UIImagePNGRepresentation에 문제가 있습니까?/이미지를 90도 회전했습니다.

Question

UIImagePickerController에서 이미지를로드하고 선택한 사진을 내 응용 프로그램의 문서 디렉토리에 저장하려고합니다. 내 문서에 이미지를 저장 한 후

UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage]; 
NSData *data1 = UIImagePNGRepresentation(image); 

NSString *fileName = "1.png"; 
NSString *path = //get Document path, then add fileName 
BOOL succ = [data1 writeToFile:path atomically:YES]; 

하지만, 나는, 사람이 문제가 어떤 건지, 이미지가 내가 UIImageJPEGRepresentation의 방법 UIImagePNGRepresentation을 변경 한 후, 90도를 회전 한 것을이 괜찮 이번에 발견?

Answer 1

나는 같은 문제가 있었는데 그 이유를 알아 냈다. 카메라가 사진을 찍을 때 iOS 4.0부터 저장하기 전에 사진을 회전시키지 않고 단순히 JPEG의 EXIF ​​데이터에 회전 플래그를 설정한다.

UIImage를 JPEG로 저장하면 회전 플래그가 설정됩니다.

PNG는 회전 플래그를 지원하지 않으므로 PNG로 UIImage를 저장하면 잘못 회전되어 플래그가 고정되어 있지 않습니다. 따라서 PNG를 원한다면 직접 회전해야합니다.

나는 이것을 PNG 저장 함수에서 버그라고 부르 겠지만, 그것은 단지 의견 일 뿐이다 (적어도 이것에 대해 경고해야한다).

Answer 2

이 문제는 다음 코드로 해결됩니다.

- (UIImage *)scaleAndRotateImage:(UIImage *)image 
{ 
    int kMaxResolution = 640; 

    CGImageRef imgRef = image.CGImage; 

    CGFloat width = CGImageGetWidth(imgRef); 
    CGFloat height = CGImageGetHeight(imgRef); 

    CGAffineTransform transform = CGAffineTransformIdentity; 
    CGRect bounds = CGRectMake(0, 0, width, height); 
    if (width > kMaxResolution || height > kMaxResolution) { 
     CGFloat ratio = width/height; 
     if (ratio > 1) { 
      bounds.size.width = kMaxResolution; 
      bounds.size.height = bounds.size.width/ratio; 
     } 
     else { 
      bounds.size.height = kMaxResolution; 
      bounds.size.width = bounds.size.height * ratio; 
     } 
    } 

    CGFloat scaleRatio = bounds.size.width/width; 
    CGSize imageSize = CGSizeMake(CGImageGetWidth(imgRef), CGImageGetHeight(imgRef)); 
    CGFloat boundHeight; 
    UIImageOrientation orient = image.imageOrientation; 
    switch(orient) { 

     case UIImageOrientationUp: //EXIF = 1 
      transform = CGAffineTransformIdentity; 
      break; 

     case UIImageOrientationUpMirrored: //EXIF = 2 
      transform = CGAffineTransformMakeTranslation(imageSize.width, 0.0); 
      transform = CGAffineTransformScale(transform, -1.0, 1.0); 
      break; 

     case UIImageOrientationDown: //EXIF = 3 
      transform = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height); 
      transform = CGAffineTransformRotate(transform, M_PI); 
      break; 

     case UIImageOrientationDownMirrored: //EXIF = 4 
      transform = CGAffineTransformMakeTranslation(0.0, imageSize.height); 
      transform = CGAffineTransformScale(transform, 1.0, -1.0); 
      break; 

     case UIImageOrientationLeftMirrored: //EXIF = 5 
      boundHeight = bounds.size.height; 
      bounds.size.height = bounds.size.width; 
      bounds.size.width = boundHeight; 
      transform = CGAffineTransformMakeTranslation(imageSize.height, imageSize.width); 
      transform = CGAffineTransformScale(transform, -1.0, 1.0); 
      transform = CGAffineTransformRotate(transform, 3.0 * M_PI/2.0); 
      break; 

     case UIImageOrientationLeft: //EXIF = 6 
      boundHeight = bounds.size.height; 
      bounds.size.height = bounds.size.width; 
      bounds.size.width = boundHeight; 
      transform = CGAffineTransformMakeTranslation(0.0, imageSize.width); 
      transform = CGAffineTransformRotate(transform, 3.0 * M_PI/2.0); 
      break; 

     case UIImageOrientationRightMirrored: //EXIF = 7 
      boundHeight = bounds.size.height; 
      bounds.size.height = bounds.size.width; 
      bounds.size.width = boundHeight; 
      transform = CGAffineTransformMakeScale(-1.0, 1.0); 
      transform = CGAffineTransformRotate(transform, M_PI/2.0); 
      break; 

     case UIImageOrientationRight: //EXIF = 8 
      boundHeight = bounds.size.height; 
      bounds.size.height = bounds.size.width; 
      bounds.size.width = boundHeight; 
      transform = CGAffineTransformMakeTranslation(imageSize.height, 0.0); 
      transform = CGAffineTransformRotate(transform, M_PI/2.0); 
      break; 

     default: 
      [NSException raise:NSInternalInconsistencyException format:@"Invalid image orientation"]; 

