CoreImage CIFeature for detecting face emotions - ios

Question

I am trying to use CoreImage CIFeature for detecting face emotions as those are the native APIs. I have created a sample view controller project and updated related code. When I launch this iOS application, it open up the camera. When I look up the camera and show smile emotion, this below sample code detects fine.
I need to also find other emotions like, Surprise, Sad and Angry emotions. I understand that CoreImage CIFeature doesn't have direct APIs for these other emotions. But, Is it possible to try manipulating the available APIs (such as hasSmile, leftEyeClosed, rightEyeClosed etc.) to detect other emotions such as Surprise, Sad and Angry through iOS program?
Could anyone come across working with this APIs, scenario and solve this issue, please suggest and share your ideas.
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, from connection: AVCaptureConnection!) {
let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
let opaqueBuffer = Unmanaged<CVImageBuffer>.passUnretained(imageBuffer!).toOpaque()
let pixelBuffer = Unmanaged<CVPixelBuffer>.fromOpaque(opaqueBuffer).takeUnretainedValue()
let sourceImage = CIImage(cvPixelBuffer: pixelBuffer, options: nil)
options = [CIDetectorSmile : true as AnyObject, CIDetectorEyeBlink: true as AnyObject, CIDetectorImageOrientation : 6 as AnyObject]
let features = self.faceDetector!.features(in: sourceImage, options: options)
for feature in features as! [CIFaceFeature] {
if (feature.hasSmile) {
DispatchQueue.main.async {
self.updateSmileEmotion()
}
}
else {
DispatchQueue.main.async {
self.resetEmotionLabel()
}
}
}
func updateSmileEmotion () {
self.emtionLabel.text = " "
self.emtionLabel.text = "HAPPY"
}
func resetEmotionLabel () {
self.emtionLabel.text = " "
}

Answer 1

There are a variety of libraries that can do sentiment analysis on images, and most of those rely on machine learning. Its highly unlikely that you are going to get the same kind of results by just looking at what CIFeature gives you because its pretty limited even in comparison to other facial recognition libraries. See Google Cloud Vison, IBM Watson Cloud iOS SDK, Microsoft Cognitive Services