AVCapturePhotoOutput iOS Camera Super Dark - ios

Question

I have an app setup to use the camera for a photo (on a timer basis) to detect the presence of a face. The detection process works fairly well when I feed the app a photo that I have added to assets. However, when I attempt to use the output of the camera directly or even after saving the image to a file, the resulting image is so dark that the face recognition is completely unreliable.
If I display the image as seen by the camera, it looks correct. I captured the following two images - one from the camera as seen live, the other of the same view after the image was created from AVCapturePhotoOutput. The same darkness happens if I simply display the captured image in an image view.
Note the comment: "I put the breakpoint here and took a screen shot". Then I took the second screen shot when the code completed. These were taken in HIGH light.
Here's the basic code:
class CRSFaceRecognitionViewController: UIViewController, UIImagePickerControllerDelegate {
var sentBy : String?
//timers
var faceTimer : Timer?
var frvcTimer : Timer?
//capture
var captureSession = AVCaptureSession()
var settings = AVCapturePhotoSettings()
var backCamera : AVCaptureDevice?
var frontCamera : AVCaptureDevice?
var currentCamera : AVCaptureDevice?
var photoOutput : AVCapturePhotoOutput?
var cameraPreviewLayer : AVCaptureVideoPreviewLayer?
var image : UIImage?
var outputImage : UIImage?
#IBOutlet weak var imageView: UIImageView!
//MARK: - Setup
override func viewDidLoad() {
super.viewDidLoad()
}//viewDidLoad
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(true)
}//viewWillAppear
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(true)
//check for camera
if (UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.camera)) {
setupCaptureSession()
setupDevices()
setupInputOutput()
setupPreviewLayer()
startRunningCaptureSession()
photoOutput?.capturePhoto(with:settings, delegate: self)
} else {
print("Camera not present")
}
}//viewDidAppear
//MARK: - Video
#objc func showFaceRecognitionViewController() {
//all this does is present the image in a new ViewController imageView
performSegue(withIdentifier: "showSavedCameraPhoto", sender: self)
}//showThePhotoView
func setupCaptureSession() {
captureSession.sessionPreset = AVCaptureSession.Preset.photo
}//setupCaptureSession
func setupDevices() {
let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [AVCaptureDevice.DeviceType.builtInWideAngleCamera], mediaType: .video, position: .unspecified)
let devices = deviceDiscoverySession.devices
for device in devices {
if device.position == AVCaptureDevice.Position.back {
backCamera = device
} else if device.position == AVCaptureDevice.Position.front {
frontCamera = device
}//if else
}//for in
currentCamera = frontCamera
}//setupDevices
func setupInputOutput() {
do {
let captureDeviceInput = try AVCaptureDeviceInput(device: currentCamera!)
captureSession.addInput(captureDeviceInput)
photoOutput = AVCapturePhotoOutput()
photoOutput?.setPreparedPhotoSettingsArray([AVCapturePhotoSettings(format: [AVVideoCodecKey: AVVideoCodecType.jpeg])], completionHandler: {(success, error) in
print("in photoOutput completion handler")
})
captureSession.addOutput(photoOutput!)
} catch {
print("Error creating AVCaptureDeviceInput:", error)
}//do catch
}//setupInputOutput
func setupPreviewLayer() {
cameraPreviewLayer = AVCaptureVideoPreviewLayer(session : captureSession)
cameraPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
cameraPreviewLayer?.connection?.videoOrientation = AVCaptureVideoOrientation.portrait
cameraPreviewLayer?.frame = view.frame
view.layer.insertSublayer(cameraPreviewLayer!, at: 0)
}//setupPreviewLayer
func startRunningCaptureSession() {
captureSession.startRunning()
}//startRunningCaptureSession
//MARK: - Segue
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showSavedCameraPhoto" {
let controller = segue.destination as! JustToSeeThePhotoViewController
controller.inImage = outputImage
}//if segue
}//prepare
//MARK: - Look for Faces
func findTheFaces() {
let myView : UIView = self.view
guard let outImage = outputImage else {return}
let imageView = UIImageView(image: outImage)
imageView.contentMode = .scaleAspectFit
let scaledHeight = myView.frame.width / outImage.size.width * outImage.size.height
imageView.frame = CGRect(x: 0, y: 0, width: myView.frame.width, height: myView.frame.height)
imageView.backgroundColor = UIColor.blue
myView.addSubview(imageView)
let request = VNDetectFaceRectanglesRequest { (req, err) in
if let err = err {
print("VNDetectFaceRectanglesRequest failed to run:", err)
return
}//if let err
print(req.results ?? "req.results is empty")
req.results?.forEach({ (res) in
DispatchQueue.main.async {
guard let faceObservation = res as? VNFaceObservation else {return}
let x = myView.frame.width * faceObservation.boundingBox.origin.x
let width = myView.frame.width * faceObservation.boundingBox.width
let height = scaledHeight * faceObservation.boundingBox.height
let y = scaledHeight * (1 - faceObservation.boundingBox.origin.y) - height
let redView = UIView()
redView.backgroundColor = .red
redView.alpha = 0.4
redView.frame = CGRect(x: x, y: y, width: width, height: height)
myView.addSubview(redView)
print("faceObservation bounding box:")
print(faceObservation.boundingBox)
//if you get here, then you have a face bounding box
}//main
})//forEach block
}//let request
guard let cgImage = outImage.cgImage else {return}
DispatchQueue.global(qos: .utility).async {
let handler = VNImageRequestHandler(cgImage: cgImage, options: [:])
do {
try handler.perform([request])
print("handler request was successful")
self.performSegue(withIdentifier: "showSavedCameraPhoto", sender: self)
} catch let reqErr {
print("Failed to perform request:", reqErr)
}
}//DispatchQueue
}//findTheFaces
//MARK: - Memory
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}//didReceiveMemoryWarning
}//class
extension CRSFaceRecognitionViewController : AVCapturePhotoCaptureDelegate {
func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
if let imageData = photo.fileDataRepresentation() {
print(imageData)
outputImage = UIImage(data : imageData)
//
//I put breakpoint here and took a screen shot
//
if let outImage = outputImage?.updateImageOrientionUpSide() {
self.outputImage = outImage
}
DispatchQueue.main.async {
self.findTheFaces()
}
}//if let imageData
}//photoOutput
}//extension
extension UIImage {
//you need to do this to ensure that the image is in portrait mode
//the face recognition method will not work if the face is horizontal
func updateImageOrientionUpSide() -> UIImage? {
if self.imageOrientation == .up {
return self
}
UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)
self.draw(in: CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height))
if let normalizedImage:UIImage = UIGraphicsGetImageFromCurrentImageContext() {
UIGraphicsEndImageContext()
return normalizedImage
}
UIGraphicsEndImageContext()
return nil
}//updateImageOrientionUpSide
}//image
I must be doing something wrong with the camera capture. Any help would be appreciated. Swift 4, iOS 11.2.5, Xcode 9.2

Answer 1

I would try adding a delay between startRunningCaptureSession() and photoOutput?.capturePhoto(with:settings, delegate: self)
For example,
DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(4), execute: {
// take a photo
startRunningCaptureSession()
photoOutput?.capturePhoto(with:settings, delegate: self)
})

Answer 2

It appears as though I have too many async pieces. I broke the code into separate functions for each major piece - async or not and put them all into a DispatchGroup. That seems to have solved the issue.