features.image_patches --> utils.extract_patches

Author: mdeff

pygsp/features.py

@@ -10,7 +10,6 @@
 from .graphs import Graph
 from .filters import Filter
 from .utils import filterbank_handler
-from skimage.util import view_as_windows, pad
 
 
 def compute_avg_adj_deg(G):
@@ -103,69 +102,3 @@ def atom(x):
 
     G.spectr = spectr
     return spectr
-
-
-def patch_features(img, patch_shape=(3, 3)):
-    r"""
-    Compute a patch feature vector for every pixel of an image.
-
-    Parameters
-    ----------
-    img : array
-        Input image.
-    patch_shape : tuple, optional
-        Dimensions of the patch window. Syntax: (height, width), or (height,),
-        in which case width = height.
-
-    Returns
-    -------
-    array
-        Feature matrix.
-
-    Notes
-    -----
-    The feature vector of a pixel `i` will consist of the stacking of the
-    intensity values of all pixels in the patch centered at `i`, for all color
-    channels. So, if the input image has `d` color channels, the dimension of
-    the feature vector of each pixel is (patch_shape[0] * patch_shape[1] * d).
-
-    Examples
-    --------
-    >>> from pygsp import features
-    >>> from skimage import data, img_as_float
-    >>> img = img_as_float(data.camera()[::2, ::2])
-    >>> X = features.patch_features(img)
-
-    """
-
-    try:
-        h, w, d = img.shape
-    except ValueError:
-        try:
-            h, w = img.shape
-            d = 0
-        except ValueError:
-            print("Image should be at least a 2-d array.")
-
-    try:
-        r, c = patch_shape
-    except ValueError:
-        r = patch_shape[0]
-        c = r
-    if d == 0:
-        pad_width = ((int((r - 0.5) / 2.), int((r + 0.5) / 2.)),
-                     (int((c - 0.5) / 2.), int((c + 0.5) / 2.)))
-        window_shape = (r, c)
-        d = 1  # For the reshape in the return call
-    else:
-        pad_width = ((int((r - 0.5) / 2.), int((r + 0.5) / 2.)),
-                     (int((c - 0.5) / 2.), int((c + 0.5) / 2.)),
-                     (0, 0))
-        window_shape = (r, c, d)
-    # Pad the image
-    img_pad = pad(img, pad_width=pad_width, mode='symmetric')
-
-    # Extract patches
-    patches = view_as_windows(img_pad, window_shape=window_shape)
-
-    return patches.reshape((h * w, r * c * d))

pygsp/graphs/nngraphs/imgpatches.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 
 from pygsp.graphs import NNGraph
-from pygsp.features import patch_features
+from pygsp import utils
 
 
 class ImgPatches(NNGraph):
@@ -33,7 +33,7 @@ class ImgPatches(NNGraph):
     def __init__(self, img, patch_shape=(3, 3), n_nbrs=8, use_flann=True,
                  dist_type='euclidean', symmetrize_type='full', **kwargs):
 
-        X = patch_features(img, patch_shape=patch_shape)
+        X = utils.extract_patches(img, patch_shape=patch_shape)
 
         super(ImgPatches, self).__init__(X,
                                          use_flann=use_flann,

pygsp/utils.py

@@ -18,6 +18,7 @@
 from scipy import kron, ones
 from scipy import sparse
 from scipy.io import loadmat as scipy_loadmat
+import skimage
 
 
 def build_logger(name, **kwargs):
@@ -391,6 +392,72 @@ def vec2mat(d, Nf):
         return np.reshape(d, (M / Nf, Nf, N), order='F')
 
 
+def extract_patches(img, patch_shape=(3, 3)):
+    r"""
+    Extract a patch feature vector for every pixel of an image.
+
+    Parameters
+    ----------
+    img : array
+        Input image.
+    patch_shape : tuple, optional
+        Dimensions of the patch window. Syntax: (height, width), or (height,),
+        in which case width = height.
+
+    Returns
+    -------
+    array
+        Feature matrix.
+
+    Notes
+    -----
+    The feature vector of a pixel `i` will consist of the stacking of the
+    intensity values of all pixels in the patch centered at `i`, for all color
+    channels. So, if the input image has `d` color channels, the dimension of
+    the feature vector of each pixel is (patch_shape[0] * patch_shape[1] * d).
+
+    Examples
+    --------
+    >>> from pygsp import utils
+    >>> import skimage
+    >>> img = skimage.img_as_float(skimage.data.camera()[::2, ::2])
+    >>> X = utils.extract_patches(img)
+
+    """
+
+    try:
+        h, w, d = img.shape
+    except ValueError:
+        try:
+            h, w = img.shape
+            d = 0
+        except ValueError:
+            print("Image should be at least a 2-d array.")
+
+    try:
+        r, c = patch_shape
+    except ValueError:
+        r = patch_shape[0]
+        c = r
+    if d == 0:
+        pad_width = ((int((r - 0.5) / 2.), int((r + 0.5) / 2.)),
+                     (int((c - 0.5) / 2.), int((c + 0.5) / 2.)))
+        window_shape = (r, c)
+        d = 1  # For the reshape in the return call
+    else:
+        pad_width = ((int((r - 0.5) / 2.), int((r + 0.5) / 2.)),
+                     (int((c - 0.5) / 2.), int((c + 0.5) / 2.)),
+                     (0, 0))
+        window_shape = (r, c, d)
+    # Pad the image
+    img_pad = skimage.util.pad(img, pad_width=pad_width, mode='symmetric')
+
+    # Extract patches
+    patches = skimage.util.view_as_windows(img_pad, window_shape=window_shape)
+
+    return patches.reshape((h * w, r * c * d))
+
+
 def import_modules(names, src, dst):
     """Import modules in package."""
     for name in names: