Merge pull request #640 from sciunto/missingdoc

DOCFIX: add docstrings to Cython grayscale dilate/erode & make them private funcs

skimage/morphology/cmorph.pyx

@@ -8,11 +8,34 @@ cimport numpy as np
 from libc.stdlib cimport malloc, free
 
 
-def dilate(np.ndarray[np.uint8_t, ndim=2] image,
-           np.ndarray[np.uint8_t, ndim=2] selem,
-           np.ndarray[np.uint8_t, ndim=2] out=None,
-           char shift_x=0, char shift_y=0):
+def _dilate(np.ndarray[np.uint8_t, ndim=2] image,
+            np.ndarray[np.uint8_t, ndim=2] selem,
+            np.ndarray[np.uint8_t, ndim=2] out=None,
+            char shift_x=0, char shift_y=0):
+    """Return greyscale morphological erosion of an image.
 
+    Morphological erosion sets a pixel at (i,j) to the minimum over all pixels
+    in the neighborhood centered at (i,j). Erosion shrinks bright regions and
+    enlarges dark regions.
+
+    Parameters
+    ----------
+    image : ndarray
+        Image array.
+    selem : ndarray
+        The neighborhood expressed as a 2-D array of 1's and 0's.
+    out : ndarray
+        The array to store the result of the morphology. If None is
+        passed, a new array will be allocated.
+    shift_x, shift_y : bool
+        shift structuring element about center point. This only affects
+        eccentric structuring elements (i.e. selem with even numbered sides).
+
+    Returns
+    -------
+    eroded : uint8 array
+        The result of the morphological erosion.
+    """
     cdef Py_ssize_t rows = image.shape[0]
     cdef Py_ssize_t cols = image.shape[1]
     cdef Py_ssize_t srows = selem.shape[0]
@@ -63,10 +86,35 @@ def dilate(np.ndarray[np.uint8_t, ndim=2] image,
     return out
 
 
-def erode(np.ndarray[np.uint8_t, ndim=2] image,
-          np.ndarray[np.uint8_t, ndim=2] selem,
-          np.ndarray[np.uint8_t, ndim=2] out=None,
-          char shift_x=0, char shift_y=0):
+def _erode(np.ndarray[np.uint8_t, ndim=2] image,
+           np.ndarray[np.uint8_t, ndim=2] selem,
+           np.ndarray[np.uint8_t, ndim=2] out=None,
+           char shift_x=0, char shift_y=0):
+    """Return greyscale morphological dilation of an image.
+
+    Morphological dilation sets a pixel at (i,j) to the maximum over all pixels
+    in the neighborhood centered at (i,j). Dilation enlarges bright regions
+    and shrinks dark regions.
+
+    Parameters
+    ----------
+
+    image : ndarray
+        Image array.
+    selem : ndarray
+        The neighborhood expressed as a 2-D array of 1's and 0's.
+    out : ndarray
+        The array to store the result of the morphology. If None, is
+        passed, a new array will be allocated.
+    shift_x, shift_y : bool
+        shift structuring element about center point. This only affects
+        eccentric structuring elements (i.e. selem with even numbered sides).
+
+    Returns
+    -------
+    dilated : uint8 array
+        The result of the morphological dilation.
+    """
 
     cdef Py_ssize_t rows = image.shape[0]
     cdef Py_ssize_t cols = image.shape[1]

skimage/morphology/grey.py

@@ -58,8 +58,8 @@ def erosion(image, selem, out=None, shift_x=False, shift_y=False):
         raise NotImplementedError("In-place erosion not supported!")
     image = img_as_ubyte(image)
     selem = img_as_ubyte(selem)
-    return cmorph.erode(image, selem, out=out,
-                        shift_x=shift_x, shift_y=shift_y)
+    return cmorph._erode(image, selem, out=out,
+                         shift_x=shift_x, shift_y=shift_y)
 
 
 def dilation(image, selem, out=None, shift_x=False, shift_y=False):
@@ -111,8 +111,8 @@ def dilation(image, selem, out=None, shift_x=False, shift_y=False):
         raise NotImplementedError("In-place dilation not supported!")
     image = img_as_ubyte(image)
     selem = img_as_ubyte(selem)
-    return cmorph.dilate(image, selem, out=out,
-                         shift_x=shift_x, shift_y=shift_y)
+    return cmorph._dilate(image, selem, out=out,
+                          shift_x=shift_x, shift_y=shift_y)
 
 
 def opening(image, selem, out=None):