def getdarkimg(self,chip):
        """
        Notes
        =====
        Return an array representing the dark image for the detector.

        The method will return an array of the same shape as the image.

        :units: electrons
        """
        sci_chip = self._image[self.scienceExt,chip]
        return np.ones(sci_chip.image_shape,dtype=sci_chip.image_dtype)*sci_chip.darkcurrent