rctest.c

#include <stdio.h>

int main()
{

  printf("P6");
  printf("1000 1000");
  printf("255");
  int x, y;
  for(y = 0; y<1000; y++)
  {
    for (x= 0; x<1000; x++)
    {

      printf("%c%c%c", (unsigned char)255, (unsigned char)0, (unsigned char)0);
    }
  }
}