Add a utility function to convert images from matplotlib format to bob format

bob/io/image/__init__.py

@@ -10,7 +10,7 @@ from . import version
 from .version import module as __version__
 
 from ._library import *
-from .utils import imshow, to_matplotlib
+from .utils import *
 
 import os
 

bob/io/image/utils.py

-#!/usr/bin/env python
+import numpy as np
+import matplotlib.pyplot as plt
 
 
 def to_matplotlib(img):
     '''Returns a view of the image compatible with matplotlib.
 
-    Parameters:
-        img (numpy.ndarray): A 2 or 3 dimensional array containing an image in
-            bob style: For a 2D array (grayscale image) should be ``(y, x)``;
-            For a 3D array (color image) should be ``(n, y, x)``.
+    Parameters
+    ----------
+    img : numpy.ndarray
+        A 2 or 3 dimensional array containing an image in bob style: For a 2D
+        array (grayscale image) should be ``(y, x)``; For a 3D array (color
+        image) should be ``(n, y, x)``.
 
-    Returns:
-        numpy.ndarray: A view of the ``img`` compatible with
-            :py:func:`matplotlib.pyplot.imshow`.
+    Returns
+    -------
+    numpy.ndarray
+        A view of the ``img`` compatible with
+        :py:func:`matplotlib.pyplot.imshow`.
     '''
-    import numpy as np
-
     if img.ndim == 3:
         img = np.moveaxis(img, 0, -1)
     return img
 
 
+def to_bob(img):
+    '''Returns a view of the image compatible with Bob.
+
+    Parameters
+    ----------
+    img : numpy.ndarray
+        A 2 or 3 dimensional array containing an image in matplotlib style: For
+        a 2D array (grayscale image) should be ``(y, x)``; For a 3D array
+        (color image) should be ``(y, x, n)``.
+
+    Returns
+    -------
+    numpy.ndarray
+        A view of the ``img`` compatible with Bob ``(n, y, x)`` for 3D images.
+    '''
+    if img.ndim == 3:
+        img = np.moveaxis(img, -1, 0)
+    return img
+
+
 def imshow(img, cmap=None, **kwargs):
     '''Plots the images that are returned by :py:func:`bob.io.base.load`
 
-    Parameters:
-        img (numpy.ndarray): A 2 or 3 dimensional array containing an image in
-            bob style: For a 2D array (grayscale image) should be ``(y, x)``;
-            For a 3D array (color image) should be ``(n, y, x)``.
-        cmap (matplotlib.colors.Colormap): Colormap, optional, default: ``None``.
-            If ``cmap`` is ``None`` and ``img.ndim`` is 2, defaults to 'gray'.
-            ``cmap`` is ignored when ``img`` has RGB(A) information.
-        kwargs: These are passed directly to :py:func:`matplotlib.pyplot.imshow`
+    Parameters
+    ----------
+    img : numpy.ndarray
+        A 2 or 3 dimensional array containing an image in
+        bob style: For a 2D array (grayscale image) should be ``(y, x)``;
+        A 3D array (color image) should be in the ``(n, y, x)`` format.
+    cmap : matplotlib.colors.Colormap
+        Colormap, optional, default: ``None``.
+        If ``cmap`` is ``None`` and ``img.ndim`` is 2, defaults to 'gray'.
+        ``cmap`` is ignored when ``img`` has RGB(A) information.
+    **kwargs
+        These are passed directly to :py:func:`matplotlib.pyplot.imshow`
+
+    Returns
+    -------
+    object
+        Returns whatever ``plt.imshow`` returns.
     '''
-    import matplotlib.pyplot as plt
 
     if cmap is None and img.ndim == 2:
         cmap = 'gray'

doc/guide.rst

@@ -82,6 +82,9 @@ Or you can just get a view (not copy) of your image that is
   >>> assert img_view_for_matplotlib.shape[-1] == 3
   >>> assert img_view_for_matplotlib.base is img
 
+You can also get the original image back using :py:func:`bob.io.image.to_bob`.
+
+
 .. testcleanup:: *
 
   import shutil

requirements.txt

 setuptools
+numpy
 bob.extension
 bob.blitz
 bob.core