How to save a TIFF photo from AVFoundations captureStillImageAsynchronouslyFromConnection to a file with EXIF metadata on an iPhone (iOS)?

Question

With this question I only ask for the possibilities I have with Xcode and iOS without external libraries. I am already exploring the possibility of using libtiff

Answer 1

As you've already cracked 1, 3 and 4, it seems the only hurdle you're missing is saving the data and metadata together. Try this (assuming the unprocessed data is in a CMSampleBufferRef called myImageDataSampleBuffer and you've done the heavy lifting of putting the graphical data into a CGImageRef called myImage):

CFDictionaryRef metadata = CMCopyDictionaryOfAttachments(kCFAllocatorDefault,
  myImageDataSampleBuffer,
  kCMAttachmentMode_ShouldPropagate);
NSFileManager* fm = [[NSFileManager alloc] init];
NSURL* pathUrl = [fm URLForDirectory:saveDir
  inDomain:NSUserDomainMask
  appropriateForURL:nil
  create:YES
  error:nil];
NSURL* saveUrl = [pathUrl URLByAppendingPathComponent:@"myfilename.tif"];
CGImageDestinationRef destination = CGImageDestinationCreateWithURL((__bridge CFURLRef)saveUrl,
  (CFStringRef)@"public.tiff", 1, NULL);
CGImageDestinationAddImage(destination, myImage, metadata);
CGImageDestinationFinalize(destination);
CFRelease(destination);

Answer 2

This thread was very helpful in resolving a very similar problem, so I thought I'd contribute a Swift 2.0 implementation of the solution in case someone comes looking.

stillImageOutput?.captureStillImageAsynchronouslyFromConnection(videoConnection, completionHandler: { (imageDataSampleBuffer, error) -> Void in


    // get image meta data (EXIF, etc)
    let metaData: CFDictionaryRef? = CMCopyDictionaryOfAttachments( kCFAllocatorDefault, imageDataSampleBuffer, kCMAttachmentMode_ShouldPropagate )


    // get reference to image
    guard let imageBuffer = CMSampleBufferGetImageBuffer( imageDataSampleBuffer ) else { return }


    // lock the buffer
    CVPixelBufferLockBaseAddress( imageBuffer, 0 )


    // read image properties
    let baseAddress = CVPixelBufferGetBaseAddress( imageBuffer )

    let bytesPerRow = CVPixelBufferGetBytesPerRow( imageBuffer )

    let width = CVPixelBufferGetWidth( imageBuffer )

    let height = CVPixelBufferGetHeight( imageBuffer )


    // color space
    let colorSpace = CGColorSpaceCreateDeviceRGB()


    // context - camera output settings kCVPixelFormatType_32BGRA
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedFirst.rawValue).union(.ByteOrder32Little)

    let newContext = CGBitmapContextCreate( baseAddress, width, height, 8, bytesPerRow, colorSpace, bitmapInfo.rawValue )


    //unlock buffer
    CVPixelBufferUnlockBaseAddress( imageBuffer, 0 )

    //Create a CGImageRef from the CVImageBufferRef
    guard let newImage = CGBitmapContextCreateImage( newContext ) else {
        return
    }


    // create tmp file and write image with metadata
    let fileName = String(format: "%@_%@", NSProcessInfo.processInfo().globallyUniqueString, "cap.tiff")
    let fileURL = NSURL(fileURLWithPath: NSTemporaryDirectory()).URLByAppendingPathComponent(fileName)

    if let destination = CGImageDestinationCreateWithURL( fileURL, kUTTypeTIFF, 1, nil) {

        CGImageDestinationAddImage( destination, newImage, metaData )

        let wrote = CGImageDestinationFinalize( destination )

        if !wrote || NSFileManager.defaultManager().fileExistsAtPath(fileURL.URLString) {

            return

        }

    }

}

p.s. for this to work, you have to configure your image buffer like this:

    stillImageOutput = AVCaptureStillImageOutput()

    stillImageOutput?.outputSettings = [ kCVPixelBufferPixelFormatTypeKey: Int(kCVPixelFormatType_32BGRA) ]