AVFoundation图像方向在预览中偏离90度,但在相机胶卷中很好

Question

发生了一些非常奇怪的事情,我正在尝试使用AVFoundation捕获图像,相机滚动图像看起来很好,但图像预览将图像旋转了90度.

这是我用来捕获图像的代码

AVCaptureConnection *videoConnection = nil;
for (AVCaptureConnection *connection in stillImageOutput.connections)
{
    for (AVCaptureInputPort *port in [connection inputPorts])
    {
        if ([[port mediaType] isEqual:AVMediaTypeVideo] )
        {
            videoConnection = connection;
            break;
        }
    }
    if (videoConnection)
    {
        break;
    }
}

//NSLog(@"about to request a capture from: %@", stillImageOutput);
[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
 {
     CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL);
     if (exifAttachments)
     {
         // Do something with the attachments.
         //NSLog(@"attachements: %@", exifAttachments);
     } else {
         NSLog(@"no attachments");
     }

     NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];

     UIImage *image = [[UIImage alloc] initWithData:imageData];

     self.vImage.image = image;

     UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
 }];

Answer 1

是的,当您在设备的纵向方向捕获图像并在应用程序中使用该图像时会发生这种情况,因为图像的默认方向是任何IOS设备中的横向,因此您需要在从Gallery中选择后更改图像的方向以使用在你的应用程序中

我已经放置代码来实现这一目标

Objective-C代码

- (UIImage *)fixOrientationOfImage:(UIImage *)image {

    // No-op if the orientation is already correct
    if (image.imageOrientation == UIImageOrientationUp) return image;

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    CGAffineTransform transform = CGAffineTransformIdentity;

    switch (image.imageOrientation) {
        case UIImageOrientationDown:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, image.size.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;

        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, 0);
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;

        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, 0, image.size.height);
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationUpMirrored:
            break;
    }

    switch (image.imageOrientation) {
        case UIImageOrientationUpMirrored:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;

        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationDown:
        case UIImageOrientationLeft:
        case UIImageOrientationRight:
            break;
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    CGContextRef ctx = CGBitmapContextCreate(NULL, image.size.width, image.size.height,
                                             CGImageGetBitsPerComponent(image.CGImage), 0,
                                             CGImageGetColorSpace(image.CGImage),
                                             CGImageGetBitmapInfo(image.CGImage));
    CGContextConcatCTM(ctx, transform);
    switch (image.imageOrientation) {
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            // Grr...
            CGContextDrawImage(ctx, CGRectMake(0,0,image.size.height,image.size.width), image.CGImage);
            break;

        default:
            CGContextDrawImage(ctx, CGRectMake(0,0,image.size.width,image.size.height), image.CGImage);
            break;
    }

    // And now we just create a new UIImage from the drawing context
    CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
    UIImage *img = [UIImage imageWithCGImage:cgimg];
    CGContextRelease(ctx);
    CGImageRelease(cgimg);
    return img;
}

SWIFT代码

func fixOrientationOfImage(image: UIImage) -> UIImage? {
   if image.imageOrientation == .Up {
      return image
   }

   // We need to calculate the proper transformation to make the image upright.
   // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
   var transform = CGAffineTransformIdentity

   switch image.imageOrientation {
   case .Down, .DownMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.width, image.size.height)
      transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
   case .Left, .LeftMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.width, 0)
      transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
   case .Right, .RightMirrored:
      transform = CGAffineTransformTranslate(transform, 0, image.size.height)
      transform = CGAffineTransformRotate(transform, -CGFloat(M_PI_2))
   default:
      break
   }

   switch image.imageOrientation {
   case .UpMirrored, .DownMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.width, 0)
      transform = CGAffineTransformScale(transform, -1, 1)
   case .LeftMirrored, .RightMirrored:
      transform = CGAffineTransformTranslate(transform, image.size.height, 0)
      transform = CGAffineTransformScale(transform, -1, 1)
   default:
      break
   }

   // Now we draw the underlying CGImage into a new context, applying the transform
   // calculated above.
   guard let context = CGBitmapContextCreate(nil, Int(image.size.width), Int(image.size.height), CGImageGetBitsPerComponent(image.CGImage), 0, CGImageGetColorSpace(image.CGImage), CGImageGetBitmapInfo(image.CGImage).rawValue) else {
      return nil
   }

   CGContextConcatCTM(context, transform)

   switch image.imageOrientation {
   case .Left, .LeftMirrored, .Right, .RightMirrored:
      CGContextDrawImage(context, CGRect(x: 0, y: 0, width: image.size.height, height: image.size.width), image.CGImage)
   default:
      CGContextDrawImage(context, CGRect(origin: .zero, size: image.size), image.CGImage)
   }

   // And now we just create a new UIImage from the drawing context
   guard let CGImage = CGBitmapContextCreateImage(context) else {
      return nil
   }

   return UIImage(CGImage: CGImage)
}

Swift 3.0

func fixOrientationOfImage(image: UIImage) -> UIImage? {
    if image.imageOrientation == .up {
        return image
    }

    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    var transform = CGAffineTransform.identity

    switch image.imageOrientation {
       case .down, .downMirrored:
        transform = transform.translatedBy(x: image.size.width, y: image.size.height)
        transform = transform.rotated(by: CGFloat(Double.pi))
    case .left, .leftMirrored:
        transform = transform.translatedBy(x: image.size.width, y: 0)
        transform = transform.rotated(by:  CGFloat(Double.pi / 2))
    case .right, .rightMirrored:
        transform = transform.translatedBy(x: 0, y: image.size.height)
        transform = transform.rotated(by:  -CGFloat(Double.pi / 2))
    default:
        break
    }

    switch image.imageOrientation {
    case .upMirrored, .downMirrored:
        transform = transform.translatedBy(x: image.size.width, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)
    case .leftMirrored, .rightMirrored:
        transform = transform.translatedBy(x: image.size.height, y: 0)
        transform = transform.scaledBy(x: -1, y: 1)
    default:
        break
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    guard let context = CGContext(data: nil, width: Int(image.size.width), height: Int(image.size.height), bitsPerComponent: image.cgImage!.bitsPerComponent, bytesPerRow: 0, space: image.cgImage!.colorSpace!, bitmapInfo: image.cgImage!.bitmapInfo.rawValue) else {
        return nil
    }

    context.concatenate(transform)

    switch image.imageOrientation {
      case .left, .leftMirrored, .right, .rightMirrored:
        context.draw(image.cgImage!, in: CGRect(x: 0, y: 0, width: image.size.height, height: image.size.width))
       default:
          context.draw(image.cgImage!, in: CGRect(origin: .zero, size: image.size))
    }

    // And now we just create a new UIImage from the drawing context
    guard let CGImage = context.makeImage() else {
        return nil
    }

    return UIImage(cgImage: CGImage)
}