首先利用ios的 AVCaptureStillImageOutput,AVCaptureSession, AVCaptureVideoPreviewLayer 抓图并显示到 UIImageView. 

然后吧UIIMage转换成opencv中的IplImage

利用下面这条语句

IplImage *image = [self CreateIplImageFromUIImage:originalImage];

剩下的就是opencv中的操作和处理

代码如下：

+ (UIImage *) opencvFaceDetect:(UIImage *)originalImage {
cvSetErrMode(CV_ErrModeParent);

IplImage *image = [self CreateIplImageFromUIImage:originalImage];

// Scaling down
IplImage *small_image = cvCreateImage(cvSize(image->width/2,image->height/2), IPL_DEPTH_8U, 3);
cvPyrDown(image, small_image, CV_GAUSSIAN_5x5);
int scale = 2;

// Load XML
NSString *path = [[NSBundle mainBundle] pathForResource:@"haarcascade_frontalface_default" ofType:@"xml"];
CvHaarClassifierCascade* cascade = (CvHaarClassifierCascade*)cvLoad([path cStringUsingEncoding:NSASCIIStringEncoding], NULL, NULL, NULL);
CvMemStorage* storage = cvCreateMemStorage(0);

// Detect faces and draw rectangle on them
CvSeq* faces = cvHaarDetectObjects(small_image, cascade, storage, 1.2f, 2, CV_HAAR_DO_CANNY_PRUNING, cvSize(20, 20), cvSize(100, 100));
cvReleaseImage(&small_image);

NSLog(@"found %d faces in image", faces->total);

// Create canvas to show the results
CGImageRef imageRef = originalImage.CGImage;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef contextRef = CGBitmapContextCreate(NULL, originalImage.size.width, originalImage.size.height, 8, originalImage.size.width * 4,
colorSpace, kCGImageAlphaPremultipliedLast|kCGBitmapByteOrderDefault);
CGContextDrawImage(contextRef, CGRectMake(0, 45, originalImage.size.width, originalImage.size.height), imageRef);

CGContextSetLineWidth(contextRef, 4);
CGContextSetRGBStrokeColor(contextRef, 0.0, 0.0, 1.0, 0.5);

// Draw results on the iamge
for(int i = 0; i < faces->total; i++) {
NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

// Calc the rect of faces
CvRect cvrect = *(CvRect*)cvGetSeqElem(faces, i);
CGRect face_rect = CGContextConvertRectToDeviceSpace(contextRef, 
CGRectMake(cvrect.x * scale, cvrect.y * scale, cvrect.width * scale, cvrect.height * scale));
CGContextStrokeRect(contextRef, face_rect);

[pool release];
}

UIImage *returnImage = [UIImage imageWithCGImage:CGBitmapContextCreateImage(contextRef)];
CGContextRelease(contextRef);
CGColorSpaceRelease(colorSpace);

cvReleaseMemStorage(&storage);
cvReleaseHaarClassifierCascade(&cascade);

return returnImage;
}

本文转自博客园知识天地的博客，原文链接：IOS 中调用opencv进行人脸检测，如需转载请自行联系原博主。