Ios 如何覆盖图像元数据？
如果使用CGImageDestination的原始图像元数据中已经存在key/val，则我似乎无法将图像元数据正确写入图像。如果在原始元数据中不存在key/val，则可以正常工作 就好像原始图像中的图像元数据属性优先于修改。这是我不知道的某种拜占庭式格式问题，我需要以某种不寻常的方式填充key/val，是一个bug，还是？还有人看到这个吗 下面的代码和输出，适用于它正常工作（如果尚未设置值）和写入失败（如果已将值设置为其他值）的两种情况 非常感谢您的帮助 以下是我创建图像数据的位置/方式：Ios 如何覆盖图像元数据？,ios,objective-c,cocoa,metadata,Ios,Objective C,Cocoa,Metadata,如果使用CGImageDestination的原始图像元数据中已经存在key/val，则我似乎无法将图像元数据正确写入图像。如果在原始元数据中不存在key/val，则可以正常工作 就好像原始图像中的图像元数据属性优先于修改。这是我不知道的某种拜占庭式格式问题，我需要以某种不寻常的方式填充key/val，是一个bug，还是？还有人看到这个吗 下面的代码和输出，适用于它正常工作（如果尚未设置值）和写入失败（如果已将值设置为其他值）的两种情况 非常感谢您的帮助 以下是我创建图像数据的位置/方式： //
// convert the existing asset to nsdata to overwrite itself
ALAssetRepresentation* rep = [asset defaultRepresentation];
Byte* buffer = (Byte*)malloc(rep.size);
NSUInteger buffered = [rep getBytes:buffer fromOffset:0.0 length:rep.size error:nil];
NSData* imageData = [NSData dataWithBytesNoCopy:buffer length:buffered freeWhenDone:YES];
// write the metadata directly into the nsdata of the image itself
NSData* newImage = [self writeMetadataIntoImageData:imageData metadata:newMetadata];
- (NSData*)writeMetadataIntoImageData:(NSData*)imageData metadata:(NSMutableDictionary*)metadataAsMutable
{
// create an imagesourceref
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef) imageData, NULL);
// read and log pre write metadata
NSDictionary* metadata = (NSDictionary *) CFBridgingRelease(CGImageSourceCopyPropertiesAtIndex(source,0,NULL));
NSLog(@"Before:\n------------------------------%@\n------------------------------", metadata);
// set the new metadata keys here
NSMutableDictionary* iptc = [metadataAsMutable[(NSString*)kCGImagePropertyIPTCDictionary] mutableCopy];
if (!iptc)
{
iptc = [NSMutableDictionary dictionaryWithCapacity:1];
}
iptc[(NSString*)kCGImagePropertyIPTCCaptionAbstract] = @"Hardcoded Caption";
metadataAsMutable[(NSString*)kCGImagePropertyIPTCDictionary] = iptc;
// log the new metadata as we want it written
NSLog(@"Parameter:\n------------------------------%@\n------------------------------", metadataAsMutable);
// this is the type of image (e.g., public.jpeg)
CFStringRef UTI = CGImageSourceGetType(source);
// create a new data object and write the new image into it
NSMutableData *dest_data = [NSMutableData data];
CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)dest_data,UTI,1,NULL);
if(!destination)
{
NSLog(@"Error: Could not create image destination");
}
// add the image contained in the image source to the destination, overidding the old metadata with our modified metadata
CGImageDestinationAddImageFromSource(destination,source,0, (__bridge CFDictionaryRef) metadataAsMutable);
BOOL success = NO;
success = CGImageDestinationFinalize(destination);
if(!success)
{
NSLog(@"Error: Could not create data from image destination");
}
// read and log post write metadata
CGImageSourceRef source2;
source2 = CGImageSourceCreateWithData((__bridge CFDataRef) dest_data, NULL);
NSDictionary *metadata2 = (NSDictionary *) CFBridgingRelease(CGImageSourceCopyPropertiesAtIndex(source2,0,NULL));
NSLog(@"After:\n------------------------------%@\n------------------------------", metadata2);
// cleanup
CFRelease(destination);
// return the new data
return dest_data;
}
Before:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = Blurry;
DateCreated = 20130923;
DigitalCreationDate = 20130923;
DigitalCreationTime = 173815;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 173815;
};
<...snip...>
}
------------------------------
Parameter:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = "Hardcoded Caption";
DateCreated = 20130923;
DigitalCreationDate = 20130923;
DigitalCreationTime = 173815;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 173815;
};
<...snip...>
}
------------------------------
After:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = Blurry;
DateCreated = 20130923;
DigitalCreationDate = 20130923;
DigitalCreationTime = 173815;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 173815;
};
<...snip...>
}
------------------------------
Before:
------------------------------{
<...snip...>
"{IPTC}" = {
DateCreated = 20130925;
DigitalCreationDate = 20130925;
DigitalCreationTime = 192856;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 192856;
