Question

我想试试像iPhone那样的iPhone上的一些图像过滤功能。我使用imagePickerController从相机胶卷中获取照片。据我所知，imagePickerController返回的图像被减少以节省内存。将原始图像加载到UIImage并不明智。但是，我如何处理图像然后将其保存为原始像素？我使用iPhone 4S作为我的开发设备。

相机胶卷中的原始照片为3264 * 2448。

UIImagePickerControllerOriginalImage返回的图像是1920 * 1440

UIImagePickerControllerEditedImage返回的图像为640 * 640

imageViewOld（使用UIImagePickerControllerCropRect [80,216,1280,1280]裁剪图像返回UIImagePickerControllerOriginalImage）是1280 * 1224

imageViewNew（使用双倍大小的UIImagePickerControllerCropRect [80,216,2560,2560]来裁剪UIImagePickerControllerOriginalImage返回的图像）是1840 * 1224.

我检查同一张照片由instagram继续是1280 * 1280

我的问题是：

为什么UIImagePickerControllerOriginalImage不会返回“原始”照片？为什么把它减少到1920 * 1440？
为什么UIImagePickerControllerEditedImage不会将图像返回1280 * 1280？作为 UIImagePickerControllerCropRect显示它被1280 * 1280平方切割？
如何将原始照片的方形切割为2448 * 2448图像？

提前致谢。以下是我的代码：

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

   NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
   if ([mediaType isEqualToString:@"public.image"])
   {

    UIImage *imageEdited = [info objectForKey:UIImagePickerControllerEditedImage];
    UIImage *imagePicked = [info objectForKey:UIImagePickerControllerOriginalImage];

    CGRect cropRect;
    cropRect = [[info valueForKey:@"UIImagePickerControllerCropRect"] CGRectValue];

    NSLog(@"Original width = %f height= %f ",imagePicked.size.width, imagePicked.size.height);
    //Original width = 1440.000000 height= 1920.000000

    NSLog(@"imageEdited width = %f height = %f",imageEdited.size.width, imageEdited.size.height);
    //imageEdited width = 640.000000 height = 640.000000

    NSLog(@"corpRect %f %f %f %f", cropRect.origin.x, cropRect.origin.y , cropRect.size.width, cropRect.size.height);
    //corpRect 80.000000 216.000000 1280.000000 1280.000000

    CGRect rectNew = CGRectMake(cropRect.origin.x, cropRect.origin.y , cropRect.size.width*2, cropRect.size.height*2);

    CGRect rectOld = CGRectMake(cropRect.origin.x, cropRect.origin.y , cropRect.size.width, cropRect.size.height);

    CGImageRef imageRefNew = CGImageCreateWithImageInRect([imagePicked CGImage], rectNew);
    CGImageRef imageRefOld = CGImageCreateWithImageInRect([imagePicked CGImage], rectOld);

    UIImageView *imageViewNew = [[UIImageView alloc] initWithImage:[UIImage imageWithCGImage:imageRefNew]];
    CGImageRelease(imageRefNew);

    UIImageView *imageViewOld = [[UIImageView alloc] initWithImage:[UIImage imageWithCGImage:imageRefOld]];
    CGImageRelease(imageRefOld);


    NSLog(@"imageViewNew width = %f height = %f",imageViewNew.image.size.width, imageViewNew.image.size.height);
    //imageViewNew width = 1840.000000 height = 1224.000000

    NSLog(@"imageViewOld width = %f height = %f",imageViewOld.image.size.width, imageViewOld.image.size.height);
    //imageViewOld width = 1280.000000 height = 1224.000000

     UIImageWriteToSavedPhotosAlbum(imageEdited, nil, nil, NULL);

     UIImageWriteToSavedPhotosAlbum([imageViewNew.image imageRotatedByDegrees:90.0], nil, nil, NULL);
     UIImageWriteToSavedPhotosAlbum([imageViewOld.image imageRotatedByDegrees:90.0], nil, nil, NULL);


    //assign the image to an UIImage Control
    self.imageV.contentMode = UIViewContentModeScaleAspectFit;
    self.imageV.frame = CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.width);
    self.imageV.image = imageEdited;


  }

  [self dismissModalViewControllerAnimated:YES];

 }

Answer 1

如您所见，UIImagePickerController将返回缩小的编辑图像，有时640x640有时320x320（取决于设备）。

你的问题：

如何将原始照片的正方形切割为2448 * 2448图像？

要执行此操作，您需要先使用UIImagePickerControllerCropRect从使用信息词典的UIImagePickerControllerOriginalImage键获取的原始图像创建新图像。使用Quartz Core方法CGImageCreateWithImageInRect，您可以创建一个新图像，其中只包含由传递的rect限定的像素;在这种情况下，裁剪矩形。您需要考虑方向才能使其正常工作。然后，您只需将图像缩放到所需的大小。重要的是要注意，裁剪矩形在正确定向后相对于原始图像，而不是从相机或照片库中出来。这就是为什么当我们开始使用Quartz方法创建新图像等时，我们需要转换裁剪矩形以匹配方向。

