如何使用找到的面坐标（核心图像）

Question

    UIImage* image = [UIImage imageNamed:@ "face.png" ];  
    UIImageView testImage = [[UIImageView alloc] initWithImage: image];  
    [testImage setTransform:CGAffineTransformMakeScale(1, -1)];  
    [[[UIApplication sharedApplication] delegate].window setTransform:  
CGAffineTransformMakeScale(1, -1)];  
    [testImage setFrame:CGRectMake(0, 0, testImage.image.size.width,  
testImage.image.size.height)];  
    [self.view addSubview:testImage];  

    CIImage* ciimage = [CIImage imageWithCGImage:imag​​e.CGImage];  
    NSDictionary* opts = [NSDictionary dictionaryWithObject:  
CIDetectorAccuracyHigh forKey:CIDetectorAccuracy];  
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace  
context:nil options:opts];  
    NSArray* features = [detector featuresInImage:ciimage];  

    for  (CIFaceFeature *faceFeature in features)
    {  

        CGFloat faceWidth = faceFeature.bounds.size.width;  

        UIView* faceView = [[UIView alloc] initWithFrame:faceFeature.bounds];                    

        faceView.layer.borderWidth = 1;  
        faceView.layer.borderColor = [[UIColor redColor] CGColor];  

        [self.view addSubview:faceView];          
    }  

how can I found the face coordinate?

I try to use facefeature.bounds.origin.x and facefeature.bounds.origin.y

but sometimes , it is not the correct coordinate

how can I found coordinate?

------------------2016/04/10------------------ This is my problem ios x,y is opposite than c#

Answer 1

Here's the basic idea behind it, CIDetector allows you to extrapolate points for the left eye, right eye, and mouth from the image. From that we can do some basic math to create a rectangle that spans between these points, eg

for  (CIFaceFeature *faceFeature in features)
{
    CGPoint lefteye = faceFeature.leftEyePosition;
    CGPoint righteye = faceFeature.rightEyePosition;
    CGPoint mouth = faceFeature.mouthPosition;
    //Face Rectangle
    CGRect faceRectangle = CGRectMake(lefteye.x, lefteye.y, righteye.x - lefteye.x, mouth.y - righteye.y);
    //Face Center
    CGPoint faceCenter = CGPointMake(faceRectangle.origin.x + (faceRectangle.size.width / 2), faceRectangle.origin.y + (faceRectangle.size.height / 2));
    UIView* faceView = [[UIView alloc] initWithFrame:faceRectangle];

    faceView.layer.borderWidth = 1;
    faceView.layer.borderColor = [[UIColor redColor] CGColor];

    [self.view addSubview:faceView];          
}

Keep in mind, I'm not on a computer right now to test this part of the function for you, but I believe the coordinates outputted by the detector are true to the resolution of the input image. This would cause inaccuracy when trying to apply the create rect to an on screen view using iOS's points coordinate system. This being said all you should have to do is run the newly created rectangle through a convertRect function to get the proper coordinates.