};
<...snip...>
}
------------------------------
Parameter:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = "Hardcoded Caption";
DateCreated = 20130925;
DigitalCreationDate = 20130925;
DigitalCreationTime = 192856;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 192856;
};
<...snip...>
}
------------------------------
After:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = "Hardcoded Caption";
DateCreated = 20130925;
DigitalCreationDate = 20130925;
DigitalCreationTime = 192856;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 192856;
};
<...snip...>
}
------------------------------
之前：
------------------------------{
“{IPTC}”={
“标题/摘要”=模糊；
创建日期=20130923；
DigitalCreationDate=20130923；
DigitalCreationTime=173815；
关键词=(
伪造的
);
补充分类=(
伪造的
);
创建的时间=173815；
};
}
------------------------------
参数：
------------------------------{
“{IPTC}”={
“标题/摘要”=“硬编码标题”；
创建日期=20130923；
DigitalCreationDate=20130923；
DigitalCreationTime=173815；
关键词=(
伪造的
);
补充分类=(
伪造的
);
创建的时间=173815；
};
}
------------------------------
之后：
------------------------------{
“{IPTC}”={
“标题/摘要”=模糊；
创建日期=20130923；
DigitalCreationDate=20130923；
DigitalCreationTime=173815；
关键词=(
伪造的
);
补充分类=(
伪造的
);
创建的时间=173815；
};
}
------------------------------
Before:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = Blurry;
DateCreated = 20130923;
DigitalCreationDate = 20130923;
DigitalCreationTime = 173815;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 173815;
};
<...snip...>
}
------------------------------
Parameter:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = "Hardcoded Caption";
DateCreated = 20130923;
DigitalCreationDate = 20130923;
DigitalCreationTime = 173815;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 173815;
};
<...snip...>
}
------------------------------
After:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = Blurry;
DateCreated = 20130923;
DigitalCreationDate = 20130923;
DigitalCreationTime = 173815;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 173815;
};
<...snip...>
}
------------------------------
Before:
------------------------------{
<...snip...>
"{IPTC}" = {
DateCreated = 20130925;
DigitalCreationDate = 20130925;
DigitalCreationTime = 192856;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 192856;
};
<...snip...>
}
------------------------------
Parameter:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = "Hardcoded Caption";
DateCreated = 20130925;
DigitalCreationDate = 20130925;
DigitalCreationTime = 192856;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 192856;
};
<...snip...>
}
------------------------------
After:
------------------------------{
<...snip...>
"{IPTC}" = {
"Caption/Abstract" = "Hardcoded Caption";
DateCreated = 20130925;
DigitalCreationDate = 20130925;
DigitalCreationTime = 192856;
Keywords = (
fake
);
SupplementalCategory = (
fake
);
TimeCreated = 192856;
};
<...snip...>
}
------------------------------
之前：
------------------------------{
“{IPTC}”={
创建日期=20130925；
DigitalCreationDate=20130925；
DigitalCreationTime=192856；
关键词=(
伪造的
);
补充分类=(
伪造的
);
创建时间=192856；
};
}
------------------------------
参数：
------------------------------{
“{IPTC}”={
“标题/摘要”=“硬编码标题”；
创建日期=20130925；
DigitalCreationDate=20130925；
DigitalCreationTime=192856；
关键词=(
伪造的
);
补充分类=(
伪造的
);
创建时间=192856；
};
}
------------------------------
之后：
------------------------------{
“{IPTC}”={
“标题/摘要”=“硬编码标题”；
创建日期=20130925；
DigitalCreationDate=20130925；
DigitalCreationTime=192856；
关键词=(
伪造的
);
补充分类=(
伪造的
);
创建时间=192856；
};
}
------------------------------
感谢用户2452250提供的提示。我也尝试了CGImageDestinationCopyImageSource，但如果您多次编辑同一文件，则会损坏JPEG数据流。苹果技术支持事件开始…你好，斯科特！有什么消息吗？我也有同样的问题！请让我知道！看看这篇文章：Image/IO在元数据方面很弱。我建议您使用Adobe的XMP工具包。您可以将XMP数据读/写为所有媒体格式，如图像、视频、pdf等。我试图在这里解释。好的，伙计们！我找到了解决办法！根据IPTC文档，描述字段绑定到TIFF和EXIF地址。更改TIFF中的值也会更新IPTC条目！既然我不能给自己投票权，如果莫哈奇可以把这个作为答案，我可以给+50而不是扔掉它！：）伟大的可以在大约一小时内分配50个！谢谢你的帮助，感谢你迟来的赏金！忘了。。给你。。及时D@mohacs-我遵循了问题中的代码，并且看起来原始图像中的图像元数据属性优先于修改。我试图应用用户2452250的答案，但可能我还不够理解。如果你想了解我的观点，我确实有一个问题：某个白痴拥有比智力更大的权威，并将其标记为另一个问题的复制品。如果有什么的话，那就是这个的复制品。你能帮忙吗？@Lucy，关于你的问题：增加DPI并不会使图像变大。DPI用于确定打印图像的大小。无任何内容。@mohacs-让我们假设我不希望图像变大。让我们假设我所要做的就是将dpi从72更改为500。有办法吗？