[PhoeniX]

Код:

procedure ParseBg(var bmp: TBitmap);
var
  x, y, i, sx, sy, w, h: integer;
  r, g, b: Byte;
  screenb:TBitmap;
begin
  w:=bmp.Width;
  h:=bmp.Height;
  screenb := TBitmap.Create;
  screenb.Width := w;
  screenb.Height := h;
  sx:=(screen.Width-w)div 2;
  sy:=(screen.Height-h)div 2;
  BitBlt(screenb.Canvas.Handle, 0, 0, w, h, GetDC(0), sx, sy, SRCCOPY);
  for y:=0 to h-1 do
    for x:=0 to w-1 do begin
      i:=bmp.Canvas.Pixels[x,y];
      r:=i and $FF;
      g:=i shr 8 and $FF;
      b:=i shr 16 and $FF;
      if (r=g)and(g=b) then begin
        i:=screenb.Canvas.Pixels[x,y];
        r:=(i and $FF)*r shr 8;
        g:=(i shr 8 and $FF)*g shr 8;
        b:=(i shr 16 and $FF)*b shr 8;
        bmp.Canvas.Pixels[x,y]:=(r or (g shl 8) or (b shl 16));
      end;
    end;
  screenb.Free;
end;

Странно, но этот метод работает даже быстрее сканлайна...