iphone - AVFoundation 图像变得异常黑暗

Question

我正在使用 AVFoundation 自动拍照，但拍出来的照片很暗。如果你在 iPhone 4 上使用闪光灯，后置摄像头还可以，但前置摄像头基本上是一个黑色方 block ，只有图片中物体最模糊的轮廓。

我为两个相机设置了以下设置，但似乎没有什么区别:

if (device.hasFlash) {
        NSLog(@"device.hasFlash turning flash mode on");
        [device lockForConfiguration:&deviceError];
        device.flashMode = AVCaptureFlashModeOn;
        [device unlockForConfiguration];
    }
    else {
        NSLog(@"Device does not have Flash");
    }

    if ([device isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
        NSLog(@"Enabling ContinuousAutoFocus");
        [device lockForConfiguration:&deviceError];
        device.focusMode = AVCaptureFocusModeContinuousAutoFocus;
        [device unlockForConfiguration];
    }
    else {
        NSLog(@"Device does not support ContinuousAutoFocus");
    }

    if ([device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
        NSLog(@"Enabling ContinuousAutoExposure");
        [device lockForConfiguration:&deviceError];
        device.exposureMode = AVCaptureExposureModeContinuousAutoExposure;
        [device unlockForConfiguration];
    }
    else {
        NSLog(@"Device does not support ContinuousAutoExposure");
    }

    if ([device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance]) {
        NSLog(@"Enabling ContinuousAutoWhiteBalance");
        [device lockForConfiguration:&deviceError];
        device.whiteBalanceMode = AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance;
        [device unlockForConfiguration];
    }
    else {
        NSLog(@"Device does not support ContinuousAutoWhiteBalance");
    }

有什么想法吗？

Answer 1

前置摄像头需要一段时间来调整其白平衡。您可能需要 KVO isAdjustingWhiteBalance 设备属性，并且仅在属性第一次从 NO 变为 YES 并返回 NO 后触发捕获。