Question

I used the code from here to find Face. Im trying to draw both the eyes and the face.
But I can only show both the eyes or the face depending which of the statements i write first. How to do this?

// Detect faces
std::vector faces;
_faceCascade.detectMultiScale(mat, faces, 1.1, 2, kHaarOptions, cv::Size(60, 60));
//Detect eyes
std::vector eyes;
_eyesCascade.detectMultiScale(mat, eyes, 1.1, 2, kHaarOptions, cv::Size(30, 30));

Here eyes.size() = 0. If i interchange the position of the two statements, i get eyes.size() = 2 and faces.size() = 0

Answer 1

If your goal is to retrieve face and eyes position on iOS, why don’t you use CoreImage capabilities?

CIImage *image = [CIImage imageWithContentsOfURL:[NSURL fileURLWithPath:@"image.jpg"]];

NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:CIDetectorAccuracyHigh, CIDetectorAccuracy, nil];

CIDetector *faceDetector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:options];

NSArray *features = [faceDetector featuresInImage:image];
for(CIFaceFeature* faceFeature in features)
{
    CGRect faceSize = faceFeature.bounds.size;
    PointF leftEyePosition;
    PointF rightEyePosition;
    PointF mouthPosition;

    if(faceFeature.hasLeftEyePosition)
        leftEyePosition = faceFeature.leftEyePosition;
    //do the same for right eye and mouth
}

It doesn’t use OpenCV, but you get the mouth position for free.