#include <graphics.h>
unsigned getpixel(int x, int y);
 

getpixel gets the color of the pixel located at (x,y).

/* getpixel example */
 
#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <dos.h>
 
#define PIXEL_COUNT 1000
#define DELAY_TIME  100  /* in milliseconds */
 
int main(void)
{
   /* request autodetection */
   int gdriver = DETECT, gmode, errorcode;
   int i, x, y, color, maxx, maxy, maxcolor, seed;
 
   /* initialize graphics and local variables */
   initgraph(&gdriver, &gmode, "");
 
   /* read result of initialization */
   errorcode = graphresult();
 
   if (errorcode != grOk) {  /* an error occurred */
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1);   /* terminate with an error code */
   }
 
   maxx = getmaxx() + 1;
   maxy = getmaxy() + 1;
   maxcolor = getmaxcolor() + 1;
   while (!kbhit()) {
seed = random(32767);  /* seed the random number generator */
srand(seed);
for (i=0; i<PIXEL_COUNT; i++) {
 
   x = random(maxx);
   y = random(maxy);
   color = random(maxcolor);
   putpixel(x, y, color);
}
delay(DELAY_TIME);
srand(seed);
for (i=0; i<PIXEL_COUNT; i++) {
   x = random(maxx);
   y = random(maxy);
   color = random(maxcolor);
   if (color == getpixel(x, y))
putpixel(x, y, 0);
}
   }
 
   /* clean up */
   getch();
   closegraph();
   return 0;
}

getimage putpixel

  no output of example at the moment
  do not hesitate and add it...