本文实现彩色图像的全局直方图均衡。分别对R/G/B三通道均衡，读写图片采用OpenCV。代码如下：

#include

//#include

//#include

//#include

#include

#include

#include

#include "EqualizeHist.h"

//typedef unsigned char uchar;

IplImage* EqualizeHistColorImage(IplImage *pImage)

{

IplImage *pEquaImage = cvCreateImage(cvGetSize(pImage), pImage->depth, 3);

// 原图像分成各通道后再均衡化,最后合并即彩色图像的直方图均衡化

const int MAX_CHANNEL = 4;

IplImage *pImageChannel[MAX_CHANNEL] = {NULL};

int i;

for (i = 0; i < pImage->nChannels; i++)

pImageChannel[i] = cvCreateImage(cvGetSize(pImage), pImage->depth, 1);

cvSplit(pImage, pImageChannel[0], pImageChannel[1], pImageChannel[2], pImageChannel[3]);

for (i = 0; i < pImage->nChannels; i++)

// cvEqualizeHist(pImageChannel[i], pImageChannel[i]);

EqualizeHist( (uchar*)(pImageChannel[i]->imageData), (uchar*)(pImageChannel[i]->imageData),pImage->width,pImage->height );

cvMerge(pImageChannel[0], pImageChannel[1], pImageChannel[2], pImageChannel[3], pEquaImage);

for (i = 0; i < pImage->nChannels; i++)

cvReleaseImage(&pImageChannel[i]);

return pEquaImage;

}

int main( int argc, char** argv )

{

IplImage* pImg; //声明IplImage指针

IplImage* pEquaImage;

clock_t start, finish;

double time;

//载入图像，强制转化为Gray

pImg = cvLoadImage( "nupt.jpg", CV_LOAD_IMAGE_UNCHANGED);

if(pImg==NULL)

return -1;

printf("Load img success\n");

start = clock();

pEquaImage = EqualizeHistColorImage(pImg);

finish = clock();

time = (double)(finish - start) / CLOCKS_PER_SEC;

printf( "finish operation for %dchannels in %lf seconds\n",pImg->nChannels,time);

cvNamedWindow("src",CV_WINDOW_AUTOSIZE);

cvNamedWindow("dst",CV_WINDOW_AUTOSIZE);

cvShowImage("src",pImg);

cvShowImage("dst",pEquaImage);

cvWaitKey(0);

cvSaveImage("ret.jpg", pEquaImage);//把图像写入文件

cvReleaseImage(&pImg); //释放图像

cvReleaseImage(&pEquaImage);

return 0;

}

//#include

#include

typedef unsigned char uchar;

void EqualizeHist( const unsigned char* src,unsigned char* dst,int width,int height )

{

int x,y;

const int hist_sz = 256;

int hist[hist_sz];

memset(hist, 0, sizeof(hist));

int size = width*height;

//统计每个灰度值出现的次数

for(x=0;x

assert(*(src+x)<257 && *(src+x)>=0);

hist[*(src+x)]++;

}

float scale = 255.f/(width*height);

int sum = 0;

uchar lut[hist_sz+1];

for(x = 0; x < hist_sz; x++ )

{

sum += hist[x];

//int val = round(sum*scale);

int val =(sum*scale+0.5);

lut[x] = val;

}

lut[0] = 0;

for( y = 0; y < size; y++ )

{

*(dst+y) = lut[*(src+y)];

if(y%100==0)

printf("%d\n",*(dst+y));

}

}

原图：

效果图