我上面的代码并将其设置为根据裁剪矩形从原始图像创建1280x1280图像。这里仍然存在一些边缘情况，即考虑到裁剪矩形有时可能具有负值（代码假设方形裁剪矩形）尚未解决。

首先变换裁剪矩形以考虑输入图像的方向和大小。此transformCGRectForUIImageOrientation函数来自NiftyBean
创建裁剪到变换后的裁剪矩形的图像。
将图像缩放（并旋转）到所需的大小。即1280x1280。
使用正确的比例和方向从CGImage创建UIImage。

以下是包含更改的代码：更新在此下方添加了新代码，可以处理丢失的案例。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
NSString *mediaType = [info objectForKey:UIImagePickerControllerMediaType];
if ([mediaType isEqualToString:@"public.image"])
{

    UIImage *imageEdited = [info objectForKey:UIImagePickerControllerEditedImage];
    UIImage *imagePicked = [info objectForKey:UIImagePickerControllerOriginalImage];

    CGRect cropRect;
    cropRect = [[info valueForKey:@"UIImagePickerControllerCropRect"] CGRectValue];

    NSLog(@"Original width = %f height= %f ",imagePicked.size.width, imagePicked.size.height);
    //Original width = 1440.000000 height= 1920.000000

    NSLog(@"imageEdited width = %f height = %f",imageEdited.size.width, imageEdited.size.height);
    //imageEdited width = 640.000000 height = 640.000000

    NSLog(@"corpRect %@", NSStringFromCGRect(cropRect));
    //corpRect 80.000000 216.000000 1280.000000 1280.000000

    CGSize finalSize = CGSizeMake(1280,1280); 
    CGImageRef imagePickedRef = imagePicked.CGImage;

    CGRect transformedRect = transformCGRectForUIImageOrientation(cropRect, imagePicked.imageOrientation, imagePicked.size);
    CGImageRef cropRectImage = CGImageCreateWithImageInRect(imagePickedRef, transformedRect);
    CGColorSpaceRef colorspace = CGImageGetColorSpace(imagePickedRef);
    CGContextRef context = CGBitmapContextCreate(NULL, 
                                                 finalSize.width, 
                                                 finalSize.height,
                                                 CGImageGetBitsPerComponent(imagePickedRef),
                                                 CGImageGetBytesPerRow(imagePickedRef),
                                                 colorspace,
                                                 CGImageGetAlphaInfo(imagePickedRef));
    CGContextSetInterpolationQuality(context, kCGInterpolationHigh); //Give the context a hint that we want high quality during the scale
    CGContextDrawImage(context, CGRectMake(0, 0, finalSize.width, finalSize.height), cropRectImage);
    CGImageRelease(cropRectImage);

    CGImageRef instaImage = CGBitmapContextCreateImage(context);
    CGContextRelease(context);

    //assign the image to an UIImage Control
    UIImage *image = [UIImage imageWithCGImage:instaImage scale:imagePicked.scale orientation:imagePicked.imageOrientation];
    self.imageView.contentMode = UIViewContentModeScaleAspectFit;
    self.imageView.image = image;
    CGImageRelease(instaImage);

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

[self dismissModalViewControllerAnimated:YES];

}

CGRect transformCGRectForUIImageOrientation(CGRect source, UIImageOrientation orientation, CGSize imageSize) {
switch (orientation) {
    case UIImageOrientationLeft: { // EXIF #8
        CGAffineTransform txTranslate = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
        CGAffineTransform txCompound = CGAffineTransformRotate(txTranslate,M_PI_2);
        return CGRectApplyAffineTransform(source, txCompound);
    }
    case UIImageOrientationDown: { // EXIF #3
        CGAffineTransform txTranslate = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
        CGAffineTransform txCompound = CGAffineTransformRotate(txTranslate,M_PI);
        return CGRectApplyAffineTransform(source, txCompound);
    }
    case UIImageOrientationRight: { // EXIF #6
        CGAffineTransform txTranslate = CGAffineTransformMakeTranslation(0.0, imageSize.width);
        CGAffineTransform txCompound = CGAffineTransformRotate(txTranslate,M_PI + M_PI_2);
        return CGRectApplyAffineTransform(source, txCompound);
    }
    case UIImageOrientationUp: // EXIF #1 - do nothing
    default: // EXIF 2,4,5,7 - ignore
        return source;
}
}

更新我已经制定了几种方法来处理其余的情况。这些步骤基本相同，只需进行一些修改。

第一个修改是正确转换和缩放上下文以处理传入图像的方向，
，第二个是支持你可以得到的非方形作物 UIImagePickerController。在这些情况下，方形图像是充满你选择的颜色。

