ImageView的人脸检测和缩放因缩放而无法正常工作？

Question

再次，我很接近，但没有香蕉。

我正在尝试按照面部识别的一些教程。几乎有以下代码，但我认为有一些我不知道如何缩放并在面部周围放置UIImageView边框。

我在照片库中的照片大小不一（出于某种莫名其妙的原因），所以我想象CIDetector找到了面孔，我正在应用CGAffineTransforms等等，试图将它们放在UIImageView中。但是，正如你从图像中看到的那样（也在下面），它并没有被绘制到正确的位置。

UIImageView为280x500，并设置为Scale to Fill。

任何有助于解决正在发生的事情的帮助都会很棒！

-(void)detectFaces {

    CIContext *context = [CIContext contextWithOptions:nil];
    CIImage *image = [CIImage imageWithCGImage:_imagePhotoChosen.image.CGImage options:nil];
    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeFace context:context options:@{CIDetectorAccuracy : CIDetectorAccuracyHigh}];
    CGAffineTransform transform = CGAffineTransformMakeScale(1, -1);
    transform = CGAffineTransformTranslate(transform, 0, -_imagePhotoChosen.image.size.height);
    NSArray *features = [detector featuresInImage:image];
    NSLog(@"I have found %lu faces", (long unsigned)features.count);
    for (CIFaceFeature *faceFeature in features)
    {   
        const CGRect faceRect = CGRectApplyAffineTransform(faceFeature.bounds, transform);
        NSLog(@"I have the original frame as: %@", NSStringFromCGRect(faceRect));
        const CGFloat scaleWidth = _imagePhotoChosen.frame.size.width/_imagePhotoChosen.image.size.width;
        const CGFloat scaleHeight = _imagePhotoChosen.frame.size.height/_imagePhotoChosen.image.size.height;

        CGRect faceFrame = CGRectMake(faceRect.origin.x * scaleWidth, faceRect.origin.y * scaleHeight, faceRect.size.width * scaleWidth, faceRect.size.height * scaleHeight);

        UIView *faceView = [[UIView alloc] initWithFrame:faceFrame];
        NSLog(@"I have the bounds as: %@", NSStringFromCGRect(faceFrame));
        faceView.layer.borderColor = [[UIColor redColor] CGColor];
        faceView.layer.borderWidth = 1.0f;

        [self.view addSubview:faceView];
    }

}

-(void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

    _imagePhotoChosen.image = info[UIImagePickerControllerOriginalImage];
    //[_imagePhotoChosen sizeToFit];

    [self.view addSubview:_viewChosenPhoto];
    [picker dismissViewControllerAnimated:YES completion:nil];
    [self detectFaces];

}

我已经离开了NSLog语句，因为我一直试图解决数学是错误的，但似乎无法看出它是不是！我也是一名数学老师......叹息......

再次感谢你能做的任何事情，指出我正确的方向。

更新

回应那些想知道我是如何解决它的人......这对我来说真的是一个愚蠢的错误。

我将子视图添加到主窗口，而不是UIImageView。因此我删除了该行：

[self.view addSubview:faceView];

并将其替换为：

[_imagePhotoChosen addSubview:faceView];

这允许将帧放置在正确的位置。接受的解决方案为我提供了线索！所以，更新后的代码（从那时起我就开始了一点：

-(void)detectFaces:(UIImage *)selectedImage {

    _imagePhotoChosen.image = selectedImage;

    CIImage *image = [CIImage imageWithCGImage:selectedImage.CGImage options:nil];

    CIDetector *detector = [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:@{CIDetectorAccuracy : CIDetectorAccuracyHigh}];
    CGAffineTransform transform = CGAffineTransformMakeScale(1, -1);
    transform = CGAffineTransformTranslate(transform, 0, -selectedImage.size.height);
    NSArray *features = [detector featuresInImage:image];
    int i = 0;
    for (CIFaceFeature *faceFeature in features)
    {

        const CGRect faceRect = CGRectApplyAffineTransform(faceFeature.bounds, transform);

        const CGFloat scaleWidth = _imagePhotoChosen.frame.size.width/_imagePhotoChosen.image.size.width;
        const CGFloat scaleHeight = _imagePhotoChosen.frame.size.height/_imagePhotoChosen.image.size.height;

        CGRect faceFrame = CGRectMake(faceRect.origin.x * scaleWidth, faceRect.origin.y * scaleHeight, faceRect.size.width * scaleWidth, faceRect.size.height * scaleHeight);

        UIView *faceView = [[UIView alloc] initWithFrame:faceFrame];
        faceView.layer.borderColor = [[UIColor redColor] CGColor];
        faceView.layer.borderWidth = 1.0f;
        faceView.tag = i;

        UITapGestureRecognizer *selectPhotoTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(selectPhoto)];
        selectPhotoTap.numberOfTapsRequired = 1;
        selectPhotoTap.numberOfTouchesRequired = 1;
        [faceView addGestureRecognizer:selectPhotoTap];

        [_imagePhotoChosen addSubview:faceView];
        i++;
    }

}

Answer 1

实际上你所做的完全正确，只需用

替换这一行

    CGRect faceFrame = CGRectMake(_imagePhotoChosen.frame.origin.x+ faceRect.origin.x * scaleWidth,_imagePhotoChosen.frame.origin.y+ faceRect.origin.y * scaleHeight, faceRect.size.width * scaleWidth, faceRect.size.height * scaleHeight);