Need a little help increasing the speed of this code...

[Superbatman]

Hey, I have some code, which is quite slow - so would anybody out there be able to optimize it for me??

#include <windows.h> 
 
int main(int argc, char *argv[]) { 
    HDC hDC; int Width; int Height; long ThisColor;

    hDC = (HDC)atoi(argv[1]); 
    Width = atoi(argv[2]);
    Height = atoi(argv[3]);

    for(int x=0;x<Width;x++)
    {
      for(int y=0;y<Height;y++)
      {
        ThisColor = GetPixel(hDC, x, y);
        if (ThisColor==16579836) {
          SetPixelV(hDC, x, y, RGB(248,232,248));
        }
        if (ThisColor==11842740) {
          SetPixelV(hDC, x, y, RGB(160,208,248));
        }
        if (ThisColor==10526880) {
          SetPixelV(hDC, x, y, RGB(200,224,216));
        }
        if (ThisColor==6579300) {
          SetPixelV(hDC, x, y, RGB(24,16,16));
        }
      }
    }
    return 0; 
}

Thanks~