Try this function instead: Func _GDIPlus_ImageCompare($hImage1, $hImage2, $bFastCmp = True) Local Const $iW = _GDIPlus_ImageGetWidth($hImage1), $iH = _GDIPlus_ImageGetHeight($hImage1) If ($iW <> _GDIPlus_ImageGetWidth($hImage2)) Then Return SetError(1, 0, 0) If ($iH <> _GDIPlus_ImageGetHeight($hImage2)) Then Return SetError(2, 0, 0) Local $t = TimerInit() Local $tBitmapData1 = _GDIPlus_BitmapLockBits($hImage1, 0, 0, $iW, $iH, $GDIP_ILMREAD, $GDI