opencv 使较暗的物体变亮_opencv 黑夜变白天

测试图片：

code：

方案1：

#include "cv.h"
 
#include "highgui.h"
 
 
#define HDIM    256    // bin of HIST, default = 256
 
 
int main( int argc, char** argv )
 
{
 
    IplImage *src = 0, *dst = 0;
 
    CvHistogram *hist = 0;
 
 
    int n = HDIM;
 
    double nn[HDIM];
 
    uchar T[HDIM];
 
    CvMat *T_mat;
 
 
    int x;
 
    int sum = 0; // sum of pixels of the source image 图像中象素点的总和
 
    double val = 0;
 
 
        src=cvLoadImage("1.jpg", 0);
 
 
 
    cvNamedWindow( "source", 1 );
 
    cvNamedWindow( "result", 1 );
 
 
    // calculate histgram 计算直方图
 
    hist = cvCreateHist( 1, &n, CV_HIST_ARRAY, 0, 1 );
 
    cvCalcHist( &src, hist, 0, 0 );
 
 
    // Create Accumulative Distribute Function of histgram
 
    val = 0;
 
    for ( x = 0; x < n; x++)
 
    {
 
        val = val + cvGetReal1D (hist->bins, x);
 
        nn[x] = val;
 
    }
 
 
    // Compute intensity transformation 计算变换函数的离散形式
 
    sum = src->height * src->width;
 
    for( x = 0; x < n; x++ )
 
    {
 
        T[x] = (uchar) (255 * nn[x] / sum); // range is [0,255]
 
    }
 
 
    // Do intensity transform for source image
 
    dst = cvCloneImage( src );
 
    T_mat = cvCreateMatHeader( 1, 256, CV_8UC1 );
 
    cvSetData( T_mat, T, 0 );
 
    // directly use look-up-table function 直接调用内部函数完成 look-up-table 的过程
 
    cvLUT( src, dst, T_mat );
 
 
 
        int y;
 
        for(y=0;y<dst->height;y++)
 
        {
 
                for(x=0;x<dst->width;x++)
 
                {
 
                        int dstV,srcV;
 
 
                        dstV = cvGetReal2D(dst,y,x);
 
                        srcV = cvGetReal2D(src,y,x);
 
 
                        int newV ;
 
                        newV = (srcV*0.7+dstV*0.4);
 
                        newV = newV > 255 ? 255 : newV;
 
 
                                cvSetReal2D(dst,y,x,newV);
 
                        
                }
 
        }
 
 
    cvShowImage( "source", src );
 
    cvShowImage( "result", dst );
 
    cvWaitKey(0);
 
 
    cvDestroyWindow("source");
 
    cvDestroyWindow("result");
 
    cvReleaseImage( &src );
 
    cvReleaseImage( &dst );
 
    cvReleaseHist ( &hist );
 
    return 0;
 
}

效果：

方案2：

#include "stdafx.h"
 
 
#include "cv.h"
 
#include "cxcore.h"
 
#include "highgui.h"
 
 
 
 
 
int main(int argc, char* argv[])
 
{
 
        IplImage* src;
 
        src = cvLoadImage("1.jpg");
 
 
        IplImage* srcSmooth;
 
 
        srcSmooth= cvCreateImage(cvGetSize(src),8,3);
 
 
        cvSmooth(src,srcSmooth,CV_GAUSSIAN,35,35,0,0);
 
        
        IplImage* srcGray=cvCreateImage(cvGetSize(src),8,1);
 
        cvCvtColor(srcSmooth,srcGray,CV_BGR2GRAY);
 
        
 
 
        CvMat* points = cvCreateMat(srcGray->height*srcGray->width , 1 , CV_32FC1);
 
        CvMat* clusters= cvCreateMat(srcGray->height*srcGray->width , 1 , CV_32SC1);
 
 
 
        uchar* image_data = (uchar*)srcGray->imageData;
 
        int width_step = srcGray->widthStep;
 
 
        int x,y;
 
        for(y=0;y<src->height;y++)
 
        {
 
                for(x=0;x<src->width;x++)
 
                {
 
                        points->data.fl[y*srcGray->width+x] = (float)(*(image_data + y*width_step + x));
 
                }
 
        }
 
 
        cvKMeans2(points,3,clusters ,cvTermCriteria(CV_TERMCRIT_EPS+CV_TERMCRIT_ITER,10,1.0));
 
 
                float cluster_0_count=0,cluster_1_count=0;
 
        float sum_cluster_0 =0 , sum_cluster_1 = 0;
 
 
        for(y=0;y<srcGray->height;y++)
 
        {
 
                for(x=0;x<srcGray->width;x++)
 
                {
 
                        int cluster_id = clusters->data.i[y*srcGray->width+x];
 
 
                        if(cluster_id == 0 || cluster_id==2)
 
                        {
 
                                sum_cluster_0 = sum_cluster_0 + (float)(*(image_data + y*width_step + x));
 
                                cluster_0_count  = cluster_0_count + 1;
 
 
                                *(image_data + y*width_step + x) = 255;
 
 
                        }
 
                        else if(cluster_id == 1 )
 
                        {
 
                                sum_cluster_1 = sum_cluster_1 + (float)(*(image_data + y*width_step + x));
 
 
                                *(image_data + y*width_step + x) = (int)cvGetReal2D(srcGray,y,x);
 
                        }
 
                        else
 
                        {
 
                        }
 
                }
 
        }
 
 
 
        cvNamedWindow("src");
 
        cvShowImage("src",src);
 
 
        cvNamedWindow("s");
 
        cvShowImage("s",srcSmooth);
 
 
        cvNamedWindow("g");
 
        cvShowImage("g",srcGray);
 
 
        cvWaitKey(0);
 
        return 0;
 
}

效果：