从OpenCV到PS，羽化的艺术是如何炼成的？

作者：翟天保Steven
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功能函数

// 羽化
cv::Mat Eclosion(cv::Mat src, cv::Point center,float level)
{
	if (level>0.9)
		level = 0.9f;
	float diff = (1-level) * (src.rows / 2 * src.rows / 2 + src.cols / 2 * src.cols / 2);
	cv::Mat result = src.clone();
	for (int i = 0; i < result.rows; ++i)
	{
		for (int j = 0; j < result.cols; ++j)
		{
			float dx = float(center.x - j);
			float dy = float(center.y - i);
			float ra = dx * dx + dy * dy;
			float m = ((ra-diff) / diff * 255)>0? ((ra - diff) / diff * 255):0;
			int b = result.at<Vec3b>(i, j)[0];
			int g = result.at<Vec3b>(i, j)[1];
			int r = result.at<Vec3b>(i, j)[2];
			b = (int)(b+ m);
			g = (int)(g + m);
			r = (int)(r + m);
			result.at<Vec3b>(i, j)[0] = (b > 255 ? 255 : (b < 0 ? 0 : b));
			result.at<Vec3b>(i, j)[1] = (g > 255 ? 255 : (g < 0 ? 0 : g));
			result.at<Vec3b>(i, j)[2] = (r > 255 ? 255 : (r < 0 ? 0 : r));
		}
	}
	return result;
}

测试代码

#include <iostream>
#include <opencv2/opencv.hpp>
using namespace std;
using namespace cv;
cv::Mat Eclosion(cv::Mat src, cv::Point center, float level);
int main()
{
	cv::Mat src = imread("test.jpg");
	/***********       羽化   ***********************/
	cv::Mat eclosion1 = Eclosion(src, cv::Point(src.cols / 2, src.rows / 2), 0.5f);
	cv::Mat eclosion2 = Eclosion(src, cv::Point(src.cols / 2, src.rows / 2), 0.3f);
	imshow("原图", src);
    imshow("羽化1", eclosion1);
	imshow("羽化2", eclosion2);
	waitKey(0);
	return 0;
}
// 羽化
cv::Mat Eclosion(cv::Mat src, cv::Point center,float level)
{
	if (level>0.9)
		level = 0.9f;
	float diff = (1-level) * (src.rows / 2 * src.rows / 2 + src.cols / 2 * src.cols / 2);
	cv::Mat result = src.clone();
	for (int i = 0; i < result.rows; ++i)
	{
		for (int j = 0; j < result.cols; ++j)
		{
			float dx = float(center.x - j);
			float dy = float(center.y - i);
			float ra = dx * dx + dy * dy;
			float m = ((ra-diff) / diff * 255)>0? ((ra - diff) / diff * 255):0;
			int b = result.at<Vec3b>(i, j)[0];
			int g = result.at<Vec3b>(i, j)[1];
			int r = result.at<Vec3b>(i, j)[2];
			b = (int)(b+ m);
			g = (int)(g + m);
			r = (int)(r + m);
			result.at<Vec3b>(i, j)[0] = (b > 255 ? 255 : (b < 0 ? 0 : b));
			result.at<Vec3b>(i, j)[1] = (g > 255 ? 255 : (g < 0 ? 0 : g));
			result.at<Vec3b>(i, j)[2] = (r > 255 ? 255 : (r < 0 ? 0 : r));
		}
	}
	return result;
}

测试效果

本文提供的PS羽化操作函数，可以实现类似PS中羽化的效果，即目标区域中心区不变，边缘区模糊化，center参数是羽化中心，level是羽化强度，该值越大则羽化程度越大，使整张图被羽化的区域变大~

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