如何在iPhone SDK中自動對焦照片？

我正在創建一個應用程序，用戶在該應用程序中使用文本拍攝圖片並上傳到服務器。我使用AVCaptureSession來打開攝像頭並放置一個條形按鈕，它捕獲最新的幀並將其上傳到服務器。在這個應用程序中，用戶可以通過單擊條形圖按鈕，將多個圖像逐個發送到服務器。如何在iPhone SDK中自動對焦照片？

我想知道是否有可能用戶不必按下按鈕來捕捉框架。這是否有可能通過自動對焦自動捕捉當前幀？就像用戶只需將相機放在圖像上一秒鐘，當圖像聚焦時，它會自動捕獲，以便用戶可以移動到下一個圖像，而無需按任何按鈕？

我的代碼來捕獲框架如下：

- (void)initCapture { 

    AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput 
              deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] 
              error:nil]; 

    AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init]; 

    captureOutput.alwaysDiscardsLateVideoFrames = YES; 







    /*We create a serial queue to handle the processing of our frames*/ 
    dispatch_queue_t queue; 
    queue = dispatch_queue_create("cameraQueue", NULL); 
    [captureOutput setSampleBufferDelegate:self queue:queue]; 
    dispatch_release(queue); 
    // Set the video output to store frame in BGRA (It is supposed to be faster) 
    NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey; 
    NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]; 
    NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key]; 
    [captureOutput setVideoSettings:videoSettings]; 
    /*And we create a capture session*/ 
    captureSession = [[AVCaptureSession alloc] init]; 
    /*We add input and output*/ 
    [captureSession addInput:captureInput]; 
    [captureSession addOutput:captureOutput]; 





    AVCaptureConnection *conn = [captureOutput connectionWithMediaType:AVMediaTypeVideo]; 

    if (conn.supportsVideoMinFrameDuration) 
     conn.videoMinFrameDuration = CMTimeMake(5,1); 
    if (conn.supportsVideoMaxFrameDuration) 
     conn.videoMaxFrameDuration = CMTimeMake(5,1); 





    [captureSession setSessionPreset:AVCaptureSessionPresetPhoto]; 

    customLayer = [CALayer layer]; 
    customLayer.frame = self.view.bounds; 
    customLayer.transform = CATransform3DRotate(CATransform3DIdentity, M_PI/2.0f, 0, 0, 1); 
    customLayer.contentsGravity = kCAGravityResizeAspectFill; 
    //[self.view.layer addSublayer:customLayer]; 
    /*We add the imageView*/ 



    imageView = [[UIImageView alloc] init]; 
    imageView.frame = CGRectMake(0, 0, 100, 100); 
    //imageView.frame = self.view.bounds; 
    [self.view addSubview:imageView]; 



    [captureSession startRunning]; 

}

我將是你的幫助表示感謝。謝謝。

來源

2012-07-10 Pankaj Kainthla

你得到這個工作？只要標準在感興趣的區域實現，我需要自動捕獲圖像。所以，如果我正確理解這一點，我需要添加AVCaptureVideoDataOutput來接收相機信息，並使用adjustFocus觀察者來捕獲靜物圖像。你有什麼想法，我怎樣才能定義感興趣的區域（視圖的子部分），並忽略其餘的視圖？ – Patricia 2014-09-04 17:26:28

你必須adjustingFocus觀察者添加到您的視頻輸入：

[[[captureManager videoInput] device] addObserver:self forKeyPath:@"adjustingFocus" options:NSKeyValueObservingOptionNew context:nil];

然後添加observeValueForKeyPath方法，它在調節對焦完成一張照片：

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context { 
if([keyPath isEqualToString:@"adjustingFocus"]){ 
    BOOL adjustingFocus = [ [change objectForKey:NSKeyValueChangeNewKey] isEqualToNumber:[NSNumber numberWithInt:1] ]; 

    if (!adjustingFocus) { 
      [[self captureManager] captureStillImage:self]; 
     } 
    } 
}

來源

2013-03-06 09:15:22

captureManager在哪裏聲明？ – Biranchi 2015-05-21 08:06:05

如何在iPhone SDK中自動對焦照片？

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