EMD2d.py 文件源码

def find_extrema(cls, image):
        """
        Finds extrema, both mininma and maxima, based on local maximum filter.
        Returns extrema in form of two rows, where the first and second are
        positions of x and y, respectively.

        Parameters
        ----------
        image : numpy 2D array
            Monochromatic image or any 2D array.

        Returns
        -------
        min_peaks : numpy array
            Minima positions.
        max_peaks : numpy array
            Maxima positions.
        """

        # define an 3x3 neighborhood
        neighborhood = generate_binary_structure(2,2)

        # apply the local maximum filter; all pixel of maximal value
        # in their neighborhood are set to 1
        local_min = maximum_filter(-image, footprint=neighborhood)==-image
        local_max = maximum_filter(image, footprint=neighborhood)==image

        # can't distinguish between background zero and filter zero
        background = (image==0)

        #appear along the bg border (artifact of the local max filter)
        eroded_background = binary_erosion(background,
                                structure=neighborhood, border_value=1)

        # we obtain the final mask, containing only peaks,
        # by removing the background from the local_max mask (xor operation)
        min_peaks = local_min ^ eroded_background
        max_peaks = local_max ^ eroded_background

        min_peaks[[0,-1],:] = False
        min_peaks[:,[0,-1]] = False
        max_peaks[[0,-1],:] = False
        max_peaks[:,[0,-1]] = False

        min_peaks = np.nonzero(min_peaks)
        max_peaks = np.nonzero(max_peaks)

        return min_peaks, max_peaks