【数字图像处理】1.2:灰度变换，gama变换，对数，反对数变换

#include <cv.h>
#include <highgui.h>
#include <stdio.h>
#include <math.h>
#define CONTRASTFUNC0 -1	//翻转
#define CONTRASTFUNC1 0		//分段
#define CONTRASTFUNC2 1		//对数
#define CONTRASTFUNC3 2		//反对数
#define CONTRASTFUNC4 3		//n次幂
#define CONTRASTFUNC5 4		//n次根
#define CONTRASTGAMA  5     //gama
#define GRAYLEVEL 8
#define MAX_PVALUE (1<<GRAYLEVEL)

#define GETPIX(image,x,y) ((unsigned char) (image->imageData)[(x)*image->width+(y)])
#define SETPIX(image,x,y,value) (((image->imageData)[(x)*image->width+y])=((unsigned char)value))

unsigned char ContrastTable[MAX_PVALUE];//映射表

void ContrastStretch(IplImage *src,IplImage *dst,int method,
  double p0,double p1,int p2,int p3){
  if(method==CONTRASTFUNC0){//图像翻转
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[i]=MAX_PVALUE-1-i;
  }
  else if(method==CONTRASTFUNC1){//分段拉伸
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[i]=i<=p0?i*p1/p0                 :
		     i<=p2?(i-p0)*(p3-p1)/(p2-p0)+p1:
		     (i-p2)*(MAX_PVALUE-1-p3)/(MAX_PVALUE-1-p2)+p3;
  }
  else if(method==CONTRASTFUNC2){//对数
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[i]=46*log(double(1+i));//46*log(256)近似于256

  }
  else if(method==CONTRASTFUNC3){//反对数
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[(int)(46*log(double(1+i)))]=i;
    for(int i=0;i<MAX_PVALUE;i++)
      if(ContrastTable[i]==0)
        ContrastTable[i]=ContrastTable[i-1];

  }
  else if(method==CONTRASTFUNC4){//N次方
    double coef=255/pow(255.,(double) p0);//coef为系数，即255要映射到255
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[i]=coef*pow((double)i,(double)p0);

  }
  else if(method==CONTRASTFUNC5){//N次根
    double coef=255/pow(255.,(double) p0);//coef为系数，即255要映射到255
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[(int)(coef*pow((double)i,(double)p0))]=i;
    for(int i=0;i<MAX_PVALUE;i++)
      if(ContrastTable[i]==0)
        ContrastTable[i]=ContrastTable[i-1];
  }
  else if(method==CONTRASTGAMA){//gama
    double gama=p0;
    double coef=255/pow(255.,gama);//coef为系数，即255的gama次幂要映射到255
    coef=(p1<=coef&&p1>0.0)?p1:coef;
    for(int i=0;i<MAX_PVALUE;i++)
      ContrastTable[i]=coef*pow((double)i,gama);
  }

///////////////////////////////重新映射/////////////////////////////////////////////
  for(int i=0;i<256;i++)
    printf("%d->%d\n",i,ContrastTable[i]);
    for(int i=0;i<src->width;i++)
      for(int j=0;j<src->height;j++)
        SETPIX(dst,i,j,ContrastTable[GETPIX(src,i,j)]);
}

int main(){
  IplImage * image = cvLoadImage("e:\\OpenCV_Image\\lena.jpg",0);
  IplImage * test =cvCreateImage(cvSize(512,512),image->depth,1);
  //meanfilter(image,test,3);
  ContrastStretch(image,test,0,100,0,100,255);
  cvNamedWindow("原图");
  cvNamedWindow("变换");
  cvShowImage("原图",image);
  cvShowImage("变换",test);
  cvSaveImage("e:\\OpenCV_Image\\lena_thr100.jpg",test);
  cvWaitKey();
  cvReleaseImage(&image);
}