diff --git a/skimage/filter/thresholding.py b/skimage/filter/thresholding.py
index 022cacc5..3f8acdef 100644
--- a/skimage/filter/thresholding.py
+++ b/skimage/filter/thresholding.py
@@ -16,7 +16,7 @@ def threshold_adaptive(image, block_size, method='gaussian', offset=0,
 
     Parameters
     ----------
-    image : NxM ndarray
+    image : (N, M) ndarray
         Input image.
     block_size : int
         Uneven size of pixel neighborhood which is used to calculate the
@@ -45,7 +45,7 @@ def threshold_adaptive(image, block_size, method='gaussian', offset=0,
 
     Returns
     -------
-    threshold : NxM ndarray
+    threshold : (N, M) ndarray
         Thresholded binary image
 
     References
diff --git a/skimage/transform/radon_transform.py b/skimage/transform/radon_transform.py
index b716a6f1..f80cc3cb 100644
--- a/skimage/transform/radon_transform.py
+++ b/skimage/transform/radon_transform.py
@@ -100,7 +100,7 @@ def iradon(radon_image, theta=None, output_size=None,
         the image corresponds to a projection along a different angle.
     theta : array_like, dtype=float, optional
         Reconstruction angles (in degrees). Default: m angles evenly spaced
-        between 0 and 180 (if the shape of `radon_image` is nxm)
+        between 0 and 180 (if the shape of `radon_image` is (N, M)).
     output_size : int
         Number of rows and columns in the reconstruction.
     filter : str, optional (default ramp)