Opencv学习笔记三-直方图点运算（直方图基本点算子、直方图正规化、直方图均衡化）

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三：直方图均衡化

直方图均衡化是一个非线性处理过程，其目的是通过一种合适人类视觉分析的方法来增强图像的亮度。它对图像进行改变，使得图像具有更平坦的直方图，所有亮度及等概率出现。其数学原理请参照：http://www.cnblogs.com/cfantaisie/archive/2011/06/05/2073406.html和附件：http://download.csdn.net/detail/fullyfulei/5303040。

直方图均衡化OpenCV实现：

http://blog.csdn.net/xiaowei_cqu/article/details/7606607

直方图均衡化C语言实现：（网上找的代码自己并未测试过，看过原理实现应该比较简单）

http://blog.sina.com.cn/s/blog_633b2a530101cyxh.html

#include <stdio.h>#include <stdlib.h>#include <malloc.h>#include <string.h>#include <math.h>unsigned char **get_matrix_space(int m,int n){int i;unsigned char **a;a=(unsigned char **)calloc(m,sizeof(unsigned char *));for(i=0;i<m;i++)a[i]=(unsigned char *)calloc(n,sizeof(unsigned char));return a;}main(){FILE *fs,*ft;char c1,c2;int width,height,L,i,j,max,min;int n[256]={0};double p[256]={0};double c[256]={0};unsigned char **s,**t,**get_matrix_space(int,int);if((fs= fopen("source.pgm","rb")) ==NULL){printf("can't open %s\n","source.pgm");exit(1);}if((ft = fopen("destination.pgm","wb")) ==NULL){printf("can't open %s\n","destination.pgm");exit(1);}fscanf(fs,"%c%c\n%d%d\n%d\n",&c1,&c2,&width,&height,&L);s=get_matrix_space(height,width);t=get_matrix_space(height,width);for(i=0;i<height;i++){for(j=0;j<width;j++){fread(&s[i][j],sizeof(unsigned char),1,fs);}}for(i=0;i<height;i++){for(j=0;j<width;j++){n[s[i][j]]++;}}for(i=0;i<256;i++){p[i] = (double)n[i]/(height*width);}for(i=0;i<256;i++){for(j=0;j<=i;j++){c[i]+=p[j];}}max=min=s[0][0];for(i=0;i<height;i++){for(j=0;j<width;j++){if(max<s[i][j]){max=s[i][j];}else if(min>s[i][j]){min=s[i][j];}}}printf("%d %d\n",max,min);for(i=0;i<height;i++){for(j=0;j<width;j++){t[i][j]=c[s[i][j]]*(max-min)+min;}}fprintf(ft,"%c%c\n%d %d\n%d\n",'P','5',width,height,L);for(i=0;i<height;i++){for(j=0;j<width;j++){fwrite(&t[i][j],sizeof(unsigned char),1,ft);}}}