    } 

    UIGraphicsBeginImageContext(bounds.size); 

    CGContextRef context = UIGraphicsGetCurrentContext(); 

    if (orient == UIImageOrientationRight || orient == UIImageOrientationLeft) { 
     CGContextScaleCTM(context, -scaleRatio, scaleRatio); 
     CGContextTranslateCTM(context, -height, 0); 
    } 
    else { 
     CGContextScaleCTM(context, scaleRatio, -scaleRatio); 
     CGContextTranslateCTM(context, 0, -height); 
    } 

    CGContextConcatCTM(context, transform); 

    CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, width, height), imgRef); 
    UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 

    return imageCopy; 
} 

Answer 3

다음과 같은 신속한 기능으로 문제가 해결됩니다. 그 그래

var rotatedCopy: UIImage { 
    if (imageOrientation == UIImageOrientation.Up) { 
     return self 
    } 

    UIGraphicsBeginImageContext(size) 

    drawInRect(CGRect(origin: CGPoint.zeroPoint, size: size)) 
    let copy = UIGraphicsGetImageFromCurrentImageContext() 

    UIGraphicsEndImageContext() 

    return copy 
} 

는 drawInRect 기능을 고려하여 이미지 방향 걸릴해서, 간단하다.

Answer 4

는 시도이 하나

func rotateImage(image: UIImage) -> UIImage { 

    if (image.imageOrientation == UIImageOrientation.Up) { 
     return image 
    } 

    UIGraphicsBeginImageContext(image.size) 

    image.drawInRect(CGRect(origin: CGPoint.zero, size: image.size)) 
    let copy = UIGraphicsGetImageFromCurrentImageContext() 

    UIGraphicsEndImageContext() 

    return copy 
} 

Answer 5

내가 this response에 따라, UIImagePNGRepresentation이 문제를 해결하기 위해이있는 UIImage 확장을 만들었습니다. 그래서이 클래스 func UIImage.PNGRepresentation(img: UIImage) UIKit func UIImagePNGRepresentation 대신 사용하도록 제안합니다.

스위프트 3 코드 :

// MyUIImage.swift 
// MyEasyMovie-Public-App 
// 
// Created by Ahmed Zahraz on 19/12/2016. 
// Copyright © 2016 AhmedZahraz. All rights reserved.  

import Foundation 
import UIKit 

extension UIImage { 


    public class func PNGRepresentation(_ img: UIImage) -> Data? { 
     // No-op if the orientation is already correct 
     if (img.imageOrientation == UIImageOrientation.up) { 
      return UIImagePNGRepresentation(img); 
     } 
     // 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 = CGAffineTransform.identity 

     if (img.imageOrientation == UIImageOrientation.down 
      || img.imageOrientation == UIImageOrientation.downMirrored) { 

      transform = transform.translatedBy(x: img.size.width, y: img.size.height) 
      transform = transform.rotated(by: CGFloat(M_PI)) 
     } 

     if (img.imageOrientation == UIImageOrientation.left 
      || img.imageOrientation == UIImageOrientation.leftMirrored) { 

      transform = transform.translatedBy(x: img.size.width, y: 0) 
      transform = transform.rotated(by: CGFloat(M_PI_2)) 
     } 

     if (img.imageOrientation == UIImageOrientation.right 
      || img.imageOrientation == UIImageOrientation.rightMirrored) { 

      transform = transform.translatedBy(x: 0, y: img.size.height); 
      transform = transform.rotated(by: CGFloat(-M_PI_2)); 
     } 

     if (img.imageOrientation == UIImageOrientation.upMirrored 
      || img.imageOrientation == UIImageOrientation.downMirrored) { 

      transform = transform.translatedBy(x: img.size.width, y: 0) 
      transform = transform.scaledBy(x: -1, y: 1) 
     } 

     if (img.imageOrientation == UIImageOrientation.leftMirrored 
      || img.imageOrientation == UIImageOrientation.rightMirrored) { 

      transform = transform.translatedBy(x: img.size.height, y: 0); 
      transform = transform.scaledBy(x: -1, y: 1); 
     } 


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

     ctx.concatenate(transform) 


     if (img.imageOrientation == UIImageOrientation.left 
      || img.imageOrientation == UIImageOrientation.leftMirrored 
      || img.imageOrientation == UIImageOrientation.right 
      || img.imageOrientation == UIImageOrientation.rightMirrored 
      ) { 


      ctx.draw(img.cgImage!, in: CGRect(x:0,y:0,width:img.size.height,height:img.size.width)) 

     } else { 
      ctx.draw(img.cgImage!, in: CGRect(x:0,y:0,width:img.size.width,height:img.size.height)) 
     } 


     // And now we just create a new UIImage from the drawing context 
     let cgimg:CGImage = ctx.makeImage()! 
     let imgEnd:UIImage = UIImage(cgImage: cgimg) 

     return UIImagePNGRepresentation(imgEnd) 
    } 

}