自定義相機AVCaptureDevice近距離拍照模糊,無法聚焦問題。
問題描述
最近在寫iOS身份證識別demo的時候發現,使用iPhone14Pro近距離識別的時候,身份證距離手機攝像頭20CM以內,非常模糊根本看不清,各種辦法都嘗試了就是不行。
問題分析、決絕:
在 iPhone 14 Pro 上,近距離拍攝時,系統會自動切換到微距模式,這通常是使用超廣角鏡頭(Ultra Wide Camera)來實現的。具體來說:
1. 主鏡頭(Wide Angle Camera):焦距通常適用于中等距離(通常約為 20-30 cm),如果拍攝距離太近,主鏡頭可能無法對焦清晰。
2. 超廣角鏡頭(Ultra Wide Camera):焦距更近,能夠支持更短的拍攝距離(通常大約 2-5 cm),因此在進行近距離拍攝時,系統會自動切換到這個鏡頭。
3. 遠攝鏡頭(Telephoto Camera):用于遠距離拍攝,不適合近距離對焦。
因此,在近距離拍攝時,iPhone 14 Pro 會使用 超廣角鏡頭 來實現微距拍攝。如果你使用的是第三方應用(比如自己開發的應用),并且沒有實現鏡頭切換功能,可能會遇到無法自動切換鏡頭的問題。
代碼展示OC
- (AVCaptureDevice *)device {
if (_device == nil) {
// 獲取所有可用的攝像頭(包括主鏡頭、超廣角鏡頭和遠攝鏡頭)
NSArray *devices = [AVCaptureDeviceDiscoverySession
discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera,
AVCaptureDeviceTypeBuiltInUltraWideCamera,
AVCaptureDeviceTypeBuiltInTelephotoCamera]
mediaType:AVMediaTypeVideo
position:AVCaptureDevicePositionBack].devices;
// 遍歷攝像頭設備,選擇超廣角鏡頭
AVCaptureDevice *selectedDevice = nil;
for (AVCaptureDevice *device in devices) {
if ([device.deviceType isEqualToString:AVCaptureDeviceTypeBuiltInUltraWideCamera]) {
selectedDevice = device;
break;
}
}
// 如果找到了超廣角鏡頭
if (selectedDevice) {
NSError *error = nil;
if ([selectedDevice lockForConfiguration:&error]) {
// 進行相關的配置(例如對焦、曝光、白平衡等)
if ([selectedDevice isSmoothAutoFocusSupported]) {
selectedDevice.smoothAutoFocusEnabled = YES;
}
if ([selectedDevice isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
selectedDevice.focusMode = AVCaptureFocusModeContinuousAutoFocus;
}
if ([selectedDevice isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
selectedDevice.exposureMode = AVCaptureExposureModeContinuousAutoExposure;
}
if ([selectedDevice isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance]) {
selectedDevice.whiteBalanceMode = AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance;
}
[selectedDevice unlockForConfiguration];
}
// 設置為選中的超廣角鏡頭
_device = selectedDevice;
} else {
NSLog(@"未找到超廣角鏡頭");
}
}
return _device;
}
- (AVCaptureSession *)session {
if (_session == nil) {
_session = [[AVCaptureSession alloc] init];
_session.sessionPreset = AVCaptureSessionPresetHigh;
NSError *error = nil;
// 使用選中的超廣角鏡頭作為輸入設備
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:&error];
if (error) {
UIAlertAction *okAction = [UIAlertAction actionWithTitle:@"確定" style:UIAlertActionStyleDefault handler:nil];
[self alertControllerWithTitle:@"沒有攝像設備" message:error.localizedDescription okAction:okAction cancelAction:nil];
} else {
if ([_session canAddInput:input]) {
[_session addInput:input];
}
if ([_session canAddOutput:self.videoDataOutput]) {
[_session addOutput:self.videoDataOutput];
}
if ([_session canAddOutput:self.metadataOutput]) {
[_session addOutput:self.metadataOutput];
// 設置需要檢測的元數據類型,例如 AVMetadataObjectTypeFace(人臉)、AVMetadataObjectTypeQRCode(二維碼)等。
self.metadataOutput.metadataObjectTypes = @[AVMetadataObjectTypeFace];
}
}
}
return _session;
}
代碼展示Swift
var device: AVCaptureDevice? {
if _device == nil {
// 獲取所有可用攝像頭(包括主鏡頭、超廣角鏡頭和遠攝鏡頭)
let discoverySession = AVCaptureDevice.DiscoverySession(
deviceTypes: [.builtInWideAngleCamera, .builtInUltraWideCamera, .builtInTelephotoCamera],
mediaType: .video,
position: .back
)
let devices = discoverySession.devices
// 遍歷攝像頭設備,選擇超廣角鏡頭
var selectedDevice: AVCaptureDevice?
for device in devices {
if device.deviceType == .builtInUltraWideCamera {
selectedDevice = device
break
}
}
// 如果找到超廣角鏡頭
if let selectedDevice = selectedDevice {
do {
try selectedDevice.lockForConfiguration()
// 配置自動對焦、曝光和白平衡等
if selectedDevice.isSmoothAutoFocusSupported {
selectedDevice.isSmoothAutoFocusEnabled = true
}
if selectedDevice.isFocusModeSupported(.continuousAutoFocus) {
selectedDevice.focusMode = .continuousAutoFocus
}
if selectedDevice.isExposureModeSupported(.continuousAutoExposure) {
selectedDevice.exposureMode = .continuousAutoExposure
}
if selectedDevice.isWhiteBalanceModeSupported(.continuousAutoWhiteBalance) {
selectedDevice.whiteBalanceMode = .continuousAutoWhiteBalance
}
selectedDevice.unlockForConfiguration()
} catch {
print("配置超廣角鏡頭失?。篭(error)")
}
_device = selectedDevice
} else {
print("未找到超廣角鏡頭")
}
}
return _device
}
var session: AVCaptureSession? {
if _session == nil {
_session = AVCaptureSession()
_session?.sessionPreset = .high
do {
// 使用選中的超廣角鏡頭作為輸入設備
let input = try AVCaptureDeviceInput(device: device ?? AVCaptureDevice())
if _session?.canAddInput(input) == true {
_session?.addInput(input)
}
if let videoOutput = videoDataOutput, _session?.canAddOutput(videoOutput) == true {
_session?.addOutput(videoOutput)
}
if let metadataOutput = metadataOutput, _session?.canAddOutput(metadataOutput) == true {
_session?.addOutput(metadataOutput)
// 設置需要檢測的元數據類型,例如人臉檢測或二維碼檢測
metadataOutput.metadataObjectTypes = [.face]
}
} catch {
showAlert(title: "沒有攝像設備", message: error.localizedDescription)
}
}
return _session
}