（代码2）读入一幅图像将之反色并显示

#include
#include
#include
#include
#include  
 
int main(int argc, char *argv[])
{
  IplImage* img = 0; 
  int height,width,step,channels;
  uchar *data;
  int i,j,k; 
 
  // load an image  
  const char* imagename = "lena.jpg";
  img=cvLoadImage(imagename);
  if(!img){
    printf("Could not load image file: %s\n",argv[1]);
    exit(0);
  } 
 
  // get the image data
  height    = img->height;
  width     = img->width;
  step      = img->widthStep;
  channels  = img->nChannels;
  data      = (uchar *)img->imageData;
  printf("Processing a %dx%d image with %d channels\n",height,width,channels); 
 
  // create a window
  cvNamedWindow("mainWin", CV_WINDOW_AUTOSIZE); 
  cvMoveWindow("mainWin", 100, 100); 
 
  // invert the image
  // 相当于 cvNot(img);用这个函数前面的许多代码（// get the image data）都可以不要了。。。
  // IplImage *pDstImg = cvCreateImage(cvGetSize(img),img->depth,img->nChannels);

  // cvNot(img, pDstImg); 

  for(i=0;i

     for(j=0;j

        for(k=0;k

              data[i*step+j*channels+k]=255-data[i*step+j*channels+k]; 
 
  // show the image
  cvShowImage("mainWin", img ); //如果之前用的cvNot，则这里是 pDstImg
 
  // wait for a key
  cvWaitKey(0); 
 
  // release the image
  cvReleaseImage(&img );
  return 0;
}