在iOS中使用openCV进行图像处理

我希望仅保留红色像素并使图像中的所有其他图像变暗。我想使用openCv。我通过以下代码设法过滤了红色，这要归功于SO，从对象中检测颜色并更改其颜色ios。

// Create Mat from UIimage
cv::Mat img = [self cvMatFromUIImage:[UIImage imageNamed:@"rgb1.jpg"]];
// Convert to HSV
cv::Mat hsvImage = cvCreateImage(img.size(),8, 3);
cv::cvtColor(img, hsvImage, CV_BGR2HSV);

std::vector<cv::Mat>channels;

// splitting the channels of HSV
cv::split(hsvImage, channels);
// Getting only the hue from channels
cv::Mat hue = channels[0];
// Creating a temporary image using the hue
cv::Mat dest;
cv::Mat temp = cvCreateImage(img.size(), 8, 3);

// Giving the threshold range
cv::inRange(hsvImage, cv::Scalar(90,50,50), cv::Scalar(130,255,255), dest);

// I guess image temp Image and Original image gets merged here
// I would appreciate some explanation here
cv::merge(channels, temp);
temp.setTo(cv::Scalar(90,50,50),dest);
cv::split(temp, channels);
cv::merge(channels, dest);

// Converting the HSV Image back to BGR
cv::cvtColor(dest, hsvImage, CV_HSV2BGR);
// Converting Mat to UIImage
self.imageView.image=[self UIImageFromCVMat:hsvImage];

但是我想保持红色不变，并使其余颜色变暗或模糊。我很困惑应该在哪里进行这些逆向操作以及如何进行逆向操作。

任何帮助，将不胜感激。

更新：

对我有用的代码，希望它对在那里的人有所帮助。

cv::Mat img = [self cvMatFromUIImage:[UIImage imageNamed:@"rgb1.jpg"]];
cv::Mat hsvImage;
cv::cvtColor(img , hsvImage, CV_BGR2HSV);

cv::Mat mask;
cv::inRange(hsvImage, cv::Scalar(90,50,50), cv::Scalar(130,255,255), mask);  //  This picks red color
//    cv::inRange(hsvImage, cv::Scalar(0,50,50), cv::Scalar(30,255,255), mask);  //  This picks blue color

self.imageView.image = [self UIImageFromCVMat:mask];

cv::Mat maskRgb;
cv::cvtColor(mask, maskRgb, CV_GRAY2BGR);

cv::Mat result;
//    cv::bitwise_and(img ,maskRgb ,result); // @berak but app crashed at this line
img.copyTo(result, mask);  //  This line writes the new masked image over the original image, I'm not sure if thats the right way instead of bitwise_and???
self.imageView1.image = [self UIImageFromCVMat:result];