解读XMP元数据中ALAssetRepresentation

 

当用户进行某些更改（裁剪，消除红眼，...），在内置 Photos.app iOS上，这些更改将不会应用到由相应

fullResolutionImage

返回的

ALAssetRepresentation

照片.

但是，这些更改应用到

thumbnail

并由

fullScreenImage

返回的

ALAssetRepresentation

.
此外，有关应用的更改信息可以在

ALAssetRepresentation

的元数据字典通过key

@"AdjustmentXMP"

发现.

我想这些更改应用到

fullResolutionImage

自己保持一致性.我发现在 iOS6的+

CIFilter

的

filterArrayFromSerializedXMP: inputImageExtent:error:

可以在此XMP元数据转换的

CIFilter

数组的：

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];
}

 

然而，这仅适用于某些过滤器（裁剪，自动提升），但不是为别人像去除红眼.在这些情况下，

CIFilter

s有没有可见的效果.因此，我的问题：

• 有没有人知道的方式来创建红眼消除

  CIFilter

  ？ （在与Photos.app一致的方式，与关键

  kCIImageAutoAdjustRedEye

  该过滤器是不够的.例如，它没有考虑对眼睛的位置参数.）

• 有没有一种可能的iOS 5下产生并应用这些过滤器？

 

 

 

解答

 

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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, free the buffer after

NSData *adata = [[NSData alloc] initWithBytesNoCopy:buffer length:representation.size freeWhenDone:YES];

// setup a dictionary with a UTI hint. The UTI hint identifies the type of image we are dealing with (ie. 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);

// cleanup memory

CFRelease(imagePropertiesDictionary);