#include <iostream>
#include <opencv2/core.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>
void Histogram_equalization(cv::Mat& src, cv::Mat& dst){
CV_Assert(src.depth() == CV_8U);
src.copyTo(dst);
int nr = src.rows;
int nc = src.cols;
int pixnum = nr*nc;
if (src.channels() == 1){
//统计直方图
int gray[256] = { 0 };
for (int i = 1; i < nr; ++i){
const uchar* ptr = src.ptr<uchar>(i);
for (int j = 0; j < nc; ++j){
gray[ptr[j]]++;
}
}
//计算分布函数
int LUT[256];
int sum = 0;
for (int k = 0; k < 256; k++){
sum = sum + gray[k];
LUT[k] = 255 * sum / pixnum;
}
//灰度变换（赋值）
for (int i = 1; i < nr; ++i){
const uchar* ptr_src = src.ptr<uchar>(i);
uchar* ptr_dst = dst.ptr<uchar>(i);
for (int j = 0; j < nc; ++j){
ptr_dst[j] = LUT[ptr_src[j]];
}
}
}
else{
//统计直方图
int B[256] = { 0 };
int G[256] = { 0 };
int R[256] = { 0 };
for (int i = 0; i < nr; ++i){
for (int j = 0; j < nc; ++j){
B[src.at<cv::Vec3b>(i, j)[0]]++;
G[src.at<cv::Vec3b>(i, j)[1]]++;
R[src.at<cv::Vec3b>(i, j)[2]]++;
}
}
//计算分布函数
int LUT_B[256], LUT_G[256], LUT_R[256];
int sum_B = 0, sum_G = 0, sum_R = 0;
for (int k = 0; k < 256; k++){
sum_B = sum_B + B[k];
sum_G = sum_G + G[k];
sum_R = sum_R + R[k];
LUT_B[k] = 255 * sum_B / pixnum;
LUT_G[k] = 255 * sum_G / pixnum;
LUT_R[k] = 255 * sum_R / pixnum;
}
//灰度变换（赋值）
for (int i = 0; i < nr; ++i){
for (int j = 0; j < nc; ++j){
dst.at<cv::Vec3b>(i, j)[0] = LUT_B[src.at<cv::Vec3b>(i, j)[0]];
dst.at<cv::Vec3b>(i, j)[1] = LUT_G[src.at<cv::Vec3b>(i, j)[1]];
dst.at<cv::Vec3b>(i, j)[2] = LUT_R[src.at<cv::Vec3b>(i, j)[2]];
}
}
}
}
int main(){
cv::Mat src = cv::imread("I:/Learning-and-Practice/2019Change/Image process algorithm/Img/ya.png");
if (src.empty()){
return -1;
}
cvtColor(src, src, CV_RGB2GRAY);
cv::Mat dst;
Histogram_equalization(src, dst);//直方图均衡
cv::namedWindow("src");
cv::imshow("src", src);
cv::namedWindow("dst");
cv::imshow("dst", dst);
cv::imwrite("I:/Learning-and-Practice/2019Change/Image process algorithm/Histogram equalization/Histogram equalization/ya.jpg",dst);
cv::waitKey(0);
}
