如何裁剪检测到的人脸答案

【问题标题】：How to crop the detected face如何裁剪检测到的人脸
【发布时间】：2014-05-30 14:51:35
【问题描述】：

我使用CoreImage 来检测人脸。我想在人脸检测后裁剪人脸。我用这个 sn-p 来检测人脸：

-(void)markFaces:(UIImageView *)facePicture{


CIImage* image = [CIImage imageWithCGImage:imageView.image.CGImage];

CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                          context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyHigh forKey:CIDetectorAccuracy]];


NSArray* features = [detector featuresInImage:image];


CGAffineTransform transform = CGAffineTransformMakeScale(1, -1);
transform = CGAffineTransformTranslate(transform, 0, -imageView.bounds.size.height);


for(CIFaceFeature* faceFeature in features)
{
    // Get the face rect: Translate CoreImage coordinates to UIKit coordinates
    const CGRect faceRect = CGRectApplyAffineTransform(faceFeature.bounds, transform);


    faceView = [[UIView alloc] initWithFrame:faceRect];
    faceView.layer.borderWidth = 1;
    faceView.layer.borderColor = [[UIColor redColor] CGColor];


    UIGraphicsBeginImageContext(faceView.bounds.size);
    [faceView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //Blur the UIImage with a CIFilter
    CIImage *imageToBlur = [CIImage imageWithCGImage:viewImage.CGImage];
    CIFilter *gaussianBlurFilter = [CIFilter filterWithName: @"CIGaussianBlur"];
    [gaussianBlurFilter setValue:imageToBlur forKey: @"inputImage"];
    [gaussianBlurFilter setValue:[NSNumber numberWithFloat: 10] forKey: @"inputRadius"];
    CIImage *resultImage = [gaussianBlurFilter valueForKey: @"outputImage"];
    UIImage *endImage = [[UIImage alloc] initWithCIImage:resultImage];

    //Place the UIImage in a UIImageView
    UIImageView *newView = [[UIImageView alloc] initWithFrame:self.view.bounds];
    newView.image = endImage;
    [self.view addSubview:newView];

    CGFloat faceWidth = faceFeature.bounds.size.width;

    [imageView addSubview:faceView];

    // LEFT EYE
    if(faceFeature.hasLeftEyePosition)
    {

        const CGPoint leftEyePos = CGPointApplyAffineTransform(faceFeature.leftEyePosition, transform);

        UIView *leftEyeView = [[UIView alloc] initWithFrame:CGRectMake(leftEyePos.x - faceWidth*EYE_SIZE_RATE*0.5f,
                                                                       leftEyePos.y - faceWidth*EYE_SIZE_RATE*0.5f
                                                                       ,faceWidth*EYE_SIZE_RATE,
                                                                       faceWidth*EYE_SIZE_RATE)];

        NSLog(@"Left Eye X = %0.1f Y = %0.1f Width = %0.1f Height = %0.1f",leftEyePos.x - faceWidth*EYE_SIZE_RATE*0.5f,
              leftEyePos.y - faceWidth*EYE_SIZE_RATE*0.5f,faceWidth*EYE_SIZE_RATE,
              faceWidth*EYE_SIZE_RATE);

        leftEyeView.backgroundColor = [[UIColor magentaColor] colorWithAlphaComponent:0.3];
        leftEyeView.layer.cornerRadius = faceWidth*EYE_SIZE_RATE*0.5;


        [imageView addSubview:leftEyeView];
    }


    // RIGHT EYE
    if(faceFeature.hasRightEyePosition)
    {

        const CGPoint rightEyePos = CGPointApplyAffineTransform(faceFeature.rightEyePosition, transform);


        UIView *rightEye = [[UIView alloc] initWithFrame:CGRectMake(rightEyePos.x - faceWidth*EYE_SIZE_RATE*0.5,
                                                                    rightEyePos.y - faceWidth*EYE_SIZE_RATE*0.5,
                                                                    faceWidth*EYE_SIZE_RATE,
                                                                    faceWidth*EYE_SIZE_RATE)];



        NSLog(@"Right Eye X = %0.1f Y = %0.1f Width = %0.1f Height = %0.1f",rightEyePos.x - faceWidth*EYE_SIZE_RATE*0.5f,
              rightEyePos.y - faceWidth*EYE_SIZE_RATE*0.5f,faceWidth*EYE_SIZE_RATE,
              faceWidth*EYE_SIZE_RATE);

        rightEye.backgroundColor = [[UIColor blueColor] colorWithAlphaComponent:0.2];
        rightEye.layer.cornerRadius = faceWidth*EYE_SIZE_RATE*0.5;
        [imageView addSubview:rightEye];
    }


    // MOUTH
    if(faceFeature.hasMouthPosition)
    {

        const CGPoint mouthPos = CGPointApplyAffineTransform(faceFeature.mouthPosition, transform);


        UIView* mouth = [[UIView alloc] initWithFrame:CGRectMake(mouthPos.x - faceWidth*MOUTH_SIZE_RATE*0.5,
                                                                 mouthPos.y - faceWidth*MOUTH_SIZE_RATE*0.5,
                                                                 faceWidth*MOUTH_SIZE_RATE,
                                                                 faceWidth*MOUTH_SIZE_RATE)];

        NSLog(@"Mouth X = %0.1f Y = %0.1f Width = %0.1f Height = %0.1f",mouthPos.x - faceWidth*MOUTH_SIZE_RATE*0.5f,
              mouthPos.y - faceWidth*MOUTH_SIZE_RATE*0.5f,faceWidth*MOUTH_SIZE_RATE,
              faceWidth*MOUTH_SIZE_RATE);


        mouth.backgroundColor = [[UIColor greenColor] colorWithAlphaComponent:0.3];
        mouth.layer.cornerRadius = faceWidth*MOUTH_SIZE_RATE*0.5;
        [imageView addSubview:mouth];

    }
}
}

我想要的只是裁剪脸部。

【问题讨论】：

您发布了一些代码，这些代码使用面部检测来执行与您想做的事情无关的事情。该代码确实包括以图像坐标计算图像中每个人脸的矩形。您的下一个任务是调整该代码以将该矩形提取并成像到另一个图像中。您应该能够创建一个与所需输出图像大小相同的上下文，然后使用 drawInRect 将您的脸部部分渲染到该图像上下文中。试一试，如果遇到问题，请发布您的代码并寻求帮助。

标签： ios crop face-detection core-image

【解决方案1】：

您可以使用此功能轻松裁剪人脸。它已经过测试并且可以正常工作。

-(void)faceWithFrame:(CGRect)frame{
    CGRect rect = frame;
    CGImageRef imageRef = CGImageCreateWithImageInRect([self.imageView.image CGImage], rect);
    UIImage *cropedImage = [UIImage imageWithCGImage:imageRef];
    self.cropedImg.image =cropedImage;
}

你只需传递人脸框，上面的函数就会给出裁剪人脸图像。

【讨论】：