Filtering Bitmaps

 #include <iostream>
#include <windows.h>
using namespace std;
 
int main() {
  // The pixel we're scanning for
  COLORREF tofind = RGB( 255, 0, 0 );
 
  // Screen size
  int screen_width = GetSystemMetrics( SM_CXSCREEN );
  int screen_height = GetSystemMetrics( SM_CYSCREEN );
 
  // Get HBITMAP from our HDC of the screen
  HDC hdc = GetDC( NULL );
  HDC hdcMem = CreateCompatibleDC( hdc );
 
  HBITMAP bmp = CreateCompatibleBitmap( hdcMem, screen_width, screen_height );
  SelectObject( hdcMem, bmp );
  BitBlt( hdcMem , 0, 0, screen_width, screen_height, hdc, 0, 0, SRCCOPY );
 
  // bmp now contains the screenshot
}