diff --git a/skimage/transform/pyramids.py b/skimage/transform/pyramids.py
index a7492043..dd274834 100644
--- a/skimage/transform/pyramids.py
+++ b/skimage/transform/pyramids.py
@@ -140,8 +140,12 @@ def pyramid_gaussian(image, max_layer=-1, downscale=2, sigma=None, order=1,
     """Yield images of the gaussian pyramid formed by the input image.
 
     Recursively applies the `pyramid_reduce` function to the image, and yields
-    the downscaled images. Note that the first image of the pyramid will be the
-    original, unscaled image.
+    the downscaled images.
+
+    Note that the first image of the pyramid will be the original, unscaled
+    image. The total number of images is `max_layer + 1`. In case all layers are
+    computed, the last image is either a one-pixel image or the image where the
+    reduction does not change its shape.
 
     Parameters
     ----------
@@ -214,7 +218,15 @@ def pyramid_laplacian(image, max_layer=-1, downscale=2, sigma=None, order=1,
     """Yield images of the laplacian pyramid formed by the input image.
 
     Each layer contains the difference between the downsampled and the
-    downsampled plus smoothed image.
+    downsampled, smoothed image::
+
+        layer = resize(prev_layer) - smooth(resize(prev_layer))
+
+    Note that the first image of the pyramid will be the difference between the
+    original, unscaled image and its smoothed version. The total number of
+    images is `max_layer + 1`. In case all layers are computed, the last image
+    is either a one-pixel image or the image where the reduction does not change
+    its shape.
 
     Parameters
     ----------