Function susan

jni/venus/region_operation.cpp:225–259

}

cv::Mat susan(const cv::Mat& image, int radius, int tolerance)
{
	assert(image.type() == CV_8UC1);  // only handles gray image
	const int cols = image.cols, rows = image.rows;
	Mat result(rows, cols, CV_8UC1);

	const int rr = radius * radius;
	for(int r = 0; r < rows; ++r)
	for(int c = 0; c < cols; ++c)
	{
		int sum = 0, hit = 0;
		uint8_t center = image.at<uint8_t>(r, c);
		for(int dy = -radius; dy < radius; ++dy)
		{
			int y = r + dy;
			for(int dx = -radius; dx < radius; ++dx)
			{
				int x = c + dx;
				if(0 <= x && x < cols && 0 <= y && y < rows)
				if(dx*dx + dy*dy <= rr)  // comment this line if you want to detect squared region.
				{
					++sum;
					if(std::abs(image.at<uint8_t>(y, x) - center) <= tolerance)
						++hit;
				}
			}
		}

		float g = static_cast<float>(sum - hit)/sum;
//		if(g < 0.4f || g > 0.5f)
//			g = 0.0f;
		result.at<uint8_t>(r, c) = cvRound(g*255);
	}
	return result;
}

/*
	here are some useful links about hypot, I tried to use std::hypot(x, y), later changed to std::sqrt(a*a + b*b);