从 CIImage 创建垫子的最佳方式

Question

我正在使用CIDetector来检测人脸，然后在每张脸的下半部分使用OpenCV来检测任何微笑的大小。我正在使用下面的代码来创建 OpenCV 可以执行检测的 cv：：mat，因为您可以看到图像经历了 -> Cropped CIImage -> NSBitmapImage -> CGImage -> cv::mat CIImage 的步骤。

- (void)OpenCVdetectSmilesIn:(CIFaceFeature *)faceFeature usingImage:ciFrameImage
{
    CGRect lowerFaceRectFull = faceFeature.bounds;
    lowerFaceRectFull.size.height *=0.5;
    CIImage *lowerFaceImageFull = [ciFrameImage imageByCroppingToRect:lowerFaceRectFull];

    NSBitmapImageRep* rep = [[[NSBitmapImageRep alloc] initWithCIImage:lowerFaceImageFull] autorelease];
    CGImage *lowerFaceImageFullCG = rep.CGImage;
    //TODO: find alternative method of creating cv::mat from ciFrameImage.
    std::vector<cv::Rect> smileObjects;
    cv::Mat frame_gray;
    CGColorSpaceRef colorSpace = CGImageGetColorSpace(lowerFaceImageFullCG);
    CGFloat cols = lowerFaceRectFull.size.width;
    CGFloat rows = lowerFaceRectFull.size.height;
    cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels
    CGContextRef contextRef = CGBitmapContextCreate(cvMat.data,                 // Pointer to backing data
                                                    cols,                      // Width of bitmap
                                                    rows,                     // Height of bitmap
                                                    8,                          // Bits per component
                                                    cvMat.step[0],              // Bytes per row
                                                    colorSpace,                 // Colorspace
                                                    kCGImageAlphaNoneSkipLast |
                                                    kCGBitmapByteOrderDefault); // Bitmap info flags
    CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), lowerFaceImageFullCG);
    CGContextRelease(contextRef);
    cvtColor( cvMat, frame_gray, CV_BGR2GRAY );
    equalizeHist( frame_gray, frame_gray );
    smileCascade.detectMultiScale( frame_gray, smileObjects, 1.1, 0, 0 | CV_HAAR_SCALE_IMAGE, cv::Size(30, 30) );

它正在工作，但我时不时地在NSBitmapImageRep行中崩溃，但我找不到重现崩溃的模式。我不确定这一点，但某种"本能"告诉我，我从 CIImage 创建 cv：：mat 映像的方法既混乱又低效 - 更不用说我怀疑 CPU 不必要地用于 NSBitmapImageRep 步骤，而所有其他步骤都保留在 GPU 中......我说的对吗？

有谁知道从裁剪框架创建 cv：：mat 的更好方法？

请注意，ciFrameImage 来自示例缓冲区委托方法：

CIImage *ciFrameImage = [CIImage imageWithCVImageBuffer:cvFrameBuffer options:settings];

Answer 1

找到了摆脱崩溃的解决方案：使用 createCGImage:fromRect 跳过NSBitmapImageRef步骤：

- (void)OpenCVdetectSmilesIn:(CIFaceFeature *)faceFeature usingImage:ciFrameImage
{
    CGRect lowerFaceRectFull = faceFeature.bounds;
    lowerFaceRectFull.size.height *=0.5;
    CIImage *lowerFaceImageFull = [ciFrameImage imageByCroppingToRect:lowerFaceRectFull];
    // Create the context and instruct CoreImage to draw the output image recipe into a CGImage
    if( self.context == nil ) {
    self.context = [CIContext contextWithCGContext:nil options: nil];
    }
    CGImageRef lowerFaceImageFullCG = [_context createCGImage:lowerFaceImageFull fromRect:lowerFaceRectFull];

确保

    CGImageRelease(lowerFaceImageFullCG);

完成后

。