如何解决相机图像方向
| 在我的应用中,我正在使用相机拍摄图像。这些作为NSData表示形式存储在NSArray中。当我将NSData转换回图像时,现在的方向是横向,而不是我所拍摄的纵向。 NSData *data = UIImagePNGRepresentation([arrayImage objectAtIndex:0]);
UIImage *tmp = [UIImage imageWithData:data];
有人解释吗?谢谢。
解决方法
您应该按照以下代码固定相机拍摄的图像的方向,
默认情况下,相机图像的方向不正确
- (UIImage *)fixrotation:(UIImage *)image
{
if (image.imageOrientation == UIImageOrientationUp) return image;
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,0);
transform = CGAffineTransformRotate(transform,M_PI_2);
break;
case UIImageOrientationRight:
case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform,-M_PI_2);
break;
case UIImageOrientationUp:
case UIImageOrientationUpMirrored:
break;
}
switch (image.imageOrientation) {
case UIImageOrientationUpMirrored:
case UIImageOrientationDownMirrored:
transform = CGAffineTransformTranslate(transform,0);
transform = CGAffineTransformScale(transform,-1,1);
break;
case UIImageOrientationLeftMirrored:
case UIImageOrientationRightMirrored:
transform = CGAffineTransformTranslate(transform,image.size.height,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,CGImageGetBitsPerComponent(image.CGImage),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,image.size.width),image.CGImage);
break;
default:
CGContextDrawImage(ctx,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;
}
,我认为这是SDK的错误。我遇到了这个确切的问题,然后切换到UIImageJPEGRepresentation来解决问题。
,-[UIImage imageOrientation]可能会有所帮助:)
图像方向会影响绘制图像数据时的显示方式。默认情况下,图像以“向上”方向显示。但是,如果图像具有关联的元数据(例如EXIF信息),则此属性包含该元数据指示的方向。有关此属性的可能值的列表,请参见“ UIImageOrientation”。
由于该属性是只读的,并且取决于您要执行的操作,因此可能的解决方案(但难看)可能是:
UIImage *sourceImage = [arrayImage objectAtIndex:0];
NSData *data = UIImagePNGRepresentation(sourceImage);
UIImage *tmp = [UIImage imageWithData:data];
UIImage *fixed = [UIImage imageWithCGImage:tmp.CGImage
scale:sourceImage.scale
orientation:sourceImage.imageOrientation];
(未经测试,可能/必须有清洁的东西)
编辑:第一部分是您的问题的答案,不仅仅是解决方法的解释。
这个和这个(旧的?)博客文章可能对您来说很有趣。奇怪的是,当我使用UIImageJPEGRepresentation
将图像发送到服务器时,我从未遇到过此问题...您正在使用哪个iOS版本?那可能是旧的SDK错误?
,//iOS Swift 3
func fixRotation(image: UIImage) -> UIImage
{
if (image.imageOrientation == .up)
{
return image
}
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: .pi)
case .left,.leftMirrored:
transform = transform.translatedBy(x: image.size.width,y: 0)
transform = transform.rotated(by: .pi / 2)
case .right,.rightMirrored:
transform = transform.translatedBy(x: 0,y: image.size.height)
transform = transform.rotated(by: -(.pi / 2))
case .up,.upMirrored:
break
}
switch image.imageOrientation {
case .upMirrored,y: 0)
transform = transform.scaledBy(x: -1,y: 1)
case .leftMirrored,.rightMirrored:
transform = transform.translatedBy(x: image.size.height,y: 1)
case .up,.down,.left,.right:
break
}
// Now we draw the underlying CGImage into a new context,applying the transform
// calculated above.
let cgimage = image.cgImage
let bitsPerComponent = cgimage?.bitsPerComponent
let colorSpace = cgimage?.colorSpace
let bitmapInfo = cgimage?.bitmapInfo
let ctx = CGContext(data: nil,width: Int(image.size.width),height: Int(image.size.height),bitsPerComponent: bitsPerComponent!,bytesPerRow: 0,space: colorSpace!,bitmapInfo: bitmapInfo!.rawValue)
ctx?.concatenate(transform)
switch image.imageOrientation {
case .left,.leftMirrored,.right,.rightMirrored:
// Grr...
