private: Mat IWSP(Mat inputImg){
bool needFilter = false;
int g = 0, N = 0;
for(int r = 0; r < inputImg.cols; r++){
	for(int c = 0; c < inputImg.rows; c++){
		if((inputImg.at<uchar>(cv::Point(r, c)) == 255) || (inputImg.at<uchar>(cv::Point(r, c)) == 0))
		{
			needFilter = true;
		}
		else
		{
			// For Computation of Trimmed Global Mean in case we will need to filter image
			g = g + inputImg.at<uchar>(cv::Point(r, c));
			N++;
		}
	}
}
if(!needFilter) return inputImg;
// Trimmed Global Mean
g = g / N;
Mat fImg = inputImg.clone();
// Start filtering
for(int r = 0; r < inputImg.cols; r++){
	for(int c = 0; c < inputImg.rows; c++){
		// Proceeded Pixel P(r,c), continue if pixel is not corrupted
		if(inputImg.at<uchar>(cv::Point(r, c)) != 0 && inputImg.at<uchar>(cv::Point(r, c)) != 255) continue;					 
		// Window
		std::vector<int> window;
		int sum = 0, index = 0;
		for (int wr = -1; wr < 2; wr++){
			for (int wc = -1; wc < 2; wc++)	{
				// тут ошибка
				window.push_back(inputImg.at<uchar>(cv::Point(r + wr, c + wc)));
				sum += inputImg.at<uchar>(cv::Point(r + wr, c + wc));
				index++;
			}
		}
		// Case 1: selected window contains all the elements as only 0'
		if(sum == 0){
			fImg.at<uchar>(cv::Point(r, c)) = 255;
			// we will need more iterations
			needFilter = true;
			continue;
		}
		// Case 2: selected window contains all the elements as only 255'
		if(sum == 255*9){
			fImg.at<uchar>(cv::Point(r, c)) = 0;
			// we will need more iterations
			needFilter = true;
			continue;
		}
		// Case 3: selected window contains all the elements as only 255' or 0'
		bool Case3 = true;
		for(int i = 0; i < 9; i++){
			if(window[i] != 255 && window[i] != 0) Case3 = false;
		}
		if(Case3){
			fImg.at<uchar>(cv::Point(r, c)) = g;
			continue;
		}
		// Case 4: selected window contains not all the elements as only 255' or 0'
		std::vector<int> trimmedMean;
		int median = 0;
		sum = 0;
		for(int i = 0; i < 9; i++){
			if(window[i] != 0 && window[i] != 255) trimmedMean.push_back(window[i]);
			sum++;
		}
		std::sort (std::begin(trimmedMean), std::end(trimmedMean));
		if(sum == 1){
			median = trimmedMean[0];
		}
		else if(sum%2 == 0){
			median = (trimmedMean[sum/2 - 1] + trimmedMean[sum/2])/2;
		}
		else{
			median = trimmedMean[sum/2];
		}
		fImg.at<uchar>(cv::Point(r, c)) = median;
	}
}
// из-за этого появляется ошибка
if(needFilter) fImg = IWSP(fImg.clone());
return fImg;
}