小弟友執行效率上的困惱 想請問各位大大有更精簡的寫法嗎    

 
//主程式 多階Harr
void DWTImage_Haar(short int **img,int Height,int Width,int Layer)
{
  for(int i=0;i<Layer;i  )
  {
    HOR_SD_Short(img,Height,Width);
    VER_SD_Short(img,Height,Width);
    Height = Height >> 1;
    Width = Width >> 1;
  }
}    //--------2D horizontal sub-band decomposition
// img: input image
// Height: image height;    N: image width      N even;
static void HOR_SD_Short(short int **img,int Height,int N)
{
  short int *y=NULL, *x=NULL;
    /* allocate memory for y */
  int size=N*sizeof(short int);
  if ((y = (short int *) malloc(size)) == NULL)
  {
     printf("Not enough memory to allocate buffer\n");
     exit(1);  /* terminate program if out of memory */
  }
  register int i=0,j=0,k=0;
  int h=N>>1;
  for(k=0;k>1;
  for(k=0;k>1;
      *(*(x h i) k)=(*(y j)-*(y j 1))>>1;
    }
  }
  free(y);
}    

承蒙指教 不勝感激

swindler你好： HOR_SD_Short和VER_SD_Short在呼叫malloc上一共重複了2*Layer次，如果改成在DWTImage_Haar一次就直接配置最大的size。再傳給HOR_SD_Short和VER_SD_Short，那就只要呼叫一次的malloc。不過如果Layer不大的話，就沒什麼差別了。