ctx?.draw(image.cgImage!,in: CGRect(x: 0,y: 0,width: image.size.height,height: image.size.width))
default:
ctx?.draw(image.cgImage!,width: image.size.width,height: image.size.height))
}
let cgimg: CGImage = ctx!.makeImage()!
let img = UIImage(cgImage: cgimg)
return img
}
,dispatch_async([self sessionQueue],^{
// Update the orientation on the still image output video connection before capturing.
[[[self stillImageOutput] connectionWithMediaType:AVMediaTypeVideo] setVideoOrientation:[[(AVCaptureVideoPreviewLayer *)[[self previewView] layer] connection] videoOrientation]];
// Flash set to Auto for Still Capture
[AVCamViewController setFlashMode:AVCaptureFlashModeAuto forDevice:[[self videoDeviceInput] device]];
// Capture a still image.
[[self stillImageOutput] captureStillImageAsynchronouslyFromConnection:[[self stillImageOutput] connectionWithMediaType:AVMediaTypeVideo] completionHandler:^(CMSampleBufferRef imageDataSampleBuffer,NSError *error) {
if (imageDataSampleBuffer)
{
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage *image = [[UIImage alloc] initWithData:imageData];
[[[ALAssetsLibrary alloc] init] writeImageToSavedPhotosAlbum:[image CGImage] orientation:(ALAssetOrientation)[image imageOrientation] completionBlock:nil];
}
}];
});
https://developer.apple.com/library/content/samplecode/AVCam/Introduction/Intro.html
,这是对最佳答案的Xamarin.iOS(C#)版本的略微修改,因此您也不必手动重写它;-)。
public static UIImage FixCameraImageRotation(UIImage image)
{
if (image.Orientation == UIImageOrientation.Up) return image;
var transform = CGAffineTransform.MakeIdentity();
//handle orientation
switch (image.Orientation)
{
case UIImageOrientation.Down:
case UIImageOrientation.DownMirrored:
transform.Rotate((float)Math.PI);
transform.Translate(image.Size.Width,image.Size.Height);
break;
case UIImageOrientation.Left:
case UIImageOrientation.LeftMirrored:
transform.Rotate((float)Math.PI / 2);
transform.Translate(image.Size.Width,0);
break;
case UIImageOrientation.Right:
case UIImageOrientation.RightMirrored:
transform.Rotate(-(float)Math.PI / 2);
transform.Translate(0,image.Size.Height);
break;
}
//handle mirroring
switch (image.Orientation)
{
case UIImageOrientation.UpMirrored:
case UIImageOrientation.DownMirrored:
transform.Translate(image.Size.Width,0);
transform.Scale(-1,1);
break;
case UIImageOrientation.LeftMirrored:
case UIImageOrientation.RightMirrored:
transform.Translate(image.Size.Height,1);
break;
}
//create context and apply transformation
using (var context = new CGBitmapContext(
IntPtr.Zero,(nint)image.Size.Width,(nint)image.Size.Height,image.CGImage.BitsPerComponent,image.CGImage.BytesPerRow,image.CGImage.ColorSpace,image.CGImage.BitmapInfo))
{
context.ConcatCTM(transform);
//draw image
switch (image.Orientation)
{
case UIImageOrientation.Left:
case UIImageOrientation.LeftMirrored:
case UIImageOrientation.Right:
case UIImageOrientation.RightMirrored:
context.DrawImage(new CGRect(0,image.Size.Height,image.Size.Width),image.CGImage);
break;
default:
context.DrawImage(new CGRect(0,image.Size.Width,image.Size.Height),image.CGImage);
break;
}
//convert result to UIImage
using (var cgImage = context.ToImage())
{
var result = UIImage.FromImage(cgImage);
return result;
}
}
}
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