即使打开闪光灯,AVCaptureOutput也会拍摄黑暗照片

Question

我想出了AVFoundation和ImageIO的实现来处理我的应用程序中的照片.不过,我有一个问题.即使闪光灯熄灭,我拍摄的图像也总是很暗.这是我使用的代码:

        [[self currentCaptureOutput] captureStillImageAsynchronouslyFromConnection:[[self currentCaptureOutput].connections lastObject]
                                        completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {

                                            [[[blockSelf currentPreviewLayer] session] stopRunning];
                                            if (!error) {
                                                NSData *data            = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                                                CGImageSourceRef source = CGImageSourceCreateWithData((CFDataRef) data, NULL);

                                                if (source) {

                                                    UIImage *image = [blockSelf imageWithSource:source];
                                                    [blockSelf updateWithCapturedImage:image];
                                                    CFRelease(source);

                                                }

                                            }

                                        }];

有没有什么可以导致图像不包括闪光灯？

Answer 1

我发现如果在此次通话之前立即设置了AVCaptureSession,我有时会出现黑暗图像.也许自动曝光和白平衡设置需要一段时间才能自行调整.

解决方案是设置AVCaptureSession,然后在调用之前等待AVCaptureDevice adjustingExposure和adjustingWhiteBalance属性NO(用KVO观察)-[AVCaptureStillImageOutput captureStillImageAsynchronouslyFromConnection: completionHandler:].