";
            SubjectArea =             (
                1023,
                767,
                614,
                614
            );
            WhiteBalance = 0;
        };
        "{TIFF}" =         {
            DateTime = "2011:02:14 10:26:17";
            Make = Apple;
            Model = "iPhone 3GS";
            Software = "4.2.1";
            XResolution = 72;
            YResolution = 72;
        };
    };
    UIImagePickerControllerMediaType = "public.image";
    UIImagePickerControllerOriginalImage = "<UIImage: 0x40efb50>";
}

However picture returns imageOrientation == 1;

UIImage *picture = [info objectForKey:UIImagePickerControllerOriginalImage];             

回答1:

I just started working on this issue in my own app.

I used the UIImage category that Trevor Harmon crafted for resizing an image and fixing its orientation, UIImage+Resize.

Then you can do something like this in -imagePickerController:didFinishPickingMediaWithInfo:

UIImage *pickedImage = [info objectForKey:UIImagePickerControllerEditedImage];
UIImage *resized = [pickedImage resizedImageWithContentMode:UIViewContentModeScaleAspectFit bounds:pickedImage.size interpolationQuality:kCGInterpolationHigh];

This fixed the problem for me. The resized image is oriented correctly visually and the imageOrientation property reports UIImageOrientationUp.

There are several versions of this scale/resize/crop code out there; I used Trevor's because it seems pretty clean and includes some other UIImage manipulators that I want to use later.

回答2:

This what I have found for fixing orientation issue; Works for me

UIImage *initialImage = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
NSData *data = UIImagePNGRepresentation(self.initialImage);

UIImage *tempImage = [UIImage imageWithData:data];
UIImage *fixedOrientationImage = [UIImage imageWithCGImage:tempImage.CGImage
                                     scale:initialImage.scale
                               orientation:self.initialImage.imageOrientation];
initialImage = fixedOrientationImage;

回答3:

Here's a Swift snippet that fixes the problem efficiently:

let orientedImage = UIImage(CGImage: initialImage.CGImage, scale: 1, orientation: initialImage.imageOrientation)!

回答4:

I use the following code that I have put in a separate image utility object file that has a bunch of other editing methods for UIImages:

+ (UIImage*)imageWithImage:(UIImage*)sourceImage scaledToSizeWithSameAspectRatio:(CGSize)targetSize
{
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor > heightFactor) {
            scaleFactor = widthFactor; // scale to fit height
        }
        else {
            scaleFactor = heightFactor; // scale to fit width
        }

        scaledWidth  = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the image
        if (widthFactor > heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }
        else if (widthFactor < heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }

    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);

    }

    // In the right or left cases, we need to switch scaledWidth and scaledHeight,
    // and also the thumbnail point
    if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, M_PI_2); // + 90 degrees
        CGContextTranslateCTM (bitmap, 0, -targetHeight);

    } else if (sourceImage.imageOrientation == UIImageOrientationRight) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, -M_PI_2); // - 90 degrees
        CGContextTranslateCTM (bitmap, -targetWidth, 0);

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

    CGContextDrawImage(bitmap, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

And then I call

UIImage *pickedImage = [info objectForKey:UIImagePickerControllerOriginalImage];
        UIImage *fixedOriginal = [ImageUtil imageWithImage:[mediaInfoDict objectForKey:UIImagePickerControllerOriginalImage] scaledToSizeWithSameAspectRatio:pickedImage.size];

回答5:

In iOS 7, I needed code dependent on UIImage.imageOrientation to correct for the different orientations. Now, in iOS 8.2, when I pick my old test images from the album via UIImagePickerController, the orientation will be UIImageOrientationUp for ALL images. When I take a photo (UIImagePickerControllerSourceTypeCamera), those images will also always be upwards, regardless of the device orientation. So between those iOS versions, there obviously has been a fix where UIImagePickerController already rotates the images if neccessary. You can even notice that when the album images are displayed: for a split second, they will be displayed in the original orientation, before they appear in the new upward orientation.

回答6:

The only thing that worked for me was to re-render the image again which forces the correct orientation.

if (photo.imageOrientation != .up) {
   UIGraphicsBeginImageContextWithOptions(photo.size, false, 1.0);
   let rect = CGRect(x: 0, y: 0, width: photo.size.width, height: photo.size.height);
   photo.draw(in: rect)
   let newImage = UIGraphicsGetImageFromCurrentImageContext()
   UIGraphicsEndImageContext()
   photo = newImage;
}