1. histogram (PDF) 구하고
2. CDF 구하고
3. Y(imageout) = CDF(imagein)
#pragma warning(disable: 4819)
#include "opencv2/opencv.hpp"
#include <iostream>
using namespace cv;
using namespace std;
int main(void)
{
Mat src = imread("lenna.bmp", IMREAD_GRAYSCALE);if (src.empty()) { cerr << "Image load failed!" << endl; return -1; }
int hist[256] = { 0, };
for (int j = 0; j < src.rows; j++) {
for (int i = 0; i < src.cols; i++) {
hist[src.at<uchar>(j,i)]++;
}
}
int hist_max = 0;
for (int i = 0; i < 256; i++) {
if (hist[i] > hist_max)
hist_max = hist[i];
}
Mat histogram_original;
histogram_original.create(256,256, CV_8U);
histogram_original.setTo(0);
int N=0;
for (int i = 0; i < 256; i++) {
int v = (double) (255.* hist[i])/ hist_max;
v = cvRound(v);
for (int j = 0; j < v; j++) {
histogram_original.at<uchar>(255-j, i) = 255;
}
}
int CDF[256] = { 0, };
CDF[0] = 0;
for (int i = 1; i < 256; i++) {
CDF[i] = hist[i] + CDF[i - 1];
}
//CDF normalize
for (int i = 1; i < 256; i++) {
CDF[i] = cvRound(255.*CDF[i]/CDF[255]);
// CDF[i] = 255.*CDF[i] / CDF[255];
}
Mat CDFdrawing;
CDFdrawing.create(256, 256, CV_8U);
CDFdrawing.setTo(255);
for (int i = 0 ; i < 256; i++) {
line(CDFdrawing, Point(i, 255 - CDF[i]), Point(i, 255 - CDF[i]), 0);
}
//imshow("dst", dst);
//CDF function Y(output) = CDF(input)
Mat src2 = src.clone();
Mat dst(src2.rows, src2.cols, src2.type());
for (int i = 0; i < src2.rows; i++) {
for (int j = 0; j < src2.cols; j++) {
dst.at<uchar>(j, i) = CDF[(uchar)src2.at<uchar>(j, i)];
}
}
imshow("src", src);
imshow("histogram_original", histogram_original);
imshow("CDFdrawing", CDFdrawing);
imshow("dst", dst);
//check equalized Image historam, CDF
int hist2[256] = { 0, };
for (int j = 0; j < dst.rows; j++) {
for (int i = 0; i < dst.cols; i++) {
hist2[dst.at<uchar>(j, i)]++;
}
}
int hist2_max = 0;
for (int i = 0; i < 256; i++) {
if (hist2[i] > hist2_max)
hist2_max = hist2[i];
}
Mat histogram_equalized;
histogram_equalized.create(256, 256, CV_8U);
histogram_equalized.setTo(0);
int N2 = 0;
for (int i = 0; i < 256; i++) {
int v = (double)(255.* hist2[i]) / hist2_max;
v = cvRound(v);
for (int j = 0; j < v; j++) {
histogram_equalized.at<uchar>(255 - j, i) = 255;
}
}
int CDF2[256] = { 0, };
CDF2[0] = 0;
for (int i = 1; i < 256; i++) {
CDF2[i] = hist2[i] + CDF2[i - 1];
}
//CDF normalize
for (int i = 1; i < 256; i++) {
CDF2[i] = cvRound(255.*CDF2[i] / CDF2[255]);
// CDF[i] = 255.*CDF[i] / CDF[255];
}
Mat CDFdrawing2;
CDFdrawing2.create(256, 256, CV_8U);
CDFdrawing2.setTo(255);
for (int i = 0; i < 256; i++) {
line(CDFdrawing2, Point(i, 255 - CDF2[i]), Point(i, 255 - CDF2[i]), 0);
}
imshow("histogram_equalized", histogram_equalized);
imshow("CDF_equalized", CDFdrawing2);
waitKey(0);
return 0;
}
