3

带着这个问题，我只询问我在没有外部库的情况下使用 Xcode 和 iOS 的可能性。我已经在探索libtiff在另一个问题中使用的可能性。

问题

几周以来，我一直在筛选堆栈溢出，并为自己的每一个问题找到了可行的解决方案。我有 4 件事需要做：

  1. 我需要来自相机的 RGBA 数据，没有任何压缩
  2. 我需要尽可能多的元数据，尤其是 EXIF
  3. 我需要保存为 TIFF 格式，以便与其他软件兼容和无损
  4. 我需要通过保存在文件而不是照片库中来防止随意查看

我可以使用 JPEG 获得 2 和 4。我可以使用从相机缓冲区制作的原始数据（分别为 NSData）获得 1、3 和 4。我可以使用 Xcode 和 iOS 满足所有 4 个先决条件吗？我即将放弃并寻找您的意见作为最后的手段。

在仍在探索这一点的同时，我也被困在了我尝试过的另一条途径libtiff上。我还在努力，虽然...

这是我尝试过的好建议列表，我自己的代码只是从堆栈溢出源中组合而成，如下所示：

解决方案

完整的动作序列captureStillImageAsynchronouslyFromConnection：

[[self myAVCaptureStillImageOutput] captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
 {
     //get all the metadata in the image
     CFDictionaryRef metadata = CMCopyDictionaryOfAttachments(kCFAllocatorDefault, imageSampleBuffer, kCMAttachmentMode_ShouldPropagate);
     // get image reference
     CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(imageSampleBuffer);
     // >>>>>>>>>> lock buffer address
     CVPixelBufferLockBaseAddress(imageBuffer, 0);

     //Get information about the image
     uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
     size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
     size_t width = CVPixelBufferGetWidth(imageBuffer);
     size_t height = CVPixelBufferGetHeight(imageBuffer);

     // create suitable color space
     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

     //Create suitable context (suitable for camera output setting kCVPixelFormatType_32BGRA)
     CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);

     // <<<<<<<<<< unlock buffer address
     CVPixelBufferUnlockBaseAddress(imageBuffer, 0);

     // release color space
     CGColorSpaceRelease(colorSpace);

     //Create a CGImageRef from the CVImageBufferRef
     CGImageRef newImage = CGBitmapContextCreateImage(newContext);

     // release context
     CGContextRelease(newContext);

     // create destination and write image with metadata
     CFURLRef url = (__bridge CFURLRef)[NSURL fileURLWithPath:filePath isDirectory:NO];
     CGImageDestinationRef destination = CGImageDestinationCreateWithURL(url, kUTTypeTIFF, 1, NULL);
     CGImageDestinationAddImage(destination, imageRef, metadata);

     // finalize and release destination
     CGImageDestinationFinalize(destination);
     CFRelease(destination);
 }

静止图像输出相关的相机设置为：

[[self myAVCaptureSession] setSessionPreset:AVCaptureSessionPresetPhoto];

和

NSDictionary *outputSettings = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA], (id)kCVPixelBufferPixelFormatTypeKey, nil];
[myAVCaptureStillImageOutput setOutputSettings:outputSettings];

我得到了一个带有所有元数据的标称 TIFF 格式的标称未压缩图像。（它在其他系统上进行了镜像，但现在我可以编写 EXIF 和其他元数据，我也可以对其进行微调，我敢肯定）。

再次感谢Wildaker的帮助！

4

2 回答 2

2

由于您已经破解了 1、3 和 4，看来您缺少的唯一障碍是将数据和元数据保存在一起。试试这个（假设未处理的数据在CMSampleBufferRef被调用并且你已经完成了将图形数据放入被调用myImageDataSampleBuffer的繁重工作）：CGImageRefmyImage

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);
于 2013-07-01T06:43:00.107 回答
2

这个线程对于解决一个非常相似的问题非常有帮助，所以我想我会贡献一个解决方案的 Swift 2.0 实现，以防有人来看。

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

        }

    }

}

ps 为此，您必须像这样配置图像缓冲区：

    stillImageOutput = AVCaptureStillImageOutput()

    stillImageOutput?.outputSettings = [ kCVPixelBufferPixelFormatTypeKey: Int(kCVPixelFormatType_32BGRA) ]
于 2016-06-03T09:06:36.227 回答