問題描述

我知道如何使用 ALAssets 保存元數據.但是，我想保存圖像，或將其上傳到某個地方，exif 完好無損.我有 exif 數據作為 NSDictionary.但是我怎樣才能將它正確地注入 UIImage(或者可能是 NSData JPEG 表示)?

I am aware of how to save metadata using ALAssets. But, I want to save an image, or upload it somewhere, with exif intact. I have exif data as an NSDictionary. But how can I inject it properly into a UIImage (or probably an NSData JPEG representation)?

推薦答案

UIImage 不包含元數據信息(被剝離).因此，如果您想在不使用 imagepicker 方法的情況下保存它(不在相機膠卷中):

UIImage does not contain metadata information (it is stripped). So if you want to save it without using the imagepicker method (not in camera roll):

按照此處的答案寫入元數據完整的文件:

Follow the answer here to write to a file with the metadata intact:

圖片的exif數據設置問題

不知道為什么會被否決，但方法如下:

no idea why would this be downvoted but here is the method:

在這種情況下，我通過 AVFoundation 獲取圖像，這就是

In this case im getting the image through AVFoundation and this is what goes in the

[[self stillImageOutput] captureStillImageAsynchronouslyFromConnection:videoConnection 
                                                     completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error) 
{
    // code here
}

塊代碼:

    CFDictionaryRef metaDict = CMCopyDictionaryOfAttachments(NULL, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);

    CFMutableDictionaryRef mutable = CFDictionaryCreateMutableCopy(NULL, 0, metaDict);

    // Create formatted date
    NSTimeZone      *timeZone   = [NSTimeZone timeZoneWithName:@"UTC"];
    NSDateFormatter *formatter  = [[NSDateFormatter alloc] init]; 
    [formatter setTimeZone:timeZone];
    [formatter setDateFormat:@"HH:mm:ss.SS"];

    // Create GPS Dictionary
    NSDictionary *gpsDict   = [NSDictionary dictionaryWithObjectsAndKeys:
                               [NSNumber numberWithFloat:fabs(loc.coordinate.latitude)], kCGImagePropertyGPSLatitude
                               , ((loc.coordinate.latitude >= 0) ? @"N" : @"S"), kCGImagePropertyGPSLatitudeRef
                               , [NSNumber numberWithFloat:fabs(loc.coordinate.longitude)], kCGImagePropertyGPSLongitude
                               , ((loc.coordinate.longitude >= 0) ? @"E" : @"W"), kCGImagePropertyGPSLongitudeRef
                               , [formatter stringFromDate:[loc timestamp]], kCGImagePropertyGPSTimeStamp
                               , [NSNumber numberWithFloat:fabs(loc.altitude)], kCGImagePropertyGPSAltitude
                               , nil];  

    // The gps info goes into the gps metadata part

    CFDictionarySetValue(mutable, kCGImagePropertyGPSDictionary, (__bridge void *)gpsDict);

    // Here just as an example im adding the attitude matrix in the exif comment metadata

    CMRotationMatrix m = att.rotationMatrix;
    GLKMatrix4 attMat = GLKMatrix4Make(m.m11, m.m12, m.m13, 0, m.m21, m.m22, m.m23, 0, m.m31, m.m32, m.m33, 0, 0, 0, 0, 1);

    NSMutableDictionary *EXIFDictionary = (__bridge NSMutableDictionary*)CFDictionaryGetValue(mutable, kCGImagePropertyExifDictionary);

    [EXIFDictionary setValue:NSStringFromGLKMatrix4(attMat) forKey:(NSString *)kCGImagePropertyExifUserComment];

    CFDictionarySetValue(mutable, kCGImagePropertyExifDictionary, (__bridge void *)EXIFDictionary);

    NSData *jpeg = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer] ;

在此代碼之后，您將在 jpeg nsdata 中獲得您的圖像，并在可變 cfdictionary 中獲得該圖像的對應字典.

After this code you will have your image in the jpeg nsdata and the correspoding dictionary for that image in the mutable cfdictionary.

你現在要做的就是:

    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)jpeg, NULL);

    CFStringRef UTI = CGImageSourceGetType(source); //this is the type of image (e.g., public.jpeg)

    NSMutableData *dest_data = [NSMutableData data];


    CGImageDestinationRef destination = CGImageDestinationCreateWithData((__bridge CFMutableDataRef)dest_data,UTI,1,NULL);

    if(!destination) {
        NSLog(@"***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, (CFDictionaryRef) mutable);

    //tell the destination to write the image data and metadata into our data object.
    //It will return false if something goes wrong
    BOOL success = CGImageDestinationFinalize(destination);

    if(!success) {
        NSLog(@"***Could not create data from image destination ***");
    }

    //now we have the data ready to go, so do whatever you want with it
    //here we just write it to disk at the same path we were passed

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); 
    NSString *documentsDirectory = [paths objectAtIndex:0]; // Get documents folder
    NSString *dataPath = [documentsDirectory stringByAppendingPathComponent:@"ImagesFolder"];

    NSError *error;
    if (![[NSFileManager defaultManager] fileExistsAtPath:dataPath])
        [[NSFileManager defaultManager] createDirectoryAtPath:dataPath withIntermediateDirectories:NO attributes:nil error:&error]; //Create folder

    //    NSString *imageName = @"ImageName";

    NSString *fullPath = [dataPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.jpg", name]]; //add our image to the path

    [dest_data writeToFile:fullPath atomically:YES];

    //cleanup

    CFRelease(destination);
    CFRelease(source);

請注意我不是使用 ALAssets 而是直接保存到我選擇的文件夾中.

Note how I'm not saving using the ALAssets but directly into a folder of my choice.

順便說一句，大部分代碼都可以在我最初發布的鏈接中找到.

Btw most of this code can be found in the link I posted at first.

這篇關于如何將 exif 元數據寫入圖像(不是相機膠卷，只是 UIImage 或 JPEG)的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！