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POHow to get shutter speed, aperture, and ISO values on iPhone
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copied!<p>I have written code like this : </p> <pre><code>-(IBAction)startCapture { //session object captureSession = [[AVCaptureSession alloc]init]; captureSession.sessionPreset = AVCaptureSessionPresetMedium; AVCaptureVideoPreviewLayer *previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession]; previewLayer.frame = CGRectMake(0, 10, 320, 200); ////self.view.frame; // [self.view.layer addSublayer:previewLayer]; NSError *error = nil; AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; //input object AVCaptureDeviceInput *inputDevice = [[AVCaptureDeviceInput alloc]initWithDevice:device error:&error]; [captureSession addInput:inputDevice]; stillImageOutput = [[AVCaptureStillImageOutput alloc] init]; NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil]; [stillImageOutput setOutputSettings:outputSettings]; [captureSession addOutput:stillImageOutput]; [captureSession startRunning]; } -(IBAction) captureNow { AVCaptureConnection *videoConnection = nil; for (AVCaptureConnection *connection in stillImageOutput.connections) { for (AVCaptureInputPort *port in [connection inputPorts]) { if ([[port mediaType] isEqual:AVMediaTypeVideo] ) { videoConnection = connection; break; } } if (videoConnection) { break; } } NSLog(@"about to request a capture from: %@", stillImageOutput); [stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) { CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL); NSLog(@"exif Attachments:%@",exifAttachments); if (exifAttachments) { NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer]; UIImage *image = [[UIImage alloc] initWithData:imageData]; self.vImage.image = image; // Do something with the attachments. } else NSLog(@"no attachments"); }]; } </code></pre> <p>to capture the images. But I want to know the shutter speed, ISO value and aperture while capturing. How can I find out these values? I tried the following:</p> <pre><code>[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) { CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL); NSDictionary *exifDict = (NSDictionary *)exifAttachments; NSLog(@"\n exif data = %@",exifDict); CFNumberRef aperaturevalue = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifApertureValue, NULL); NSNumber *num = (NSNumber *)aperaturevalue; NSLog(@"\n AperatureValue : %@",num); CFNumberRef shutter = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifShutterSpeedValue, NULL); NSNumber *shunum = (NSNumber *)shutter; NSLog(@"\n shuttervalue : %@",shunum); CFArrayRef isoRef = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifISOSpeedRatings, NULL); NSArray *iso = (NSArray *)isoRef; NSLog(@"Iso value : %@",iso); } </code></pre> <p>but it is giving output like this:</p> <pre class="lang-none prettyprint-override"><code>exif data = { ApertureValue = "2.970853605202583"; ExposureMode = 0; ExposureProgram = 2; FNumber = "2.8"; Flash = 32; MeteringMode = 1; SceneType = 1; SensingMethod = 2; WhiteBalance = 0; } 2011-06-23 14:35:14.955 CameraExample[1464:307] AperatureValue : (null) 2011-06-23 14:35:14.981 CameraExample[1464:307] shuttervalue : (null) 2011-06-23 14:35:14.999 CameraExample[1464:307] Iso value : (null) </code></pre>

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