【15】OSTU

【1】c++源碼(自己編寫)

#include <iostream>
#include<opencv2/core.hpp>
#include<opencv.hpp>
#include<time.h>
#include <math.h>

using namespace cv;
using namespace std;

int Otsu1(Mat & src)
{
	int th;
	const int GrayScale = 256;	//單通道圖像總灰度256級
	int pixCount[GrayScale] = { 0 };//每個灰度值所佔像素個數
	int pixSum = src.cols * src.rows;//圖像總像素點
	float pixPro[GrayScale] = { 0 };//每個灰度值所佔總像素比例
	float w0, w1, u0tmp, u1tmp, u0, u1, deltaTmp, deltaMax = 0;
	for (int i = 0; i < src.cols; i++){
		for (int j = 0; j < src.rows; j++){
			pixCount[src.at<uchar>(j, i)]++;//統計每個灰度級中像素的個數  
		}
	}
	for (int i = 0; i < GrayScale; i++){
		pixPro[i] = pixCount[i] * 1.0 / pixSum;//計算每個灰度級的像素數目佔整幅圖像的比例  
	}
	for (int i = 0; i < GrayScale; i++)//遍歷所有從0到255灰度級的閾值分割條件，測試哪一個的類間方差最大
	{
		w0 = w1 = u0tmp = u1tmp = u0 = u1 = deltaTmp = 0;
		for (int j = 0; j < GrayScale; j++)	{
			if (j <= i)//背景
			{
				w0 += pixPro[j];
				u0tmp += j * pixPro[j];
			}
			else//前景
			{
				w1 += pixPro[j];
				u1tmp += j * pixPro[j];
			}
		}
		u0 = u0tmp / w0;
		u1 = u1tmp / w1;
		deltaTmp = (float)(w0 *w1* pow((u0 - u1), 2)); //類間方差公式 g = w1 * w2 * (u1 - u2) ^ 2
		if (deltaTmp > deltaMax)
		{
			deltaMax = deltaTmp;
			th = i;
		}
	}
	return th;
}

【2】threshold自帶

threshold(inputImg, thresholdImg, 130, 255, THRESH_OTSU);