使用 CoreImage 裁剪出脸部

Question

我需要从给定图像中裁剪出一张/多个面孔，并将裁剪后的脸部图像用于其他用途。我正在使用 CoreImage 中的 CIDetectorTypeFace。问题是仅包含检测到的脸部的新 UIImage 需要更大的尺寸，因为头发被剪掉或下颌被剪掉。initWithFrame:faceFeature.bounds我如何增加??的大小？我正在使用的示例代码：

    CIImage* image = [CIImage imageWithCGImage:staticBG.image.CGImage];
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                          context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyHigh forKey:CIDetectorAccuracy]];
    NSArray* features = [detector featuresInImage:image];

    for(CIFaceFeature* faceFeature in features)
    {
       UIView* faceView = [[UIView alloc] initWithFrame:faceFeature.bounds];
       faceView.layer.borderWidth = 1;
       faceView.layer.borderColor = [[UIColor redColor] CGColor];
       [staticBG addSubview:faceView];

       // cropping the face
       CGImageRef imageRef = CGImageCreateWithImageInRect([staticBG.image CGImage], faceFeature.bounds);
       [resultView setImage:[UIImage imageWithCGImage:imageRef]];
       CGImageRelease(imageRef);
    }

注意：我用来显示检测到的面部区域的红框与裁剪后的图像根本不匹配。也许我没有正确显示框架，但由于我不需要显示框架，我真的需要裁剪掉的脸，我不太担心它。

Answer 1

不确定，但你可以尝试

CGRect biggerRectangle = CGRectInset(faceFeature.bounds, someNegativeCGFloatToIncreaseSizeForXAxis, someNegativeCGFloatToIncreaseSizeForYAxis);
CGImageRef imageRef = CGImageCreateWithImageInRect([staticBG.image CGImage], biggerRectangle);

https://developer.apple.com/library/mac/#documentation/graphicsimaging/reference/CGGeometry/Reference/reference.html#//apple_ref/c/func/CGRectInset