opencv 伽马变换

Posted 2021-08-21 qianbo_insist

1、算法原理

伽马变换一种灰度变换，属于简单图像增强，也称幂律变换
先介绍两个函数

1、normalize

归一化

normalize(imageGamma, imageGamma, 0, 255, CV_MINMAX);

2、convertScaleAbs

可实现图像增强等相关操作的快速运算,then by calculating an absolute value of the result.
计算绝对值。

cv::convertScaleAbs()用于实现对整个图像数组中的每一个元素进行输入输出操作

void cv::convertScaleAbs(
	cv::InputArray src, // 输入数组
	cv::OutputArray dst, // 输出数组
	double alpha = 1.0, // 乘数因子
	double beta = 0.0 // 偏移量
);

使用以上两步骤先把增强后的图片归一化后进行取绝对值，就得到了我们的效果

show me the code

#include <opencv2/highgui/highgui.hpp>      
#include <opencv2/imgproc/imgproc.hpp>  


using namespace cv;

int main(int argc, char *argv[])
{
	Mat image = imread("images/girl.jpg");
	Mat imageGamma(image.size(), CV_32FC3);
	Mat imageGamma1(image.size(), CV_32FC3);
	Mat imageGamma2(image.size(), CV_32FC3);
	for (int i = 0; i < image.rows; i++)
	{
		for (int j = 0; j < image.cols; j++)
		{
		imageGamma.at<Vec3f>(i, j)[0] = (image.at<Vec3b>(i, j)[0])*(image.at<Vec3b>(i, j)[0])*(image.at<Vec3b>(i, j)[0]);
			imageGamma.at<Vec3f>(i, j)[1] = (image.at<Vec3b>(i, j)[1])*(image.at<Vec3b>(i, j)[1])*(image.at<Vec3b>(i, j)[1]);
			imageGamma.at<Vec3f>(i, j)[2] = (image.at<Vec3b>(i, j)[2])*(image.at<Vec3b>(i, j)[2])*(image.at<Vec3b>(i, j)[2]);
			imageGamma1.at<Vec3f>(i, j)[0] = (image.at<Vec3b>(i, j)[0])*(image.at<Vec3b>(i, j)[0]);//*(image.at<Vec3b>(i, j)[0]+100);
			imageGamma1.at<Vec3f>(i, j)[1] = (image.at<Vec3b>(i, j)[1])*(image.at<Vec3b>(i, j)[1]);// *(image.at<Vec3b>(i, j)[1] + 100);
			imageGamma1.at<Vec3f>(i, j)[2] = (image.at<Vec3b>(i, j)[2])*(image.at<Vec3b>(i, j)[2]);// *(image.at<Vec3b>(i, j)[2] + 100);
			imageGamma2.at<Vec3f>(i, j)[0] = (image.at<Vec3b>(i, j)[0])*255;//*(image.at<Vec3b>(i, j)[0]+100);
			imageGamma2.at<Vec3f>(i, j)[1] = (image.at<Vec3b>(i, j)[1])*255;// *(image.at<Vec3b>(i, j)[1] + 100);
			imageGamma2.at<Vec3f>(i, j)[2] = (image.at<Vec3b>(i, j)[2])*255;// *(image.at<Vec3b>(i, j)[2] + 100);
			imageGamma0.at<Vec3f>(i, j)[0] = (image.at<Vec3b>(i, j)[0])/20;//*(image.at<Vec3b>(i, j)[0]+100);
			imageGamma0.at<Vec3f>(i, j)[1] = (image.at<Vec3b>(i, j)[1])/20;// *(image.at<Vec3b>(i, j)[1] + 100);
			imageGamma0.at<Vec3f>(i, j)[2] = (image.at<Vec3b>(i, j)[2])/20;// *(image.at<Vec3b>(i, j)[2] + 100);
		}
	}
	//归一化到0~255    
	normalize(imageGamma, imageGamma, 0, 255, CV_MINMAX);
	normalize(imageGamma1, imageGamma1, 0, 255, CV_MINMAX);
	normalize(imageGamma2, imageGamma2, 0, 255, CV_MINMAX);//转换成8bit图像显示    
	convertScaleAbs(imageGamma, imageGamma);
	convertScaleAbs(imageGamma1, imageGamma1);
	convertScaleAbs(imageGamma2, imageGamma2);
	imshow("原图", image);
	imshow("伽马变换图像增强效果", imageGamma);
	imshow("伽马变换图像增强效果1", imageGamma1);
	imshow("伽马变换图像增强效果2", imageGamma2);
	waitKey();
	return 0;
}

结果