新代码

// CropRect is assumed to be in UIImageOrientationUp, as it is delivered this way from the UIImagePickerController when using AllowsImageEditing is on.
// The sourceImage can be in any orientation, the crop will be transformed to match
// The output image bounds define the final size of the image, the image will be scaled to fit,(AspectFit) the bounds, the fill color will be
// used for areas that are not covered by the scaled image. 
-(UIImage *)cropImage:(UIImage *)sourceImage cropRect:(CGRect)cropRect aspectFitBounds:(CGSize)finalImageSize fillColor:(UIColor *)fillColor {

CGImageRef sourceImageRef = sourceImage.CGImage;

//Since the crop rect is in UIImageOrientationUp we need to transform it to match the source image.
CGAffineTransform rectTransform = [self transformSize:sourceImage.size orientation:sourceImage.imageOrientation];
CGRect transformedRect = CGRectApplyAffineTransform(cropRect, rectTransform);

//Now we get just the region of the source image that we are interested in.
CGImageRef cropRectImage = CGImageCreateWithImageInRect(sourceImageRef, transformedRect);

//Figure out which dimension fits within our final size and calculate the aspect correct rect that will fit in our new bounds
CGFloat horizontalRatio = finalImageSize.width / CGImageGetWidth(cropRectImage);
CGFloat verticalRatio = finalImageSize.height / CGImageGetHeight(cropRectImage);
CGFloat ratio = MIN(horizontalRatio, verticalRatio); //Aspect Fit
CGSize aspectFitSize = CGSizeMake(CGImageGetWidth(cropRectImage) * ratio, CGImageGetHeight(cropRectImage) * ratio);


CGContextRef context = CGBitmapContextCreate(NULL,
                                             finalImageSize.width,
                                             finalImageSize.height,
                                             CGImageGetBitsPerComponent(cropRectImage),
                                             0,
                                             CGImageGetColorSpace(cropRectImage),
                                             CGImageGetBitmapInfo(cropRectImage));

if (context == NULL) {
    NSLog(@"NULL CONTEXT!");
}

//Fill with our background color
CGContextSetFillColorWithColor(context, fillColor.CGColor);
CGContextFillRect(context, CGRectMake(0, 0, finalImageSize.width, finalImageSize.height));

//We need to rotate and transform the context based on the orientation of the source image.
CGAffineTransform contextTransform = [self transformSize:finalImageSize orientation:sourceImage.imageOrientation];
CGContextConcatCTM(context, contextTransform);

//Give the context a hint that we want high quality during the scale
CGContextSetInterpolationQuality(context, kCGInterpolationHigh); 

//Draw our image centered vertically and horizontally in our context.
CGContextDrawImage(context, CGRectMake((finalImageSize.width-aspectFitSize.width)/2, (finalImageSize.height-aspectFitSize.height)/2, aspectFitSize.width, aspectFitSize.height), cropRectImage);

//Start cleaning up..
CGImageRelease(cropRectImage);

CGImageRef finalImageRef = CGBitmapContextCreateImage(context);
UIImage *finalImage = [UIImage imageWithCGImage:finalImageRef];

CGContextRelease(context);
CGImageRelease(finalImageRef);
return finalImage;
}

//Creates a transform that will correctly rotate and translate for the passed orientation.
//Based on code from niftyBean.com
- (CGAffineTransform) transformSize:(CGSize)imageSize orientation:(UIImageOrientation)orientation {

CGAffineTransform transform = CGAffineTransformIdentity;
switch (orientation) {
    case UIImageOrientationLeft: { // EXIF #8
        CGAffineTransform txTranslate = CGAffineTransformMakeTranslation(imageSize.height, 0.0);
        CGAffineTransform txCompound = CGAffineTransformRotate(txTranslate,M_PI_2);
        transform = txCompound;
        break;
    }
    case UIImageOrientationDown: { // EXIF #3
        CGAffineTransform txTranslate = CGAffineTransformMakeTranslation(imageSize.width, imageSize.height);
        CGAffineTransform txCompound = CGAffineTransformRotate(txTranslate,M_PI);
        transform = txCompound;
        break;
    }
    case UIImageOrientationRight: { // EXIF #6
        CGAffineTransform txTranslate = CGAffineTransformMakeTranslation(0.0, imageSize.width);
        CGAffineTransform txCompound = CGAffineTransformRotate(txTranslate,-M_PI_2);
        transform = txCompound;
        break;
    }
    case UIImageOrientationUp: // EXIF #1 - do nothing
    default: // EXIF 2,4,5,7 - ignore
        break;
}
return transform;

}

如何在相机胶卷中对照片进行方形切割？

1 个答案: