得到“修饰过的”来自ALAssetRepresentation的图像 [英] Get the "retouched" image from ALAssetRepresentation

问题描述

鉴于 ALAssetRepresentation ，是否可以获得全分辨率修饰图像？

Given an ALAssetRepresentation, is it possible to get its full resolution retouched image?

如果我使用方法 fullResolutionImage 我会获得完整分辨率图像，但无法以任何方式调整。

If I use the method fullResolutionImage I get the full resolution image, but unadjusted in any way.

如果我使用方法 fullScreenImage 我得到了修饰后的图像，但缩小为适合显示全屏。

If I use the method fullScreenImageI get the retouched image, but reduced to an appropriate for displaying full screen.

推荐答案

这不是那么容易，但你可以。请注意，这也将应用用户在Photos.app中完成的任何裁剪：

It’s not that easy, but you can. Notice that this will also apply any cropping done by the user in the Photos.app:

ALAssetRepresentation *representation = asset.defaultRepresentation;
CGImageRef fullResolutionImage = CGImageRetain(representation.fullResolutionImage);
// AdjustmentXMP constains the Extensible Metadata Platform XML of the photo
// This XML describe the transformation done to the image.
// http://en.wikipedia.org/wiki/Extensible_Metadata_Platform
// Have in mind that the key is not exactly documented.
NSString *adjustmentXMP = [representation.metadata objectForKey:@"AdjustmentXMP"];

NSData *adjustmentXMPData = [adjustmentXMP dataUsingEncoding:NSUTF8StringEncoding];
NSError *__autoreleasing error = nil;
CGRect extend = CGRectZero;
extend.size = representation.dimensions;
NSArray *filters = [CIFilter filterArrayFromSerializedXMP:adjustmentXMPData inputImageExtent:extend error:&error];
if (filters)
{
  CIImage *image = [CIImage imageWithCGImage:fullResolutionImage];
  CIContext *context = [CIContext contextWithOptions:nil];
  for (CIFilter *filter in filters)
  {
    [filter setValue:image forKey:kCIInputImageKey];
    image = [filter outputImage];
  }

  CGImageRelease(fullResolutionImage);
  fullResolutionImage = [context createCGImage:image fromRect:image.extent];
}

// At this moment fullResolutionImage will be the filtered image, or the full
// resolution one if no filters were applied.
// You will need to CGImageRelease fullResolutionImage after you have finished
// working with it.

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