解释XMP-Metadata在Alassetresentation中

Question

当用户对内置的 photos.app 中的照片进行一些更改（裁剪，红眼删除等）时，更改不应用于相应的ALAssetRepresentation返回的fullResolutionImage。

但是，更改应用于thumbnail和ALAssetRepresentation返回的fullScreenImage。此外，有关应用更改的信息可以通过键@"AdjustmentXMP"在ALAssetRepresentation的元数据字典中找到。

我想将这些更改应用于fullResolutionImage自己以保持一致性。我发现在 ios6 CIFilter的filterArrayFromSerializedXMP: inputImageExtent:error:上可以将此XMP-Metadata转换为CIFilter'S的数组：

ALAssetRepresentation *rep; 
NSString *xmpString = rep.metadata[@"AdjustmentXMP"];
NSData *xmpData = [xmpString dataUsingEncoding:NSUTF8StringEncoding];
CIImage *image = [CIImage imageWithCGImage:rep.fullResolutionImage];
NSError *error = nil;
NSArray *filterArray = [CIFilter filterArrayFromSerializedXMP:xmpData 
                                             inputImageExtent:image.extent 
                                                        error:&error];
if (error) {
     NSLog(@"Error during CIFilter creation: %@", [error localizedDescription]);
}
CIContext *context = [CIContext contextWithOptions:nil];
for (CIFilter *filter in filterArray) {
     [filter setValue:image forKey:kCIInputImageKey];
     image = [filter outputImage];
}

但是，这仅适用于某些过滤器（裁剪，自动启动），但不适合其他诸如Red-Eye删除的其他过滤器。在这些情况下，CIFilter S没有明显的效果。因此，我的问题：

• 有人知道一种创建红眼去除CIFilter的方法吗？（以某种方式与照片一致。应用。带键kCIImageAutoAdjustRedEye的过滤器还不够。
• 是否有可能根据iOS 5生成和应用这些过滤器？

Answer 1

ALAssetRepresentation* representation = [[self assetAtIndex:index] defaultRepresentation];
// Create a buffer to hold the data for the asset's image
uint8_t *buffer = (Byte*)malloc(representation.size); // Copy the data from the asset into the buffer
NSUInteger length = [representation getBytes:buffer fromOffset: 0.0  length:representation.size error:nil];
if (length==0)
    return nil;
// Convert the buffer into a NSData object, and free the buffer after.
NSData *adata = [[NSData alloc] initWithBytesNoCopy:buffer length:representation.size freeWhenDone:YES];
// Set up a dictionary with a UTI hint. The UTI hint identifies the type
// of image we are dealing with (that is, a jpeg, png, or a possible
// RAW file).
// Specify the source hint.
NSDictionary* sourceOptionsDict = [NSDictionary dictionaryWithObjectsAndKeys:
(id)[representation UTI], kCGImageSourceTypeIdentifierHint, nil];
// Create a CGImageSource with the NSData. A image source can
// contain x number of thumbnails and full images.
CGImageSourceRef sourceRef = CGImageSourceCreateWithData((CFDataRef) adata,  (CFDictionaryRef) sourceOptionsDict);
[adata release];
CFDictionaryRef imagePropertiesDictionary;
// Get a copy of the image properties from the CGImageSourceRef.
imagePropertiesDictionary = CGImageSourceCopyPropertiesAtIndex(sourceRef,0, NULL);
CFNumberRef imageWidth = (CFNumberRef)CFDictionaryGetValue(imagePropertiesDictionary, kCGImagePropertyPixelWidth);
CFNumberRef imageHeight = (CFNumberRef)CFDictionaryGetValue(imagePropertiesDictionary, kCGImagePropertyPixelHeight);
int w = 0;
int h = 0;
CFNumberGetValue(imageWidth, kCFNumberIntType, &w);
CFNumberGetValue(imageHeight, kCFNumberIntType, &h);
// Clean up memory
CFRelease(imagePropertiesDictionary);